HR: 0800h
AN: A31B-0057    [Abstracts]
TI: Are Soil H2 Concentrations a Biologically Relevant Proxy for Soil Redox Status in Upland Tropical Soils?
AU: * Pett-Ridge, J
EM: jeffiner@nature.berkeley.edu
AF: University of California, Berkeley, 151 Hilgard Hall #3110, Berkeley, CA 94720 United States
AU: Silver, W L
EM: wsilver@nature.berkeley.edu
AF: University of California, Berkeley, 151 Hilgard Hall #3110, Berkeley, CA 94720 United States
AU: Firestone, M K
EM: mkfstone@nature.berkeley.edu
AF: University of California, Berkeley, 151 Hilgard Hall #3110, Berkeley, CA 94720 United States
AB: Wet upland tropical and temperate rainforest soils may play a major role in production and consumption of H2, yet this redox-active gas has been nearly ignored by soil scientists. We explored whether belowground H2 concentrations could be used to quantify the amplitude and temporal extent of major pE shifts in upland soils by testing D. Lovley and F.H. Chapelle's "TEAP" (terminal electron accepting process) model in both field and laboratory settings. Using soils from the Luquillo Experimental Forest in Puerto Rico, we measured soil H2 concentrations along with levels of other redox-active chemical species (O2, N2O, CH4, CO2, CO) and developed a model to correlate this data, so that thereafter, [H2] might be used alone as an indicator of the predominant TEAP occurring in the soil. This method has not been used previously in un-saturated soils, and there is some concern that the heterogeneity of co-occurring TEAPs may make it difficult to use as a precise indicator of soil pE. However, the method appears to give a qualitative indication of the redox processes that are dominating at any given point in time.
DE: 0315 Biosphere/atmosphere interactions
DE: 0322 Constituent sources and sinks
DE: 0330 Geochemical cycles
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting