Skidaway Institute of Oceanography, Savannah, GA 31416, U.S.A.. (Received 5 April, 1993; accepted in final form 15 October, 1993). Abstract. Water samples ...
MERCURY SPECIES IN POTABLE GROUND WATER IN SOUTHERN NEW JERSEY EILEEN A. MURPHY NJ Dept. of Environmental Protection, Division of Science & Research, Trenton, NJ 08625, U.S.A.
JOHN DOOLEY NJ Department of Environmental Protection, NJ Geological Survey, Trenton, NJ 08625, U.S.A.
and HERBERT L. WINDOM and RALPH G. SMITH, JR. Skidaway Institute of Oceanography, Savannah, GA 31416, U.S.A. (Received 5 April, 1993; accepted in final form 15 October, 1993) Abstract. Water samples from 78 private potable wells in southern New Jersey were collected for
mercury analysis in 1991-1992. Analyses were performed for the quantification of reactive, volatile and methyl mercury species. Relationships of mercury with other water quality parameters were evaluated also. Total mercury concentrations varied from < 1 ng L -1 to over 36 #g L -1. The dominant forms in which mercury occurred in the wells sampled were Hg ~ and HgC12~ although methyl mercury was present in some wells and comprised up to 8% of the total mercury in the ground water samples.
1. Introduction In the late 1980's, private drinking water wells in Atlantic County, New Jersey (NJ) were found to contain levels of mercury above the 2 micrograms per liter (#g L -1 or parts per billion) maximum contaminant level (MCL) set by the U.S. Environmental Protection Agency (USEPA) for public drinking water (USEPA, 1991). To date, water samples from more than 250 potable domestic wells completed in the upper Kirkwood-Cohansey aquifer system in the NJ Coastal Plain have been found to exceed the 2 #g L-1 MCL for mercury. Specific point sources of mercury to account for the extensive contamination of wells have not been identified. Currently, NJ is investigating the impact of landfills, atmospheric deposition, historical use of mercurial pesticides and abandoned munitions depositories on mercury contamination of ground water. Preliminary results indicate that multiple sources are responsible. This project focuses on the evaluation of analytical methodologies for mercury determinations and speciation in ground water from contaminated as well as unaffected wells in southem NJ. The species or type of mercury compound is important to identify because different mercury species behave differently in the environment as well as in the human body. The study described here represents one of the first detailed investigations of mercury species in ground water in the available literature. Water, Air and Soil Pollution 78: 61-72, 1994. (~ 1994 Kluwer Academic Publishers. Printed in the Netherlands.
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2. Experimental 2.1. SAMPLINGDESIGN Thirty-three private, potable wells in Atlantic County, NJ were selected based on prior water sampling conducted by the Atlantic County Department of Health (ACDOH) and by NJ Department of Environmental Protection and Energy (NJDEPE). The remaining 45 wells were selected from areas in surrounding counties where prior water sampling had not occurred, no known instances of mercury contamination had occurred, no known point sources existed within 5 miles of the well, and where no previous data had been collected. Although formal well records were not available for all wells sampled, they were available for the majority of wells. In other cases, information was retrieved through interviews with well owners. All wells were less than 46 m deep. Well construction materials consisted of either PVC pipe or stainless steel. There was no correlation in the ACDOH database between well construction materials and mercury contamination. The wells were purged at maximum flow rate for 5-10 min, based on the depth of the well and the diameter of the bore/casing (typically 5 cm). In most cases, purging and sampling was conducted at taps before holding tanks. When samples were collected after the holding tank, the well was purged an addition few minutes. Wells were purged thusly to ensure that representative formation waters were collected rather than standing water in the well. Water samples for mercury analysis were collected and stored in borosilicate glass bottles. These bottles were thoroughly cleaned by washing with Micro (International Products Corp.) detergent followed by soaking in hot concentrated HNO3 for 72 hr. Tap water at the Skidaway lab was found to have lower mercury levels (
