Details

Autor(en) / Beteiligte

• Beaulieu, Jake J
• Tank, Jennifer L
• Hamilton, Stephen K
• Wollheim, Wilfred M
• Hall, Robert O. Jr
• Mulholland, Patrick J
• Peterson, Bruce J
• Ashkenas, Linda R
• Cooper, Lee W
• Dahm, Clifford N
• Dodds, Walter K
• Grimm, Nancy B
• Johnson, Sherri L
• McDowell, William H
• Poole, Geoffrey C
• Valett, H. Maurice
• Arango, Clay P
• Bernot, Melody J
• Burgin, Amy J
• Crenshaw, Chelsea L
• Helton, Ashley M
• Johnson, Laura T
• O'Brien, Jonathan M
• Potter, Jody D
• Sheibley, Richard W
• Sobota, Daniel J
• Thomas, Suzanne M

Titel

Nitrous oxide emission from denitrification in stream and river networks

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 2011-01, Vol.108 (1), p.214-219

Ort / Verlag

United States: National Academy of Sciences

Erscheinungsjahr

2011

Link zum Volltext

Quelle

EZB-FREE-00999 freely available EZB journals

Beschreibungen/Notizen

• Nitrous oxide (N₂O) is a potent greenhouse gas that contributes to climate change and stratospheric ozone destruction. Anthropogenic nitrogen (N) loading to river networks is a potentially important source of N₂O via microbial denitrification that converts N to N₂O and dinitrogen (N₂). The fraction of denitrified N that escapes as N₂O rather than N₂ (i.e., the N₂O yield) is an important determinant of how much N₂O is produced by river networks, but little is known about the N₂O yield in flowing waters. Here, we present the results of whole-stream ¹⁵N-tracer additions conducted in 72 headwater streams draining multiple land-use types across the United States. We found that stream denitrification produces N₂O at rates that increase with stream water nitrate (NO₃⁻) concentrations, but that <1% of denitrified N is converted to N₂O. Unlike some previous studies, we found no relationship between the N₂O yield and stream water NO₃⁻. We suggest that increased stream NO₃⁻ loading stimulates denitrification and concomitant N₂O production, but does not increase the N₂O yield. In our study, most streams were sources of N₂O to the atmosphere and the highest emission rates were observed in streams draining urban basins. Using a global river network model, we estimate that microbial N transformations (e.g., denitrification and nitrification) convert at least 0.68 Tg·y⁻¹ of anthropogenic N inputs to N₂O in river networks, equivalent to 10% of the global anthropogenic N₂O emission rate. This estimate of stream and river N₂O emissions is three times greater than estimated by the Intergovernmental Panel on Climate Change.