Academic journal article Journal of Environmental Health

Fate and Transport of Enteric Microbes from Septic Systems in a Coastal Watershed

Academic journal article Journal of Environmental Health

Fate and Transport of Enteric Microbes from Septic Systems in a Coastal Watershed

Article excerpt

Introduction

During the 2007-2010 surveillance periods, the U.S. National Waterborne Disease and Outbreak Surveillance System reported that more than half of drinking water-associated disease outbreaks were associated with untreated or inadequately treated groundwater, indicating that contamination of groundwater remains a public health problem (Hilborn et al., 2013). Fecal contamination from humans and animals is one of the primary factors contributing to microbial pollution of both groundwater intended for drinking (Geary & Whitehead, 2001; Hagedorn, Mc Coy, & Rahe, 1981; Scandura & Sobsey, 1997; Whitehead & Geary, 2000; Yates, 1985) and coastal surface waters (Bechdol, Gold, & Gorres, 1981; Carroll, Hargreaves, & Goonetilleke, 2005; Lipp, Farrah, & Rose, 2001; Rose, Griffin, & Nicosia, 1999). Microbial contamination of groundwater continues to be a public health concern as nearly 2.7 million North Carolinians rely on private groundwater wells for drinking water (North Carolina Groundwater Association, n.d.), and approximately 60% of residences use onsite wastewater treatment systems (OSTW) in coastal North Carolina (North Carolina National Estuarine Research Reserve, 2004). After analyzing data from 2011 made available by the U.S. Environmental Protection Agency (U.S. EPA, 2012), the National Resources Defense Council reported the third highest number of beach closing and advisory days in the U.S. in 22 years. Sixty-nine percent of these beach closings/advisories were due to increased bacteria levels exceeding beach water quality standards, indicating the presence of human or animal feces in the water (Dorfman & Rosselot, 2012). From 2010 to May 2013, over 230 proclamations of polluted waters were released (not including individual closures), resulting in temporary closures of shellfish waters in North Carolina (North Carolina Department of Environmental and Natural Resources, 2012).

OWTS discharge septic effluent into the subsurface and are frequently reported as a source of groundwater contamination, resulting in environmental and public health risks (Carroll et al., 2005; Hagedorn et al., 1981; Yates, 1985; Yates & Yates, 1989). Along with high densities of OWTS, groundwater contamination can occur as a result of improper construction and maintenance of septic systems, leading to their malfunction (Ahmed, Neller, & Katouli, 2005; Geary & Gardner, 1998; Geary & Whitehead, 2001; Lipp et al., 2001; Whitehead & Geary, 2000; Yates, 1985). An average of nearly 1,500 septic systems in coastal North Carolina hydraulically malfunction each year (Humphrey, 2010), creating significant impacts on groundwater and adjacent surface waters (Ahmed et al., 2005).

This two-year study was conducted to evaluate the impact of two household septic systems on shallow groundwater and adjacent surface water quality in coastal North Carolina.

Microbial indicators of fecal contamination were studied to help improve understanding of the nature and extent of potential impacts of OWTS discharge to aquifer systems and nearby surface waters. Previous researchers have recommended using a suite of indicator microbes for better assessments of water quality, including E. coli, enterococci, and Clostridium perfringens (Griffin, Lipp, McLaughlin, & Rose, 2001). Molecular microbial source tracking for human- and animal-specific markers was also evaluated to provide additional evidence indicating whether OWTS are a source of groundwater contamination. Microbial source tracking using Bacteroides gene targets and mitochondrial DNA has been reported to identify human (Haugland et al., 2010; Shanks, Kelty, Sivaganesan, Varma, & Haugland, 2009) and animal (Caldwell & Levine, 2009; Schill & Mathes, 2008) waste sources in surface water, but application of such microbial source tracking tools to groundwater investigations has been less frequently reported. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.