Geology topics

Paul D. Capel

Publications and source records attributed to Paul D. Capel.

At least 37 records · Page 2Linked to original sources

USGS2012

Eleven-year trend in acetanilide pesticide degradates in the Iowa River, Iowa

Trends in concentration and loads of acetochlor, alachlor, and metolachlor and their ethanasulfonic (ESA) and oxanilic (OXA) acid degradates were studied from 1996 through 2006 in the main stem of the Iowa River, Iowa and in the South Fork Iowa River, a small tributary near the headwaters of the Iowa River. Concentration trends were determined using the parametric regression model SEAWAVE-Q, which accounts for seasonal and flow-related variability. Daily estimated concentrations generated from the model were used with daily streamflow to calculate daily and yearly loads. Acetochlor, alachlor, metolachlor, and their ESA and OXA degradates were generally present in >50% of the samples collected from both sites throughout the study. Their concentrations generally decreased from 1996 through 2006, although the rate of decrease was slower after 2001. Concentrations of the ESA and OXA degradates decreased from 3 to about 23% yr -1 . The concentration trend was related to the decreasing use of these compounds during the study period. Decreasing concentrations and constant runoff resulted in an average reduction of 10 to >3000 kg per year of alachlor and metolachlor ESA and OXA degradates being transported out of the Iowa River watershed. Transport of acetochlor and metolachlor parent compounds and their degradates from the Iowa River watershed ranged from <1% to about 6% of the annual application. These trends were related to the decreasing use of these compounds during the study period, but the year-to-year variability cannot explain changes in loads based on herbicide use alone. The trends were also affected by the timing and amount of precipitation. As expected, increased amounts of water moving through the watershed moved a greater percentage of the applied herbicides, especially the relatively soluble degradates, from the soils into the rivers through surface runoff, shallow groundwater inflow, and subsurface drainage.

Iowa;Minnesota↗

USGS2012

Selected historic agricultural data important to environmental quality in the United States

This report and the accompanying tables summarize some of the important changes in American agriculture in the form of a timeline and a compilation of selected annual time-series data that can be broadly related to environmental quality. Although these changes have been beneficial for increasing agricultural production, some of them have resulted in environmental concerns. The agriculture timeline is divided into four categories (1) crop and animal changes, (2) mechanical changes, (3) biological and chemical changes, and (4) regulatory and societal changes. The timeline attempts to compile events that have had a lasting impact on agriculture in the United States. The events and data presented in this report may help to improve the connections between agricultural activist and environmental concerns.

Data Series↗

USGS2012

Changes in water budgets and sediment yields from a hypothetical agricultural field as a function of landscape and management characteristics--A unit field modeling approach

Crop agriculture occupies 13 percent of the conterminous United States. Agricultural management practices, such as crop and tillage types, affect the hydrologic flow paths through the landscape. Some agricultural practices, such as drainage and irrigation, create entirely new hydrologic flow paths upon the landscapes where they are implemented. These hydrologic changes can affect the magnitude and partitioning of water budgets and sediment erosion. Given the wide degree of variability amongst agricultural settings, changes in the magnitudes of hydrologic flow paths and sediment erosion induced by agricultural management practices commonly are difficult to characterize, quantify, and compare using only field observations. The Water Erosion Prediction Project (WEPP) model was used to simulate two landscape characteristics (slope and soil texture) and three agricultural management practices (land cover/crop type, tillage type, and selected agricultural land management practices) to evaluate their effects on the water budgets of and sediment yield from agricultural lands. An array of sixty-eight 60-year simulations were run, each representing a distinct natural or agricultural scenario with various slopes, soil textures, crop or land cover types, tillage types, and select agricultural management practices on an isolated 16.2-hectare field. Simulations were made to represent two common agricultural climate regimes: arid with sprinkler irrigation and humid. These climate regimes were constructed with actual climate and irrigation data. The results of these simulations demonstrate the magnitudes of potential changes in water budgets and sediment yields from lands as a result of landscape characteristics and agricultural practices adopted on them. These simulations showed that variations in landscape characteristics, such as slope and soil type, had appreciable effects on water budgets and sediment yields. As slopes increased, sediment yields increased in both the arid and humid environments. However, runoff did not increase with slope in the arid environment as was observed in the humid environment. In both environments, clayey soils exhibited the greatest amount of runoff and sediment yields while sandy soils had greater recharge and lessor runoff and sediment yield. Scenarios simulating the effects of the timing and type of tillage practice showed that no-till, conservation, and contouring tillages reduced sediment yields and, with the exception of no-till, runoff in both environments. Changes in land cover and crop type simulated the changes between the evapotransporative potential and surface roughness imparted by specific vegetations. Substantial differences in water budgets and sediment yields were observed between most agricultural crops and the natural covers selected for each environment: scrub and prairie grass for the arid environment and forest and prairie grass for the humid environment. Finally, a group of simulations was performed to model selected agricultural management practices. Among the selected practices subsurface drainage and strip cropping exhibited the largest shifts in water budgets and sediment yields. The practice of crop rotation (corn/soybean) and cover cropping (corn/rye) were predicted to increase sediment yields from a field planted as conventional corn.

Scientific Investigations Report↗

USGS2011

Discrete and continuous water-quality data and hydrologic parameters from seven agricultural watersheds in the United States, 2002-09

Field and analytical methods; discrete organic and non-organic water-quality data and associated quality-control data; and continuous hydrologic and water-quality parameters are reported for sites in California, Indiana, Iowa, Maryland, Mississippi, Nebraska, and Washington. The sites were sampled as part of the U.S. Geological Survey National Water-Quality Assessment Program?s Agricultural Chemicals Team study to better understand how environmental processes and agricultural practices interact to determine the transport and fate of agricultural chemicals in the environment.

Data Series↗

USGS2011

Environmental factors that influence the location of crop agriculture in the conterminous United States

This report presents and describes high-resolution geospatial data identifying the range of environmental conditions that influence the location of cropped agricultural lands in the conterminous United States. Also presented are estimates of the extent of land where environmental constraints limit agricultural production (marginal land) and the extents of land where modifications overcome environmental constraints. The report is the result of the compilation and manipulation of datasets from numerous sources; it consists of an explanatory text and a series of appendixes and associated tables that document the data sources and data-manipulation methods in detail. Environmental factors that influence the extent of crop agriculture are terrain, climate, soil properties, and soil water. It is the combination of these four factors that allow specific crops to be grown in certain areas. Today, in order to maximize production, most of the cultivated croplands and grasslands for commercial agriculture are in areas where crops and livestock are well suited to local conditions. In the United States, cropland (row crops, closely sown crops (except hay), fruits, nuts, vegetables) occupies about 13 percent of the total land area. Grassland and rangeland occupy another 41 percent of the land area. Most crops are grown on land with shallow slope where the temperature, precipitation, and soils are favorable. In areas that are too steep, wet, or dry, landscapes have been modified to allow cultivation. Some of the limitations of the environmental factors that determine the location of agriculture can be overcome through modifications, but others cannot. On a larger-than-field scale, agricultural modifications commonly influence water availability through irrigation and (or) drainage and soil fertility and (or) organic-matter content through amendments such as manure, commercial fertilizer and lime. In general, it is not feasible to modify the other environmental factors, soil texture, soil depth, soil mineralogy, temperature, and terrain at large scales.

Scientific Investigations Report↗

USGS2008

Pesticides in rain in four agricultural watersheds in the United States

Rainfall samples were collected during the 2003 and 2004 growing seasons at four agricultural locales across the USA in Maryland, Indiana, Nebraska, and California. The samples were analyzed for 21 insecticides, 18 herbicides, three fungicides, and 40 pesticide degradates. Data from all sites combined show that 7 of the 10 most frequently detected pesticides were herbicides, with atrazine (70%) and metolachlor (83%) detected at every site. Dacthal, acetochlor, simazine, alachlor, and pendimethalin were detected in more than 50% of the samples. Chlorpyrifos, carbaryl, and diazinon were the only insecticides among the 10 most frequently detected compounds. Of the remaining pesticide parent compounds, 18 were detected in fewer than 30% of the samples, and 13 were not detected. The most frequently detected degradates were deethylatrazine; the oxygen analogs (OAs) of the organophosphorus insecticides chlorpyrifos, diazinon, and malathion; and 1-napthol (degradate of carbaryl). Deethylatrazine was detected in nearly 70% of the samples collected in Maryland, Indiana, and Nebraska but was detected only once in California. The OAs of chlorpyrifos and diazinon were detected primarily in California. Degradates of the acetanilide herbicides were rarely detected in rain, indicating that they are not formed in the atmosphere or readily volatilized from soils. Herbicides accounted for 91 to 98% of the total pesticide mass deposited by rain except in California, where insecticides accounted for 61% in 2004. The mass of pesticides deposited by rainfall was estimated to be less than 2% of the total applied in these agricultural areas.

Journal of Environmental Quality↗

USGS2005

Evaluation of unsaturated-zone solute-transport models for studies of agricultural chemicals

Seven unsaturated-zone solute-transport models were tested with two data sets to select models for use by the Agricultural Chemical Team of the U.S. Geological Survey's National Water-Quality Assessment Program. The data sets were from a bromide tracer test near Merced, California, and an atrazine study in the White River Basin, Indiana. In this study the models are designated either as complex or simple based on the water flux algorithm. The complex models, HYDRUS2D, LEACHP, RZWQM, and VS2DT, use Richards' equation to simulate water flux and are well suited to process understanding. The simple models, CALF, GLEAMS, and PRZM, use a tipping-bucket algorithm and are more amenable to extrapolation because they require fewer input parameters. The purpose of this report is not to endorse a particular model, but to describe useful features, potential capabilities, and possible limitations that emerged from working with the model input data sets. More rigorous assessment of model applicability involves proper calibration, which was beyond the scope of this study. Uncalibrated ("cold") simulations were run using all seven models to predict the transport of bromide (Merced) and the transport and fate of atrazine and three of its transformation products (White River Basin). Among the complex models, HYDRUS2D successfully predicted both the surface retention and accumulation of bromide at depth at the Merced site, whereas RZWQM and VS2DT predicted only the latter. RZWQM predictions of atrazine were closest to observed values at the White River Basin site, where preferential flow has been observed. LEACHP predicted smaller solute concentrations than observed at both the Merced and White River Basin sites. Among the simple models, CALF predicted the highest values of atrazine and deethylatrazine at the measurement depth of 1.5 meters. CALF includes the Addiscott flow option for preferential flow, and also accepts user-specified dispersivity. PRZM underpredicted solute concentrations, probably because control of dispersion is a problem with this model. GLEAMS has a maximum simulation depth of 1.5 meters, which is limiting for mass-balance purposes because it creates a potential disconnect between unsaturated-zone transport and the water table. Of the models tested, RZWQM, HYDRUS2D, VS2DT, GLEAMS and PRZM had graphical user interfaces. Extensive documentation was available for RZWQM, HYDRUS2D, and VS2DT. RZWQM can explicitly simulate water and solute flux in macropores, and both HYDRUS2D and VS2DT can simulate water and solute flux in two dimensions. The version of RZWQM tested had a maximum simulation depth of 3 meters. The complex models simulate the formation, transport, and fate of degradates of up to three to five compounds including the parent, with the exception of VS2DT, which simulates the transport and fate of a single compound.

California, Indiana↗

USGS2004

Studies by the U.S. Geological Survey on sources, transport, and fate of agricultural chemicals

The U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program is assessing the sources, transport, and fate of chemicals applied to crops in agricultural basins across the Nation (referred to as "study units," see map). Chemicals selected for study include nutrients (nitrogen and phosphorus) and about 50 commonly used pesticides and their transformation products, including triazine and acetanilide herbicides such as atrazine and metolachlor, and organophosphorus insecticides such as chlorpyrifos and diazinon. The basins in the studies represent a range of agricultural settings—with varying crop types and agricultural practices related to tillage, irrigation, artificial drainage, and chemical use—as well as a range of landscapes with different geology, soils, topography, climate, and hydrology. Consistent methodology and analysis allow comparisons among the different basins. This study design leads to an improved understanding of the many factors that can affect the movement of water and chemicals in different agricultural settings (see "Complex factors," next page). Information from these studies will help with decision-making related to chemical use, conservation, and other farming practices that are used to reduce runoff of agricultural chemicals and sediment from fields. This information also will benefit the U.S. Environmental Protection Agency, the Department of Agriculture, local and regional water managers, and agricultural chemical manufacturers who are involved in managing chemical use and pesticide registration.

Fact Sheet↗

USGS2002

Application of headspace analysis to the study of sorption of hydrophobic organic chemicals to α-Al 2 O 3

The sorption of hydrophobic organic chemicals (HOCs) to ??-Al2O3 was investigated with a headspace analysis method. The semiautomated headspace analyzer gave rapid, precise, and accurate results for a homologous series alkylbenzenes even at low percentages of solute mass sorbed (3-50%). Sorption experiments carried out with benzene alone indicated weak interactions with well-characterized aluminum oxide, and a solids concentration effect was observed. When the sorption coefficients for benzene alone obtained by headspace analysis were extrapolated up to the solids concentrations typically used in batch sorption experiments, the measured sorption coefficients agreed with reported sorption coefficients for HOCs and sediments of low fractional organic carbon content. Sorbed concentrations increased exponentially with aqueous concentration in isotherms with mixtures of alkylbenzenes, indicating solute-solute interactions at the mineral surface. Sorption was, however, greater than predicted for partitioning of a solute between its pure liquid phase and water, indicating additional influences of the surface and/or the structured liquid near the mineral surface. ?? 1993 American Chemical Society.

Environmental Science & Technology↗

USGS2002

Accumulation and diagenesis of chlorinated hydrocarbons in lacustrine sediments

Two sediment cores were taken from the Rochester Basin of eastern Lake Ontario and analyzed for the radionuclides 210Pb and 137Cs and several high molecular weight chlorinated hydrocarbons (CHs). The two sites are geographically proximate but differ in sedimentation rate, permitting sedimentation-dependent processes to be factored out. The 210Pb chronology showed a mixed depth of 3-5 cm and an intrinsic time resolution of 11-14 years. Vertically integrated numbers of deposit-feeding oligochaete worms and burrowing organisms are insufficient to homogenize the sediment on the time scale of CH inputs, which are non steady state. U.S. production and sales of polychlorinated biphenyls (PCBs), DDT, Mirex, and hexachlorobenzene (HCB), as determinants of the shape of the input function, adequately predict the overall shape and, in many cases, details in the sedimentary profile. Sediment focusing factors (FF) inferred from 137Cs and 210Pb inventories averaged 1.17 and 1.74 for cores E-30 and G-32, respectively. This permitted CH accumulation rates to be corrected for focusing. Apparent molecular diffusion coefficients modeled for many of the CHs were about (1-3) ?? 10-9 cm2/s.

Environmental Science and Technology↗

USGS2001

National-scale, field-based evaluation of the biota - Sediment accumulation factor model

The biota - sediment accumulation factor (BSAF) model has been suggested as a simple tool to predict bioaccumulation of hydrophobic organic compounds (HOCs)in fish and other aquatic biota from measured concentrations in sediment based on equilibrium partitioning between the sediment organic carbon and biotic lipid pools. Currently, evaluation of this model as a predictive tool has been limited to laboratory studies and small-scale field studies, using a limited number of biotic species. This study evaluates the model, from field data, for a suite of organochlorine HOCs from paired fluvial sediment and biota (fish and bivalves) samples throughout the United States and over a large range of biotic species. These data represent a real-world, worst-case scenario of the model because environmental variables are not controlled. Median BSAF values for fish (3.3) and bivalves (2.8) were not statistically different but are higher than theoretically predicted values (1-2). BSAF values varied significantly in a few species. Differences in chemical-specific BSAF values were not observed in bivalves but were statistically significant in fish. The HOCs with differing BSAF values were those known to be biotransformed. Sediment organic carbon content and biota lipid content had no effect on BSAF values in fish and only a weak effect in bivalves. This study suggests that the BSAF model could be useful under in situ riverine conditions as a first-level screening tool for predicting bioaccumulation; however, variability in BSAF values may impose limits on its utility.

Environmental Science & Technology↗

USGS2001

Selected data from field studies of pesticide runoff to surface waters

Citations from the scientific literature for studies that quantified selected pesticides in field runoff or streams were obtained from two computerized bibliographic databases: Chemical Abstracts and AGRICOLA. Selected data were extracted from studies in field environments that lasted longer than a day and are summarized here. The data extracted from each article, if available, include pesticide information, environmental setting, year of study, and the mass of the pesticide in runoff as a percent of the mass applied. Data from two national studies of pesticides in surface waters done by the U.S. Geological Survey (National Water-Quality Assessment Program, 1992?1995, and National Stream-Quality Accounting Network, 1996-1998) also are summarized.

Water-Resources Investigations Report↗

USGS2000

Pesticides in stream sediment and aquatic biota— Current understanding of distribution and major influences

This report summarizes a comprehensive analysis of existing information on pesticides in bed sediment and aquatic biota of United States rivers and streams: their geographic distribution, sources, trends, environmental fate, and biological significance. It is one of a four-part series that synthesizes current knowledge and understanding of pesticides in the nation’s water resources as part of the National Water-Quality Assessment Program.

Fact Sheet↗

USGS2000

Organochlorine pesticides and PCBs in stream sediment and aquatic biota—initial results from the National Water-Quality Assessment Program, 1992–1995

One of the goals of the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey is to assess the status and trends in the nation's water quality and to understand the natural and anthropogenic factors that affect water-quality conditions. This report summarizes the occurrence and distribution of 33 organochlorine compounds in fluvial bed sediment and aquatic biota (whole freshwater fish and freshwater bivalves) sampled by NAWQA investigations between 1991 and 1994. These include historically used insecticides (DDT and metabolites, chlordane and its various components, and dieldrin), some currently used pesticides (permethrin and dacthal) and some industrial chemicals and byproducts (PCBs and hexaclorobenzene). Samples were collected at approximately 500 sites in 19 large hydrologic basins throughout the United States. Contaminant levels in bed sediment and aquatic biota are summarized, first on a national basis, and then by land-use classification (for example, urban, cropland, pasture and rangeland, and forest). Nationally, detection frequencies are highest in sediment and biota for the more persistent organochlorine compounds: total DDT, total chlordane, dieldrin, and total PCBs. Organochlorine compounds were detected more frequently in whole fish than in bivalves or bed sediment. Organochlorine pesticide concentrations were relatively high in agricultural regions with histories of high use. The highest organochlorine compound concentrations in both sediment and biota generally were associated with urban areas. Some organochlorine concentrations in sediment exceeded guidelines for the protection of aquatic organisms. A screening-level comparison of measured organochlorine concentrations in whole fish was made with human health guidelines that are applicable to edible fish. This comparison indicates stream sites at which additional sampling of game fish fillets may be warranted, depending on local patterns of fish consumption. A comparison of current national contaminant levels with previous studies of this scope suggests a gradual decrease in organochlorine contaminant levels, at least in fish.

Water-Resources Investigations Report↗

USGS1999

Pesticides in streams of the United States : initial results from the National Water-Quality Assessment Program

Water samples from 58 rivers and streams across the United States were analyzed for pesticides as part of the National Water-Quality Assessment Program of the U.S. Geological Survey. The sampling sites represent 37 diverse agricultural basins, 11 urban basins, and 10 basins with mixed land use. Forty-six pesticides and pesticide degradation products were analyzed in approximately 2,200 samples collected from 1992 to 1995. The target compounds account for approximately 70 percent of national agricultural use in terms of the mass of pesticides applied annually. All the target compounds were detected in one or more samples. Herbicides generally were detected more frequently and at higher concentrations than insecticides. Nationally, 11 herbicides, 1 herbicide degradation product, and 3 insecticides were detected in more than 10 percent of samples. The number of target compounds detected at each site ranged from 7 to 37. The herbicides atrazine, metolachlor, prometon, and simazine were detected most frequently; among the insecticides, carbaryl, chlorpyrifos, and diazinon were detected the most frequently. Distinct differences in pesticide occurrence were observed in streams draining the various agricultural settings. Relatively high levels of several herbicides occurred as seasonal pulses in corn-growing areas. Several insecticides were frequently detected in areas where the dominant crops consist of orchards and vegetables. The number of pesticides detected and their concentrations were lower in wheat-growing areas than in most other agricultural areas. In most urban areas, the herbicides prometon and simazine and the insecticides carbaryl, chlorpyrifos, diazinon, and malathion were commonly detected. Concentrations of pesticides rarely exceeded standards and criteria established for drinking water, but some pesticides commonly exceeded criteria established for the protection of aquatic life.

Water-Resources Investigations Report↗

USGS1998

Wet atmospheric deposition of pesticides in Minnesota, 1989-94

All of the rain samples during the growing season had detectable quantities of at least one pesticide, but most of the pesticides were only infrequently observed. The most frequently detected compounds were the herbicides alachlor, atrazine, cyanazine, and metolachlor, and in 1994, its first year of registration, acetochlor. Peak concentrations of most herbicides in rainfall occurred shortly after their application periods in the spring. Peak concentrations of most of the insecticides occurred later in the summer. The majority of the wet depositional flux of pesticides occurred between early May and October. The annual wet depositional flux of pesticides is 5 orders of magnitude less than is the "annual flux" normally applied on an agricultural field, although some of the pesticides in rain are deposited in areas far removed from agricultural fields. The annual variability in pesticide deposition can be explained by year-to-year differences in climate and pesticide use patterns. The one sampling site (Lamberton) that was in an area dominated by row crop agriculture showed a significantly greater annual flux than the other four sampling sites that were in areas of either urbanization or less intensive agricultural. Regional deposition, away from a local source, can be inferred from these four sites because they have annual pesticide fluxes that are very similar for any given year. The observation of agricultural pesticides (not registered for home and garden use) in rain and storm runoff in the urban area indicates their transport from areas of agricultural use. Urban areas may be the best locations for assessing changes in regional use and deposition of agricultural pesticides. The pesticide fluxes in the streams out of the small three watersheds was compared to the pesticide flux into the watersheds in rain. The data indicate that flux into the watersheds from the rain is generally much greater than the flux from the watersheds in the streams. Therefore, a large fraction of the pesticides deposited in rain is retained within the watersheds. For the urban area, this is on the order of 98 percent for the four most commonly observed herbicides in rain and runoff.

Minnesota↗

USGS1997

Pesticides in surface waters: Current understanding of distribution and major influences

This report summarizes a comprehensive analysis of existing information on national and regional patterns of pesticide occurrence in surface waters of the United States and the major influences on the sources and transport of pesticides. It is one of a four-part series that synthesizes current knowledge and understanding of pesticides in the nation's water resources as part of the National Water Quality Assessment Program.

Fact Sheet↗

USGS1997

Pesticides in surface waters: distribution, trends, and governing factors

Pesticde use in agriculture and non-agriculture settings has increased dramatically over the last several decades. Concern about adverse effects on the environment and human health has spurred an enormous amount of research into their environmental behavior and fate. Pesticides in Surface Waters presents a comprehensive summary of this research. This book evaluates published studies that focus on measuring pesticide concentration. The studies chosen include peer reviewed scientific literature, government reports, laboratory studies, and those using microcosms and artificial streams and ponds. The authors used this information to develop their overview of pesticide contamination of surface waters. The exhaustive compilation of data along with the fundamental science make this book essential for those involved in pesticide use, environmental protection, water quality, and human or ecological risk assessment. Pesticides in Surface Waters covers the results of actual studies, sources of pesticides to surface water, fate and transport, and environmental significance. Hundreds of data-packed tables, maps, charts, and drawings illustrate the key points, making research and application easy and cost effective.

Book↗