Environmental Science & Technology: Heavier rainfall due to climate change will exacerbate the effects of increased fertilizer use for corn-based ethanol production, causing a significant increase in nitrogen levels in rivers, according to a new study in ES&T (DOI 10.1021/es801985x). The good news is that if farmers choose organic practices and reduce fertilizer use, the impact of heavy rains will lessen and nitrogen pollution levels might drop to below present-day levels, the study concludes.The study by research fellow Haejin Han of the University of Michigan and colleagues is the first to simultaneously model the changes in nitrogen runoff across space – 18 watersheds in the Lake Michigan basin – and over time, the past 20 years. Using a model they developed, the researchers then project future variations in nitrogen loading under different land-use and climate scenarios.
The study reinforces an old message for lawmakers: current decisions on land use and agriculture will have a strong impact on the future availability of freshwater and the health of our aquatic and coastal ecosystems, says David Allan, one of the authors on the study. It also reinforces the notion that two factors drive the future of nitrogen pollution, he notes: climate change and how much nitrogen humans use on land.
…The authors also found that a 7-fold increase in nitrogen input from humans caused river nitrogen levels to increase 8-fold, but when the rainfall increases by 7-fold, nitrogen levels double in the rivers. This suggests that human impact is greater than that of climate on the nitrogen levels, especially in agricultural areas….
Image of a canal by Alfredobi, Wikimedia Commons
No comments:
Post a Comment