Trace Gas Concentrations in Small Streams of the Georgia Piedmont
Burke, Roger A.
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We have been measuring concentrations of the trace gases nitrous oxide (N₂O), methane (CH₄), and carbon dioxide (CO₂) and other parameters in 17 headwater streams within the South Fork Broad River (SFBR) watershed on a monthly basis since January 2001. Land use within each watershed was calculated from the National Land Cover Data (NLCD) database. The concentrations of all three gases have varied widely over the course of the study, and have frequently (N₂O) or always (CH₄ and CO₂) exceeded levels expected if the streams were in equilibrium with atmospheric concentrations of these gases. Streams draining highly developed watersheds have the highest N₂O and CO₂ concentrations and streams draining pasture-dominated watersheds have the highest CH₄ concentrations. Streams draining forested watersheds have the lowest N₂2O, CO₂, and CH₄ concentrations. The concentrations of all three of these trace gases exhibit significant positive correlations with dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) concentrations suggesting that they may be useful indicators of organic waste and/or nutrient inputs to streams. In some cases, elevated stream trace gas concentrations may serve as early warning indicators of watershed disturbance.