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1.
The transport and potential toxicity of pesticides in Queensland (QLD) catchments from agricultural areas is a key concern for the Great Barrier Reef (GBR). In 2009, a pesticide monitoring program was established as part of the Australian and QLD Governments' Reef Plan (2009). Samples were collected at eight End of System sites (above the tidal zone) and three sub-catchment sites. At least two pesticides were detected at every site including insecticides, fungicides, herbicides, and the Reef Plan's (2009) five priority photosystem II (PSII) herbicides (diuron, atrazine, hexazinone, tebuthiuron and ametryn). Diuron, atrazine and metolachlor exceeded Australian and New Zealand water quality guideline trigger values (TVs) at eight sites. Accounting for PSII herbicide mixtures increased the estimated toxicity and led to larger exceedances of the TVs at more sites. This study demonstrates the widespread contamination of pesticides, particularly PSII herbicides, across the GBR catchment area which discharges to the GBR.  相似文献   

2.
Soil-pore water sampling by suction lysimeters monitors the fate of soil contaminants as a function of depth and time. However, sampling campaigns must be planned to most effectively monitor the migration of contaminants with a minimum expenditure of resources. The vertical migration of pesticides was studied at two sites treated with systemic s-triazine herbicides and equipped with suction lysimeters. The measured concentrations were compared with those calculated by a simulation model. This modeling was based on the processes that control the transport and fate of pesticide within the soil. The usefulness of such a tool was demonstrated by the good approximation obtained for pesticide concentrations and arrival times. Moreover, the significant spatial variability of concentrations observed justifies the use of a stochastic approach in modeling that takes into account the spatial variability of soil parameters. Also, the rapid transformation of herbicides observed in unsaturated soil zones demonstrates the importance of taking into account the sum of the toxic residues when evaluating the fate of s-triazines in soil.  相似文献   

3.
We began a study, in 1996, to compare ground water quality under irrigated and nonirrigated agriculture, sewered and nonsewered residential developments, industrial, and nondeveloped land uses. Twenty-three monitoring wells were completed in the upper meter of an unconfined sand aquifer. Between 1997 and 2000, sampling occurred quarterly for major ions, trace inorganic chemicals, volatile organic compounds (VOCs), herbicides, and herbicide degradates. On single occasions, we collected samples for polynuclear aromatic hydrocarbons (PAHs), perchlorate, and coliform bacteria. We observed significant differences in water chemistry beneath different land uses. Concentrations of several trace inorganic chemicals were greatest under sewered urban areas. VOC detection frequencies were 100% in commercial areas, 52% in sewered residential areas, and <10% for other land uses. Median nitrate concentrations were greatest under irrigated agriculture (15,350 microg/L) and nonsewered residential areas (6080 microg/L). Herbicides and degradates of acetanilide and triazine herbicides were detected in 86% of samples from irrigated agricultural areas, 68% of samples from nonirrigated areas, and <10% of samples from other land uses. Degradates accounted for 96% of the reported herbicide mass. We did not observe seasonal differences in water chemistry, but observed trends in water chemistry when land use changes occurred. Our results show land use is the dominant factor affecting shallow ground water quality. Trend monitoring programs should focus on areas where land use is changing, while resource managers and planners must consider potential impacts of land use changes on ground water quality.  相似文献   

4.
Since 1995, a network of municipal wells in Iowa, representing all major aquifer types (alluvial, bedrock/karst region, glacial drift, bedrock/nonkarst region), has been repeatedly sampled for a broad suite of herbicide compounds yielding one of the most comprehensive statewide databases of such compounds currently available in the United States. This dataset is ideal for documenting the insight that herbicide degradates provide to the spatial and temporal distribution of herbicides in ground water. During 2001, 86 municipal wells in Iowa were sampled and analyzed for 21 herbicide parent compounds and 24 herbicide degradates. The frequency of detection increased from 17% when only herbicide parent compounds were considered to 53% when both herbicide parents and degradates were considered. Thus, the transport of herbicide compounds to ground water is substantially underestimated when herbicide degradates are not considered. A significant difference in the results among the major aquifer types was apparent only when both herbicide parent compounds and their degradates were considered. In addition, including herbicide degradates greatly improved the statistical relation to the age of the water being sampled. When herbicide parent compounds are considered, only 40% of the wells lacking a herbicide detection could be explained by the age of the water predating herbicide use. However, when herbicide degradates were also considered, 80% of the ground water samples lacking a detection could be explained by the age of the water predating herbicide use. Finally, a temporal pattern in alachlor concentrations in ground water could only be identified when alachlor degradates were considered.  相似文献   

5.
Pollution of ground water by agricultural practices has gained considerable attention in recent years. Mathematical models have been developed to evaluate the effects of agricultural best management practices on pesticide transport to ground water. The GLEAMS model was evaluated to determine its suitability for use in predicting managerial effects on pesticide leaching from agricultural systems in the Atlantic Coastal Plain. Model predictions of pesticide concentrations in percolation from the root zone were compared to observed concentrations in ground water beneath field-sized areas. The model underpredicted runoff from these areas. Model predictions were used to produce rankings of the magnitudes of pesticide losses that paralleled rankings of observed ground water data in some cases but not others. Differences in observed and predicted rankings were assessed to be the result of sampling schedule inefficiences. The magnitudes of predicted pesticide concentrations in leachate from the root zone were three to seven times higher than observed concentrations in shallow ground water. Results support the use of GLEAMS for comparison of managerial effects on pesticide movement to ground water if appropriate limitations are recognized.  相似文献   

6.
Assessing Arkansas Ground Water for Pesticides: Methodology and Findings   总被引：1，自引：0，他引：1  
During 1985 to 1987, 119 wells, Springs and municipal drinking water supplies throughout Arkansas were monitored for the presence of pesticides. Pesticides selected for analysis included acifluorfen, alachlor, aldicarb, atrazine, benomyl, cyanazine, cypermethrin, 2,4-D, dichlorprop, diuron, fenvalerate, fluometuron, hexazinone, linuron, metolachlor, permethrin, picloram, and propanil. Not every sample was analyzed for every pesticide. Overall, results indicated that the 18 herbicides, fungicides, and insecticides were not present in the ground water samples studied. (Note: Detectable concentrations of three herbicides – alachlor, atrazine, and metolachlor – were found in one irrigation well, at 5.5,5.8, and 6.9 μg/L, respectively. However, since previous and subsequent sampling failed to detect these compounds, their presence is attributed to a localized spill or handling error rather than agricultural application.)  相似文献   

7.
The rational use of pesticides generates an impact which is normally reversed and eliminated by the environment itself. However, the indiscriminate use of pesticides makes its natural degradation rhythm difficult, prolonging their presence in the soil for a great deal of time. Aiming towards a decrease in the environmental impact of pesticides, soil microorganisms capable of degrading pesticides, such as propanil, were investigated. An Enterobacter cloacae strain, isolated from rice field soil, was exposed to the herbicide propanil alone and in a mixture containing also bentazone, clomazone, quinclorac, and 2,4‐D. This bacterium was able to eliminate 100% of the applied propanil in 28 days. Propanil degradation in the 5‐herbicide mixture was much lower than that of individual pesticide degradation. The aeration of the system helped to degrade propanil and its subproduct 3,4‐dichloroaniline much faster. LC with UV detection was used to determine the remaining concentrations of the herbicides and their subproducts.  相似文献   

8.
The 8-km2 Morcille catchment, which is a sub-catchment of the 150-km2 Ardières catchment in the Beaujolais region of France, is one of the first sites in Europe where research has been conducted on surface water contamination by pesticides. A consolidated hydrological and chemical dataset has been set up with data collected since 2002 on the Morcille River and since 2011 on the Ardières River. Additional data on the ecotoxicological and ecological impacts of pesticides on aquatic microbial communities and macroinvertebrates has also been recorded in both rivers since 2005. The ‘Site Atelier Ardières-Morcille Dataset’ described here combines rainfall and stream water height measurements at gauged stations with concentrations of two trace elements and nine pesticides (mainly herbicides, fungicides and some of their metabolites) in both the Ardières and Morcille rivers. All contaminant concentration data showed spatial and temporal variability in water quality associated with pesticide use and rainfall patterns. This long-term monitoring framework made it possible to estimate the persistence of two herbicides (diuron and norflurazon) after legislation banning them. It took 4 years for diuron and more than 10 years for norflurazon concentrations to fall below 0.1 μg/L. Concurrent biological data showed a gradient of impacts consistent with chemical anthropogenic pressure, and rapid recovery of phototrophic microbial communities after the diuron ban. Finally, monitoring data on pesticide transport in a grassed strip set on a slope of the Morcille catchment confirmed that vegetative filter strips can effectively reduce diuron fluxes in surface runoff (>80% abatement) and infiltration water (>70% abatement). The full dataset offers a valuable resource for the validation of hydrological models and the development of global approaches to better understand the pressure–transport–exposure–impact chain and aquatic community resilience at the small catchment scale.  相似文献   

9.
The current study documents the fate of current-use pesticides in an agriculturally-dominated central California coastal estuary by focusing on the occurrence in water, sediment and tissue of resident aquatic organisms. Three fungicides (azoxystrobin, boscalid, and pyraclostrobin), one herbicide (propyzamide) and two organophosphate insecticides (chlorpyrifos and diazinon) were detected frequently. Dissolved pesticide concentrations in the estuary corresponded to the timing of application while bed sediment pesticide concentrations correlated with the distance from potential sources. Fungicides and insecticides were detected frequently in fish and invertebrates collected near the mouth of the estuary and the contaminant profiles differed from the sediment and water collected. This is the first study to document the occurrence of many current-use pesticides, including fungicides, in tissue. Limited information is available on the uptake, accumulation and effects of current-use pesticides on non-target organisms. Additional data are needed to understand the impacts of pesticides, especially in small agriculturally-dominated estuaries.  相似文献   

10.
Pesticide residues in ground water of the San Joaquin Valley, California   总被引：1，自引：0，他引：1  
A regional assessment of non-point-source contamination of pesticide residues in ground water was made of the San Joaquin Valley, an intensively farmed and irrigated structural trough in central California. About 10% of the total pesticide use in the USA is in the San Joaquin Valley. Pesticides detected include atrazine, bromacil, 2.4-DP, diazinon, dibromochloropropane, 1,2-dibromoethane, dicamba, 1,2-dichloropropane, diuron, prometon, prometryn, propazine and simazine. All are soil applied except diazinon.

Pesticide leaching is dependent on use patterns, soil texture, total organic carbon in soil, pesticide half-life and depth to water table. Leaching is enhanced by flood-irrigation methods except where the pesticide is foliar applied such as diazinon. Soils in the western San Joaquin Valley are fine grained and are derived primarily from marine shales of the Coast Ranges. Although shallow ground water is present, the fewest number of pesticides were detected in this region. The fine-grained soil inhibits pesticide leaching because of either low vertical permeability or high surface area; both enhance adsorption on to solid phases. Soils of the valley floor tend to be fine grained and have low vertical permeability. Soils in the eastern part of the valley are coarse grained with low total organic carbon and are derived from Sierra Nevada granites. Most pesticide leaching is in these alluvial soils, particularly in areas where depth to ground water is less than 30m. The areas currently most susceptible to pesticide leaching are eastern Fresno and Tulare Counties.

Tritium in water molecules is an indicator of aquifer recharge with water of recent origin. Pesticide residues transported as dissolved species were not detected in non-tritiated water. Although pesticides were not detected in all samples containing high tritium, these samples are indicative of the presence of recharge water that interacted with agricultural soils.  相似文献   


11.
Pesticide concentration in sediment from irrigation areas can provide information required to assess exposure and fate of these chemicals in freshwater ecosystems and their likely impacts to the marine environment. In this study, 103 sediment samples collected from irrigation channels and drains in 11 agricultural areas of Queensland were analysed for a series of past and presently used pesticides including various organochlorines, synthetic pyrethroids, benzoyl ureas, triazines and organophosphates. The most often detected compounds were endosulphans (, β and/or endosulphan sulphate) which were detectable in 78 of the 103 samples and levels ranged from below the limit of quantification (0.1 ng g−1 dw) up to 840 ng g−1 dw. DDT and its metabolites were the second most often detected pesticide investigated (74 of the 103 samples) with concentrations up to 240 ng g−1 dw of ∑DDTs. Mean ∑endosulphan and ∑DDT concentrations were 1–2 orders of magnitude higher in sediments from the irrigation areas which are dominated by cotton cultivation compared to those which are dominated by sugarcane cultivation. In contrast to these insecticides, the herbicides diuron, atrazine and ametryn were the compounds which were most often detected in sediments from irrigation drains in sugarcane areas with maximum concentrations in areas of 120, 70 and 130 ng g−1 dw, respectively. In particular during flood events, when light is limiting, transport of these photosynthesis inhibiting herbicides from the sugarcane cultivation areas to the marine environment may result in additional stress of marine plants.  相似文献   

12.
The area under study covers 3500 km2 in the upstream part of the closed catchment basin of the salt crust of Uyuni. This crust is a remnant of the saline Lake Tauca, which covered the area about 15,000 years ago. In the downstream part of the aquifer, the Cl concentration of ground water and Cl content in the unsaturated zone exceed 20 meq/L and 18 kg/m2, respectively. With the present hydrological conditions under semiarid conditions, the ground water residence time in the study area exceeds 3000 years. Transient simulations over 11,000 years were made using initial conditions as the retreat of Lake Tauca and taking into account a low recharge during the arid mid-Holocene period. The modeling simulates ground water flow, Cl transport, and ground water residence time. It includes the evaporation from the aquifer that leads to the accumulation of chloride in the unsaturated zone. Results of the modeling are consistent with the observations if it is assumed that the Cl previously accumulated in the unsaturated zone was flushed back into the aquifer around 2000 years B.P., contemporaneously with the end of the arid period.  相似文献   

13.
Pesticides in Nebraska's Ground Water   总被引：1，自引：0，他引：1  
More than 2263 well water samples were collected throughout Nebraska and analyzed for pesticides. Thirteen and one-half percent contained detectable levels of atrazine, but only 22 wells exceeded the health advisory of 3.0 ppb. Although the samples came from almost every county in the state, this sampling is not based solely on a randomly selected group of wells. The highest frequency of detections occurred in irrigated corn-growing areas with less than 50 feet to ground water. These areas were sampled at a greater frequency than the less vulnerable areas. Cyanazine, together with the additional triazines — simazine, propazine, prometone, and ametryne, also were detected in some well waters; however, their frequency of detection was well below that of atrazine. The triazine metribuzin was not detected.
Alachlor, propachlor, and metolachlor also were detected in trace levels in several wells. Five of 2072 samples analyzed for alachlor exceeded the health advisory of 0.4 ppb. Almost all of the contaminated wells were in vulnerable areas. The relatively high frequency of propachlor detections occurred in predominately irrigated corn-growing areas, rather than in areas where propachlor is traditionally applied.
The factors that appear most directly involved in the observed distribution of pesticides in ground water are the intensity of areal usage, pesticide persistence and mobility, irrigation, soil drainage capacity, and depth to ground water.
Fifteen pesticide residues were detected during this study. If ethylene dibromide and carbon tetrachloride, which were detected in ground water adjacent to grain elevators are included, a total of 17 pesticide residues have been detected in Nebraska's ground water.  相似文献   

14.
An important quantity in groundwater protection is the residence time of water in an aquifer. It relates to both the travel time of a pollutant to arrive at a well and the time span required for self-purification of a polluted aquifer after removal of pollutant inputs. Time scales for aquifers can be gained from artificial tracer experiments or from environmental tracer data, the latter offering the only realistic alternative if time scales of years or decades have to be taken into account.

Different tracers show different time scales due to their different transport mechanisms especially in the unsaturated zone. While solute tracers are moved advectively with the seepage water, gas tracers pass the unsaturated zone diffusively through the air phase. Depending on the properties of the unsaturated zone (hydraulic properties, thickness) this difference in behavior can be used to separate the subsurface transport process into the unsaturated and the saturated parts.

In a field study in Germany, SF6 and 3H were used as environmental tracers. Both have a relatively well-known input function. Interpretation of data from observation wells by a box model approach led to spatially and temporally varying residence times. This was an indication that the influence of the unsaturated zone could not be neglected. While the gas tracer SF6 shows only residence times in the saturated zone, the tracer 3H reflects the whole travel time of water including both the unsaturated and saturated zones. Using a one-dimensional plug-flow model for the unsaturated zone combined with a detailed two-dimensional flow and transport model for the saturated zone leads to a holistic and consistent interpretation of the measured tracer concentrations. The observed pattern of old water under thick loess cover and younger water under areas where the fractured basalt aquifer crops out is reproduced after adjusting only two parameters: the effective porosity of the saturated aquifer and the product of field capacity and thickness of the unsaturated zone. While the effective porosity of the saturated zone is adjusted by means of the SF6 data, the field capacity of the loess layer is adjusted by means of the 3H observations. The thickness of the unsaturated zone is deduced from geological and pedological maps. All flow data are obtained from a calibrated flow model, which is based on geological data, observed heads and pumping tests only.

The transport model for the saturated zone was calibrated by fitting the porosity by means of gaseous tracer concentrations (SF6). The combined saturated–unsaturated zone model was then calibrated by fitting the field capacity of the unsaturated zone by means of 3H concentrations. With this model it was possible to verify the observed NO3 concentrations at the drinking water wells and to develop predictions for their future development under various scenarios of fertilizer input reduction in specific areas.  相似文献   


15.
A low-cost, simple to use portable rainfall simulator is developed for use over a 5 m^2 plot. The simulator is easy to transport and assemble in the field, thereby allowing for necessary experimental replicates to be done. It provides rainfall intensities of between 20 and 100 mm/h by changing the number and type of silicon nozzles used. The Christiansen coefficient of uniformities obtained in the field are appropriate and vary from 79 to 94% for rainfall intensities ranging from 30 to 70 mm/h. In addition, the median volumetric drop diameters measured for rainfall intensities of 30, 50, and 70 mm/h are in the lower range of that of natural rainfall and equal to 1.10 ± 0.08,1.69 ± 0.21, and 1.66 ± 0.20 mm, respectively. The velocities of the raindrops with diameters less than 1.2 mm reached terminal velocities, while raindrops less than 2.0 mm achieved velocities reasonably close to the terminal velocity of natural rainfall. Furthermore,the average time-specific kinetic energy(KET) for rainfall intensities of 30, 50, and 70 mm/h are 257.7,760.1, and 1645.2 J/m^2/h, respectively accounting for about 78.0 and 86.5% of the KET of natural rainfall for50 and 70 mm/h rainfall intensity, respectively. The applicability of the portable rainfall simulator for herbicide transport study is investigated using two herbicides(atrazine and metolachlor); herbicide losses in runoff and sediment samples are in the ranges reported in the literature. As a percentage of the amount of herbicide applied, 5.29% of atrazine and 2.15% of metolachlor are lost due to combined water and sediment runoff. The results show that the portable rainfall simulator can be effectively used in studying processes such as pesticide runoff, infiltration mechanisms, and sediment generation and transport at a field plot scale with an emphasis on how surface characteristics such as slope and soil properties affect these processes.  相似文献   

16.
Pesticides in Austrian Running Waters – a Country-wide Overview The analyses of pesticides in Austrian running waters are major part of the country-wide water quality monitoring system which has been established in 1991. This paper summarizes the data which were collected for 29 substances between December 1991 and June 1995. The monitoring activities focus on herbicides because they are the most important pesticide group in Austria. Substances of the triazines and phenoxyalkanecarboxylic acid group analyzed within the programme represent the major part of the total amount of herbicides applied. The most detected pesticides were atrazine and its metabolite deethylatrazine. Peak concentrations were obtained in rivers situated in the eastern and southern regions of Austria with intensive agriculture. Other substances play a minor role as contaminants in running waters. These findings correspond to the data obtained by investigations of groundwater in porous media.  相似文献   

17.
Soil-gas surveys are becoming more widely accepted as a tool for the preliminary determination of the extent of soil and ground water contamination by volatile organic compounds (VOCs). The interpretation of the results of published soil-gas surveys has been necessarily limited and qualitative due to a lack of adequate models. There has been considerable effort in the recent past to characterize the transport and fate of pesticides in soil. However, the behavior of pesticides generally differ substantially from those of VOCs.
This paper presents a computer model developed to simulate the diffusive transport of VOC vapor through unsaturated soils using a two-dimensional, finite-difference, solution to Fick's second law of diffusion. An effective diffusion coefficient that incorporates the effects of tortuosity, moisture content, and soil organic carbon content is computed. Although the model has not been validated due to the unavailability of adequate field or laboratory data, nevertheless, sensitivity analyses demonstrate the importance of soil moisture and, secondarily, organic matter content in controlling the migration of VOC vapor through the unsaturated zone. The interpretation of soil-gas surveys can be complicated by unknown spatial heterogeneities in soil moisture and organic carbon content, temporal variations in moisture content, extent of contaminant migration as a non-aqueous phase liquid and by the unknown extent of VOC liquid and contaminated ground water.  相似文献   

18.
Amounts of pesticide residues determined in drinking water and in food during the last decade are compared. Whereas in drinking water pesticides were determined in concentrations of about 0.1 μg/L, the pesticide contents of fruits and vegetables were higher by a factor of 100 to 10000. Even in the grease fraction of mother's milk pesticides were found in the mg/kg range. These results may help to do the classification of drinking water as a possible health hazard concerning pesticides.  相似文献   

19.
A subregional-scale method to assess aquifer vulnerability to pesticides   总被引：4，自引：0，他引：4  
A method to predict aquifer vulnerability to pesticide contamination at the subregional scale was developed. The assessment method was designed to incorporate relevant hydrologic and pesticide-transport information and to use generally available data. The method assumes steady-state advection of pesticides in the vadose zone, including sorption and biological decay. The solution is presented as a vulnerability index (VI) that increases as the aquifer vulnerability increases. The hydrologic input data for the VI model are obtained from the soil survey geographic database. Pesticides were grouped into three leachability classes using a leachability ratio (half-life divided by organic carbon partition coefficient). Pesticide transformation is assumed to occur in the surface layer. The influence of vertical transport in the remainder of the vadose zone has been incorporated by applying a multiplying factor to the VI that varies with depth to ground water. Hydraulic conductivity is used as a surrogate for soil-water velocity for practical purposes. The performance of the VI model is evaluated using ground water data from Weld County, Colorado. The model is demonstrated to be successful at predicting relative vulnerability, defined as the magnitude of pesticide concentration and percent of wells in a unit that exhibit a pesticide detection. Areas of low, medium, and high vulnerability are assigned. Results indicate that the vulnerability classifications are most dependent on the leachability ratio, hydraulic conductivity, and organic carbon content.  相似文献   

20.
Trace organic (chlorinated pesticides, PCBs, PAHs and dioxins/furans) and trace metal concentrations were measured in surficial sediment and biological tissues (i.e., worms, crustaceans, bivalve molluscs, and fish livers) collected from the Russian Arctic. Total DDT, chlordane, PCB and PAH concentrations ranged from ND to 1.2, ND to <0.1, ND to 1.5 and <20-810 ng g(-1), respectively, in a suite of 40 surficial sediment samples from the Kara Sea and the adjacent Ob and Yenisey Rivers. High sedimentary concentrations of contaminants were found in the lower part of the Yenisey River below the salt wedge. Total dioxins/furans were analysed in a subset of 20 sediment samples and ranged from 1.4 to 410 pg g(-1). The highest trace organic contaminant concentrations were found in organisms, particularly fish livers. Concentrations as high as 89 ng g(-1) chlordane; 1010 ng g(-1) total DDTs; 460 ng g(-1) total PCBs; and 1110 ng g(-1) total PAH, were detected. A subset of 11 tissue samples was analysed for dioxins and furans with total concentrations ranging from 12 to 61 pg g(-1). Concentrations of many trace organic and metal contaminants in the Kara Sea appear to originate from riverine sources and atmospheric transport from more temperate areas. Most organic contaminant concentrations in sediments were low; however, contaminants are being concentrated in organisms and may pose a health hazard for inhabitants of coastal villages.  相似文献   

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