Monday, June 2, 2008
Reactive Nitrogen Pollution
While a large focus has been placed on carbon dioxide emissions, articles published in Science by researchers at the International Nitrogen Initiative highlight another area of growing concern: reactive nitrogen pollution.
While 78% of the atmosphere is composed of nitrogen, reactive nitrogen refers to chemical compounds which contain nitrogen in a highly reactive state. Such compounds are found in the industrial fertilizers created by the Haber-Bosch process and nitrogen oxides produced by high temperature combustion of fossil fuels.
Reactive Nitrogen in fertilizers creates nitrogen enriched runoff, which triggers intense growth of algae once the runoff meets a larger body of water. As the algae in these blooms decompose, oxygen is striped from the water, reducing the water's ability to support life and creating 'dead zones.' (see NASA's images of the 5800 mile dead zone of the coast of Texas and Louisiana here)
It is estimated that 190 million tonnes of reactive nitrogen compounds are created per year, as well as 90-120 million tonnes of natural nitrogen compounds. While fertilizer is an integral component in the current methods of industrialized farming, an article in The Economist states that the reactive nitrogen derived compounds exhibit an uptake of only 10-15% in plants, with the rest of the compounds leaving the soil in the form of runoff.
There is definitely room for improvement in the area of plant uptake, as well as in the improvement of the availability of more natural forms of nitrogen. These improvements will help reduce these dead zones and improve the quality of our oceans and rivers while increasing overall agriculture yield.