Combining Targeted Sampling and Fluorometry to Identify Sources of Human Fecal Contamination in Georgia’s Coastal Waters
G. Hartel (Dept of Crop and Soil Sciences, Univ of
Georgia, Athens, GA, USA)
GA DNR Coastal
Zone Management (through a Coastal Incentive Grant)
2006 - 2007
Our objective was to combine targeted sampling and fluorometry to detect human fecal contamination in three of four priority areas: 1) the coast of McIntosh County, 2) the Little Satilla/Satilla River watershed along the Glynn/Camden County border, 3) the upper reaches of the Ogeechee River and the Savannah–Ogeechee Canal, and 4) the Jerico River near I-95 along the Liberty/Bryan County border.
Accomplishments and Findings:
Early studies were confounded by the presence of optical brighteners in the wastewater samples (from laundry effluent), so a new fluorescence method was developed and tested.
light exposure was a simple, quick, and easy method to confirm the presence or absence of
optical brighteners in waters and, when combined with counts of fecal indicator bacteria, the
presence or absence of human fecal contamination in a water sample. The criteria for targeted
sampling and fluorometry included: a) installing a narrow wavelength emission filter in the
fluorometer, b) following the guidelines of targeted sampling, c) determining the water’s total organic carbon (TOC),
and d) establishing a suitable fluorometric cutoff value depending on the water’s TOC value.
Once these criteria were met, any water sample exceeding the fluorometric cutoff could be
exposed to UV light (30 min for glass cuvettes and 5 min for polymethacrylate cuvettes), and if
the percentage decrease in fluorometric value was >30% in the glass cuvettes or >15% in the
polymethacrylate cuvettes, then the water likely contained optical brighteners. If the
environmental water contained high numbers of fecal indicator bacteria as well, then the water
was likely positive for human fecal contamination, probably from a leaking sewer or
malfunctioning septic drainfield.
Information gleaned from the sampling missions is in preparation.
McDonald, J. L., P. G. Hartel, L. C. Gentit, C. N. Belcher, K. W. Gates, K. Rodgers, J. A. Fisher, K. A. Smith, and K. A. Payne. 2006. Identifying sources of fecal contamination inexpensively with targeted sampling and bacterial source tracking. Journal of Environmental Quality 35:889-897.
See related project, Ribotyping
to Determine the Host Origin of Fecal Contamination in Georgia's Coastal Waters