From this:

http://www.msdvetmanual.com/toxicology/nitrate-and-nitrite-poisoning/overview-of-nitrate-and-nitrite-poisoning

the problem does seem to be more with the feed, than water

stewgreen, from the same article, you will also have noticed that grass cut and stored as hay and/or silage for winter fodder can be risky due to bacterial activity during storage under damp conditions. Also, that cows are more vulnerable due to their gut bacteria.

This article reveals some of the assumptions incorporated into the models, and that Peak Application was in the 1980s:

http://www.bgs.ac.uk/research/groundwater/quality/nitrate/peaks.html

"Modelling peak movement"

"The arrival of nitrate stored in the unsaturated zone has been modelled using a simple accounting procedure within a GIS.

This assumed nitrate loading from base of the soil and that movement was vertical through the matrix, without dispersion and at constant velocity:

Nitrate leaching at the base of the soil was estimated using literature values and was compared with values calculated from pore water values back converted to time of recharge. This showed peak applications were from the late 1970s to about 1990."

"Guano (from Quechua "wani" via Spanish) is the accumulated excrement of seabirds or, for bat guano, cave-dwelling bats. As a manure due to its exceptionally high content of nitrogen, phosphate and potassium: nutrients essential for plant growth. The 19th-century guano trade played a pivotal role in the development of modern input-intensive farming practices and inspired the formal human colonization of remote bird islands in many parts of the world. During the twentieth century, guano-producing birds became an important target of conservation programs and influenced the development of environmental consciousness. Today, guano is increasingly sought after by organic farmers."

Many sea side towns would be happy to cull seabirds, and now Environmentalists have come up with a good reason.

"My conclusion: be worried, be very very worried (but not in my part of Norfolk which seems OK)."
"Seems like drama queening to me" StewQueen

Of course it's (in part) tongue in cheek (hence the bragging reference to my home county) but nevertheless it represents a very real problem that, due to the investigations of the BGS has been identified as significantly larger than before. The problem is not so much to human health (although this risk is not zero to babies), but is significant to cattle and highly significant to damaging the environment. Cleanup of excess nitrates is both long and expensive.

Use of the word "scary" in this thread seems overly dramatic.

Gwen. Seagulls are highly efficient stolen-chip converters into guano. Both intake and exiting activities are sources of entertainment for local residents.

Supertroll, Peak Application of nitrates was in the 1980s. Technology has improved so that there is no economic reason to over fertilise.

As with guano, nitrate is highly concentrated in "scrapings" taken from chicken houses. Is it that farms and fields closest to chicken houses are being overfertilised with organic chicken manure, due to the economics of transporting it any further (plus complaints about the smell)?

Poultry houses are more likely on low quality agricultural land, and the surrounding land is more likely to benefit from nitrate fertiliser, whilst being less able to hold onto the nutrients.

It is a chicken and egg problem.

Nov 13, 2017 at 8:21 AM | Supertroll

Seagulls fed on an exclusive diet of seaside chips, kebabs, icecream, takeaway curries and pizza do not seem to experience any health problems themselves, though this is the type of diet deemed inappropriate for humans, however, some seaside towns have experienced problems with the effluent discharged from their sewage works.

Golf. My reading of the problem is that its one in transit. The excess nitrate exists and is moving inexorably towards the water table where nitrates will re-enter the human environment. It is believed that where nitrates become concentrated there will be environmental consequences that will be difficult and costly to remedy.

Supertroll, doesn't some of this go back to 1970s eutrophication scare stories, some of which were true? Legislation and farming practices changed as a result.

If nitrate has taken so long to be released from permeable rock strata into water courses, why should it be released in a sudden rush? Were there bad consequences in rivers taking water from farmland with impermeable bedrock beneath?

Nitrates are crucial for plant growth, and in water courses will promote blooms of algae. I do not understand how nitrates may become concentrated, or require expensive remedial action.

We have all seen wildlife documentaries featuring animals drinking from, and peeing into dwindling water holes during African droughts. They don't succumb to nitrate poisoning, and the vegetation remains edible when the rains return.

Livestock farming, especially dairy, produces large amounts of slurry, concentrated in a small area (farmyard, milking parlour etc) that then needs to be washed down with water, creating a high volume. River pollution incidents from leaking farmyard slurry are far fewer now, but still just as damaging when they do occur. The problem is caused by BOD and COD (Biological Oxygen Demand and Chemical Oxygen Demand) ie the oxygen in the water is used up and aquatic fauna dies.

With the modern era of super sized farms, with milking parlours in almost continuous use, the volumes of slurry to be disposed of safely, increase.

The economies of scale do not favour owners of single milking herds or poultry sheds, but consumers prefer cheaper food. As a country bumpkin I have witnessed the changes in rural farming, and have a lot of sympathy for traditional sized farms.

Who is driving the latest scare stories about nitrates, and why?

Golf. Nitrates will not emerge in a sudden rush; the problem is more insidious. Imagine a slug of syrup soaking through a pile of waffles resting on your knees. At the present time there is nothing to worry about. But the syrup is slowly descending and in time your trousers will need Persil. Furthermore the sticky contamination will keep coming and will need loads and loads of kitchen towels.

I am not an aquatic ecologist but I believe the problem is one of loading. Once the nitrate levels exceed a certain level, certain algae grow wildly, use up all available oxygen and kill off most other life forms. The nitrate levels in the subsurface are commonly already high enough to cause eutrophication for decades and decades.
Many of the algae are also toxic. I once had a dog that loved swimming in the UEA lake. It was made very ill by Autumn algal blooms, but was determined to swim.

Supertroll, ref your dog, would that be toxic blue/green algae? AKA Cyanobacteria?
https://en.m.wikipedia.org/wiki/Cyanobacteria
"Cyanobacteria prefer calm waters, such as those provided by ponds and lakes. Their life cycles are disrupted when the water naturally or artificially mixes from churning currents caused by the flowing water of streams or the churning water of fountains. For this reason blooms of cyanobacteria seldom occur in rivers unless the water is flowing slowly. When the bacteria are found in rivers, they have usually come from the outfall of lakes upstream from the sampling point.

"Cyanobacteria are a growing concern for drinking water utilities who use lakes and rivers as their source water. The bacteria can interfere with treatment in various ways, primarily by plugging filters (often large beds of sand and similar media), and by producing cyanotoxins, which have the potential of causing serious illness if consumed."

I understand your point about the Lag Time between application of fertiliser, and when it manifests in water courses. Surely the Lincolnshire Fens and Norfolk Broads should have become "toxic" in the late 1970s? Did they?

The chalk South Downs are not prone to flooding, but when a series of depressions come over, water tables rise, and flooding from ground water occurs, as happened 4 years ago. This was in winter, but there were no ill effects from the sudden flushing out of nitrates.

GolfCharlie. Some Broads already affected (some severely)
https://www.eswater.co.uk/your-home/environment/bure-catchment.aspx
UEA used to be heavily involved in consultancy work.

So SG extra denitrifying bacteria and other micro organisms use up oxygen at faster rates causing even worse eutrophication. Law of cascading consequences.

Nov 13, 2017 at 2:16 PM | stewgreen

Yes. Porous limestone and chalk ought to be quite a good matrix for nitrate munchers to live in. They have had 40+ years to get settled in, even at the cooler temperatures.

Meanwhile, chalk springs keep reappearing, and it has nothing to do with Global Warming:

See this reference to the Assendon Spring, that floods a road near Henley
http://www.bgs.ac.uk/research/groundwater/datainfo/levels/sites/StonorPark.html

Or Farringdon near Alton
http://www.farringdon.biz/news/floodscheme.html

Or Hambledon near Portsmouth
http://www.bbc.co.uk/news/uk-england-hampshire-26194506

Supertroll, from your link:
"The Trinity Broads have suffered from high nitrate and phosphate input causing algal blooms and poor water quality in the past. Catchment work and a biomanipulation project have improved water quality significantly, leading to clear water and a rich aquatic habitat. Biomanipulation is the adjustment of the fish populations allowing waterfleas, that eat algae, to proliferate, causing clear water conditions. This work is a significant success story for Essex & Suffolk Water."

It is not possible to tell how much of this "success story" is due to biomanipulation and/or changes in use of fertiliser. The Norfolk Broads are a Reed Bed filtration system, and Norfolk Reed is the best product for thatched houses.

I note the cv of the author!

"Ian Skinner is Essex & Suffolk Water’s Catchment Advisor for the River Bure and Trinity Broads, and also for the River Waveney, Fritton and Lound Lakes. Ian has a degree in Agriculture from Newcastle University and an MSc. in Agriculture, Environment and Development from the University of East Anglia."

#3 Surely Nitrates and Nitrites are different ?
and shouldn't be confused

Nov 12, 2017 at 4:46 PM | Registered Commenterstewgreen

Correct.

From memory, I'll add to my original comment on unthreaded saying that nitrates may be beneficial in the diet. When I had to publicly speak on the matter it was my turn to present to the Cardiovascular Journal Club in the Department of Cardiology at the Medical University of South Carolina. The audience was mostly Post-Doctoral researchers, practising physicians, and senior teaching faculty.

My research at the time was actually in the biochemistry of Ischemic Reperfusion Injury (which translates to "heart attack" in common parlance. It is the leading cause of death. Bar none.)

The literature papers I read that actually directly referenced the historical topic of nitrates in drinking water said that the earlier studies were largely inadequate in that they were poorly designed or under-powered, i.e. statistically of not much use to draw conclusions of any sort. Just like so much else in the realm of chemophobia.

Nitrates are still considered to be largely inert to most of human biochemistry.

The more interesting bits start to emerge when you consider that they are not inert to some of the commensal bacteria inhabiting parts of the human body, primarily the gut. Here nitrates can be reduced to nitrites which can then feed into the multifarious complexities of nitric oxide (NO) formation and actions [*]. My own interest was about the protein cysteine-thiols that are damaged by the oxidative burst that occurs during ischemic reperfusion. Nitric oxide helps "cap" such damaged proteins under low-oxygen conditions such that they can be recovered if the cell lives long enough for normal house-keeping activities to supervene.

To cut a long story short, what role this nitrite/NO plays in the gut and the rest of the body is still being looked at. But at the time (2009) there were several ongoing clinical trials looking at the observed reduction in morbidity/mortality of people with diets high in nitrates and nitrites. There are some interesting facts and questions behind the observed benefits:

-Such as, what are the predominant dietary sources of nitrate and nitrite? Funnily enough, mainly leafy green vegetables and cured meats, such as are a large part of a "Mediterranean diet" that fosters low morbidity/mortality from Ischemic Reperfusion Injury.

-Even more interesting. Just what the hell are the commensal bacteria up to in the human salivary glands? These bacteria concentrate the inert nitrate in the body, and also express nitrate reductase, so nitrate and nitrite can be recycled into the saliva and hence towards the gut. These salivary bacteria appear to be tolerated by the human immune system, which suggests an evolutionary symbiosis.

I may well have read the literature entirely wrong, but no one in that audience contradicted me. And, as I said in unthreaded, you can buy toothpastes with ~15% Potassium Nitrate. If nitrates were genuinely toxic at levels seen in ground/drinking waters we would expect to see this in practice, but we don't.

[*This was alien territory before people like Ignarro, Murad and Furchgott published their Nobel-prize winning works about Nitric Oxide. Prior to that, the positive oxidation-states of nitrogen were often considered at best harmless, but usually toxic. The idea of them being an essential part of mammalian biology seemed ridiculous.]

Nov 13, 2017 at 7:43 PM | michael hart

Thank you for the biochemistry!
Looking through some of the Veterinary info about nitrate poisoning in cattle, it mentioned ruminant gut bacteria converting nitrate to nitrite. With my limited knowledge, I had assumed that ammonia to nitrites to nitrates was one way. It seems that nitrates are only a problem if converted to nitrites?

If piglets and babies are vulnerable to nitrates in water, is it possible that prior to weaning, they do not have the best combination of gut bacteria to cope with nitrates?