Investigation of the Source of Nitrate Contamination in the Upper Floridian Aquifer Near Albany, Georgia
Wenner, David B.
Reyher, Susan M.
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An area of nitrate contamination was detected in the Upper Floridan aquifer in a 20 square mile area southwest of Albany, Georgia. This area appears to originate on the Shamrock Ranch, a site where a wide variety of potential nitrate sources were used. These sources include cattle manure, synthetic inorganic fertilizers, poultry litter and municipal biosolids. Although a disused cattle feedlot was suspected of being the most probable source of groundwater contamination, questions concerning the contributions from other materials remain. To further evaluate the source of contamination, an investigation was undertaken to measure the nitrogen isotopic composition of dissolved nitrates in groundwater both on and off the ranch. This approach potentially provides a means for distinguishing different sources of nitrate-producing materials. Measurements of both nitrate concentrations and nitrogen isotopic compositions in groundwater were made of one sample from an inorganic fertilizer source, one background sample, and seven samples from within the contaminated area. Although some ambiguities remain, it appears that the disused cattle feed lots are not a major source of contamination. Rather, the nitrogen isotopic data are most consistent with a mixed source of contaminants. One of the important components of this mixture appears to be synthetic inorganic fertilizers that were used in the past.