Microbial activity in parafluvial stream sediments before and after monsoonal flow, Upper San Pedro River, Southeastern Arizona
PublisherThe University of Arizona.
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AbstractThis study examines the effects of nutrient inputs on the microbial activity in stream sediments along the San Pedro River during the 2003 monsoon season. Surface water from three flow events, as well as pore water from below a point bar were monitored for dissolved constituents. As a proxy for microbial respiraton rate, gas fluxes were measured. Immediately after the floods, in situ respiration rates increased above and below the water table. Methane, N20 and CO2 flux measurements more than tripled, signifying an increase in anaerobic respiration. During flow events dissolved levels of DOC, DON, nitrite, and nitrate measured in the stream and pore water all increased, while sulfate, chloride and bromide all decreased. Furthermore, Cl:Br and C:N concentration ratios both changed, indicating a new source of water to the system during monsoonal flows. Flow events appear to trigger both aerobic and anaerobic processes in the sediment.
Degree ProgramGraduate College
Hydrology and Water Resources