Andrews Forest LTER's Sherri Johnson, Linda Ashkenas, Stan Gregory, and Dan Sobota are among coauthors of a new publication in Nature entitled "Stream denitrification across biomes and its response to anthropogenic nitrate loading."
The publication is a product of the Lotic Intersite Nitrogen Experiment (LINX II) which uses isotopically labeled nitrogen to identify the fate of nitrogen in stream ecosystems flowing through urban, agricultural, and "reference" lands. A key concern of these studies is that land use practices can greatly increase delivery of nitrogen to streams and rivers, with detrimental impacts on water supplies and ecosystems. Synthesizing results from 72 streams in eight regions of the country, the LINX science team found that processes operating in streams can substantially decrease nitrogen loads, but that reduction of the load diminishes with increasing nitrogen concentration. In "healthy" stream ecosystems with low nitrogen concentrations, such as the Andrews Forest, 40 to 60% of the labeled nitrogen is taken up within 500 m of where it entered the stream. Many other papers are underway from this continental-scale study.