Effect of rainfall on terrestrial fluxes of global cooling gases: carbonyl sulfide (COS) and its precursor dimethyl sulfide (DMS)
Abstract
Atmospheric sulfur compounds regulate climate by affecting cloud dynamics and reducing the amount of direct solar radiation that reaches the Earth's surface, and are notable for sometimes resulting in a global cooling effect. Carbonyl sulfide (COS) is the most abundant sulfur-containing gas in the atmosphere. Dimethyl sulfide (DMS), known to be produced by phytoplankton and bacteria, is oxidized in the atmosphere by hydroxl radicals, forming a considerable portion of the total atmospheric COS. Changes in soil moisture are expected to influence the direction of net gas fluxes of both COS and DMS. With the goal of refining existing models of sulfur gas fluxes, this study observes dramatic changes in the rates of production and consumption of COS and DMS when in situ grass-covered soils are initially wetted. Here we report the effect of simulated rainfall on uncultivated marine terrace field sites near Santa Cruz, CA (37.0 °N, 122°W) in the dry season using static flux chambers. Dry plots exhibited fluxes of DMS and COS below method detection limits. Immediately after a simulated rainfall event, DMS fluxes increased, then declined from their post-rainfall maxima by 90 minutes after wetting. Fluxes of COS from wetted plots showed occasional uptake, but were not consistent between sites. These results agree with observations from our lab-based soil incubation experiments.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.B44C..07W
- Keywords:
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- 0315 ATMOSPHERIC COMPOSITION AND STRUCTURE / Biosphere/atmosphere interactions;
- 0426 BIOGEOSCIENCES / Biosphere/atmosphere interactions;
- 1030 GEOCHEMISTRY / Geochemical cycles;
- 1615 GLOBAL CHANGE / Biogeochemical cycles;
- processes;
- and modeling