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Water and sediment samples were collected from June through October 2007 from seven plots at the Rutgers Agricultural Research and Extension Center in Upper Deerfield, New Jersey, and analyzed for a suite of pesticides (including fungicides) and other physical and chemical parameters (including sediment mineralogy) by the U.S. Geological Survey. Plots were selected for inclusion in this study on the basis of the crops grown and the pesticides used. Forty-one pesticides were detected in 14 water samples; these include 5 fungicides, 13 herbicides, 1 insecticide, and 22 pesticide degradates. The following pesticides and pesticide degradates were detected in 50 percent or more of the groundwater samples: 1-amide4-hydroxy-chorothalonil, alachlor sulfonic acid, metolachlor oxanilic acid, metolachlor sulfonic acid, metalaxyl, and simazine. Dissolved-pesticide concentrations ranged from below their instrumental limit of detection to 36 micrograms per liter (for metolachlor sulfonic acid, a degradate of the herbicide metolachlor). The total number of pesticides found in groundwater samples ranged from 0 to 29. Fourteen pesticides were detected in sediment samples from continuous cores collected within each of the seven sampled plots; these include 4 fungicides, 2 herbicides, and 7 pesticide degradates. Pesticide concentrations in sediment samples ranged from below their instrumental limit of detection to 34.2 nanograms per gram (for azoxystrobin). The total number of pesticides found in sediment samples ranged from 0 to 8. Quantitative wholerock and grain-coating mineralogy of sediment samples were determined by x-ray diffraction. Whole-rock analysis indicated that sediments were predominantly composed of quartz. The materials coating the quartz grains were removed to allow quantification of the trace mineral phases present. Introduction Pesticides are used in conventional agriculture to protect crops from a loss of yield or damage due to the presence of unwanted plants, insects, and (or) fungal pathogens. More than 4,900 active ingredients are present in the approximately 64,000 pesticide products currently registered for use in the United States (U.S. Environmental Protection Agency, 2012). In 2007, 684 million pounds of active pesticide ingredients were applied for agricultural use in the United States at a total cost of more than $7.8 billion (Grube and others, 2011). Even with the use of pesticides, there were losses in yields of commodity crops (such as wheat, corn, potatoes, and rice) of 26 to 40 percent worldwide during 2001–03 (Oercke, 2006). Pesticide manufacturers are continually developing new chemicals and formulations in an effort to find more effective treatments and to outpace the rate at which agricultural pests acquire resistance to them. This research and development, together with the deregistration of pesticides by regulatory bodies, causes pesticide-use patterns to change over time. Although the presence of pesticides and pesticide degradates in groundwater supplies is well documented (Barbash and Resek, 1996; Kolpin and others, 2000; Stuart and others, 2006; Steele and others, 2008), changes in use patterns, the introduction of new pesticides, and the advent of new analytical approaches motivates continued study. The purpose of many studies to date has been to document the concentrations of pesticides in a given groundwater supply, which is accomplished by sampling drinking-water, irrigation, or monitoring wells screened within the subject aquifer. Although such studies provide valuable information about the ambient concentrations of pesticides in an aquifer, the source or sources of the pesticides present can be difficult to ascertain as a result of 2 Occurrence of Pesticides and Mineralogy of Sediments, Rutgers Agricultural Research and Extension Center, 2007 differences in the size of the contributing area, recharge rates, and pesticide usage associated with the wells. In studies in which a primary objective is to determine whether a pesticide can reach the aquifer, a more focused approach is required. To ensure that the composition of the sampled groundwater is directly related to the overlying land-use practice, the contributing area of the sampled well must be minimized. This objective can be accomplished by installing temporary monitoring wells where the well screen penetrates the aquifer only as far as is necessary to produce sufficient water for sampling. If such a well is sampled at as low a flow rate as possible, the contributing area is minimized and the effect of land use can be characterized by the practices employed near the well head. Such wells can be installed, sampled, and properly abandoned by using direct-drive systems mounted to trucks or small allterrain vehicles within 1 day. This approach allows access to sensitive areas (such as active farm fields) where larger scale drilling equipment would be disruptive and permanent well installations are not possible. This method can also be used to evaluate temporal changes in water quality by repeating the installation at the desired time intervals. A study was conducted by the U.S. Geological Survey (USGS) as part of its Toxic Substances Hydrology (Toxics) Program to measure the concentrations of currently used pesticides (especially fungicides) present in shallow groundwater (generally 1–5 feet (ft) below the water table) and in saturated and unsaturated sediments beneath fields with known pesticide use. The composition of grain coatings present on underlying sediments was determined to assess the role of grain coatings in the storage of organic and inorganic chemicals in the unsaturated and saturated zones. In 2007, field sampling focused on seven research plots at an agricultural research station in New Jersey. Water-quality results from this study can be used to focus future efforts of the USGS Toxics Program and other researchers to better understand the occurrence and fate of pesticides (particularly fungicides) in the unsaturated-zone and shallow groundwater systems. Purpose and Scope This report documents the presence of currently used pesticides and pesticide degradates (particularly fungicides) in groundwater and sediments underlying treated agricultural fields, evaluates the composition of and depositional and digenetic history of grain coatings present on Bridgeton Formation and weathered Coastal Plain sediments, and describes the role of grain coatings in the storage of organic and inorganic chemicals in the unsaturated and saturated zones. In 2007, groundwater and sediments were collected and analyzed for a suite of currently used pesticides and degradates. Sampling focused on seven research plots at the Rutgers Agricultural Research and Extension Center (RAREC) in Upper Deerfield, New Jersey (fig. 1). Six of the seven plots are routinely used by the RAREC staff to conduct variety trials of row crops that, when grown using conventional agricultural practices, are regularly treated with fungicides. The variety trial plots at RAREC are typically treated with pesticides in accordance with the recommendations that the RAREC staff provide to local growers. Consequently, the timing, amount, and type of pesticide treatments used on RAREC variety trial plots are similar to those used by local growers. This study was conducted at the RAREC to take advantage of the comprehensive pesticide application records it maintains and because RAREC was willing to permit USGS scientists to sample plots prior to harvest. Groundwater and sediment from a plot at the RAREC that has not been treated with pesticides within the past 20 years or more was included in the study to serve as a control plot. This report documents the waterand sedimentquality results from this study. Concentrations of total and dissolved organic carbon, nutrients, metals and major ions, and water-quality field parameters in water samples; physical characteristics of sediments (core descriptions, mineralogy, and grain size); and concentrations of sediment-associated organic carbon, nutrients, and ions are also presented. Geologic Setting The study area is located within an agricultural watershed in Upper Deerfield Township, New Jersey (fig. 1). The watershed is in the Coastal Plain of southern New Jersey, a seawarddipping wedge of unconsolidated sands and clays that range in age from Cretaceous to Holocene (Zapecza, 1989). Sediments that compose the unsaturated zone and the shallow aquifer in the study area are made up of the Miocene Bridgeton Formation and weathered Coastal Plain deposits (Newell and others, 2000). The Bridgeton Formation is characterized by coarse, pebbly, orange sands and was deposited in the late Miocene Epoch in a former fluvial plain environment (Zapecza, 1989; Newell and others, 2000). This formation is present as the caps of hills in the southern Coastal Plain with a maximum thickness of approximately 40 ft (Newell and others, 2000). Newell and others (2000) described weathered Coastal Plain deposits as exposures of weathered outcrops of Coastal Plain formations overlain by thin alluvium and colluvium. The Cohansey Formation underlies the Bridgeton Formation and is an unconsolidated, medium-to-coarse quartz sand with locally substantial clay beds, and was deposited in the inner neritic to nearshore environments during a Miocene regression (Zapecza, 1989). Distinctive strata local to this study area have been documented by Baehr and others (2003). Field observations distinguish the unsaturated zone from the overlying soils on the basis of differing color, grain size, and the presence of plant fragments in the soils. Salisbury (1898) first described the Bridgeton Formation as a surficial feldspathic sand. Later refinements by Salisbury and Knapp (1917) divided the formation into two members, the Glassboro phase and the Woodmansie phase. The Glassboro phase, underlying the present study location, is described as locally arkosic. Owens and Minard

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Occurrence of pesticides in groundwater and sediments and mineralogy of sediments and grain coatings underlying the Rutgers Agricultural Research and Extension Center, Upper Deerfield, New Jersey, 2007