Human activity has increased the supply of reactive nitrogen in the open oceans by nearly 50 percent above the normal range, and continues to have serious effects on Earth’s nitrogen cycles in the atmosphere and soil as well, according to a Review by Robert A. Duce (TAMU).
The authors recognize the need for more investigation into the effects of human activity on the nitrogen cycles, but they also agree that the negative consequences of human influence on global nitrogen levels will only intensify with time. In their Review, Duce and colleagues imply that the forms of anthropogenic nitrogen, i.e. that arise due to human activity, is responsible for about three percent of the new marine biological production, and contributes to about a third of the nitrous oxide and a tenth of the carbon dioxide input to the world’s oceans each year.
This influence can deplete essential oxygen levels in the water and has significant effects on climate, food production, and ecosystems.
Although local anthropogenic atmospheric reactive nitrogen (AAN) deposition seems unlikely to alter significantly local phytoplankton species composition, the community could be affected by the slow long-term fertilization of surface waters. ’Moreover, AAN inputs may stimulate N2O emissions, with possibly about two-thirds of the decrease in radiative forcing from increased CO2 uptake by the ocean being offset by the increase in radiative forcing from increased N2O emissions’ conclude the authors.
Duce R.A.; J. LaRoche; R. Langlois; A. Oschlies; K. Altieri; S. Seitzinger; K.R. Arrigo; A.R. Baker; T. Jickells; P.S. Liss; D.G. Capone; S. Cornell; F. Dentener; J. Galloway; R.S. Ganeshram; R.J. Geider*; C.M. Moore;M.M. Kuypers; S.M. Liu; J.J. Middelburg*; S. Nickovic; T. Pedersen; J. Prospero; L. Zamora; R. Schlitzer; L.L. Sorensen; M. Uematsu; O. Ulloa; M. Voss; B. Ward, 2008. Impacts of Atmospheric Anthropogenic Nitrogen on the Open Ocean, Science, 16 May 2008