© 2001 Eugene S. Takle
The addition and recycling of nitrogen in the global biosphere is creating a problem some scientists claim is as important as the global warming issue. The Second International Nitrogen Conference held 14-18 October at Potomac, Maryland, explored the implications of global increases of this essential biosphere nutrient. Excess nitrogen is introduced into the biosphere by anthopogenic sources, mainly nitrogen fertilizers (75%) and oxides of nitrogen (Nox) from fossil fuel plants (25%), according to the summary of Kaiser (2001). Humans annually put about twice as much nitrogen (150 Tg) into the global fixed nitrogen pool as do natural systems. Some progress has been made in reducing emissions of Nox, but little success has been achieved in reducing levels of nitrogen used in agriculture.
Reference
Kaiser, J., 2001: The other global pollutant: Nitrogen prove tough to curb. Science, 294, 1268-1269.