Phil Taylor and Alan Townsend have discovered that global ratios of nitrogen and carbon in the environment are inexorably linked, a finding that may lead to new strategies to help mitigate regional problems ranging from contaminated waterways to human health. Their new study focused on the growing worldwide problem of nitrogen pollution. The authors note that artificial fertilizer production, fossil fuel use, and some agricultural activities have increased the amount of reactive nitrogen in the natural environment by an order of magnitude. This reorganization of the nitrogen cycle has led to an increase in food production, but increasingly causes a number of environmental problems such as the accumulation of nitrate in both freshwater and coastal marine ecosystems.
Taylor and Townsend combed exhaustive databases containing millions of sample points from tropical, temperate, boreal and polar sites, including well-known, nitrogen-polluted areas like Chesapeake Bay, the Baltic Sea and the Gulf of Mexico. Through their data and subsequent modeling efforts, they found the ratio between nitrates and organic carbon is closely governed by ongoing microbial processes that occur in virtually all ecosystems. This surprising result shows that if there is substantially more dissolved organic carbon than nitrates, the nitrogen is sucked up by microbial communities. Townsend and Taylor's new insights can be combined with available data and techniques to make accurate evaluations of when and where nitrate pollution may pop up. The authors point out, however, that even in areas where sufficient organic carbon is present, the nitrates are probably not locked away forever. Instead, they are passed on to other ecosystems - essentially just moving pollution problems elsewhere in the environment.
The team's study was published in the April 22 issue of Nature.