Tracing atmospheric nitrate deposition in a complex semiarid ecosystem using delta17O.
The isotopic composition of nitrate collected from aerosols, fog, and precipitation was measured and found to have a large 17O anomaly with delta17O values ranging from 20 percent per thousand to 30% percent per thousand (delta17O = delta17O - 0.52(delta18O)). This 17O anomaly was used to trace atmospheric deposition of nitrate to a semiarid ecosystem in southern California. We demonstrate that the delta17O signal is a conserved tracer of atmospheric nitrate deposition and is a more robust indicator of N deposition relative to standard delta18O techniques. The data indicate that a substantial portion of nitrate found in the local soil, stream, and groundwater is of atmospheric origin and does not undergo biologic processing before being exported from the system.
Michalski
Greg
G
University of California, San Diego, La Jolla, California 92095-0356, USA. gmichalski@ucsd.edu
Meixner
Thomas
T
Fenn
Mark
M
Hernandez
Larry
L
Sirulnik
Abby
A
Allen
Edith
E
Thiemens
Mark
M
D000336:Aerosols; D002140:California; D003889:Desert Climate; D017753:Ecosystem; D004784:Environmental Monitoring; D009566:Nitrates / Q000032:analysis* / Q000737:chemistry; D010103:Oxygen Isotopes / Q000032:analysis; D011891:Rain; D012989:Soil Pollutants / Q000032:analysis*; D014873:Water Pollutants / Q000032:analysis*
D000336:Aerosols; D009566:Nitrates; D010103:Oxygen Isotopes; D012989:Soil Pollutants; D014873:Water Pollutants