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Salt additions increase soil nitrate leaching: Implications for near-coastal watershed biogeochemistry
Citation:
COMPTON, J. E., J. Cabrera-Frias, AND M. CHURCH. Salt additions increase soil nitrate leaching: Implications for near-coastal watershed biogeochemistry. JOURNAL OF ENVIRONMENTAL QUALITY. American Society of Agronomy, MADISON, WI, 40(5):1601-1606, (2011).
Impact/Purpose:
Deposition of sea salt aerosols is often elevated along the coast relative to inland areas, yet little is known about the effects of this deposition on terrestrial ecosystem biogeochemistry.
Description:
Deposition of sea salt aerosols is often elevated along the coast relative to inland areas, yet little is known about the effects of this deposition on terrestrial ecosystem biogeochemistry. Spatial patterns of stream chemistry in the Oregon Coast Range led us to hypothesize that sea salts increase nitrate leaching from coastal forests. Laboratory work examined the influence of increasing NaCl concentrations on element leaching from soils from coastal Oregon forests via short-term batch extractions (~1 day) and longer-term incubations (~1 month). Salt additions did not immediately increase nitrate, but mobilized significant amounts of ammonium. In the longer-term incubations, salt additions increased net nitrate release by nearly 50%. Salt additions also reduced leaching of dissolved organic carbon, which in turn could increase nitrate concentrations by reducing immobilization and denitrification. Our findings suggest coupled abiotic-biotic effects: exchange of sodium for ammonium, then net nitrification due to a reduction in DOC. An interaction between marine aerosol inputs and soil C and N dynamics represents a new perspective on the biogeochemistry of near coastal ecosystems, and raises the possibility that the increased frequency of salt pulses to land associated with storms could accelerate the delivery of nitrogen to sensitive coastal waters.