ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1990.tb00321.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1990.tb00322.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1990.tb00323.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractAnthropogenic agricultural chemicals of concern in ground water include nitrate and pesticides. Increased legislation and regulation of contaminant levels in ground water can be expected. Ground water contamination should be prevented from getting worse, but more research is necessary so as to base regulations on sound criteria. Health effects and acceptable risks must be better formulated. More research on chemical movement in the vadose zone is necessary for accurate predictive modeling of pesticide transport to ground water. Best management practices need to be developed so that farmers will be able to farm profitably while complying with regulations for maximum contaminant levels in underlying ground water. People from all concerned disciplines, citizens’groups, and policy‐makers need to work together to develop realistic regulatory policies and management practices that will effectively protect public health while ensuring a viable and sustainable agricult

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1990.tb00324.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThree methods were used to investigate the possibility of vertical stratification of the pore fluid in an aquifer. The wells available for the study were fully screened and had a 5cm disturbed annulus around them. The first method used a pump with a straddle packer to isolate a short section of the secreened interval. A tracer test demonstrated that most of the pumped sample came from the well bore, presumably by piping through the disturbed. annulus. The second method used induction logs to measure the formation electrical conductivity as a function of depth. Due to the presence of clays and an inability to obtain porosity information, it was not possible to determine the pore fluid electrical conductivity using induction logs. A third method, dilution sampling, was developed that used a straddle packer to isolate a segment of the well screen. A tracer was injected into the packed‐off segment, and the tracer concentration in the well was monitored. The tracer was removed from the packed‐off segment by dilution and advection by ground water. When the tracer was completely removed from the packed‐off segment, the fluid in the segment was considered to be representative of the adjacent pore fluid. Only the dilution sampling method determined unambiguously that the pore fluid was not strat

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1990.tb00325.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA test‐stand experiment was conducted on neutron probe measurements using steel and Schedule 40 PVC access tubes to determine the effect of backfill grout in boreholes. The experiment used a moveable simulated vadose zone. Access tubes and grout do have masking effects on vadose zone measurements, but vadose zone moisture was detected through all configurations tested. Steel tubing has a smaller masking effect than PVC tubing. The masking effect of grout increased with borehole diameter. Although this experiment produced numerical results, conclusions drawn are qualitative in nature, rather than a quantitative calibration of the techniqu

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1990.tb00326.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe town of Yarmouth, Massachusetts, proposed to locate a new municipal golf course within a delineated area of recharge to public water‐supply wells. Two concerns of town officials were (1) hydrologic impacts upon downgradient wells; and (2) water‐quality impacts from fertilizers and pesticides. In response to these concerns, a thorough hydrogeologic investigation was made, fertilizer and pesticide management programs were recommended, and a ground water monitoring program was developed.The golf course parcel was determined to be underlain by a sand and gravel aquifer composed primarily of glacial outwash. Water‐table maps confirmed that ground water flow was in the direction of several public water‐supply wells. A three‐dimensional finite‐difference flow model was used to determine the optimum location and pumping rates for irrigation wells. Potential nitrate‐nitrogen concentrations in the ground water were predicted to range from 5.0 to 7.9 milligrams per liter so slow‐release fertilizers were recommended.With the assistance of the EPA Office of Pesticide Programs, the list of proposed pesticides was reviewed and sorted into three categories based on the known leachability, mobility, and toxicity characteristics of each compound. Specific recommendations were made as to pesticide selection and application rate using that classification.A monitoring program was developed to provide an on‐going assessment of any effects on water quality related to the application of fertilizer or pesticide. The elements of the monitoring program include (1) specifications for monitoring wells and lysimeters, (2) a schedule for sampling and analysis, (3) specific concentrations of nitrates or pesticide compounds that require resampling and analysis, restriction of usage, or remedial action, and (4) regular reports to the Yarmouth Water Quality Advisory Committee and to the Yarmouth Water Department. In an effort to ensure the implementation of this program, a table of responsibilities was prepared, and a Memorandum of Understanding adopting the program was signed by the town agencies interested in water‐supply protection and the golf course operation.The monitoring facilities were installed with minimal problems as part of the golf course construction tasks. However, implementation of the sampling and analysis part of the program was accomplished only after some difficulty and delay. The assistance of the State Pesticide Bureau, the University of Massachusetts Department of Entymology, and the Massachusetts Pesticide Laboratory was enlisted when budgetary problems threatened to prevent implementation. It is apparent from Yarmouth's experience that the mere preparation of a plan is not sufficient by itself. Consultants who prepare the plan should make every possible effort to include implementation in thei

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1990.tb00327.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe assessment of agricultural impacts on water quality are now being redirected to include both ground water and surface water. Mathematical models have enhanced the ability of scientists’to evaluate these impacts. A variety of public domain models are available that can aid in evaluating the effects of managerial activities on pesticide movement to ground water. However, the ideal non‐point source (NPS) pollution management model does not exist. Current models fail to adequately describe the transport of chemicals to ground water and, simultaneously, the effect of managerial practices on transport mechanisms. Much more work is necessary to develop a model that can describe water quality impacts of agricultural practices in a holistic framework that includes ground water and surface water conce

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1990.tb00328.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe New York State Water Resources Institute at Cornell University undertook a two‐year sampling survey of pesticides in ground water beginning in 1985. The survey focused on areas where combinations of agricultural pesticide use, soil texture, and ground water occurrence seemed likely to lead to leaching. The sampling survey included samples from four types of sampling points: (1) monitoring wells; (2) existing water supply wells; (3) test holes; and (4) tile drains. The monitoring wells were sampled repeatedly throughout the project to attempt to characterize temporal changes in water quality corresponding with seasonal changes in ground water levels. The pesticides studied for this project were atrazine, alachlor, cyanazine, metolachlor, carbaryl, carbofuran (and a metabolite, 3‐hydroxy carbofuran), and simazine. All, except for carbaryl, have been found in ground water in other sampling surveys in the United States.The results of the sampling survey did not reflect the careful choices of enviromental characteristics and pesticide use that seemed likely to lead to leaching. Residues of three pesticides were detected in six single samples from separate sources at four of the 30 sites tested. Three of the six samples came from shallow test holes that were used to sample the shallowest possible saturated soils beneath fields. The three pesticides detected were atrazine, simazine, and 3‐hydroxy carbofuran. Of the six samples, a single sample from a test hole contained atrazine concentrations equal to the current federal health advisory for long‐term exposure to atrazine (3 ppb).The remaining detections were between the limit of detection for analytical methods and the federal health advisory for each pesticide. The federal health advisories were formulated after the end of the project. Analytical methods may have been insensitive with respect to these advisories. Sampling results from other surveys suggest that many detections of the same pesticides lie below the limits of detection used for this sampling survey.A possible explanation for the lack of detections, given the design of the sampling survey, may lie in the agricultural practices noted at sampled sites. Most of the farm managers rotated their crops and pesticides on many small fields. Although the environmental conditions chosen for sampling sites were expected to lead to contamination, reported pesticide applications varied from year to year and field to field according to rotational schedules. The inconsistency of applications from year to year may explain the lack of detections (at the limits of quantification used for analyses) noted in this sampling

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1990.tb00329.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractAldicarb was first found in ground water in Suffolk County, New York, in the late 1970s associated with its use on potatoes. Since then, there has been a substantial amount of monitoring associated with aldicarb use on potatoes nationally and on citrus in Florida. A recent monitoring study by the registrant of aldicarb supplemented limited monitoring data on other critical aldicarb uses including cotton and peanuts. This paper reports on monitoring programs and studies encompassing more than 50,000 ground water samples, of which approximately 32 percent are positive and 13 percent are above EPA's Health Advisory Level of 10 ppb. These monitoring results were used in an integrated assessment to identify areas of the United States where aldicarb is likely to leach to ground water (Lorber et al. 1989). Positive findings are reported for 61 counties in 19 states, and findings above 10 ppb are reported for 31 counties in 11 states. Monitoring data associated with the use of aldicarb on potatoes in the Northeast and upper Midwest (Wisconsin, Virginia, New York, Massachusetts, Rhode Island, Maine) are extensive and demonstrate the potential for aldicarb to impact ground water near potato‐use sites. In contrast, monitoring associated with potato use in the Northwest (Idaho, Oregon, Washington) and a three‐county potato‐growing area in Florida have shown negative results. Sampling near cotton use in the South and Southwest (Georgia, Alabama, Tennessee, Arkansa, Louisiana, Texas, Arizona) showed negative findings, while a small number of positives were found in North Carolina and South Carolina. Limited monitoring associated with peanuts showed negative results in the South (North Carolina, South Carolina, Georgia), although sampling beneath a field research site in Georgia showed trace positives. Sampling from monitoring wells established in the shallow water table aquifer beneath and downgradient from citrus use sites in Florida showed both a high frequency and high concentrations of aldicarb, with one finding above 1000 ppb and numerous findings greater than 100 ppb. However, in three separate efforts encompassing more than 1200 samples from roughly the same number of domestic drinking water wells located near citrus fields with histories of aldicarb usage, only 2 percent contained residues of aldicarb. No positives were found in 800 samples from roughly the same number of deep public drinking water wells in counties with high citrus acreage and aldicarb usage. This paper also reports on monitoring associated with lily bulb use in northern California, fernery use in Florida, sugar beet use in Montana, and smaller exploratory efforts in several other s

ISSN:1069-3629    

DOI:10.1111/j.1745-6592.1990.tb00330.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY