Occurrence of Pesticides in Shallow Groundwater of the United States:  Initial Results from the National Water-Quality Assessment Program

Abstract

The first phase of intensive data collection for the National Water-Quality Assessment (NAWQA) was completed during 1993-1995 in 20 major hydrologic basins of the United States. Groundwater land-use studies, designed to sample recently recharged groundwater (generally within 10 years) beneath specific land-use and hydrogeologic settings, are a major component of the groundwater quality assessment for NAWQA. Pesticide results from the 41 landuse studies conducted during 1993-1995 indicate that pesticides were commonly detected in shallow groundwater, having been found at 54.4% of the 1034 sites sampled in agricultural and urban settings across the United States. Pesticide concentrations were generally low, with over 95% of the detections at concentrations less than 1 µg/L. Of the 46 pesticide compounds examined, 39 were detected. The compounds detected most frequently were atrazine (38.2%), deethylatrazine (34.2%), simazine (18.0%), metolachlor (14.6%), and prometon (13.9%). Statistically significant relations were observed between frequencies of detection and the use, mobility, and persistence of these compounds. Pesticides were commonly detected in both agricultural (56.4%; 813 sites) and urban (46.6%; 221 sites) settings. Frequent detections of pesticides in urban areas indicate that, as is the case with agricultural pesticide use in agricultural areas, urban and suburban pesticide use significantly contribute to pesticide occurrence in shallow groundwater. Although pesticides were detected in groundwater sampled in urban areas and all nine of the agricultural land-use categories examined, significant variations in occurrence were observed among these categories. Maximum contaminant levels (MCLs) established by the U.S. Environmental Protection Agency for drinking water were exceeded for only one pesticide (atrazine, 3 µg/L) at a single location. However, MCLs have been established for only 25 of the 46 pesticide compounds examined, do not cover pesticide degradates, and, at present, do not take into account additive or synergistic effects of combinations of pesticide compounds or potential effects on nearby aquatic ecosystems.

On the scope and management of pesticide pollution of Swedish groundwater resources: The Scanian example

“…As noted earlier, similar indications have been demonstrated also in other regions including e.g., the US (Kolpin et al 1998) and Denmark . One could speculate whether the major urban influence might result from a relative lack of restrictions in terms of non-agricultural compared to agricultural pesticide use.…”

“…However, it is difficult to compare these numbers directly in view of varying investigative scope and approach, and this study arguably allows for a relatively more thorough assessment in view of the detailed analysis records compiled (including conducted low-LOQ analyses). Either way, pesticide pollution of Scanian groundwater seems a genuine concern on par with established situations in many other industrial countries, in terms of overall DF, concentration levels, and frequently occurring substances (Kolpin et al 1998;Haarstad and Ludvigsen 2007;Schipper et al 2008;Close and Skinner 2012;Thorling et al 2012), and questions the previous reports of no danger of pesticide pollution of groundwater for Sweden as a whole (European Environment Agency 2004).…”

Emerging organic contaminants in groundwater: A review of sources, fate and occurrence

“…Agricultural pesticides and their degradates have not been included in this review; the environmental occurrence of this group of organic contaminants is better characterised and reviewed compared with many other groups of EOCs and are better regulated with respect to drinking water standards in many countries (Leistra and Boesten, 1989;Ritter, 1990;Kolpin et al, 1998;Murray et al, 2010;Stuart et al, 2011).…”

“…Eckel et al, 1993;Holm et al, 1995), as well as indirectly through the process of groundwater-surface water (GW-SW) exchange (Buerge et al, 2009). Recent reviews have covered the occurrence of EOCs in surface waters used for public water supply (Houtman, 2010), the sources, occurrence and fate of 'emerging organic contaminants' (EOCs) in surface water sources (Pal et al, 2010), and trace pollutants and EOCs in fresh water sources (Murray et al, 2010 (Leistra and Boesten, 1989;Ritter, 1990;Kolpin et al, 1998;Murray et al, 2010;Stuart et al, 2011). …”

A field study to assess the degradation and transport of diuron and its metabolites in a calcareous soil

“…In the United States, a considerable body of work exists relating to the occurrence of both parent compound pesticides and their metabolites in aquifers (Thurman et al, 1992;Baker et al, 1993;Lawrence et al, 1993;Kolpin et al, 1996;Kolpin et al, 1998;Kolpin et al, 2000a;Kolpin et al, 2000b). In the UK the number of field studies has been limited (Clark et al, 1991;Gooddy et al, 2001;Johnson et al, 2001) with researchers often concentrating on laboratory studies of transport and degradation potential (Johnson et al, 1998;Besien et al, 2000;.…”