The isotopic composition of nitrate collected from aerosols, fog, and precipitation was measured and found to have a large 17O anomaly with Δ17O values ranging from 20‰p to 30‰ (Δ17O = δ17O - 0.52(δ18O)). This 17O anomaly was used to trace atmospheric deposition of nitrate to a semiarid ecosystem in southern California. We demonstrate that the Δ17O signal is a conserved tracer of atmospheric nitrate deposition and is a more robust indicator of N deposition relative to standard δ18O 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.
ASJC Scopus subject areas
- Environmental Chemistry