The effects on remote forests, lands and lakes are largely unknown, Schindler said. An increasing body of evidence, however, shows that the biological composition of microscopic communities in Arctic lakes changed with the arrival of human-derived nitrogen. This global nitrogen pollution may interact with climate change to produce a "double whammy" that could alter remote lakes in ways not seen in the past 10,000 years, Schindler said.
Using statistical models to analyze nitrogen characteristics of lake sediments, the authors show that the chemical fingerprint of nitrogen pollution started about 115 years ago, shortly after the Industrial Revolution, and that the rate of chemical changes increased during the last 60 years with industrial production of nitrogen for fertilizers.
"This study also provides an explicit chronology for entry of the Earth into the 'Anthropocene' a new geological era in which global biogeochemical cycles have been fundamentally altered by human activity," said co-author Peter Leavitt, professor of biology at the University of Regina and the Canada Research Chair in environmental change. "The signal will only get stronger in the future as we double fertilizer use in the next 40 years to feed 3 billion more people."
The authors conclude that climate, natural sources of nitrogen, and normal chemical processes on land and in water cannot account for the chemical signals they observe.
"Given the broad geographic distribution of our sites and the range of temperate, alpine and arctic ecosystems we believe the best explanation is that human-derived nitrogen was deposite
|Contact: Sandra Hines|
University of Washington