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From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: rec.food.veg,sci.agriculture
Subject: Re: MAD VEGETABLE DISEASE? Need info on hydroponic / aeroponic
vegetables
Date: Tue, 9 Apr 1996 17:04:44 +0100
In article <3169e20f.0@news.palm.cri.nz>, Laurie Kennedy
<kennedyl@agresearch.cri.nz> writes
>
>>nitrates (or nitrites??, I get confused) compared with regular veggies
>>and that nitrates / nitrites are cancer causing. But I don't have any
>>scientific evidence or data to back this up.
If you do come across any evidence for nitrAtes (not nitrites) causing
cancer, I would be interested. I have never been able to locate any peer
reviewed papers showing this. I have found plenty of hearsay and gossip
though.
-------------------------------
'Oz "When I knew little, all was certain. The more I learnt,
the less sure I was. Is this the uncertainty principle?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture
Subject: Re: Nitrates in well water
Date: Wed, 12 Jun 1996 07:05:17 +0100
In article <4pk6s6$ekv@vixen.cso.uiuc.edu>, "Randal L. Simonson"
<rlsimons@prairienet.org> writes
>I tested the well water on our farm in central Illinois for nitrates.
>The water had 23 ppm nitrates. Is this too high to drink?
>It sounds high to me.
>Does anybody know what level is safe?
Well you had better check up what I say but
1) The WHO nitrate safety level is 100 ppm.
2) The only epidemiological study I know of was a comparison between
parts of East Anglia (close to and sometimes exceeding 50ppm) and
Manchester (low nitrates). The only difference they found was a higher
(yes higher) level of stomach cancers in the LOW nitrate Manchester and
a lower level in E. Anglia.
3) Despite the UK maximum being 100ppm up to recent years (1980ish ?)
there has only ever been one case of 'blue baby syndrome' in the UK and
I believe this was in 1953.
4) Check out how much nitrate you get from sweet cured bacon, or a
goodly helping of vegetables.
5) I have never seen any paper showing any problem from people (other
than very young babies) drinking water above 50ppm (or even 100 ppm come
to that).
6) There is a very cheap, easy and sensitive test for nitrates which
detects down to about 100ppm (brown ring test?). This was used to detect
FECAL contamination of surface waters in the days before bacteriology
became common (ie maybe up to pre WW2). If you are going to see if the
stream that you take (or about to take) water from is contaminated by
sewage or animal excrement then you would expect higher than average
nitrate levels. The nitrate levels giving a rough but very useful
correlation with the contamination level from human and animal wastes. A
jolly useful and accurate test it was for it's time too. However I have
always wondered if this test for FECAL contamination has not over the
years got confused with nitrates to the extent that the original reason
has been forgotten and nitrates per se have become important without
anybody knowing, or remembering, why.
7) If your well checks out for bacteria, toxic elements, and other
contra-indications I would personally go ahead and use it. Up until a
few years ago our water came from a borehole on the downs. It was
lovely, people who stayed commented on how nice it was. Now the village
has been plumbed into a proper, chlorinated and treated supply and it
tastes like mud.
-------------------------------
'Oz "When I knew little, all was certain. The more I learnt,
the less sure I was. Is this the uncertainty principle?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture
Subject: Re: Nitrates in well water
Date: Thu, 13 Jun 1996 06:23:03 +0100
In article <4pnar3$c1a@ds2.acs.ucalgary.ca>, T Hodges <thodges@freenet.c
algary.ab.ca> writes
>Europe has a standard of 50 ppm of NO3, North American has a standard
>of 10 ppm of N. Molecular weight of NO3 is 62, N is 14 so they are
>nearly identical. Your 23 ppm N in Illinois is well above the limit.
1) Why did the original poster say 23ppm nitrates and not 23ppm
nitrogen?
2) Please give reference on work showing levels of nitrates at and
around 100ppm causes problems. I am interested because I have never been
able to find a paper that actually tests this. Quite a lot of 'it is
known' and 'it is believed'. The only evidence I have come across is the
epidemiological study that showed (perversely) that high nitrates were
marginally safer between E.Anglian and Midlands water catchment areas.
The only other trial was one done by ICI's insurers who demanded and
independent epidemiological study of those working in their nitrate
fertiliser plant. Now these people had very high levels of blood
nitrates, and everyone expected a big effect. Again they turned out to
be marginally healthier than average. This annoyed ICI's insurers who
were expecting to get much bigger premiums.
-------------------------------
'Oz "When I knew little, all was certain. The more I learnt,
the less sure I was. Is this the uncertainty principle?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture
Subject: Re: Nitrates in well water
Date: Thu, 13 Jun 1996 20:17:52 +0100
In article <4ppigl$t81@qvarsx.er.usgs.gov>, "Joseph L. Jones"
<jljones@usgs.gov> writes
>
>I am shocked at the misinformation in this thread. Nitrate in drinking
>water is a well studied and well documented subject. Numerous posts
>have claimed that nitrate standards are abitrary, and the risk
>is imagined. I'd like to set the record straight (acknowledging
>that several others have also tried to do this).
>
>In article <6laf1DA3W6vxEwhg@upthorpe.demon.co.uk>, Oz <Oz@upthorpe.demon.co.uk>
>writes:
>>
>> 1) Why did the original poster say 23ppm nitrates and not 23ppm
>> nitrogen?
>
>Many labs (most?) report nitrate in ppm as nitrogen, for example
>NITRATE 23 mg/L as N
>so it is easy to understand why someone unfamiliar with stoichiometry
>may not by clear on the exact meaning. My bet is Randy's well is
>above the standard.
>
>> 2) Please give reference on work showing levels of nitrates at and
>> around 100ppm causes problems. I am interested because I have never been
>> able to find a paper that actually tests this. Quite a lot of 'it is
>> known' and 'it is believed'. The only evidence I have come across is the
>> epidemiological study that showed (perversely) that high nitrates were
>> marginally safer between E.Anglian and Midlands water catchment areas.
>
>The definitive document is "Nitrate and Nitrite in Drinking Water"
>Subcommittee on Nitrate and Nitrite in Drinking Water
>Committe on Toxicology
>Board on Environmental Studies and Toxicology
>Commision on Life Sciences
>National Research Council
>National Academy Press, Wash D.C. 1995
>
>[misinformation deleted]
>
>Methemoglobinemia is a result of nitrite in the blood
>oxidizing Fe2+ in hemoglobin to Fe3+, which cannot transport O2.
Yup. Nitr*i*tes.
>Nitrite is produced from nitrate by bacteria in the mouth and
>stomach.
'Can be' would be better.
>Normal adults have adequately high gastric acidity
>to prevent the growth of nitrite producing bacteria, however
>this is not true for infants or adults with certain gastro-intestinal
>diseases, including some transient infections. Quoting the above
>document, "There are few published reports of methemoglobinemia
>occuring in infants whose drinking water contains nitrate at less
>than 50 mg/L [ppm, as NO3, or 11.4 mg/L as N -jlj], and none
>of the reported cases occurred in the United States."
Note the phrase. It does NOT say that nitrates in water caused the
methemoglobinemia. It says that (somewhere) it has been seen where water
levels are above 50ppm. Up until recently some water catchment areas in
the UK were above the 100ppm level transiently, particularly in E.Anglia
yet there has only been one case and that (I believe) was in 1953.
>Again
>quoting "EPA concluded that there are no convincing data to suggest
>that nitrate or nitrite is associated with any adverse effect other
>than methemoglobinemia, and it identified a no-observed-adverse-effect
>level (NOAEL) for nitrate of 10 mg of nitrate nitrogen per Liter
>(1.6 mg/kg-day) on the basis of epidemiological studies (Walton, 1951)
>." "To obtain a reference dose (RfD) from the NOAEL, an uncertainty
>factor of 1 was used because the NOAEL was derived from studies
>in humans of the most sensitive subpopulation."
Right. Very young babies. Here I would agree.
However note that actually many foods are toxic for very young babies
and milk is their natural food. When our kids were first born I remember
a list of common foods that we were told could seriously poison a young
baby, I wish I had kept it. It included many normal and ordinary foods.
You would not dream of banning these because they were toxic to very
young babies.
>Adults, especially vegetarians, consume very large quantities of
>nitrate, and 23 ppm as N is safe for a healthy adult to drink.
>It is not safe for infants to drink, including in baby formula.
>Many people mistakenly assume that boiling the water helps;
>nitrate is not alive, boiling won't 'kill' it.
Correct. Important. Remember it.
Remember it if you travel abroad. Many local water sources in the second
and third world have high nitrate levels. It's the cyanobacteria in
lakes etc apparently. Make the baby formula up with mineral water. Take
advice as to the age a baby can tolerate nitrates. I believe it is a
month or so (or is it a week or so, I forget) but check it out. Local
babies are probably entirely breast fed during this early time and so
never have a problem.
>Randy's biggest concern, assuming no infants in his life, would
>be selling his house. Many banks will not offer mortgages on
>homes with high-nitrate wells, and he may have to deepen
>his well to find cleaner water before he can find a buyer.
Ah, now this really IS a potential problem!
-------------------------------
'Oz "When I knew little, all was certain. The more I learnt,
the less sure I was. Is this the uncertainty principle?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture
Subject: Re: nitrates PPM
Date: Wed, 19 Jun 1996 21:22:40 +0100
In article <NEWTNews.835215317.14617.trossman@trossman.bright.net>,
trossman@bright.net writes
>Please post to sci.agriculture newsgroup for me--I don't have a
>feed for it at the moment.
>
>EPA set the maximum contaminant level for nitrate in drinking water at 44
>mg/L (that's nitrate nitrogen at 10mg/L) and nitrite at 3.3 mg/L
>(nitreite nitrogen at 1 mg/L). This is presumed to be adequate to
>protect human health--the primary human health outcome of nitrate is
>"blue baby" syndrome.
>
>I wouldn't feed any child of mine questionable water if the child were
>younger than a year. It's worth noting, however, that up to 99% of all
>dietary nitrate intake is from vegetables.
>
>There was a publication last year from the National Academy of Sciences,
>Board on Environmental Studies and Toxicology called "Nitrate and Nitrate
>in Drinking Water" that evaluated the MCLs for nitrate and nitrite. You
>can probably get a copy by calling 202-334-2387.
Well, I hope we get a report from a couple of you colonials on this
report, one for and one against at least. Us Limeys can't get a copy!
-------------------------------
'Oz "When I knew little, all was certain. The more I learnt,
the less sure I was. Is this the uncertainty principle?"
Newsgroups: sci.agriculture,sci.chem,sci.med,alt.cooking-chat,sci.environment,
sci.edu,sci.bio.food-science
Subject: Re: Nitrates are good for you.
From: Oz <Oz@upthorpe.demon.co.uk>
Date: Thu, 13 Mar 1997 06:09:55 +0000
In article <5g78r8$3at@ilink3.nis.za>, Teunis vanRee
<vanreet@ilink.nis.za> writes
>We (P Hurter, WJ Serfontein) have shown conclusively that nitrite present in
>processed meat products can form nitrosamines in the stomach, so the worry
>about nitrosamines is NOT misplaced...
Are you quite sure it's in the stomach, and not produced within the
processed meat products before it reached the stomach?
Since you were on the team I would be VERY grateful for a reprint. Where
was it published?
>Sorry about the crossposting. I didn't start it...
No, I did. I only do so for topics of general importance. In fact I am
astonished by the lack of response. The UK (a small poor country of 50M
people) is spending (from memory) some 10,000,000,000 UKP to stop
nitrates in some waters from very occasionally exceeding 50ppm. It would
appear that this is not only wasteful and provides no benefits, but may
actually be harmful. Interestingly this is in line with the early mass
epidemiological studies that were largely ignored because they were, in
effect, politically incorrect.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
Newsgroups: sci.agriculture,sci.chem,sci.med,alt.cooking-chat,sci.environment,
sci.edu,sci.bio.food-science
Subject: Re: Nitrates are good for you.
From: Oz <Oz@upthorpe.demon.co.uk>
Date: Thu, 13 Mar 1997 13:27:53 +0000
In article <5g8gh3$lbo@neon.btinternet.com>, Lewis Conquer
<Lewis.Conquer@btinternet.com> writes
>The problem with Nitate in water is caused by the reducion of nitrate to
>nitrite by the gut microflora (our old friend E.coli) this bonds
>irreversibly to Heamoglobin producing in extreme cases the "blue baby"
>syndrome. Saliva contains low levels of nitrite which can form
>nitrosamines if suitable amines are present.
Well, the whole point is this study showed otherwise. Actually I have
never seen any work that *demonstrates* that the above occurrs in the
stomach. I have seen several papers where it is proposed, but that is
another matter.
Bearing in mind the several tens of people who have died in the last 12
months from EC O157 in Scotland alone, and the zero deaths over the last
50 years from nitrates, one ought to pause for thought when work such as
this is published. [See my original post if this doesn't make sense].
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
Newsgroups: sci.agriculture,sci.chem,sci.med,alt.cooking-chat,sci.environment,
sci.edu,sci.bio.food-science
Subject: Re: Nitrates are good for you.
From: Oz <Oz@upthorpe.demon.co.uk>
Date: Fri, 14 Mar 1997 06:56:59 +0000
In article <jOCFdKAmCKKzEwA3@tomgrower.demon.co.uk>, "Robert C.Hale"
<robert@tomgrower.demon.co.uk> writes
>How as an (Agriculture/Horticulture) industry can we get this point over
>to the general public?
With great difficulty, I suspect. If it were a direct argument between
reducing nitrates further, and twenty hospitals or 100 schools it might
get some useful debate going. Otherwise these things get a political
correctness that takes decades to overcome. The replies to this thread
are typical. A restatement of old assumptions, but no requests for
further information of this important research. It was evident from the
beginning that nitrates were not harmful due to the results of the mass
epidemiological studies.
>Perhaps we have little hope when the European Community brings in
>legislation (from Jan 1997) limiting the level of nitrates in lettuce.
>As has been propounded, all the evidence points that nitrates are good
>for you. (Much work done I believe by Sterling University, Scotland).
Pretty typical of the difference between the EC and proper democratic
government where things are discussed publicly in an assembly. These
dictats are not discussed openly, with some for and some against, but
are invented by the Commission without debate. They very often get
things badly, and very expensively, wrong.
It is a typical mistake that non-scientists make that if a lot is bad,
then a little is better and none is best of all. For most biological
systems this is simply incorrect. For example copper is poisonous and a
lot is bad, however none is fatal since it is an essential mineral. Not
unsurprisingly nitrates have turned out to be much the same. The ideal
band of concentrations is rather wide, and the safe band wider still.
Nobody ever bothers to use the epidemiological work done by ICI's
insurers on the workers of the Nitram plant, who not unsurprisingly had
massive levels of nitrates in their blood yet were MORE healthy and
lived longer than the average population. To a scientist this would flag
an inherent fault in the 'nitrates are hazardous' assumption but to a
politician (and pressure groups) this is simply politically incorrect
and so ignored. The truth thus gets concealed from all of us. We then go
on to waste tens of billions of pounds on solving a problem that didn't
exist in the first place.
>Its the principle that's important.
>Besides the fact that it leads to vast resourses being expended to
>public disadvantage.
This is a tragedy. No doubt about it.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
Newsgroups: sci.agriculture,sci.chem,sci.med,alt.cooking-chat,sci.environment,
sci.edu,sci.bio.food-science
Subject: Re: Nitrates are good for you.
From: Oz <Oz@upthorpe.demon.co.uk>
Date: Fri, 14 Mar 1997 13:44:23 +0000
In article <bIZfhMAf+SKzEwHu@rileys.demon.co.uk>, Stephen Riley
<steve@rileys.demon.co.uk> writes
>I'm all for reducing nitrates in water and any other chemicals that
>farming or industry pollute the environment with. The money is well
>spent, but not enough, soon enough.
Sigh. You have not been reading the thread, have you?
The point is that recent research has indicated that LOW water nitrates
are BAD for you.
You also neatly illustrated exactly what I was talking about in another
posting.
>Tax the polluters if you don't like the public paying for the clean up.
The nitrates are used to give YOU cheap food. So the public are directly
benefitting from the use of nitrates. If you don't believe me just look
up a farmers weekly wholesale price for, say, lettuces in 1950 adjust
for relative incomes between then and now and look at today's price. You
will find the real 1950's price many many times greater in real terms.
Alternatively take grain. In 1976 it was worth 100 uk pounds per tonne
yet today it's worth 95 uk pounds per tonne. Over that period wages have
increase about tenfold so rightfully a tonne of grain should be worth
1000 pounds per tonne. One thing is absolutely for certain and that is
that the financial beneficiary of modern farming is NOT the farmer, but
the public. Sorry if this is politically incorrect, even if it is true.
>Your attitude makes Greenpeace sound like a sensible organisation and I
>always concidered them as extremists.
Quite right too. They often tell fibs too.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.chem,sci.med,alt.cooking-chat,sci.environment,
sci.edu,sci.bio.food-science
Subject: Re: Nitrates are good for you.
Date: Sun, 16 Mar 1997 16:59:35 +0000
In article <EknYKDAni+KzEwHH@rileys.demon.co.uk>, Stephen Riley
<steve@rileys.demon.co.uk> writes
>In article <KSN7xDA1LlKzEwUv@upthorpe.demon.co.uk>, Oz
><Oz@upthorpe.demon.co.uk> writes
>>
>Is is just stomach cancer at issue here? What about environmental
>changes and the affects on river ecosystems?
This is not a problem at the sub 100ppm N level. In any case phosphate
pollution (mostly from sewage works) was the main problem. Now the NRA
is divorced from the water companies this is now admitted.
>I can rationalise nitrates being good for you - up to a point. Plant
>life (and soil bacteria, etc) have probably always created nitrates in
>the soil and naturally this would tend to get washed into rivers.
Not probably. Definitely.
>So yes
>there probably is a natural/safe/beneficial nitrate level in water. I'm
>not arguing about that, or that farmers shouldn't replace nitrates in
>the soil lost through agriculture. I just don't accept that this means
>we jump to the conclusion that money is wasted in cleanup operations
>when the natural levels are exceeded - although I'd prefer that levels
>weren't exceeded such that cleanups were necessary either.
Quite. However 100ppm is well below the 'cleanup' level on biological
grounds. We are well overdoing it, that's the point.
>>Agreed. The real question is whether we should be accepting the WHO
>>level of 100ppm (which all the UK meets with ease) or 50ppm, where
>>significant areas struggle at certain times of the year.
>Not sure about that, what about measuring nitrate levels in rivers not
>exposed to any artificial changes. That must a better starting point for
>judging natural or safe limits?
Natural and satisfactory may not be the same thing. Nitrate is so
valuable to plants that under natural conditions you will get very
little nitrate in water. However you can only achieve this with woodland
and no animals, herbivores (including wild ones) have a habit of
defecating in water, this is bad news. You certainly cannot plant a crop
since ploughing, or non cropped soil, liberates copious nitrates. What
you are asking for is in fact a complex question with no really simple
answer.
>>>Taxing polluters wouldn't necessarily raise the costs, they might even
>>>lower them overall, nitrates are just the thin edge of a wedge.
>>
>>Sorry, I don't follow you.
>I mean if the following two scenarios are costed:-
>
>Allow the free use of any chemicals/fertilisers in unlimited quantities.
>When natural levels are exceeded someone else cleans up the mess
>afterwards at great cost.
>
>Tax pollution at a level that reduces chemical overuse and allows a
>natural balance between tax/benefit to come about.
>
>Scenario 1. may be cheaper for farming/industry, but to the overall
>economy more costly, wasteful, unproductive and potentially unhealthy.
>
>(Obviously I've exaggerated and biased the scenarios in favour of my
>viewpoint a little here to highlight the principle).
I agree with you. In practice however, farmers avoid wasting any input,
since they are very expensive. Nitrates going down the drain (literally)
is wasteful. In practice the areas with low nitrates in water are those
with high rainfall (actually higher nitrate losses, but more dilution),
and those with higher nitrates are those with lower rainfall. This is
why E. Anglia has the blips that go over 50ppm, it depends mostly on
rainfall or rather lack of it.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
Newsgroups: sci.agriculture,sci.chem,sci.med,alt.cooking-chat,sci.environment,
sci.edu,sci.bio.food-science
Subject: Re: Nitrates are good for you.
From: Oz <Oz@upthorpe.demon.co.uk>
Date: Fri, 21 Mar 1997 08:15:28 +0000
In article <xchhpKAzQIMzEwSr@tomgrower.demon.co.uk>, "Robert C.Hale"
<robert@tomgrower.demon.co.uk> writes
>As we use nitrate better, I would guess than nitrate levels in veg are
>probably lower than they have been for 100 years, its only in the last
>10 years that anyone has bothered to measure it. In the earlier parts of
>the century large amounts of relatively uncontrolled nitrate were
>applied as Farm Yard Manure, shoddy or until about the 1920's or 1930's,
>guano from Chile.
Not to mention the manure runoff that went straight into rivers.
A good time to bring up another anachronism. Before modern water
supplies were generally available how did you check if your stream or
well was polluted bacteriologically? Well, there is a cheap and simple
test for nitrates called the brown ring test. I guess many of you did
this test in school in chemistry. Typically it will detect nitrates down
to about 100-200ppm. In the 19C and early part of the 20C it was one of
the neatest tests about. Now in many cases bacteriological status was
strongly correlated with nitrate levels as this tracked human and animal
sewage effluent that usually (in those days) went straight into streams.
So if your supply had high nitrates, chances were that it had a high
bacteriological burden also and was unsuitable for drinking.
Bacteriological tests were difficult, but any local chemist could do a
brown ring test and this became a standard test for water quality. Note
carefully that the worry was bacteria, but the test was for nitrates.
IMHO this goes to the root of the confusion between water quality and
nitrates, particularly in Europe. Basically after a few generations,
people forgot why they did the nitrate test in the first place
(bacteria) and elevated the test to a holy grail of water quality.
Then, of course, they searched round for some excuse to rationalise the
test, since they had forgotten it's origin.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.chem,sci.med,alt.cooking-chat,sci.environment,
sci.edu,sci.bio.food-science
Subject: Re: Nitrates are good for you.
Date: Sat, 22 Mar 1997 08:52:13 +0000
**Does anyone have the LD50 for sodium nitrate and sodium chloride?
Alternatively NH4NO3 and NH4Cl?***
In article <MDtqjRAUupMzEwEX@rileys.demon.co.uk>, Stephen Riley
<steve@rileys.demon.co.uk> writes
>Didn't you say you were a farmer and don't these safety limits
>affect your day to day business.
I am a farmer, but I am NOT in a nitrate sensitive zone. I am NOT
therefore affected by the problem.
I DO care about vast sums of money being wasted on reducing nitrates for
no benefit when we have schools, hospitals and many other needy causes
that are starved of funds. 10,000,000 UK pounds would be most useful
here. If, on top of that, nitrates have an important role in protecting
us from disease, then it becomes more than tragic, the 50ppm requirement
is actually killing people. Yes, of course I care.
>>>>>Do we know that sub 100ppm is not a problem for sure.
>>>>Well WHO says it is. Based on experimental evidence with a safety
>>>>margin.
>>>But the EU and other reports say otherwise.
>>
>>And other reports dispute them.
>This is nonsense, if there is disagreement then you err on the side of
>safety, not of the vagaries of economics of any interested parties.
But in this case the inclusion of bacteriological safety requiring
elevated nitrate levels means you can no longer just demand a minimum.
You have to consider carefully.
>>Please see starting point of the thread. Nitrates are required for good
>>stomach disinfection so low levels are HAZARDOUS.
>As I said this could be rationalised, but I doubt it has been
>independantly supported. What nitrate levels are we talking about here
>in these so called scientific studies. Just to bring this into
>perspective:- ANY TOXIC SUBSTANCE WILL INCREASE STOMACH DISINFECTION.
Wrong. In fact simply untrue.
Please note up the thread. The body carefully separates nitrates out
and puts them in your saliva.
>>How many deaths since 1950 in the UK have been due to nitrates in
>>water?? Currently EC O157 has killed 50 people in Scotland this year
>>alone. How many would not have got the disease if higher nitrates in
>>their drinking water had provided adequate stomach disinfection?
>How many would have been killed if chlorine levels were increased.
You don't really mean this, do you? You propose higher chlorine levels
in drinking water? Even *I* think this is hazardous!
>Was
>EC 0157 in the water in any case, if not are you suggesting drinking
>water everytime you eat? How high a level of nitrate would be needed in
>the stomach to kill bacteria, extremly high I imagine. On second
>thoughts this arguement is just a strawman, any toxic substance could do
>this and still leave you alive. Nice try - but no banana.
Oh dear. You haven't read the Times article that started the thread.
Please do so, you have completely misunderstood the wole argument.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.chem,sci.med,alt.cooking-chat,sci.environment,
sci.edu,sci.bio.food-science
Subject: Re: Nitrates are good for you.
Date: Sat, 22 Mar 1997 15:47:10 +0000
In article <5h0qt1$703@panix2.panix.com>, Pierre Jelenc <rcpj@panix.com>
writes
>Oz <Oz@upthorpe.demon.co.uk> writes:
>>
>> **Does anyone have the LD50 for sodium nitrate and sodium chloride?
>> Alternatively NH4NO3 and NH4Cl?***
>
>NaNO3 (orally in rabbits 1.955g of anion/kg)
>NaCl (orally in rats 3.75g of salt/kg)
Many, many, thanks, and I bet you are posting from sci.chem.
Now I last did this many years ago, so am I right to proceed as follows:
NaNO3, anion Na+, so for NaNO3 it should be
1.955*(23+14+16*3)/23 = 7.22g NaNO3/kg
or about twice the toxicity of table salt.
Round figures, give or take, since rats and rabbits are not humans.
I come to the conclusion that nitrates are not very toxic at all. A 75kg
human would be at very significant risk consuming about 500g of sodium
nitrate, or about 1kg of common salt.
This essentially answers the question of the toxicity of nitrates: low.
For fun, 10% of the LD50 would be achieved by consuming about 400litres
of water at 100ppm NO3. The water would be toxic well before the
nitrates. From memory the LD50 for water for humans is around 20liters
(quickly drunk).
NB I bet this brings Torsten out of the woodwork.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.chem,sci.med,sci.environment,sci.edu,
sci.bio.food-science
Subject: Re: Nitrates are good for you.
Date: Sat, 22 Mar 1997 08:48:20 +0000
In article <bMRfgGAk8mMzEw35@rileys.demon.co.uk>, Stephen Riley
<steve@rileys.demon.co.uk> writes
>The EU have researched this and have
>found 100ppm too high,
Actually they didn't. They just took half the WHO level, assuming that
this was even better. As usual, a mistake.
>the WHO currently has 100ppm as a safe limit. In
>the face of this do you really think it is better to go for the higher
>level or the lower, bear in mind limits are often not set high enough.
>Think again, but this time with your head.
Please go back and read the Times article. Then you will know a bit
about what you are talking about, currently you don't.
>>This is a difficult one. Waiting for a risk to be 'proven' can leave a lot of
>>sick people, and once you accept a risk as possible judging whether or not it
>>is likely is difficult. On the other hand, if epidemiological studies show
>>that nitrate in water isn't a problem below a certain level then you should
>>stop worrying about it and switch your attention to a more likely health
>>hazard. Every dollar spent on reducing nitrate in water is a dollar not
>>available for cleaning up industrial sites.
>Again you miss the point, and you've got the discussion arse about face.
>The EU has said that 100ppm is not acceptable (50ppm being their safe
>maximum), the originator of this thread is concerned about the economics
>of meeting this seemingly (too him) high level on economic grounds.
No. He is concerned that 50ppm may be so low as to reduce the ability of
the stomach to reduce bacteria ingested in food and drink, as well as
the serious waste of resources that are urgently needed for genuinely
needy areas of society that is the result of the cost of needless
reduction.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.chem,sci.med,sci.environment,sci.edu,
sci.bio.food-science
Subject: Re: Nitrates are good for you.
Date: Sun, 23 Mar 1997 18:16:11 +0000
OK, just to round this up since any new information has long since
ceased to be provided.
1) At 100ppm nitrate there were no deaths and only one arguable illness
attributable to nitrates in water between 1950 and around 1990 in the UK
when the 50ppm level was operative. No dispute here.
2) The 10,000,000,000+ UK pounds (NB the correct number of zero's) that
was required to achieve this level and a continuing high cost in NSA's
will thus save no lives and no illnesses.
3) This sum of money diverted into medical areas would indisputably save
very many (1000's) of lives. Some posters regard this as unimportant.
4) Sodium Nitrate is about twice as toxic as common salt, one has to
consider this a low toxicity. It is thus inappropriate to consider
nitrates as toxic per se.
5) Nitrosamines only form when amines are exposed to nitrous acid. The
stomach is a highly oxidising environment so nitrous acid is very
rapidly converted to nitric acid which does not form nitrosamines with
aminoacids. Recent research has shown this to be the case.
6) The body deliberately excretes nitrates into the saliva to improve
the bactericidal action of the stomach. Nitrates thus have a benefical
effect as well as any (at this level unproven) detrimental effect.
7) Workers exposed to very high levels of nitrates indeed in the ICI
ammonium nitrate factory showed no ill effects, lifetime study.
8) The acceptable safe nitrate levels in water is 100ppm (WHO and the UK
prior to about 1990) and 50ppm (EC).
9) Epidemiological studies have shown some increase in gastrointestinal
cancers in France where levels were above 50ppm, but in the UK a very
large study showed the reverse. Either the effect is very small, or more
likely there are other important factors that were not identified.
Animals fed high levels of nitrates in their water showed no increase,
but very small effects would probably not have been picked up by this
method.
10) Some people think that the EC is always right and it's directives
should never be questioned. One also gets the impression that doubting
the unproven danger (at these levels) is politically incorrect, and thus
unacceptable.
11) Some people think that if a lot is bad, then none is better. The
evidence is that in biological systems there is typically an optimum.
============
P.S.
Please note that I am specifically talking about nitrates in water here.
Personally I am not very happy about sweet cured meats where high levels
of nitrates (over 1% or 10,000+ppm) are infused into meats which are
then allowed to cure for extended periods. I would not be surprised to
find that significant nitrite production and an acidic environment
produces significant levels of nitrosamines. Given the large quantities
involved I am suspicious that this IS a potential risk. However it's
hard to find salt cured bacon (and meats like salami), and in any case
they are, well, rather salty.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger? Was: N are good for you
Date: Wed, 2 Apr 1997 16:31:09 +0100
In article <5htkdb$3bj@news.interlog.com>, Byron Bodo
<bodo@interlog.com> writes
>In article <6THwWvBy2DB@gengler.iaf.nl>, Lourens@gengler.iaf.nl says...
>>
>>It seems to me that you refer to areas where water is flowing rapidly
>>through or over soils. If this is the case, I can immagine levels to
>>rise according to use of fertilising.
>>
>>I was speaking of soils with slow ground water movements, Where
>>bacteria have time to do there work.
>
>And how slow is that? Groundwater surveys show wide spread increases
>in all common ag soil classes. Increases have occurred most rapidly
>& NO3 levels are highest in sandy & sandy loam soils / aquifers.
Well, these not only have the fastest percolation rates but also have by
far the lowest level of ion exchange throughout the soil profile, the
lowest level of bacterial activity in the topsoil, the lowest level of
organic matter in the topsoil and are likely to be aerobic to some depth
so it's exactly what you would expect.
I would expect it to be very different on clay soils.
>In virtually all predominantly ag streams [100+] I've examined in
>southern Ontario, NO3 levels have been / are increasing since whenever
>records begin [generally 1965-75]. At best the rates of increase
>have declined somewhat.
>
>I've seen no evidence whatsoever, to suggest that ground & surface
>water levels of NO3 will not continue to increase under the current
>cropping & fertilizer usage patterns. That seems to be the prevailing
>opinion in the US also.
It depends on what the level is now, high >100ppm NO3, medium ~50ppm NO3
or low <50ppm NO3. For surface waters I would expect changes to largely
follow land use. So increases in spring cropping, autumn N usage,
organic farming, forestry clearance and urbanisation (sewage, car
exhaust etc) would all be expected to result in increased nitrates in
water. I don't know what agricultural changes have occurred in Ontario,
but in the UK agricultural nitrate applications have generally been
changing only very slowly, autumn applications reduced drastically, and
spring cropping is very much less. I haven't seen any figures lately but
I would expect to find UK NO3 levels typically stable except in the
nitrate sensitive areas where they have significantly reduced.
In any case, where is the evidence of damage caused by <100ppm nitrate
levels in water?
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger? Was: N are good for you
Date: Fri, 4 Apr 1997 07:37:37 +0100
In article <5i0tro$mia@news.interlog.com>, Byron Bodo
<bodo@interlog.com> writes
>From the beginning of looking at this thread, I've been skeptical that
>the concern NO3 has been only about drinking water.
Me too, but I expect for different reasons.
>I recall reading
>some years back that the North Sea Commission or whatever they're called,
>made commitments to reduce P & N inputs from adjacent land areas to 50%
>of 1985 levels by some target date. Ag runoff controls would be part
>of that.
As I have said before P leaching from agriculture is very small indeed.
If people had stopped and thought, instead of believing the UK
Waterboards, then eutrophication of rivers due to P could have been
reduced some decades earlier. This is the problem when you use
agriculture as a scapegoat, you miss the real cause of the problem and
significantly delay it's solution. I am not saying agriculture does not
alter the environment, of course it does, but we should try to
distinguish between real problems and apparent ones. Otherwise we waste
valuable resources and time 'solving' a non-problem.
I expect you are referring to the proposed banning (now, I believe, in
operation) of the dumping of truly huge amounts of sewage sludge in the
North Sea. I forget the amounts but most of London and a considerable
number of STW along the Eastern coast had used this disposal method for
some decades (at least).
>I'm also suspicious of the cost figure you're tossing about, e.g., see
Anyone can publish anything in a URL, unless it's moderated or from an
offical body I take little notice.
OK, dispute the figure. As I said it was widely quoted a decade ago when
this was being carried out and I don't have any breakdown today. There
is little doubt that it's large though. Let's guess that E.Anglia
contains about 250,000ac of cropping land which is going to be about the
right order, and that losses are around 100 UKP (150$) due to the
enforced lower nitrate usage. Then the annual losses are 25M UKP (35M$)
per annum. When you consider that much of E.Anglia is vegetable,
sugarbeet etc the 100UKP/Ac is very much on the low side. Upgrade a few
hundred sewage works at 10M UKP ea, some reservoirs, denitrification
plants at water treatment works and trunk watermains and sewage pipes
and it's not so hard to see where such a figure might have come from.
You ought to see the amounts quoted as being spent fixing water leaks in
pipes by the UK Waterboards, each seem to be spending billions of UKP
annually to fix this.
Upon reflection the sewage part of this was probably essential in the
latter half of the 20C anyway, so I will indeed allow you a significant
reduction in the amount available for transfer to 'good works'.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger?
Date: Tue, 1 Apr 1997 11:23:58 +0100
In article <5hpkoq$n5t@news.interlog.com>, Byron Bodo
<bodo@interlog.com> writes
>To return to the original subject, some unpublished gov't groundwater
>reports do suggest N levels might get rather high in some areas
>of high N fertilizer usage. There is evidence that NO3 percolating
>deep into O2 depleted aquifers will de-nitrify & that the resulting
>NH3 / NH4+ could present greater problems for users of such waters.
Odd. NO3 > NH3 is not exactly a good energy source.
The usual mode of breakdown is denitrification (rather than reduction to
NH4). This is typical in anaerobic conditions and basically is 2NO3 > N2
+ 3O2.The oxygen is of course used for respiration as is the large
energy from combining the two nitrogens to nitrogen gas . Another route
is 6NH4 + 4NO3 > 5N2 + 12H2O.
Denitrifying to nitrogen gas is, of course, very very favourable
energetically.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger?
From: Oz <Oz@upthorpe.demon.co.uk>
Date: Tue, 1 Apr 1997 19:59:05 +0100
In article <5hrdem$6nu@news.interlog.com>, Byron Bodo
<bodo@interlog.com> writes
>In article <JJ1L3BA+IOQzEwUU@upthorpe.demon.co.uk>, Oz@upthorpe.demon.co.uk
>says...
>Statistical generalizations derived from some groundwater data sets
>show NO3 decreasing & NH4+ increasing with depth.
Is this in actual terms or relative terms?
I am inherently suspicious of statements that say "statistical
generalisations" as it usually seems to mean cooked, and with the word
'some' also included usually means burnt to a crisp.
However, no matter.
<Snip of statement with no point.>
>>The usual mode of breakdown is denitrification (rather than reduction to
>>NH4). This is typical in anaerobic conditions and basically is 2NO3 > N2
>>+ 3O2.The oxygen is of course used for respiration as is the large
>>energy from combining the two nitrogens to nitrogen gas . Another route
>>is 6NH4 + 4NO3 > 5N2 + 12H2O.
>>
>>Denitrifying to nitrogen gas is, of course, very very favourable
>>energetically.
>
>In water resources lit, de-nitrification [in aqueous, usually surface water
>systems] usually refers to NO3 -> NO2 -> NH4+/NH3 & organic NHx forms.
Things are obviously different in the states, which I find surprising.
De-nitrification in the UK, and I think europe also, refers to nitrogen
being removed. As in de-capitation, removal of the head. The only common
way that this happens is by it's conversion to nitogen gas. In the
absence of energy hungry pathways eg lightening, some blue-green algae
and nitrogen fixing bacteria in legumes, the reverse reaction is too
energy demanding to occur. In subterranean aquifers high-energy energy
sources are, to say the least, rare.
Your pathway is a route that removes nitrates, but as you have observed,
it doesn't remove the nitrogen from being active in the local biosphere.
A better description would be a reduction of the nitrates to ammonia. It
certainly does happen in anaerobic conditions, which in general surface
waters should not be.
>The usage maybe sloppy for some scientific purists.
In fact so sloppy as to be positively inaccurate.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger?
Date: Wed, 2 Apr 1997 07:54:58 +0100
In article <5hrubg$jmh@news.interlog.com>, Byron Bodo
<bodo@interlog.com> writes
>In article <sikytZA5rVQzEwCE@upthorpe.demon.co.uk>, Oz@upthorpe.demon.co.uk
>says...
>>
>>>Statistical generalizations derived from some groundwater data sets
>>>show NO3 decreasing & NH4+ increasing with depth.
>>
>>Is this in actual terms or relative terms?
>
>Average NO3 concentrations decreased with depth. Average NH4 increased.
Ok, so I guess there was a reduction in total N. This is as expected.
Denitrifying bacteria in soils (and slurry tanks/lagoons) that are
anaerobic (at least in part) can reduce N considerably. Figures vary,
probably because conditions of test have varied, but I have seen N
reductions of 15-80+% quoted. In sewage works I understand that this
mechanism (ie N03+NH4>> N2 + H2O) is actively used to reduce nitrogen
levels in water to be returned to rivers.
So yes, this is good, nitrogen compounds are being effectively removed
from the water.
>>De-nitrification in the UK, and I think europe also, refers to nitrogen
>>being removed. As in de-capitation, removal of the head.
>
>Then, in your world, nitrification must mean adding N.
Well, I have certainly seen this usage many times.
Ok, there is a certain lack of rigour in the usage of 'nitrification'.
Come to think of it it is indeed a term that is used rather too loosely,
probably because nitrateification is an ugly word. In fact I can think
of a whole series of transformations described as 'nitrification', none
of which have much connection to each other except that they involve
nitrogen. A term best avoided without qualification, I think.
However I have never come across "de-nitrification", ever, except to
mean removal of nitrogen, never as reduction of nitrates.
> Again, in the
>water lit, nitrification is commonly used for the NHx -- > NO2 --> NO3
>conversion processes with no implication that N is introduced from
>outside the system.
Yes (see above) it is one of the terms described as 'nitrification',
however I have NEVER seen the reverse reaction described as 'de-
nitrification'. It is also used for the breakdown of organic (ie
protein) material to ammonia, nitrite and/or nitrate as well as other
pathways.
>>In subterranean aquifers high-energy energy
>>sources are, to say the least, rare.
>
>Are they?
Yes.
>Bacteria have been found deep in the earth.
Quite correct. Very, very deep in fact (see recent Scientific American
article). They all, however, show symptoms of operating close to
starvation level, except in unusual circumstances.
>NO3 would
>make a nice O2 source.
For extracting energy from carbohydrates, true. If you have many
carbohydates about as food of course. However you should compare the
energy available from (dropping all the balancing):
C(H20)x + NO3 > CO2 + NH4 (noting that NH4 is high in energy)
compared to
NO3 + NH4 > H2O + N2 (noting that N2 is low in energy)
You will be surprised how much more energy can be produced in the second
reaction compared to the first, and without loosing valuable C(H2O)x
that would be better used for structural purposes. For energy starved
subterranean bacteria, the second is a better route where nitrates and
ammonia are available. If no ammonia, then it's easily made by reducing
the nitrates.
>Hypoxic & anaerobic conditions occur frequently enough, e.g., stagnant
>agricultural ponds & drains in the heat of the summer. Reducing
>conditions prevail beneath the 1st few cm of sediment in most lakes and
>many streams.
Indeed so. However they do not, by definition (stagnant) flow into
watercourses and only form on impervious ground (so no flow into
aquifers), otherwise they would have dried out.
Incidentally the stagnant water doesn't actually care whether they are
*agricultural* ponds and drains, any will do, natural or otherwise.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger?
Date: Wed, 2 Apr 1997 13:58:52 +0100
In article <5htb5q$s2h@news.interlog.com>, Byron Bodo
<bodo@interlog.com> writes
>In article <CnKpMiACLgQzEwW2@upthorpe.demon.co.uk>, Oz@upthorpe.demon.co.uk
>says...
>
>> In sewage works I understand that this
>>mechanism (ie N03+NH4>> N2 + H2O) is actively used to reduce nitrogen
>>levels in water to be returned to rivers.
>
>Some form of oxidation has long been used to induce NH4 --> NO3
>conversion, prior to release of effluents. More recently,
>bio-mediated treatments to lower NO3 & total N content of effluents
>are appearing, or so indicate several bulletins I've seen in the
>last few months. Don't know much about it as yet.
Well, it ain't hard to do. Provide suitable conditions for the bacteria
(reasonable temp, some agitation and a food source) and aerate on
occasion when NO3 levels become a bit low. AFAIK it's been done for
decades in some UK sewage plants.
>>Incidentally the stagnant water doesn't actually care whether they are
>>*agricultural* ponds and drains, any will do, natural or otherwise.
>
>But, agriculture can be a good source of organic, oygen consuming muck that
>can accumulate in the bottoms of sluggish, exposed drains & streams. Might see
>seasonal problems in poorly drained areas depending on the local agricultural
>practice.
I cannot believe regulations for agricultural contamination of surface
water in the US are so slack as to allow this. Certainly in the UK were
a farmer to dump organic material into a stream he would be picked up
rapidly and fined circa $10,000. The main problem with stream
contamination is domestic rubbish.
Indeed riverbanks are perfectly capable of contaminating watercourses
with organic debris, entirely naturally. Certainly algal growth in
stagnant water is frequently vigorous, with nitrogen provided by the
blue-green algae. Indeed in paddy fields (ie rice production) the amount
of N fixed by blue-green algae in the stagnant planting ponds is huge, I
forget the amount but 100+kg/HaN is the figure that comes to mind. Of
course when it rots .....
The problem with agriculture being blamed for all sorts of things is
that streams and drains are typically found in rural areas. People find
(quite natural) green slimy stagnant pools of water and think "Oh-ho
agricultural contamination again", without giving it any further thought
and certainly without considering if it is quite natural or not. In
practice these days (at least in the UK) the fines for minor
transgressions are so large that HUGE care is taken to prevent
contamination of water. Nothing, however, will prevent the natural
processes from continuing and indeed to maintain biodiversity it's
important that nothing does, however unsightly it might appear to urban
people.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger? Was: N are good for you
From: Oz <Oz@upthorpe.demon.co.uk>
Date: Thu, 3 Apr 1997 14:18:24 +0100
In article <5i08dj$9mf@news.interlog.com>, Byron Bodo
<bodo@interlog.com> writes
>In article <9z2mJNAy$0QzEwR9@upthorpe.demon.co.uk>, Oz@upthorpe.demon.co.uk
>says...
>
>>EC regulations
>>have forced hugely expensive nitrate reduction zones on Eastern England
>>that has reduced nitrate levels below 50ppm. It's this huge expenditure
>>(some 10,000,000,000 UKP) to achieve no known benefit that that I find
>>mindless.
>
>Perhaps. What precisely was all that money spent on? Or is that just
>another dubious figure cranked by the yellow press, e.g., representing
>someone's wild estimate of the potential cost of returning all ag-land
>back to forest or something similarly absurd?
It was widely quoted at the time. I expect it includes new reservoirs,
pipelines, work on sewage works, agricultural losses etc. By now I would
expect a significant amount of it to have already been spent.
Unfortunately these days large construction works do cost a lot of cash,
and lots of them comes to even more lots of cash. Equally to restrict
production on the most fertile land in the UK, and a large area at that,
doesn't come cheap at all, and that costs every year, year in and year
out. Oh, no, it's not conversion to forest, it's mostly significant
reductions in nitrate applications to crops that are very responsive,
although I seem to remember that some areas got big grants to switch to
low output grassland which with milk quotas probably meant beef or
sheep.
I am not in this area so have not kept absolutely up to date with the
detail.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger? Was: N are good for you
Date: Thu, 3 Apr 1997 17:00:03 +0100
A propos of nothing I have been handed the Report from the local
Environment Agency on the Upper Thames:
15 rivers have water of good quality suitable for all fish species.
1 more should reach this by 2006.
2 rivers of fair quality suitablefor coarse fish populations.
1 more to reach this by 2006
1 river of poor quality likely to limit coarse fish populations.
(NB The above is downstream of a sewage works, 1.9km long).
P16. Concern at pollution levels from runoff from urban areas.
The Thames is considered 'sensitive' (eutrophic). The report (p23)
states that "macrophye surveys have been conducted on the river Wye,
upstream and downstream of High Wycombe (NB a local area of high
population) STW (sewage treatment works) ... Preliminary results show
that STW discharge may be causing eutropication as far downstream as the
confluence of the river Thames. (No reference is made to agriculture
here.)
There are several references to sewage contamination.
A solvent plume has contaminated groundwater round Harwell (NB A Nuclear
research establuishment).
A spring fed pool in the Pang valley was showing signs of intermittent
pollution (source unknown). All farms in the valley were inspected and
problems (where found) have been addressed.
P51 Aesthetics. Sometimes the appearance of the water may indicate
pollution ... In other cases visually unpleasant sights such as foaming
or scums may result from natural causes.
Hmm, I've come to the end and no references to nitrates at all. Bother.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger? Was: N are good for you
Date: Sat, 5 Apr 1997 09:01:52 +0100
In article <5i3ln8$p9j@news.interlog.com>, Byron Bodo
<bodo@interlog.com> writes
>In article <6zPnZLAW50QzEwQy@upthorpe.demon.co.uk>, Oz@upthorpe.demon.co.uk
>says...
>
>>>Big shift to intensive corn / row cropping with great increase in N
>>>fertilizer usage since the early 1960s. Gross N fertilizer inputs
>>>may have finally stabilized in the 90s.
>>
>>Ah, they have found the optimum then.
>
>Remains to be seen if / when someone assembles the data. That's
>inputs. Circumstances in receiving waters likely require years [if
>not a decade] to approach a quasi-steady state, assuming input & land
>practice remain stable.
Well, it didn't take that long in the UK for surface waters (ie flowing
streams). Nitrates don't tend to hang about that long in an active
biosphere (ie topsoil, including lakebottoms) because they rapidly get
used by plants and micro-organisms. This is why regular applications are
required through the growing season for cropping.
>>Of course from European experience the most effective way to improve
>>catches would be to stop overfishing.
>
>No doubt, the North Sea authorities & fisher folk eagerly await you're
>profound insights.
Nope. It's pretty well agreed what needs to be done, catch a lot less
fish and no juveniles. The problem is in policing a multi-national
operation and what to do with the fishermen for a decade or so whilst
fish stocks recover from overfishing. It's a very difficult problem,
taken all in all, which is why we have got to the point where there are
almost no fish, fished by lots of fishermen, the situation is getting
rapidly worse and the action taken is always inadequate.
A very sad story indeed. As far as I understand it's happening all over
the world and is a serious problem. Doubtless when there are essentially
no fish and all the fishing fleets are bust, then some proper system
will be enforced. Not a very smart way to carry on though.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger? Was: N are good for you
From: Oz <Oz@upthorpe.demon.co.uk>
Date: Sat, 5 Apr 1997 09:14:24 +0100
In article <5i3mqa$p9j@news.interlog.com>, Byron Bodo
<bodo@interlog.com> writes
>In article <6zPnZLAW50QzEwQy@upthorpe.demon.co.uk>, Oz@upthorpe.demon.co.uk
>says...
>
>>>As the hypoxic dead zone due to summer eutrophication effects at
>>>the mouth of the Mississippi is increasing [7000+ sq mi a few yrs ago]
>>>with nasty effects on the Gulf of Mexico fisheries, the Yanks may be
>>>prodded into action, & Canada will bumble along & follow suit.
>>
>>You are sure this is not mostly due to reduced flow, aren't you?
>>You are sure that this is not due to sewage works and domestic
>>pollution, aren't you?
>
>Yup. Relative nutrient sources have been well documented. Ag overwhelms
>by a large measure, all other nutrient sources.
OK. I have no information about the US situation so I concur with your
statements. Seems like you have some education to do if US farmers,
despite being close to bankrupcy in many states, continue to waste vast
quantities of fertiliser. Odd, I was under the impression that the US
extension service was pretty effective.
>>>As for fertilizers & agrochemicals generally, my impression is that
>>>there is grotesque wastage. Huge quantities of chemical are tossed
>>>about, of which only minor amounts actually reach intended targets,
>>>most just blowing off into water, air, soil systems.
>>
>>Either:
>>
>>1) Your farmers are stupid, ignorant, wealthy, and wasteful and your ag.
>>advisors equally stupid, ignorant and uncaring.
>>
>>2) Your impression is incorrect.
>>
>>In fact I am quite certain, given the knife edge that N. American
>>farmers operate on, that they are using well below the optimum because
>>of cost, and applying it as efficiently as it is possible for them to
>>do. If not then anyone doing it properly would make a fortune farming,
>>and posts to sci.agriculture indicate that this is most definitely not
>>the case.
>
>The fact that current ag economics makes high fertilizer inputs feasible,
>in no way implies that the process is not grotesquely wasteful and
>with significant dis-benefits to the external world that aren't being
>properly accounted. Your attitude consistently seems to be that agriculture
>enjoys special rights to pollute wantonly and without repercussion.
Actually if World agriculture had significant restrictions on fertiliser
usage this would be most excellent for farmers. It only takes a minute
excess of consumption over production for prices to rise by factors of
2, 3, 4 and even more. A world reduction in fertiliser usage would mean
consumption of food far exceeded production and would result in mass
starvation in many areas of the third world, and food prices in your
shops to double, triple and more. The equivalent prices for grain would
probably jump by five or tenfold and farming would be very profitable.
If this is what you want, then rationally, as a farmer I am all for it.
In fact I am not because it would result in famine, death and in the
first world a reduction if GNP of many tens of percent which would cause
serious social problems and unemployment.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger? Was: N are good for you
Date: Sat, 5 Apr 1997 10:22:56 +0100
In article <5i3ale$jd0@news.interlog.com>, Byron Bodo
<bodo@interlog.com> writes
>In article <N93KapAxGKRzEwfF@upthorpe.demon.co.uk>, Oz@upthorpe.demon.co.uk
>says...
>
>>>some years back that the North Sea Commission or whatever they're called,
>>>made commitments to reduce P & N inputs from adjacent land areas to 50%
>>>of 1985 levels by some target date. Ag runoff controls would be part
>>>of that.
>>
>>As I have said before P leaching from agriculture is very small indeed.
>
>Generally P moves with surface runoff attached to fine sediments,
Hmm, I don't disagree with you here. However in the UK erosion like this
is very rare. I accept that with the US having a higher and more violent
rainfall than the UK then this might be a problem.
>but
>dissolved PO4 can move in appreciable quantities through tile drains
>and sandy soils.
If the pH is low. Go lime your soils.
>There's indisputable mountains of evidence that Ag P
>is a major cause of eutrophication in fresh receiving waters, particularly
>if total P levels > .03 ppm (running water) or > .02 ppm (still waters).
>Even lower concentrations have been observed to induce algal blooms.
>For some lakes in BC, ag & municipal P inputs that raised levels
>from .005 ppm [natural] to .01 ppm, began causing problems.
Hmmm. According to my reference seawater contains .088ppm of P.
Are you saying that you want waters in BC to return to .005ppm? Is this
possible with a viable agriculture? What are you going to eat?
>All of which says what? Evidently, you feel agriculture enjoys
>special rights to pollute freely. I don't see ag being singled
>out any more than any other sector.
You haven't been in the UK for the last couple of decades, clearly.
The evidence is that if you want productive and efficient agriculture
you are going to have to accept a small, and in the *vast* majority of
cases totally unimportant, increase in mineral and nitrate levels in
water. Plants require these elements for efficient growth and you cannot
prevent traces from getting into water. If you wish to ban agriculture
in N. America for the sake of a spurious purity of water then go right
agead. Europe, Asia, S. America and Africa will happily sell you very
high priced products to eat for as long as you can afford to pay. This
will, of course, result in the demise of N.America as a world power
which probably won't be to the benefit of the world, but some people
just gotta learn the hard way.
>The approach to the North Sea is no different than any other water
>body where eutrophication is being / has been addressed [Great Lakes,
>Baltic, Med, and a great many smaller inland lakes & reservoirs].
The North sea may be not too good for pollution but compared to lake
Erie it's pure!
<Snip of overblown description of N. European sea water.>
>>>I'm also suspicious of the cost figure you're tossing about, e.g., see
>
>>Anyone can publish anything in a URL, unless it's moderated or from an
>>offical body I take little notice.
>
>You said it. Same goes for usenet posts.
Indeed quite true.
>>OK, dispute the figure. As I said it was widely quoted a decade ago when
>>this was being carried out and I don't have any breakdown today. There
>>is little doubt that it's large though. Let's guess that E.Anglia
>>contains about 250,000ac of cropping land which is going to be about the
>>right order, and that losses are around 100 UKP (150$) due to the
>>enforced lower nitrate usage. Then the annual losses are 25M UKP (35M$)
>>per annum. When you consider that much of E.Anglia is vegetable,
>>sugarbeet etc the 100UKP/Ac is very much on the low side.
>
>If so, it's not unreasonable to invest in research to develop
>more efficient techniques to deliver nutrients to the plants &
>limit the external losses.
Being done, every year for at least the last 20 years. Fertiliser is a
major cost and the less you need to use the slower you reach bankrupcy.
I have to say that ultimately this is not controlled by technology, but
by the weather, plants and soiltypes. Indeed the lowest losses and use
per tonne produced comes from the highest use of fertiliser, the
optimum.
>Infrastructure doesn't last forever, & improvement would occur anyway
>sooner or later.
Some lasts a very long time. Much of London still uses sewers built by
the Victorians.
>Major $ are being spent on infrastructure upgrade
>all over the planet. Modern treatment generally has to be more
>effective, as waste loads keep increasing wherever populations
>[human & animal] are expanding.
Hmm. Well the UK population is barely increasing at all, and it's
actually been decreasing in W.Germany for some time. Animal populations
in the UK are not increasing by much either, indeed in some areas such
as dairy cows it's decreasing under quotas and higher yields.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger?
Date: Sat, 5 Apr 1997 08:51:40 +0100
In article <5i3kpc$p9j@news.interlog.com>, Byron Bodo
<bodo@interlog.com> writes
>In article <aTMvhHAYa0QzEw29@upthorpe.demon.co.uk>, Oz@upthorpe.demon.co.uk
>says...
>
>>>Can't speak for the US, but there are pockets of southern Ontario
>>>where anoxia occurs routinely. One is an area of organic rich muck
>>>soil & the anoxia is natural [insofar as conditions go in drainage
>>>ditches carved out of former marshland].
>>
>>Oh, so completely natural then. I mean, former marshland means it was
>>naturally a marsh and marshes are anaerobic. Marsh gas is a good pointer
>>here.
>
>If you consider long narrow ponds with gates & other flow controls cut
>in grid patterns as natural water courses, so be it. The P content of
>the bottom sediments is most definitey not natural.
You said the water derived from an organic rich soil dug in former
marshland. Marshland is formed in anaerobic conditions, and usually
liberates copious nutrients naturally once it is drained. This is why it
is so naturally fertile. Also marshland usually has very limited fall
for drainage, this is why it was a marsh in the first place. You ought
to expect stagnant pools where the ditch has a less than pergect fall,
or water plants impede drainage. In these stagnant pools, due to the
lack of flow and high organic matter of the parent soil, you will
(surprise, surprise) get micro environments just like the original
marsh. Anaerobic. Add a few blue-green algae for nitrogen fixing and you
can have a completely natural system that is anaerobic and high in
nitrates. So it could easily be (and in this case probably is)
completely natural. Phosphates in the bottom sediments may well also be
natural, this would involve a closer look at the details of the
formation of the marshland and the effects of it's oxidation on
phosphorus liberation. If it's acidic (quite common on marshland) then
phosphates can move to areas where they get precipitated out. Of course
it could be farmers stupidly spreading phosphatic fertiliser into their
ditches too, but it's by no means a certainty.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger? Was: N are good for you
Date: Mon, 7 Apr 1997 07:54:01 +0100
In article <5i89a4$css@news.interlog.com>, Byron Bodo
<bodo@interlog.com> writes
>In article <iGHxURAwnhRzEwI+@upthorpe.demon.co.uk>, Oz@upthorpe.demon.co.uk
>says...
>
>>Hmmm. According to my reference seawater contains .088ppm of P.
>
>And what's the Cl content vis-a-vis freshwaters?
About 2%. I trust you are not going to come off P eutropication and say
that Cl is bad in freshwater etc etc. Marine organisms have had a few
billion years to cope with high salinity and one ought to expect them to
react to high P in a similar way to freshwater.
>Natural P levels in Ontario surface waters can range down to
>1 ppb and maybe lower in some cases. My best guess at pre-colonial
>total P levels in streams of sedimentary southern Ontario were
>10-20 ppb.
>
>>Are you saying that you want waters in BC to return to .005ppm? Is this
>>possible with a viable agriculture? What are you going to eat?
>
>Just indicating that there are some sensitive water bodies
>out there.
Ah. Well, that presumably means there are some insensitive ones also, so
it's not quite a clearcut as you would have us believe.
>>The evidence is that if you want productive and efficient agriculture
>>you are going to have to accept a small,
>
>>and in the *vast* majority of
>>cases totally unimportant, increase in mineral and nitrate levels in
>>water.
>
>The latter part of this is a sweeping statement of religious belief.
No, it's an observation from the UK. Agricultural use of P (and N), and
probably at a much higher level than would be used in much of Canada, is
NOT causing problems. I gave you some extracts from the Environment
Agency report for Thames Valley. Whilst I will accept that specific
areas may well be of different sensitivity, it's a little hard to
believe that all of Canada is supersensitive while the UK is not.
>>Plants require these elements for efficient growth and you cannot
>>prevent traces from getting into water. If you wish to ban agriculture
>>in N. America for the sake of a spurious purity of water then go right
>>agead. Europe, Asia, S. America and Africa will happily sell you very
>>high priced products to eat for as long as you can afford to pay. This
>>will, of course, result in the demise of N.America as a world power
>>which probably won't be to the benefit of the world, but some people
>>just gotta learn the hard way.
>
>Silly, over-the-top religious twaddle from an unrepetant polluter.
I note your learned, considered and well though out reply to a very
serious problem if you are to significantly reduce fertiliser usage.
If you think that my statement is silly then you had better do some
research on the response of agriculture to the input of vanishingly low
levels of P for a few years. It is certainly true that there are many
shades of grey in this discussion but you won't come to an optimum
solution if you simply ignore facts that don't agree with your position.
>from an unrepetant polluter.
Incidentally I checked out the quality of the stream that flows round
the border of my farm with the Environment Agency. It is "water of good
quality suitable for all fish species", this hardly surprised me since
we have herons, kingfishers and snipe on our farm ditches. I am sorry to
disappoint you here. Oh, and yes, we do use quite a bit of N and P but
we avoid putting them into watercourses. We also have cowslips growing
on our ditchsides because we avoid spraying our ditches too. So it would
seem to be possible to have the advantages of modern agriculture without
too adversely affecting wild areas of the farm. You may find this
dissapointing, but I don't.
>Major problems are emerging in the coastal seas all over the
>world. Ag isn't the only cause, but it's a prominent one.
>
>>The North sea may be not too good for pollution but compared to lake
>>Erie it's pure!
>
>Ah ..... so you're an expert on the North Sea and Lake Erie.
>I've seen no evidence of either.
There have been articles in, for example, Scientific American on the
Lakes ecosystem. However many of them are known to be seriously
polluted, mostly from industry (there is a lot round Chicago, I'm told).
The main problem exacerbating the pollution is that they are relatively
small, relatively shallow bodies of water with a poor flow. Whilst there
are localised areas of pollution, the mouth of the Rhine and from the
old iron-curtain countries, and in some estuaries, the North Sea it is a
far larger and deeper body of water than the Lakes and has strong
currents and tides that provide (compared to the Lakes) a rapid turnover
of the waters. On top of that most of the rivers in Western Europe have
been drastically cleaned up. The Thames now has salmon whilst in the
50's it was completely dead and barren, for example.
I suggest you take a map and compare the volumes and flows in the two
bodies of water as a starting point.
>>... the lowest losses and use
>>per tonne produced comes from the highest use of fertiliser, the
>>optimum.
>
>And when has an ag economic analysis ever considered any external
>dis-benefits & associated costs to other sectors of society?
Oh, frequently. Properly done one should consider the effect on society
with, and without, fertiliser. Quite correct. As I have said before the
effect of enforced serious reduction in fertiliser usage will
drastically move food prices upwards by several times, and have little
(my view) of quite a lot (your view) effect on water quality although
the economic benefits of this may be elusive. High prices are good for
farmers and bad for society. Now what is the positive *economic* effect
from reducing nitrate levels from 50ppm NO3 to 20ppm NO3 and phosphate
levels from, well what is your target, 40ppb to 10ppb??
Of course if you conveniently ignore the effect on food prices, you
still have to consider the loss in profit of Canadian farmers, probably
many hundreds of $/ac over what I expect is a very large area indeed.
In fact I rather doubt you have made an estimate of this simple
analysis, hence you rather weak case.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger? Was: N are good for you
Date: Mon, 14 Apr 1997 16:30:12 +0100
In article <5itapc$e8i@news.interlog.com>, Byron Bodo
<bodo@interlog.com> writes
>In article <o+qzKGAJoJSzEwzm@upthorpe.demon.co.uk>, Oz@upthorpe.demon.co.uk
>says...
>>
>>>from an unrepetant polluter.
>>
>>Incidentally I checked out the quality of the stream that flows round
>>the border of my farm with the Environment Agency. It is "water of good
>>quality suitable for all fish species", this hardly surprised me since
>>we have herons, kingfishers and snipe on our farm ditches. I am sorry to
>>disappoint you here. Oh, and yes, we do use quite a bit of N and P but
>>we avoid putting them into watercourses. We also have cowslips growing
>>on our ditchsides because we avoid spraying our ditches too. So it would
>>seem to be possible to have the advantages of modern agriculture without
>>too adversely affecting wild areas of the farm. You may find this
>>dissapointing, but I don't.
>
>Not at all. Contrary to the tone of most of your remarks, you may
>regard, albeit grudgingly, rural water courses as having value beyond
>serving as convenient sewers for agriculture.
Dear oh dear. When have I ever said the above. It's a pity that you
persistently feel the urge to be gratuitously rude when you lose an
argument. It does rather deflate any good arguments you might have as it
makes you look rather puerile.
>>There have been articles in, for example, Scientific American on the
>>Lakes ecosystem. However many of them are known to be seriously
>>polluted, mostly from industry (there is a lot round Chicago, I'm told).
>
>Chicago is at the bottom of L. Michigan which has it's unique problems.
>Erie is the shallowest of the lakes, has the least hydraulic retention
>time [2.6 yrs], receives the largest proportion of agricultural drainage
>& is historically the one most affected by eutrophication. The severe
>eutrophy of the 1960s has been largely cleaned up though other
>problems remain.
I am pleased to note that you have pretty well solved your main problems
here. I seem to remember that one of the main reasons for the success
was that urban sewage was properly treated and spread on the land
instead of dumped in the lakes.
>>The main problem exacerbating the pollution is that they are relatively
>>small, relatively shallow bodies of water with a poor flow.
>
>You are a fairly shameless fabricator [polite term for bullshit
>artist], n'est-ce pas?
Dear, oh, dear. Here you go again. It only requires you to point out
differently, there is no need for schoolboy taunts.
>The mean & max depth of Superior are ca. 150 m and 400 m. The mean
>depths of Michigan, Huron, & Ontario are 60-85 m. Haven't seen
>mean depth reported for the North Sea, but the German chart I have
>suggests it's of similar order to the lower lakes over most of it's
>extent, deepening to > 200 m in the Norwegian trench.
Max depth is actually 661m (2170ft) but this is in a relatively small
area of the total.
>The combined surface area of the Great Lakes is slightly greater
>to that of England, Wales, Scotland & Northern Ireland combined.
>They hold about 23,000 km^3 of water, about the same as Lake Baikal,
>the largest freshwater body on the planet.
Ok, from my data the area is 246km^2, so that gives the average depth as
95m. I have to admit that this is quite a bit deeper than my memory
suggested. With an area of about 600km^2 and a depth probably only
slightly greater this makes the North sea between two and three times
the volume.
>>Whilst there
>>are localised areas of pollution, the mouth of the Rhine and from the
>>old iron-curtain countries, and in some estuaries, the North Sea it is a
>>far larger and deeper body of water than the Lakes and has strong
>>currents and tides that provide (compared to the Lakes) a rapid turnover
>>of the waters.
>
>And if exchange with the open Atlantic didn't dominate the water
>flux through the system, the North Sea would be an exceptionally
>foul mess the way it's been historically used as a regional waste
>chemical cess pool.
Have I ever suggested otherwise?
The sea tides and currents are however many orders greater than is
provided by the St Lawrence, and more importantly sweep the whole sea,
unlike the lakes where there are inevitably rather large areas with very
little net flow at all. Anyway, you agree with me, the lakes are a much
bigger problem with pollution than the North Sea, so that's one item
dealt with. There must be shorter ways to agree than this.
>Don't forget to mention that the currents conveniently sweep down the
>GB east coast & move GB contaminants over to the continental shore.
>Ditto for discharges into the English Channel. Shows up nicely on
>satellite imagery.
Well the flow is from the North sea into the Atlantic through the
English Channel, and the circulatory system is indeed anticlockwise.
However the pollution from the UK is hugely reduced from earlier this
century and now is only a problem in a few rivers. There is hugely more
from the former Iron Curtain countries, and of course the Rhine.
>>On top of that most of the rivers in Western Europe have
>>been drastically cleaned up.
>
>Some have, but contamination was very high and most remain
>significantly contaminated in some respect or other. Some remain
>exceptionally filthy by global standards [don't go wading in the
>Seine].
Of course. Indeed for most of the contaminated sediments the best thing
is to leave them where they are, undisturbed. This means that (where
heavy metals are concerned) they will remain contaminated for millennia.
>>The Thames now has salmon whilst in the
>>50's it was completely dead and barren, for example.
>
>So I've read, but the Thames is not your typical rural GB
>watercourse.
True, it was very heavily polluted indeed.
>Most nutrient flux to the North Sea from GB is
>from water courses between the Thames & the Scottish border.
Well, if you think about it ALL the pollution into the North sea from
England is between the Thames and the Scottish border, by definition and
no matter how small!
>>Oh, frequently. Properly done one should consider the effect on society
>>with, and without, fertiliser. Quite correct. As I have said before the
>>effect of enforced serious reduction in fertiliser usage will
>>drastically move food prices upwards by several times, and have little
>>(my view) of quite a lot (your view) effect on water quality although
>>the economic benefits of this may be elusive. High prices are good for
>>farmers and bad for society. Now what is the positive *economic* effect
>>from reducing nitrate levels from 50ppm NO3 to 20ppm NO3 and phosphate
>>levels from, well what is your target, 40ppb to 10ppb??
>
>Getting P levels within acceptable ranges is doable and mainly involves
>the same measures required to reduce endemic soil erosion & sedimentation
>problems.
Well, since erosion is insignificant in lowland UK, this may explain why
we have little problem apart from sewage works. I am always amused by
Brits who mutter on about erosion in the UK being a problem when they
see a bit of dirt on the road. They have clearly not seen erosion as it
takes place in asia and parts of the US where erosion really IS erosion.
>My concerns about N have to do with steadily rising levels
>everywhere I've looked including UK & western Europe.
As I have said before either your data is old, or biassed (perish the
thought). N increases in the UK (and given the same laws apply in the
EC, I would imagine most of Europe as well) have declined due to the
(IMHO rather silly) Nitrate Reduction Zones.
>Nobody has a clear
>notion where this is leading in freshwater systems, although eutrophication
>problems are increasingly evident in downstream brackish & marine systems
>where N is the limiting nutrient.
Well, our largest area of this sort is in E.England where the NRZ are
having the greatest effect. Having lived in this area some time ago
eutrophication was not noticeable except in the Broads, which was
eventually traced to sewage works and the (rather unsanitary)
recreational boating that that area is famous for.
>>Of course if you conveniently ignore the effect on food prices, you
>>still have to consider the loss in profit of Canadian farmers, probably
>>many hundreds of $/ac over what I expect is a very large area indeed.
>
>I have yet to see evidence that anyone is suffering unduly. Your doom
>& gloom mongering is essentially the same stuff that I've heard ad nauseum
>for the past 25 years from polluters faced with restrictions. We're still
>here and neither the western economy nor agriculture have collapsed.
Well, have your farmers had restrictions placed on them to reduce
phosphate levels to, what was it you wanted .005ppm and NO3 levels to
10ppm?? That would SERIOUSLY hammer production, to Europe's benefit.
Mind you the sewage works would also be in deep, er, problem. At these
levels there is no way they could even put their purified water back
into the rivers. Still, I'm sure a several hundred percent increase in
sewage costs would be appreciated by the general population if they knew
it was to, er, what was it supposed to do?
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger? Was: N are good for you
Date: Tue, 22 Apr 1997 09:46:14 +0100
In article <5j1rdf$kj9$1@news.uni-c.dk>, Torsten Brinch <iaotb@inet.uni-
c.dk> writes
>
>We certainly have a problem with N in the eastern part of the North Sea;
>it might be different over there at the UK coast, although I doubt it.
>It was not always the situation that the only thing which limits
>the growth of algae in the North Sea is ... sunlight.
Well, it probably isn't even now but certainly N & P were considered
inadequate for optimum growth, as was the case for most soils on land.
They probably are still inadequate for optimum growth although I believe
that significant quantities of NO3 are synthesised by assorted marine
algae if temperatures and sunlight levels are adequate.
>But this seems to be the situation now. P was never a limiting factor
>in the North Sea, but N used to be, at least in the summer months.
>This has changed.
>
>So what _is_ the predicament with N? What happened?
>
>Annual Nitrogen balance (1000 tons), appr.values,
>Danish agriculture in 1950 and 1980,
>(no change in N-content of ag.soil assumed)
>
> 1950 1980-90
> Imported feed 55 180
> Artificial fertilizer 65 375
> N2 fixation (clover) 190 30
> Atmospheric deposition 15 45
> ------------------------------------------
> Input total 325 630
>
> Agricultural products 50 90
> Lost to water and air 275 540
> ------------------------------------------
> Output total 325 630
Please can you add population of Denmark 1950 and 1980?
Even better give the consumption of N since in 1950 I would expect far
lower meat consumption as against 1980, although that may have changed
by 1995.
Where does your sewage go?
Why has the atmospheric deposition increased threefold?
>Interestingly the utilization ratio N(agricultural products): N(input)
>has changed very little. 1 N-atom out of 6 N-atoms input is found
>in agricultural products, the rest is lost to the environment.
Work in the UK has indicated that denitrification to nitrogen gas is a
major loss of soluble N. This increases significantly (in % terms) as
agricultural N levels increase. The losses of nitrate to the environment
excluding N2 to the air may well this be very much less than your
figures suggest.
In grassland there is considerable storage of N which is liberated when
the grass is ploughed up and this is also true when manure is spread in
the autumn and ploughed in for a spring crop.
>In other words it would be unfair to say that our farmers have
>become more wasteful with Nitrogen. They have (appr)
>doubled the N input, doubled the production, ---
>and doubled the amount of N lost to the environment.
I would *guess* that for the UK the balance would have improved. In the
50's spring cropping was the major crop type. Much of this was after
organic manuring in the autumn. Spring cropping is very leaky of
nitrates. Much is lost during the winter and early spring by leaching
since there is no crop and much N is produced then due to nitrate
production from protein oxidation in the soil. Winter cropping is now
predominant, and the old technique of applying autumn nitrogen has
largely ceased. Also far less pastureland is ploughed up which is a
major source of nitrates in water.
>The increased nitrogen loss has largely contributed to
>the eutrophication of the sea, and it has contaminated our
>freshwater streams, lakes and groundwater with nitrate.
We will have to disagree about this as a serious problem in a well run
agriculture. In general it is not hard to maintain water nitrate levels
below 50ppm AVERAGE, and below ~100ppm peak. At these levels I don't
believe that nitrate levels cause significant problems in general.
Phosphate levels are quite another thing though. Historically this has
been blamed on agriculture in the UK but separation of water treatment
and pollution enforcement has shown the blame to be largely due to
sewage outfalls. This surprises me not at all since phosphate applied to
agricultural soils (proper pH and not absurdly sandy) is rapidly locked
up so even plants need mycorhyzial fungi to extract enough anyway.
>And we are consequently loosing huge amounts of good plant
>nutrients from our agriculture.
Of which only some can be utilised, perfection is never possible.
There is a real problem with vegetable production and heavy application
of animal manures to soil.
Generally vegetables are spring sown and require large nitrate
applications for optimum production. Neither of these are conducive to
minimising nitrate losses, however vegetables need to be grown. Legumes
do not require nitrate applications but unfortunately when the
residues/roots are ploughed up in the autumn their breakdown results in
a sharp increase in readily leachable nitrates during that
winter/spring. Pity really.
Application of animal manures is another problem. Moderate applications
to the soil surface can easily be dealt with by plant growth and soil
absorbtion. Heavy applications should IMHO only be made in the spring
after any risk of leaching has ceased, but unfortunately this is
typically too late for sowing and the soil structure in such situations
is usually abysmal resulting in poor plant growth (and more chance of
autumn leaching of any residue). Light applications to winter crops in
the spring is much better but you need 12 months storage and a lot of
area to maintain a light dose. Also it stinks appallingly unless treated
before spreading.
Soil injection reduces the smell considerably but of course places the
manure below the topsoil so leaching is greatly facilitated. Late
spring/summer applications should be OK, but I personally don't feel
happy that this is a good method to reduce leaching. The biological
activity of the topsoil is greatly underestimated by many people IMHO.
It is a powerhouse of microbial action and packed with roots able to
absorb nutrients quickly and efficiently. It has evolved so as to
minimise nutrient loss and maximise breakdown for hundreds of millions
of years.
So of course you ask how I deal with the slurry from my cows. Well,
situated in a village composed mostly of ex-city dwellers we have first
to minimise smell. We do this by spreading the slurry fresh (little
smell) every few days very thinly (<< 1mm) on established grassland. The
straw based youngstock and some of the cattle slurry is spread on set
aside in the summer to be plouged in for *winter* cropping. I am easily
able to run well below the standards set down for this sort of system
despite a moderate stocking rate of about 2.4 cows/Ha. Those with large
numbers of pigs or poultry in predominantly arable areas have, IMHO, a
serious problem. The same can be said of high numbers of people who do
produce a lot of effluent themselves.
>That's how it is. So what can we do about it?
>
>Logically there are only two possibilities:
>a) decrease the input
>b) increase the utilization ratio
>
>We may wish to decrease the loss, simply by decreasing the input.
>But this would lead to an immediate decrease in agricultural
>production; if we target a 50 % reduction in order to return
>to the situation in 1950, this would lead to a 50 % reduction
>in the output of agricultural products.
>10 % reduction is tolerable, maybe, but _not_ 50 %!
>
>In other words: we will have to supplement with methods to utilize
>a larger proportion of the nitrogen input to our farms.
First we must really prove, open mindedly, whether nitrate water levels
of ~100ppm are indeed a problem. It is politically, but is it actually
quite livable with? I think it is not a serious problem in most
situations.
I am much more doubtful about phosphate levels. In practice this is
probably the more limiting factor as many ecosystems can produce
surprisingly high levels of nitrates from the air, particularly aquatic
ones. You may remember the selections from the Thames valley water
quality report I quoted earlier. Apart from a point case that appeared
to be due to agricultural contamination the main problem was from sewage
outfalls. As a user of sewage sludge I am aware that sewage contains
large quantities of phosphate and note that the sewage outfalls go
straight into the watercourses.
Of course it is politically much easier to blame farmers than to suggest
that huge quantities of money should be spent removing phosphate from
sewage outfalls with the concomittant increase in sewage charges for all
the public. However blaming the wrong group merely ensures that the
problem is not solved.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Where did all the clover go? [Was: Are Nitrates a danger? ...]
Date: Tue, 22 Apr 1997 11:40:32 +0100
In article <E918Lx.8GI@planet.mh.dpi.qld.gov.au>, Ian Staples <staplei@p
lanet.mh.dpi.qld.gov.au> writes
>
>During the prevailing interminable discussion of nitrate pollution etc.,
>iaotb@inet.uni-c.dk (Torsten Brinch) wrote:
Actually (on sci.agric at any rate) it was dead until Torsten woke it up
again.
>[...]
>>Annual Nitrogen balance (1000 tons), appr.values,
>>Danish agriculture in 1950 and 1980,
>>(no change in N-content of ag.soil assumed)
>>
>> 1950 1980-90
>> Imported feed 55 180
>> Artificial fertilizer 65 375
>> N2 fixation (clover) 190 30 <==== *
>> Atmospheric deposition 15 45
>> ------------------------------------------
>> Input total 325 630
>
>* Now this really _is_ interesting! ;-)
>
>What has happened to clover over there? Is N fertiliser now being
>used in situations where farmers once relied on clover to maintain
>fertility; and is N fertilised grass replacing mixed grass/legume
>pasture for animal production?
The UK position would be similar. In 1950 (only a few years after the
war) energy and thus fertiliser N was very expensive, probably hard to
get, the spreading equipment was new, expensive and unreliable and most
farmers who had grass would have been very small scale with just a few
sheep and cows and probably couldn't afford a tractor. Of course their
main source of pasture nitrogen would inevitably have come from legumes,
encouraged by (contractor spread) basic slag. Indeed at that time in the
UK even in arable areas red clover was used as an N-enriching part of
the rotation. Even in the 60's my staff can remember taking 4 and 5T
tractor trailers to the sidings (three miles away) and unloading
railcars filled with fertiliser (by hand of course) in 1cwt bags and
bringing it back to the farm. (NB Before my time here).
Basically the continual reduction in the real farmgate price of food
made such systems fail through bankrupcy (in effect) as it only became
possible to make a living using the much more efficient manufactured N.
>There is currently much research interest here in Oz in developing
>credible ley pastures to assist in maintaining soil fertility in
>the cropping areas of the tropics and subtropics [subterranean
>clover has long played such a role in the temperate wheat/sheep
>belt in southern Australia]. The target soils are the naturally
>fertile heavier soils which are being run down through more or
>less continuous cropping in farming systems where bagged N is not
>economic to use.
I thought that much of the Australian soils were basically only highly
deficient in phosphate and it pretty much only required adequate P for
clover to grow abundantly. Perhaps I am thinking of the 'temperate'
zones, back of Sydney to the Queensland border.
>In terms of pastures, there has been a big swing to "brachy + N"
>[i.e. N fertilised pure grass pastures of _Brachiaria decumbens_
>(signal grass) ] for high production pastures (especially for
>dairying) in the tropics and subtropics. There are many advantages
>of the grass + N approach in terms of management and, usually,
>levels of production per hectare.
So you find that manufactured nitrates are highly effective too.
Plus ca change.
>Has something similar happened in Denmark, and other parts of
>Europe (including the islands ;-) ?
Well, I guess plant physiology is pretty much the same the world over.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger? Was: N are good for you
Date: Wed, 23 Apr 1997 08:04:01 +0100
In article <5jipqd$j7b$1@news.uni-c.dk>, Torsten Brinch <iaotb@inet.uni-
c.dk> writes
Arrived 06.30 23/4/97
>Oz wrote:
>See the following paragraph. AFAIK this is the situation.
>July and August used to be limited by N, because the available
>N had been tied up in organic matter. This is not the case anymore.
>The rest of the year, temp and sun limited production and
>it still does. A period with calm weather and strong sun
>(in summer of course :-) is enough to produce a massive bloom
>of algae. This is the new thing.
As far as I understand 'red tides' have existed for quite a long time
although they may well (indeed probably are) more frequent than they
were. Since many marine algae can fix their own N I find it a tad hard
to believe that N from rivers in summer is the major cause. This is
particularly so in that total N leaching in summer from the land is
generally very small since it is well used by the terrestrial plants and
leaching is at a minmum.
As I understand it their exact cause is not known but the predator/prey
ratios are important. I can imagine that (chemical) pollution from
rivers might affect the predators more than the algae particularly as
summer flows are reduced and pollutants more concentrated.
>
>1950: 4.2M, 1980 4.9M. Your point being?
No wonder our supermarkets are full of Danish bacon. I'm sure the Danes
cannot possibly consume that much food themselves. :-)
>To sewage works for the city population, even quite small
>cities have them installed now. I think the discharge
>limit started out at 8 squeezing down to 5 mg N/L from
>sewage works serving more than 15,000 Person equivalents.
Excellent. No fault here under 50ppn NO3. :-)
>Cp. table above.
>1980 figures estimated N-loss from:
>denitrification 100 ktons (as N2)
>fields inorganic N 165 ktons (leaching/runoff)
>fields organic N 75 ktons (leaching/runoff)
>field organic N 100 ktons (ammonia to air)
>onfarm animals 45 ktons (leaching/runoff)
>onfarm animals 45 ktons (to air)
>straw burn, fields 10 ktons
What is the agricultural area of Dk?
>And yes, this, coupled with other actions has improved
>the N-balance. We still loose something like 200 ktons
>nitrogen from our fields.
>
>Yes, most of the P loss from Danish farmland comes from surface
>runoff, carrying the P in particulate form.
OK in river and stream beds this will produce more luxuriant growth of
waterweeds, but have little effect on suspended algal growth. You need
more ducks, morehens, geese and swans ......
>The sewage
>works discharge limits is, I think 1.5 mg/L.
Let's play with this. Take a town of 20K producing say 200L/d per
household of 4 or 10^6 litres/day, most of which is discharged to a
stream. The discharge into the stream is thus 1.5kg per DAY or 5T of P
per year. This is a LOT, and it's soluble and encourages algal growth if
the stream is only of moderate size. It's a linear pollution.
Let's look at soils. A deficient soil would contain about 10ppm and a
fertile one about 30ppm (I think these are actually as P2O5 equivalent
in which case reduce by 0.4) of available phosphate. So we are talking
the equivalent of 200,000 T of soil runoff per annum. I rather doubt
that this level of soil runoff would occur unless the rainfall was very
high, slopes rather great and the soils were not protected by crops.
This would, of course, be true in the tropics or parts of the US where
truly huge erosion can, and does, take place.
>Currently
>(and this has been true for many years) P is accumulating
>in Danish soil. In other words, particulate run-off becomes
>richer in P.
Correct. Indeed essential if good crops are to be grown IMHO up to 30-
40ppm available. Above this it is more than is required.
>A vanishingly small percentage of the area is being used for
>vegetable production in Denmark. The nitrate loss/unit area
>may be large, but the total amount from vegetable production
>is insignificant.
This is of course not true in the areas of the UK where the 50ppm limit
causes problems. This area does grow large quantities of vegetables.
>Yes, the storage option has been (almost fully) implemented on Danish
>farms. It was pushed, and aided onto the farmers, as they
>neither had the will or the capital to do it voluntarily.
>N-husbandry had been neglected. This has improved quite a lot.
When is it applied to the land and to what crops?
>If smell means less N-loss, that smell is the smell of money.
Well, the smell is the loss of ammonia, H2S and PH3 to the atmosphere so
it means MORE N-loss. A little aerobic treatment would have converted
these to NO3 (OK and N2), SO4 and PO4 which are not volatile.
>Yes, the low N discharge rate from, say a forest is really impressive.
So is it's appallingly low N production. Also trees do not taste very
good and are poor in nutrients for humans.
>Or from grassland for that matter.I guess this points to us,
>that we should aim to have something
>growing continually on the area we have taken control over. We
>won't be able to compete with the forest. Just aspire.
Correct.
>To me, your practise sounds very reasonable. Denmark is a PIG country.
>With an annual production close to 20M pigs, the 5M people pales
>in comparison. Yes pig-farming in this scale is hard to tackle.
What is the agricultural area of Dk??
>>First we must really prove, open mindedly, whether nitrate water levels
>>of ~100ppm are indeed a problem. It is politically, but is it actually
>>quite livable with? I think it is not a serious problem in most
>>situations.
>
>At the very least it is a waste of good plant nutrients, i.e.
>it could be a waste of money. In these terms, the question must be
>in which situations it would cost less to avoid the loss, than
>the value of the lost N. And what sorts of actions would
>give most bang for the buck.
Agreed. Research should continue.
>Secondly, we might perceive a value in having clean streams,
>lakes and estuaries.
Indeed so. They certainly DO have a value.
>It is difficult to evaluate, and we
>can hardly expect the farmers to pay the costs.
Well they would, quite simply, go bust. International trade agreements
makes it difficult to raise the farmgate price of food to allow for the
increased costs of significant pollution control so grants for improved
handling and payments for reducing inputs are really the only choice.
>We have
>a full blown aid system going already, you know. We just
>have to use it. Money in one hand, a claim in the other.
Hollow laugh from the UK that last year removed all grants for waste
handling and disposal.
>For heavy metals we have been somewhat succesful already,
>although there is still some way to go. Mercury is
>almost gone, lead much diminished. Cadmium, tough,
>but possible.
Not forgetting Chromium, zinc .....
>The next thing to go for is the bad organics, outphasing
>sources of say, alkylphenoxylates, LAS etc. It is an
>ongoing process, the end of which is at least 10 years
>away.
Do not underestimate the power of topsoil to consume these as food and
lock them up whilst they are doing so. The breakdown of soil applied
herbicides increases rapidly (2+ x) the year after the first
application. Anyway, quite a few of these organics are soluble and end
uo leaving from the sewage works outfall.
>And therefore blame can now (correctly) be pointed at farmers here.
Well, SOME of the blame. I am still somewhat unconvinced that the levels
you talk about (ie properly done applications) causes *significant*
actual damage that is not merely an observation of small changes.
>The problem is, as I have tried to point out, that farmers are not
>magicians. There are natural, as well as economic limits
>to how far we can go down in N-discharge, without
>bombing Danish agriculture to oblivion. But doing what's
>feasible, that's OK. We'll see how far we can go.
Agreed. However for each intelligent exponent of this view there are
fifty rabid anti-farmer unthinking eco-warriors who are more difficult
to have a rational discussion with than Saddam.
>By boosting the market for pork with BSE,
We would export under 30 month boned out Best British Beef to you
tomorrow if we could. Believe me the quality is truly amazing now there
are no old cows to toughen it up. Unfortunately some EC countries regard
any UK food exports as unacceptable competition.
>swine diseases etc.
>our competitors are not really helpful at the moment :-).
!!!!!!!!
Actually pig producers in the Uk are in some trouble getting planning
permission for new units, mostly because of smell. Remember there are no
grants for waste handling in the UK.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger? Was: N are good for you
Date: Fri, 2 May 1997 18:54:04 +0100
In article <3368255E.4FB4@icx.net>, "David B. Hedrick"
<davidbhedrick@icx.net> writes
>Hi:
>
> Just an American who thought I might contribute.
Pile in, it's free access.
>"Red Tide" is due to dinoflagellates, which do not fix nitrogen. Their
>blooms are linked to nutrient-rich conditions.
Agreed. The observation was that 'red tides' occur is summer and
terrestrial nitrate losses are at a minimum in summer.
>> As I understand it their exact cause is not known but the predator/prey
>> ratios are important.
>
>Yes. As I understand it, the survival strategy of the "red tide"
>dinoflagellates is: much nutrient -> bloom -> local death due to poison
>-> more nutrients -> more bloom, etc. More dinoflagellate preditors
>would help, unless the conditions were exceptionally rich.
In passing seawater contains:
Tons per km^3
P: 88 ppb 88
N: 160 ppb 160
>> I can imagine that (chemical) pollution from
>> rivers might affect the predators more than the algae particularly as
>> summer flows are reduced and pollutants more concentrated.
>
>You miss the point here. What we call "pollution" the dinoflagellate
>sees as food. What we call pollution can be toxic or eutrophic. In
>this case, we are giving them lots of N and P, and they grow.
I don't know if this is true of various chlorinated hydrocarbons. As I
understand it some of the predatory single celled microflora are highly
susceptible to some of these.
There is also the observation that the overfishing in the N. Sea and
elsewhere has reduced predation although I would be loath to put too
much emphasis on this since the subject is complex. Although most
commercial fishes are not, I believe, primary plankton feeders their fry
may be and in any case modern fishing takes a lot of species out that
are not primarily commercial. What is without doubt is that the numbers
of commercial fish left in the N. Sea is a tiny fraction of what it was
a few decades ago. (Judging from the reduction in fleets under 1%).
>> Well, the smell is the loss of ammonia, H2S and PH3 to the atmosphere so
>> it means MORE N-loss.
>
>PH3? What is that? Phosphine? Is this released from anaerobic
>processes?
Surely is. If ammonia can be produced from nitrates, then phosphine from
phosphates doesn't sound so unlikely. Actually it is highly implicated
in barn hay fires if the moisture is a little too high since it
spontaneously ignites rather readily. Indeed the luminescence (ahem:
phosphorescence) seen in marshes, although usually attributed to
methane, probably comes from phosphine since methane does not
spontaneously ignite in air.
>> >>First we must really prove, open mindedly, whether nitrate water levels
>> >>of ~100ppm are indeed a problem. It is politically, but is it actually
>> >>quite livable with? I think it is not a serious problem in most
>> >>situations.
>
>It depends upon what the water is used for. To drink, too much.
<sigh> We have been through all that.
I hope you don't eat fresh vegetables .....
>> >For heavy metals we have been somewhat succesful already,
>> >although there is still some way to go. Mercury is
>> >almost gone, lead much diminished. Cadmium, tough,
>> >but possible.
>
>Us in the US have very high Hg, Pb, Cd, and Cr, in spots.
Mines?
>> Unfortunately some EC countries regard
>> any UK food exports as unacceptable competition.
>
>BSE was politically convenient for them.
Since most EC countries now have indiginous cases, and almost certainly
all actually have, it illustrates the danger of inciting scare stories
for political reasons. Particularly when the scientific evidence is
against it. Mind you the US is as bad as the EC in this respect. The UK
is absurdly lax, we should be banning all pork from those countries with
swine fever out of common sense.
>
>> 'Oz "Is it better to seem ignorant and learn,
>> - or seem wise and stay ignorant?"
>
>Better to stay silent and appear a fool, than to open your mouth and
>prove it.
Personally I don't give a hoot if I seem a fool, so long as I am
learning something. It is silence that allows ignorance to flourish.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: Are Nitrates a danger?
Date: Sun, 6 Apr 1997 20:28:50 +0100
In article <5i84ib$ag6@news.interlog.com>, Byron Bodo
<bodo@interlog.com> writes
>In article <SHItkGAMSgRzEw+k@upthorpe.demon.co.uk>, Oz@upthorpe.demon.co.uk
>says...
>
>>>If you consider long narrow ponds with gates & other flow controls cut
>>>in grid patterns as natural water courses, so be it. The P content of
>>>the bottom sediments is most definitey not natural.
>
>...
>> Of course
>>it could be farmers stupidly spreading phosphatic fertiliser into their
>>ditches too, but it's by no means a certainty.
>
>There's no question of ag P inputs not being significant here, but
>"stupidly" is your choice of expression. There've been 10+ yrs of studies,
>including efforts to refine P modelling to include internal recycling
>from sediments. According to a recent paper, as the last phase of this
>effort, a comprehensive watershed-wide modelling exercise has been
>underway to establish P input objectives for the main lake (Simcoe)
>plus all the point and non-point sources within the watershed.
Good. I await the result without prejudgement.
Mind you after 10 years I would imagine that if farmer P applications
were causing a serious problem someone would have encouraged farmers to
improve their spreading by now. After all I expect farmers enjoy fishing
in their streams and lakes too, in fact they almost certainly do it a
lot more than anyone else.
--
'Oz "Is it better to seem ignorant and learn,
- or seem wise and stay ignorant?"
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