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ORGANIC WASTE CONTAMINATION INDICATORS IN SMALL GEORGIA PIEDMONT STREAMS
Citation:
Burke Jr., R A. AND J. Molinero. ORGANIC WASTE CONTAMINATION INDICATORS IN SMALL GEORGIA PIEDMONT STREAMS. In Proceedings, 2005 Georgia Water Resources Conference, Athens, GA, April 25 - 27, 2005. University of Georgia, Athens, GA, 529-532, (2003).
Impact/Purpose:
The overall objective of this task is to identify or develop useful indicators of organic waste enrichment in aquatic systems that are easily measured and based on basic underlying ecosystem processes so that they will be widely applicable. These activities will primarily contribute to an APG within Long Term Goal 2 of the Water Quality Research Program Multiyear Plan: the 2008 APG on equipping EPA Regions, States, and Tribes with knowledge, skills and tools to determine the causes of impairments for freshwater and coastal systems required in various regulations and will also contribute to EPA Strategic Plan 2003-2008 Sub-objective 2.2.2: Improve Coastal and Ocean Waters. Activities that address the 2008 Water Quality APG will focus primarily on small streams of the Georgia Piedmont, which receive human and agricultural waste inputs. The activities related to EPA Sub-objective 2.2.2 will focus on the nearshore marine ecosystem of the Pacific Ocean, which receives treated wastes from the approximately 15 million people who live in the coastal zone of southern California and northern Baja California, Mexico, and on the nearshore marine ecosystem of the Gulf of California, which receives little anthropogenic pollution. The indicators that will be evaluated or developed will include concentrations of trace gases (N2O, CH4, and CO2), dissolved oxygen (DO), nutrients, and dissolved organic matter (DOM), other key parameters such as temperature, conductivity or salinity, flow rate, alkalinity, and pH, rates of key processes such as denitrification and DO consumption, and stable isotope ratios of various pools and substrates such as plants, animals, sediments, and DO.
Description:
We monitored concentrations of nitrous oxide, methane, carbon dioxide, nutrients and other parameters (T, conductivity, dissolved oxygen, alkalinity, pH, DOC, DON, flow rate) in 17 headwater streams (watershed sizes from 0.5 to 3.4 kilometers) of the South Fork Broad River watershed on a monthly basis for a year. We measured the stable nitrogen isotope ratio of plants growing in the channel and potential denitrification rate in the sediments on a few dates. Land use in the small watersheds that we studied was derived from the National Land Cover Data (NLCD) database. Based on monthly monitoring results our initial research suggested that although TDN, DOC, nitrous oxide, methane, and carbon dioxide in streams are all effective indicators of stream impairment by organic wastes and/or nutrients from septic tanks and/or animal manure, the trace gas concentrations are more sensitive indicators that respond to lower levels of waste contamination than do TDN and DOC. Our recent research suggests that stable nitrogen isotope ratios and potential denitrification rates are positively correlated with estimates of watershed waste loading and thus also appear to be potentially effective indicators of waste contamination in these watersheds. Trace gas, isotopic, potential denitrification rate, and other biogeochemical indicators of organic waste and/or nutrient contamination may have value to managers and regulators trying to protect water quality.