According to scientists the natural nitrogen cycle* no longer exists. It has been replaced by what is now being called the Nitrogen Cascade. This has been caused by the large scale burning of fossil fuels and the industrial production of nitrogen fertilisers which have been poured over our farmland in the last hundred years.
Despite the fact that fertiliser use has helped increase food yield, which would seem to be a positive outcome for the hungry of the world, the impact of excessive nitrogen being introduced into the environment is proving severely detrimental. Some scientists are so concerned they are suggesting that the over production of nitrogen will be a much greater threat to our planet than that of carbon dioxide.
One reason for this is the potential impact of nitrogen on human and animal health. In the short term exposure to oxides of nitrogen can cause respiratory problems, fatigue, gastric upsets and vomiting, while in the long term it has been linked with heart disease and damage to the nervous system.
A specific example of the effects of nitrogen on human health is cited by Rowan Hooper in an article in ‘New Scientist’ (January 2006). He describes the link between nitrates from farm run-off getting into the drinking water and ‘blue baby syndrome’, or methaemoglobinaemia. This condition is caused by nitrates blocking the ability of haemoglobin to carry oxygen round the body, causing the usual symptoms of fatigue, diarrhoea, etc, and in extreme cases loss of consciousness and even death. According to Rowan Hooper, ‘The syndrome has become a major problem in parts of the US and the Netherlands, which has the highest levels of nitrogen deposition in the world.’
The effect on ecosystems can also be devastating, for example, when nitrates are washed from soils into watercourses it can make rivers and lakes too rich in nutrients. As a direct result algae thrives, then the bacteria feeding on the algae feeds on the oxygen from the water which other life forms need to survive. This has already generated dead zones in waters such as the Gulf of Mexico, and in parts of Europe and South-east Asia.
It’s not so long ago that acid rain was the environmental problem which made it to the front page of the daily papers: it still is a huge environmental issue around the globe and one which is intimately connected to the bigger nitrogen problem. This is because nitrogen dioxide, nitrous acid and nitric oxide all contribute to acid rain. And if climate change is the current headline news it should be remembered that the nitrogen issue is also inextricably linked to that problem too: nitrous oxide is a greenhouse gas which is some 300 times more potent than carbon dioxide.
In a response similar to the Kyoto Protocol, forces are already gathering to deal with the issue - the Nanjing declaration was presented in 2004 at the third international Nitrogen conference and it has already been adopted by the European Union.
However, as is often the case with environmental degradation, we know the nitrogen problem is one fuelled by a growing human population and the impact this has on the planet. So the overriding question has to be will we be able to change our life-styles quickly enough to adjust to the new cycles we have created? Sometimes it seems we just have to face the same old problems wrapped up in another guise.
* The nitrogen cycle: at its simplest bacteria in the soil reduce nitrogen gas to ammonia which is then absorbed by plants. The plants grow, then decay, and bacteria and fungi return the nitrogen to the atmosphere which are again fixed by bacteria in the soil.
About the author:Article written by Raichael Lock
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