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Paul D. Capel

Publications and source records attributed to Paul D. Capel.

49 records · Page 3Linked to original sources
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↗
USGS1996

Temperature-dependent sorption of naphthalene, phenanthrene, and pyrene to low organic carbon aquifer sediments

Sorption experiments were conducted with naphthalene, phenanthrene, and pyrene on low organic carbon sediments at 4 and 26 °C using batch and column techniques. Experimental controls ensured the absence of biologic and photolytic activity and colloid-free solution supernatants. Equilibrium distribution coefficients ( K d ) increased 1.1−1.6 times with a decrease in temperature of 22 °C. Fraction instantaneous sorption ( F ) values did not change significantly with a decrease in temperature of 22 °C. Desorption rate constants ( k 2 ) decreased 1.2−2.6 times with a decrease in temperature of 22 °C. Times to equilibrium were at least 40 h. The magnitude of observed K d and k 2 values and the effect of temperature on K d (e.g., low enthalpy of sorption) are consistent with sorbate partitioning between the aqueous phase and small amounts of organic matter ( f oc = 0.02%) on the sediments. The temperature dependence of K d and k 2 may be small as compared to the effects of heterogeneities in field-scale aquifer systems. Thus, thermal gradients may not be of major importance in most saturated subsurface regimes when predicting solute transport. However, aquifer remediation pump-and-treat times could be decreased because increased temperature decreases both retardation and tailing.

Environmental Science & Technology↗
USGS1996

Pesticides in the atmosphere: distribution, trends, and governing factors

Most people know about the presence and health effects of pesticide residues in the water they drink. However, they may not realize the impact of atmospheric transportation and deposition of pesticides on water quality. Scientific studies of pesticides in various atmospheric matrices (air, rain, snow, aerosols, and fog) provide some of the answers. Pesticides in the Atmosphere focuses on the review and interpretation of direct measurements of pesticides in the environment. An exhaustive compilation, the book examines hundreds of studies in detailed tabular listings, with accompanying maps that include such features as spatial and temporal domain studies, target analytes, detection limits, and compounds detected. Working with the foundation of forty years of scientific studies, the editors synthesize this research to characterize the common threads and main conclusions. They use this information to identify where we need to improve our understanding of pesticides in the atmosphere and their significance to water quality. Pesticides in the Atmosphere serves as a resource, text, and reference to a wide spectrum of scientists, water managers, and students. It includes extensive compilations of references, interpretive analyses and conclusions. For those not familiar with the atmospheric transportation and deposition of pesticides it provides a comprehensive introduction.

Book↗
USGS1995

Relations between pesticide use and riverine flux in the Mississippi River Basin

In an intensive subcontimental study of pesticides in surface waters of the United States, concentrations of 26 high-use pesticides were measured at nine sites in the Mississippi River basin from May 1991 through March 1992. Calculated total fluxes were combined with agricultural-use data to estimate the percentage of applied pesticide reaching the mouths of the Mississippi River and six major tributaries. For most pesticides, the riverine flux was less than 2% of the mass applied agriculturally. The insecticide diazinon was detected frequently in rivers draining the three basins with the highest population densities, apparently as a result of urban use.

Mississippi River basin↗
USGS1995

Bibliography of synthetic pyrethroid insecticides in the environment

Citations from the scientific literature on the environmental behavior and occurrence of synthetic pyrethroid insecticides were obtained from three computerized bibliographic databases: Agricola, Chemical Abstracts, and Selected Water Resources Abstracts. Approximately 10,000 citations were found but more than half were eliminated because they were directed strictly toward agricultural or industrial uses. The remaining 4,000 were categorized by environmental process, occurrence, analysis, toxicity, or physical/chemical property. The information is available in ASCII files on 3 1/2-inch diskette.

Open-File Report↗
USGS1995

Pesticides in the atmosphere; distribution, trends, and governing factors

A comprehensive review of existing literature on the occurrence and distribution of pesticides in the atmosphere of the United States and adjoining Canadian provinces showed that the atmosphere is an important part of the hydrologic cycle that acts to distribute and deposit pesticides in areas far removed from their application sites. A compilation of existing data shows that pesticides have been detected in the atmosphere throughout the nation. Most of the available information on pesticides in the atmosphere is from small-scale, short-term studies that seldom lasted more than one year. Only two national-scale, multi-year studies were done since the late 1960's that analyzed for a wide variety of pesticides in air that were in current use at the time. Another large-scale study was done during 1990-91, but was limited to the midwestern and northeastern United States and only analyzed for two classes of herbicides in wet deposition. Most of the pesticides analyzed for were detected in either air or rain, and represent about 25 percent of the total number of insecticides, herbicides, and fungicides in current use. The geographical distribution of studies, and the type of sampling and analysis were highly variable with most of the historical study efforts concentrated in the Great Lakes area and California. Air and rain were the main atmospheric matrices sampled, but pesticides were also detected in fog and snow. Reported pesticide concentrations in air and rain were frequently positively correlated to their regional agricultural use. Deviations from this relation could usually be explained by non-agricultural use of pesticides, sampling and analytical difficulties, and environmental persistence. High concentrations of locally used pesticides were found to occur seasonally, usually in conjunction with spring planting of row crops and warm temperatures, but high concentrations also occurred during winter months in those areas where dormant orchards were sprayed. The environmentally more persistent pesticides were detected in the atmosphere at low concen- trations throughout the year. Deposition of airborne pesticides can have significant effects on water quality, but neither the nature of nor the magnitude of these effects can be determined with certainty on the basis of the type of data currently available. The lack of consistent, long-term regional and national monitoring and study of pesticides in atmospheric matrices severely limits assessment capability.

Open-File Report↗
USGS1995

Precision of a splitting device for water samples

Two identical cone splitters, devices designed to split water and its suspended solids into equal aliquots for semi-volatile organic chemical and trace element analyses, were evaluated for their precision. The water-splitting evaluations consisted of experiments to test the effect of water volume, the effect of combining outlet ports, and the effect of different techniques of water introduction. The solids-splitting evaluations consisted of experi- ments to test the effect of particle size (nine different particle diameters ranging from very coarse sand to clay) and suspended-solids concentration. In general, water was equally split with a precision of less than 5 percent relative standard deviation. The accuracy of splitting the solids was a function of particle size. Clay, silt, and fine and medium sand were split with a precision relative standard deviation of less than 7 percent, and coarse sand was split with a relative standard deviation between 12 and 45 percent.

Open-File Report↗
USGS1994

Guidelines for collecting and processing samples of stream bed sediment for analysis of trace elements and organic contaminants for the National Water-Quality Assessment Program

A major component of the U.S. Geological Survey's National Water-Quality Assessment program is to assess the occurrence and distribution of trace elements and organic contaminants in streams. The first phase of the strategy for the assessment is to analyze samples of bed sediments from depositional zones. Fine-grained particles deposited in these zones are natural accumulators of trace elements and hydrophobic organic compounds. For the information to be comparable among studies in many different parts of the Nation, strategies for selecting stream sites and depositional zones are critical. Fine-grained surficial sediments are obtained from several depositional zones within a stream reach and composited to yield a sample representing average conditions. Sample collection and processing must be done consistently and by procedures specifically designed to separate the fine material into fractions that yield uncontaminated samples for trace-level analytes in the laboratory. Special coring samplers and other instruments made of Teflon are used for collection. Samples are processed through a 2.0-millimeter stainless-steel mesh sieve for organic contaminate analysis and a 63-micrometer nylon-cloth sieve for trace-element analysis. Quality assurance is maintained by strict collection and processing procedures, duplicate samplings, and a rigid cleaning procedure.

Open-File Report↗