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D. A. Goolsby

Publications and source records attributed to D. A. Goolsby.

At least 19 recordsLinked to original sources
USGS2009

Source and transport of desethylatrazine and desisopropylatrazine to groundwater of the midwestern United States

Based on usage of the parent compounds and studies of their dissipation in corn fields, atrazine (6-chloro-N-ethyl-N'-(1-methylethyl-1,3,5-triazine-2,4-diamine)), cyanazine (2-[[4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl]amino]-2-methylpropionitrile), and simazine (6-chloro-N,N'diethyl-1,3,5-triazine-2,4-diamine) are thought to be the important contributors of desethylatrazine (6-chloro-N-(1-methylethyl)-1,3,5-triazine-2,4-diamine) or DEA and desisopropylatrazine(6-chloro-N-ethyl)-1,3,5-triazine-2,4-diamine) or DIA to ground water. Atrazine degrades to both DEA and DIA by dealkylation. DEA is transported through the unsaturated zone more readily than DIA because of the more rapid degradation of DIA in the shallow unsaturated zone. Both cyanazine and simazine degrade to DIA by dealkylation, and DIA may be an indicator of leaching and subsequent degradation from both parent compounds. Because cyanazine has an acid intermediate that is mobile in the unsaturated zone, it may be an important source for DIA transport to ground water. Based on a regional survey of ground water of the Midwest during the Spring and Summer of 1991, DEA occurs most frequently with detections of DEA (15.4%) > atrazine (14.7%) > DIA (4%) > simazine (0.7%) > cyanazine (0.3%) > propazine (no detections). The DEA to atrazine ratio (DAR) is an indicator of atrazine source and transport, with the lowest ratios indicating most rapid transport.

ACS Symposium Series↗
USGS2007

Regression models of herbicide concentrations in outflow from reservoirs in the midwestern USA, 1992-1993

Reservoirs are used to store water for public water supply, flood control, irrigation, recreation, hydropower, and wildlife habitat, but also often store undesirable substances such as herbicides. The outflow from 76 reservoirs in the midwestern USA, was sampled four times in 1992 and four times in 1993. At least one herbicide was detected in 82.6 percent of all samples, and atrazine was detected in 82.1 percent of all samples. Herbicide properties; topography, land use, herbicide use, and soil type in the contributing drainage area; residence time of water in reservoirs; and timing of inflow, release, and rainfall all can affect the concentration of herbicides in reservoirs. A GIS was used to quantify characteristics of land use, agricultural chemical use, climatic conditions, topographic character, and soil type by reservoir drainage basins. Multiple linear and logistic regression equations were used to model mean herbicide concentrations in reservoir outflow as a function of these characteristics. Results demonstrate a strong association between mean herbicide concentrations in reservoir outflow and herbicide use rates within associated drainage basins. Results also demonstrate the importance of including soils and basin hydrologic characteristics in models used to estimate mean herbicide concentrations.

Journal of the American Water Resources Associatio↗
USGS2006

Test hold in aquifer with many water-bearing zones at Jacksonville, Florida

One of the deepest water ‐exploration wells in the southeastern United States was completed in 1966 at Jacksonville , Florida . It was drilled to a depth of nearly 2,500 feet to supply geologic and hydrologic information on the deeper unexplored part of the Floridan aquifer . This aquifer consists of a series of water producing zones separated by nonproducing zones . An important new fresh‐ water producing zone was found, and the contact between the fresh water and salt water was located. The well was completed in three separate zones so that it could be used to monitor the the deeper part of the aquifer to detect any salt‐ water encroachment. This paper describes the objectives, techniques, and results of drilling the test well.

Florida↗
USGS2002

Herbicides in surface waters of the midwestern United States: The effect of spring flush

Approximately three-fourths of all preemergent herbicides used in the United States are applied to row crops over a 12-state area, called the "corn belt" (I). The application of these compounds may cause widespread degradation of water quality (2). Because herbicides are water soluble, there is the potential for leaching into groundwater and surface water (3, 4), as well as aerial transport and Occurrence in precipitation (5). Monitoring studies in the Midwest have shown widespread detection of herbicides in groundwater and in surface water (3,4); however, little is known about the regional impact of herbicide application (6). The objective of our research was to assess the mag. nitude and persistence of herbicide runoff in the spring flush at the regional scale.

Environmental Science & Technology↗
USGS2002

A reconnaissance study of herbicides and their metabolites in surface water of the midwestern united states using immunoassay and gas chromatography/mass spectrometry

Preemergent herbicides and their metabolites, particularly atrazine, deethylatrazine, and metolachlor, persisted from 1989 to 1990 in the majority of rivers and streams in the midwestern United States. In spring, after the application of herbicides, the concentrations of atrazine, alachlor, and simazine were frequently 3-10 times greater than the U.S. Environmental Protection Agency maximum contaminant level (MCL). The concentration of herbicides exceeded the MCLs both singly and in combination. Two major degradation products of atrazine (deisopropylatrazine and deethylatrazine) also were found in many of the streams. The order of persistence of the herbicides and their metabolites in surface water was atrazine > deethylatrazine > metolachlor > alachlor > deisopropylatrazine > cyanazine. Storm runoff collected at several sites exceeded the MCL multiple times during the summer months as a function of stream discharge, with increased concentrations during times of increased streamflow. It is proposed that metabolites of atrazine may be used as indicators of surface-water movement into adjacent alluvial aquifers.

Environmental Science & Technology↗
USGS2001

Nitrogen input to the Gulf of Mexico

Historical streamflow and concentration data were used in regression models to estimate the annual flux of nitrogen (N) to the Gulf of Mexico and to determine where the nitrogen originates within the Mississippi Basin. Results show that for 1980-1996 the mean annual total N flux to the Gulf of Mexico was 1 568 000 t yr-1. The flux was about 61% nitrate N, 37% organic N, and 2% ammonium N. The flux of nitrate N to the Gulf has approximately tripled in the last 30 years with most of the increase occurring between 1970 and 1983. The mean annual N flux has changed little since the early 1980s, but large year-to-year variations in N flux occur because of variations in precipitation. During wet years the N flux can increase by 50% or more due to flushing of nitrate N that has accumulated in the soils and unsaturated zones in the basin. The principal source areas of N are basins in southern Minnesota, Iowa, Illinois, Indiana, and Ohio that drain agricultural land. Basins in this region yield 1500 to more than 3100 kg N km-2 yr-1 to streams, several times the N yield of basins outside this region.

Mississippi–Atchafalaya River basin↗
USGS2001

Differentiating nonpoint sources of deisopropylatrazine in surface water using discrimination diagrams

Pesticide degradates account for a significant portion of the pesticide load in surface water. Because pesticides with similar structures may degrade to the same degradate, it is important to distinguish between different sources of parent compounds that have different regulatory and environmental implications. A discrimination diagram, which is a sample plot of chemical data that differentiates between different parent compounds, was used for the first time to distinguish whether sources other than atrazine (6-chloro- N 2 -ethyl- N 4 -isopropyl-1,3,5-triazine-2,4-diamine) contributed the chlorinated degradate, deisopropylatrazine (DIA; 6-chloro- N -ethyl-1,3,5-triazine-2,4-diamine) to the Iroquois and Delaware Rivers. The concentration ratio of deisopropylatrazine to deethylatrazine [6-chloro- N -(1-methylethyl)-1,3,5-triazine-2,4-diamine], called the D 2 R, was used to discriminate atrazine as a source of DIA from other parent sources, such as cyanazine (2-[[4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl]amino]-2-methylpropionitrile) and simazine (6-chloro- N , N ′-diethyl-1,3,5-triazine-2,4-diamine). The ratio of atrazine to cyanazine (ACR) used in conjunction with the D 2 R showed that after atrazine, cyanazine was the main contributor of DIA in surface water. The D 2 R also showed that cyanazine, and to a much lesser extent simazine, contributed a considerable amount (∼40%) of the DIA that was transported during the flood of the Mississippi River in 1993. The D 2 R may continue to be a useful discriminator in determining changes in the nonpoint sources of DIA in surface water as cyanazine is currently being removed from the market.

Kansas↗
USGS2000

Nitrogen flux and sources in the Mississippi River Basin

Nitrogen from the Mississippi River Basin is believed to be at least partly responsible for the large zone of oxygen-depleted water that develops in the Gulf of Mexico each summer. Historical data show that concentrations of nitrate in the Mississippi River and some of its tributaries have increased by factors of 2 to more than 5 since the early 1900s. We have used the historical streamflow and concentration data in regression models to estimate the annual flux of nitrogen (N) to the Gulf of Mexico and to determine where the nitrogen originates within the Mississippi Basin. Results show that for 1980–1996 the mean annual total N flux to the Gulf of Mexico was 1 568 000 t/year. The flux was approximately 61% nitrate as N, 37% organic N, and 2% ammonium as N. The flux of nitrate to the Gulf has approximately tripled in the last 30 years with most of the increase occurring between 1970 and 1983. The mean annual N flux has changed little since the early 1980s, but large year-to-year variations in N flux occur because of variations in precipitation. During wet years the N flux can increase by 50% or more due to flushing of nitrate that has accumulated in the soils and unsaturated zones in the basin. The principal source areas of N are basins in southern Minnesota, Iowa, Illinois, Indiana, and Ohio that drain agricultural land. Basins in this region yield 800 to more than 3100 kg total N/km 2 per year to streams, several times the N yield of basins outside this region. Assuming conservative transport of N in the Mississippi River, streams draining Iowa and Illinois contribute on average approximately 35% of the total N discharged by the Mississippi River to the Gulf of Mexico. In years with high precipitation they can contribute a larger percentage.

Science of Total Environment↗
USGS2000

Atmospheric nitrogen in the Mississippi River Basin: Amissions, deposition and transport

Atmospheric deposition of nitrogen has been cited as a major factor in the nitrogen saturation of forests in the north-eastern United States and as a contributor to the eutrophication of coastal waters, including the Gulf of Mexico near the mouth of the Mississippi River. Sources of nitrogen emissions and the resulting spatial patterns of nitrogen deposition within the Mississippi River Basin, however, have not been fully documented. An assessment of atmospheric nitrogen in the Mississippi River Basin was therefore conducted in 1998-1999 to: (1) evaluate the forms in which nitrogen is deposited from the atmosphere; (2) quantify the spatial distribution of atmospheric nitrogen deposition throughout the basin; and (3) relate locations of emission sources to spatial deposition patterns to evaluate atmospheric transport. Deposition data collected through the NADP/NTN (National Atmospheric Deposition Program/National Trends Network) and CASTNet (Clean Air Status and Trends Network) were used for this analysis. NO(x) Tier 1 emission data by county was obtained for 1992 from the US Environmental Protection Agency (Emissions Trends Viewer CD, 1985-1995, version 1.0, September 1996) and NH3 emissions data was derived from the 1992 Census of Agriculture (US Department of Commerce. Census of Agriculture, US Summary and County Level Data, US Department of Commerce, Bureau of the Census. Geographic Area series, 1995:1b) or the National Agricultural Statistics Service (US Department of Agriculture. National Agricultural Statistics Service Historical Data. Accessed 7/98 at URL, 1998. http://www.usda.gov/nass/pubs/hisdata.htm). The highest rates of wet deposition of NO3- were in the north-eastern part of the basin, downwind of electric utility plants and urban areas, whereas the highest rates of wet deposition of NH4+ were in Iowa, near the center of intensive agricultural activities in the Midwest. The lowest rates of atmospheric nitrogen deposition were on the western (windward) side of the basin, which suggests that most of the nitrogen deposited within the basin is derived from internal sources. Atmospheric transport eastward across the basin boundary is greater for NO3- than NH4+, but a significant amount of NH4+ is likely to be transported out of the basin through the formation of (NH4)2SO4 and NH4NO3 particles - a process that greatly increases the atmospheric residence time of NH4+. This process is also a likely factor in the atmospheric transport of nitrogen from the Midwest to upland forest regions in the North-East, such as the western Adirondack region of New York, where NH4+ constitutes 38% of the total wet deposition of N.

Science of Total Environment↗
USGS2000

Pesticides in the atmosphere of the Mississippi River Valley, part I: Rain

Weekly composite rainfall samples were collected in three paired urban and agricultural regions of the Midwestern United States and along the Mississippi River during April–September 1995. The paired sampling sites were located in Mississippi, Iowa, and Minnesota. A background site, removed from dense urban and agriculture areas, was located near Lake Superior in Michigan. Herbicides were the predominant type of pesticide detected at every site. Each sample was analyzed for 47 compounds and 23 of 26 herbicides, 13 of 18 insecticides, and three of three related transformation products were detected in one or more sample from each paired site. The detection frequency of herbicides and insecticides were nearly equivalent at the paired Iowa and Minnesota sites. In Mississippi, herbicides were detected more frequently at the agricultural site and insecticides were detected more frequently at the urban site. The highest total wet depositional amounts (μg pesticide/m 2 per season) occurred at the agricultural sites in Mississippi (1980 μg/m 2 ) and Iowa (490 μg/m 2 ) and at the urban site in Iowa (696 μg/m 2 ). Herbicides accounted for the majority of the wet depositional loading at the Iowa and Minnesota sites, but methyl parathion (1740 μg/m 2 ) was the dominant compound contributing to the total loading at the agricultural site in Mississippi. Atrazine, CIAT (a transformation product of atrazine and propazine) and dacthal were detected most frequently (76, 53, and 53%, respectively) at the background site indicating their propensity for long-range atmospheric transport.

Mississippi River Valley↗
USGS2000

Changes in herbicide concentrations in Midwestern streams in relation to changes in use, 1989-1998

Water samples were collected from Midwestern streams in 1994–1995 and 1998 as part of a study to help determine if changes in herbicide use resulted in changes in herbicide concentrations since a previous reconnaissance study in 1989–1990. Sites were sampled during the first significant runoff period after the application of pre-emergent herbicides in 1989–1990, 1994–1995, and 1998. Samples were analyzed for selected herbicides, two atrazine metabolites, three cyanazine metabolites, and one alachlor metabolite. In the Midwestern USA, alachlor use was much greater in 1989 than in 1995, whereas acetochlor was not used in 1989 but was commonly used in 1995. The use of atrazine, cyanazine, and metolachlor was approximately the same in 1989 and 1995. The median concentrations of atrazine, alachlor, cyanazine, and metolachlor were substantially higher in 1989–1990 than in 1994–1995 or 1998. The median acetochlor concentration was higher in 1998 than in 1994 or 1995.

Science of Total Environment↗
USGS1999

Seasonal and annual load of herbicides from the Mississippi River Basin to the Gulf of Mexico

Water samples collected from rivers in the Mississippi River Basin were analyzed for selected herbicides to evaluate their discharge to the Gulf of Mexico and to identify their predominant source areas within the basin. Samples were collected from the Mississippi River at Baton Rouge, LA from 1991 to 1997 and from sites on the upper Mississippi, the Missouri, and the Ohio Rivers from 1996 to 1997. Atrazine, metolachlor, and alachlor ESA (an alachlor metabolite) were the most frequently detected herbicides in the Mississippi River at Baton Rouge, and, in general, were present in the largest concentrations. The peak annual herbicide load was in 1993 when about 640 metric tons of atrazine, 320 metric tons of cyanazine, 215 metric tons of metolachlor, 53 metric tons of simazine, and 50 metric tons of alachlor were discharged to the Gulf of Mexico. The annual load of atrazine and cyanazine was generally 1−3% of the amount annually applied in the Mississippi River drainage basin; the annual load of acetochlor, alachlor, and metolachlor was generally less than 1%. During 1996−1997 the Ohio River contributed about 50% of the discharge and 50% or more of the herbicide load to the Gulf of Mexico.

Environmental Science & Technology↗
USGS1999

Occurrence and transport of acetochlor in streams of the Mississippi River Basin

The herbicide acetochlor [2-chloro- N -(ethoxymethyl)- N -(2-ethyl-6-methylphenyl) acetamide] was first used on corn ( Zea mays L.) in the USA during the growing season of 1994. By 1996, it was the third most heavily used corn herbicide in the midwestern USA. During the growing season of 1997, 78% of 375 samples collected at 32 stream sites in the Mississippi River Basin contained detectable concentrations of acetochlor. However, concentrations in only 2% of the samples exceeded 2/µg/L, the maximum annual average concentration allowable in public water supplies derived primarily from surface water. The largest acetochlor concentrations were detected in streams draining basins in parts of Illinois, Indiana, and Iowa. The median concentration of acetochlor in streams was about 10% that of atrazine (6-chloro- N -ethyl- N -isopropyl-1,3,5-triazine-2,4-diamine), about 25% that of metolachlor [2-chloro- N -(2-ethyl-6-methylphenyl)- N -(2-methoxy-1-methylethyl) acetamide], about 50% that of cyanazine [2-[[4-chloro-6-(ethylamino)-l,3,5-triazin-2-yl]amino]-2-methylpropionitrile], and about threefold that of alachlor [2-chloro-2′,6′-diethyl- N -(methoxymethyl) acetanilide]. Load estimates indicate that, during the growing season of 1997, agricultural subbasins draining areas of Illinois, Indiana, and Iowa contributed about 37 000 kg, or 74%, of the 50 000 kg of acetochlor measured in streams of the Mississippi River Basin.

Journal of Environmental Quality↗
USGS1998

Evaluation of microtiter-plate enzyme-linked immunosorbent assay for the analysis of triazine and chloroacetanilide herbicides in rainfall

Triazine and chloroacetanilide concentrations in rainfall samples collected from a 23-state region of the United States were analyzed with microtiter-plate enzyme-linked immunosorbent assay (ELISA). Thirty-six percent of rainfall samples (2072 out of 5691) were confirmed using gas chro matography/mass spectrometry (GC/MS) to evaluate the operating performance of ELISA as a screening test. Comparison of ELISA to GC/MS results showed that the two ELISA methods accurately reported GC/MS results ( m = 1), but with more variability evident with the triazine than with the chloroacetanilide ELISA. Bayes's rule, a standardized method to report the results of screening tests, indicated that the two ELISA methods yielded comparable predictive values (80%), but the triazine ELISA yielded a false-positive rate of 11.8% and the chloroacetanilide ELISA yielded a false-negative rate of 23.1%. The false-positive rate for the triazine ELISA may arise from cross reactivity with an unknown triazine or metabolite. The false-negative rate of the chloroacetanilide ELISA probably resulted from a combination of low sensitivity at the reporting limit of 0.15 μg/L and a distribution characterized by 75% of the samples at or below the reporting limit of 0.15 μg/L.

Environmental Science & Technology↗
USGS1998

Herbicides in ground water of the Midwest: A regional study of shallow aquifers, 1991-94

The intensive herbicide use associated with the 'Corn Belt' marks the Midwestern United States as a region where herbicide contamination of ground water could be a problem. To better understand the regional occurrence of herbicides in shallow aquifers of the Midwest, a sampling network of 303 wells across 12 States was developed. The results documented relatively widespread, low-level concentrations of herbicides in the shallow aquifers sampled. The most frequently detected compounds, however, were the transformation products of these herbicides. A relation was determined between herbicide occurrence and the general age of the ground water sampled. Water that recharged ground water within the past 40 years was much more likely to contain herbicides than water recharged earlier.

Midwest↗