Frequently co‐occurring pesticides and volatile organic compounds in public supply and monitoring wells, southern New Jersey, USA

Abstract

One or more pesticides were detected with one or more volatile organic compounds (VOCs) in more than 95% of samples collected from 30 public supply and 95 monitoring wells screened in the unconsolidated surficial aquifer system of southern New Jersey, USA. Overall, more than 140,000 and more than 3,000 unique combinations of pesticides with VOCs were detected in two or more samples from the supply and monitoring wells, respectively. More than 400 of these combinations were detected in 20% or more of the samples from the supply wells, whereas only 17 were detected in 20% or more of the samples from the monitoring wells. Although many constituent combinations detected in water from the supply and monitoring wells are similar, differences in constituent combinations also were found and can be attributed, in part, to differences in the characteristics of these two well types. The monitoring wells sampled during this study yield water that typically was recharged beneath a single land-use setting during a recent, discrete time interval and that flowed along relatively short paths to the wells. Public supply wells, in contrast, yield large volumes of water and typically have contributing areas that are orders of magnitude larger than those of the monitoring wells. These large contributing areas generally encompass multiple land uses; moreover, because flow paths that originate in these areas vary in length, these wells typically yield water that was recharged over a large temporal interval. Water withdrawn from public supply wells, therefore, contains a mixture of waters of different ages that were recharged beneath various land-use settings. Because public supply wells intercept water flowing along longer paths with longer residence times and integrate waters from a larger source area than those associated with monitoring wells, they are more likely to yield water that contains constituents that were used in greater quantities in the past, that were introduced from point sources, and/or that are derived from the degradation of parent compounds along extended flow paths.

Persistence of pharmaceutical compounds and other organic wastewater contaminants in a conventional drinking-water-treatment plant

“…Moreover, drinking-water criteria currently are based on the toxicity of individual compounds and not combinations of compounds. The possibility that exposure to multiple organic compounds, even at low concentrations, may have a synergistic humanhealth consequence is an area of recent research (Birader and Rayburn, 1995;Marinovich et al, 1996), and the co-occurrence of organic compounds in drinking-water supplies has recently been documented (Stackelberg et al, 2001;Squillace et al, 2002). In this study, 11-17 different OWCs were detected in each of the four samples of finished water.…”

Pharmaceuticals, Hormones, and Other Organic Wastewater Contaminants in U.S. Streams, 1999−2000: A National Reconnaissance

“…Thus, the results of this study suggest that additional research on the toxicity of the target compounds should include not only the individual OWCs but also mixtures of these compounds. The prevalence of multiple compounds in water resources has been previously documented for other contaminants (52,53). In addition, research has shown that select chemical combinations can exhibit additive or synergistic toxic effects (54)(55)(56), with even compounds of different modes of action having interactive toxicological effects (57).…”

VOCs, Pesticides, Nitrate, and Their Mixtures in Groundwater Used for Drinking Water in the United States

“…Shallower wells generally are considered more prone to anthropogenic contamination than deeper wells. Public supply wells can have high pumping rates and large capture zones, which can increase the number of potential contamination sources (8). Unconfined aquifers generally are considered more prone to contamination than confined aquifers.…”

“…Nevertheless, identification of common mixtures of contaminants in water can be viewed as a first step toward defining exposure. Common mixtures on a national scale may differ from those on a regional or local scale; consequently, there is also a need to conduct smallerscale studies such as was done in southern New Jersey (8). Common mixtures in groundwater may not be the most toxic from a health perspective, but human exposure to these mixtures is prevalent.…”