共查询到20条相似文献，搜索用时 62 毫秒
1.
Thomas D. Papiernik Sharon K. Widmer Roy F. Spalding 《Ground Water Monitoring & Remediation》1996,16(1):80-84
Studies have shown that materials, such us polytetra-fluoroethylene (PTFE), rigid polyvinyl chloride (rigid PVC). flexible polyvinyl chloride (flexible PVC), stainless steel (SS). low-density polyethylene (LDPE), and high-density polyethylene (HDPE), have the potential to influence certain analyte concentrations in ground water samples. The effects of HDPE, LDPE, PTFE, rigid PVC, and SS on aqueous concentrations of nitrate-N, atrazine, deethylatrazine (DEA), and deisopropylatrazine (DIA) were evaluated in a field study A laboratory study was conducted to evaluate sorption of atrazine DEA, DIA, cyanazine, alachlor, metolachlor, and butachlor to PTFE, HDPE, and SS materials. Butachlor is rarely use in the United States, but was included because of its expected high sorptivity. No significant differences between HDPE, LDPE, PTFE, rigid PVC, and SS were determined for any of the analytes tested in the field study. In the laboratory study, sorption of DIA to PTFE and SS was significant at 2.6 × 10−5 and 4.1 × 10−5 μg/m2 respectively. Sorption of DIAA to HDPE was not significantly > 0 sorption of all other compounds to HDPE, PTFE, and SS were also not significantly >0. Results of the two studies indicate that for these analytes (relatively polar or ionized compounds), representative ground water samples are not dependent on the materials used for multilevel sampler construction. When considering these compounds, it appears that the least expensive materials (HDPE, rigid PVC, and LDPE) are good choices for the construction of ground water monitoring wells. 相似文献
2.
Louise V. Parker Alan D. Hewitt Thomas F. Jenkins 《Ground Water Monitoring & Remediation》1990,10(2):146-156
Four well casing materials — polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), and stainless steel 304 (SS 304) and 316 (SS 316) — were examined to determine their suitability for monitoring inorganic and organic constituents in well water.
The inorganic study used a factorial design to test the effect of concentration of mixed metals (arsenic [As], chromium [Cr], lead [Pb], and cadmium [Cd]), pH, and organic carbon. Sample times were 0.5, 4, 8, 24, and 72 hours. Except for slow loss of Pb, PTFE well casings had no significant effect on the concentration of metals in solution. For the other casings, changes in analyte concentration often exceeded 10 percent in eight hours or less and, thus, could bias analyses of samples taken from wells constructed with these materials. Specifically, PVC casings sorbed Pb and leached Cd; SS 316 casings sorbed As and Pb and leached Cd; and SS 304 casings sorbed As, Cr, and Pb and leached Cd. Both stainless steel casing materials showed markedly poorer performance than the PVC casings.
The well casings were also tested for sorption/desorption of 10 organic substances from the following classes: chlorinated alkehes, chlorinated aromatics, nitroaromatics and nitramines. Sample times were 0, 1, 8, 24, and 72 hours, seven days, and six weeks. There were no detectable losses of analytes in any of the sample solutions containing stainless steel well casings. Significant loss of some analytes was observed in sample solutions containing plastic casings, although losses were always more rapid with the PTFE casings than with PVC. Chlorinated organic substances were lost most rapidly. For samples containing PTFE casings, losses of some of these compounds were rapid enough (>10 percent in eight hours) to be of concern for ground water monitoring. Losses of hydrophobic organic constituents in samples containing PTFE casings were correlated with the compound's octanol/water partition coefficient. 相似文献
The inorganic study used a factorial design to test the effect of concentration of mixed metals (arsenic [As], chromium [Cr], lead [Pb], and cadmium [Cd]), pH, and organic carbon. Sample times were 0.5, 4, 8, 24, and 72 hours. Except for slow loss of Pb, PTFE well casings had no significant effect on the concentration of metals in solution. For the other casings, changes in analyte concentration often exceeded 10 percent in eight hours or less and, thus, could bias analyses of samples taken from wells constructed with these materials. Specifically, PVC casings sorbed Pb and leached Cd; SS 316 casings sorbed As and Pb and leached Cd; and SS 304 casings sorbed As, Cr, and Pb and leached Cd. Both stainless steel casing materials showed markedly poorer performance than the PVC casings.
The well casings were also tested for sorption/desorption of 10 organic substances from the following classes: chlorinated alkehes, chlorinated aromatics, nitroaromatics and nitramines. Sample times were 0, 1, 8, 24, and 72 hours, seven days, and six weeks. There were no detectable losses of analytes in any of the sample solutions containing stainless steel well casings. Significant loss of some analytes was observed in sample solutions containing plastic casings, although losses were always more rapid with the PTFE casings than with PVC. Chlorinated organic substances were lost most rapidly. For samples containing PTFE casings, losses of some of these compounds were rapid enough (>10 percent in eight hours) to be of concern for ground water monitoring. Losses of hydrophobic organic constituents in samples containing PTFE casings were correlated with the compound's octanol/water partition coefficient. 相似文献
3.
Alan D. Hewitt 《Ground Water Monitoring & Remediation》1992,12(2):131-136
Static leaching and sorption laboratory studies were performed to assess the potential of polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), and two types of stainless steel (SS 304 and SS 316) well casing materials to influence metal concentrations in ground water solutions with low dissolved oxygen. Overall, PTFE was inert, whereas one or both stainless steels significantly altered the solution concentrations of Cd, Cr, Cu, Pb, Fe, and Ni. PVC was generally more reactive than PTFE, but did not significantly alter the solution metal concentrations as often, or as greatly, as either of the stainless casings. 相似文献
4.
Twenty polymeric tubings were filled with a test solution containing eight organic solutes. The test solutions were monitored for losses, indicating that sorption had occurred, and for signs that leaching of organic constituents had occurred. The tubings tested included seven flexible products and eight fluoropolymers. Among the rigid tubings tested, three fluoropolymers (fluorinated ethylene propylene [FEP], FEP-lined polyethylene, polyvinylidene fluoride) were the least sorptive tubings. However, even these tubings readily sorbed some of the analytes. Among the flexible tubings tested, a fluoroelastomer tubing and a tubing made of a copolymer of vinylidene fluoride and hexafluoropropylene were the least sorptive.
Several of the tubings tested leached constituents into the test solution. The polyurethane, polyamide, flexible polyvinyl chloride (PVC), polyester-lined PVC, and silicone-modified thermoplastic elastomer tubings were found to leach the most constituents. We were unable to detect any constituents leaching from the polyethylene tubings, the rigid fluoropolymer tubings, and one of the plasticized polypropylene tubings. 相似文献
Several of the tubings tested leached constituents into the test solution. The polyurethane, polyamide, flexible polyvinyl chloride (PVC), polyester-lined PVC, and silicone-modified thermoplastic elastomer tubings were found to leach the most constituents. We were unable to detect any constituents leaching from the polyethylene tubings, the rigid fluoropolymer tubings, and one of the plasticized polypropylene tubings. 相似文献
5.
This report examines sorption of low ppb levels of organic solutions by polytetra- fluoroethylene (PTFE), rigid polyvinyl chloride (PVC), and stainless steel 304 and 316 well casings. Nineteen organics were selected, including several munitions and chlorinated solvents. Compounds were selected to offer a range of physical properties, such as solubility in water, octanol/water partition coefficient, and molecular structure. When these results were compared with the results from a similar study conducted at ppm levels, the rate and extent of sorption by PTFE and PVC were the same as seen previously for almost all analytes. There were no losses of any compounds associated with stainless steel. At these low levels (ppm and ppb), the rate of diffusion within the polymer (PVC and PTFE) is independent of concentration. Only with PTFE are the rates rapid enough to be of concern when monitoring for some contaminants in ground water. Tetrachloroethylene was the compound PTFE sorbed the most rapidly. The study showed that PVC well casings are suitable for monitoring low levels (ppm and ppb) of organics. 相似文献
6.
W.M. Schuh R.L. Cline M.J. Kosse D.W. Sletton 《Ground Water Monitoring & Remediation》1997,17(1):81-90
A field experiment was conducted to examine the effect of short-term (one minute) contact of pesticide-laden water with a polyvinyl chloride (PVC) bailer on quantitative laboratory measurements of seven pesticide concentrations in distilled water samples subsequently decanted from the bailer. Pesticides were tested at two initial concentrations (low. based on current FPA maximum contaminant levels, or MCL: and high, based on a multiple of approximately lour times the MCL). Pesticide species included bromoxynil, diclofop-m, dimethoate. MCPA, methyl parathion, propiconazole, and trifluralin. Dimethoate recoveries were poor for all treatments. For all other pesticides there was no systematic difference between pesticide concentrations measured before and after bailer contact. Effectiveness of bailer decontamination treatments consisting of distilled water rinse alone was related to water solubility (S) for each species. Distilled water samples decanted from a rigid PVC bailer following initial bailer contact with pesticide-spiked water, and after the bailer had been cleaned with a single distilled water rinse, had measured pesticide concentrations of less than 2 percent of the pesticide concentration in the initial pesticide-spiked water, regardless of S. A single distilled water rinse effectively removed all trace of contaminants having S> 500 mg/L. Multiple distilled water rinses, and multiple distilled water rinses followed by 15 bailings of a well, effectively removed all trace of contaminants having S> 50 mg/L. Below threshold S, cleaning effectiveness decreased as a power function of S. 相似文献
7.
This is the second part of a study conducted to determine whether polymeric sampling tubing can affect organic analyte concentrations during a sampling event. In this part of the study, we looked for sorption and desorption of tricholoroethylene (TCE) and leaching of organic constituents in water pumped through five types of polymeric tubing. The materials tested were a rigid fluoropolymer, a flexible fluoropolymer, low-density polyethylene (LDPE), and two plasticized polypropylene tubings. The effects of tubing length and flow rate were examined.
The least sorptive tubings, both initially and at equilibrium, were the fluoropolymers. However, in some instances the LDPE tubing had little effect on TCE concentrations. This was when a slow flow rate was used to sample relatively shallow wells (50 feet [15 m] or less) or when a faster flow rate (1 L/min) was used to sample wells that are less than 500 feet (152 m). Further testing is recommended using more sorptive analytes.
Using high performance liquid chromatography (HPLC), we were unable to detect any constituents leaching from any of the tubings used in these studies, even when a slow flow rate was used. However, desorption of sorbed analytes is a concern for all the tubings tested, including the rigid fluoropolymer. 相似文献
The least sorptive tubings, both initially and at equilibrium, were the fluoropolymers. However, in some instances the LDPE tubing had little effect on TCE concentrations. This was when a slow flow rate was used to sample relatively shallow wells (50 feet [15 m] or less) or when a faster flow rate (1 L/min) was used to sample wells that are less than 500 feet (152 m). Further testing is recommended using more sorptive analytes.
Using high performance liquid chromatography (HPLC), we were unable to detect any constituents leaching from any of the tubings used in these studies, even when a slow flow rate was used. However, desorption of sorbed analytes is a concern for all the tubings tested, including the rigid fluoropolymer. 相似文献
8.
This series of experiments was initiated to determine the overall suitability of three alternative polymeric well casing materials (fluorinated ethylene propylene [FEP], fiberglass-reinforced epoxy [FRE], and fiberglass-reinforced plastic [FRP]) for use in ground water monitoring wells and to compare these materials with polyvinyl chloride (PVC) and polytetrafluoroethylene (PTFE) well casings. This paper focuses on sorption and leaching of metals.
Generally, the fiberglass materials leached more metal contaminants than PVC, FEP, and PTFE. However, with one exception (Pb leaching from FRP), leached concentrations were below maximum allowable limits set by the U.S. Environmental Protection Agency (EPA) for drinking water. With respect to sorption, none of the polymers sorbed the anions tested, but all of them sorbed one or more of the cations tested. FEP and PTFE were much less sorptive than the other materials. 相似文献
Generally, the fiberglass materials leached more metal contaminants than PVC, FEP, and PTFE. However, with one exception (Pb leaching from FRP), leached concentrations were below maximum allowable limits set by the U.S. Environmental Protection Agency (EPA) for drinking water. With respect to sorption, none of the polymers sorbed the anions tested, but all of them sorbed one or more of the cations tested. FEP and PTFE were much less sorptive than the other materials. 相似文献
9.
Worldwide pesticide usage has increased dramatically during the last three decades, coinciding with changing practices and increasing by intensive agriculture. This widespread use of pesticides for agricultural and non‐agricultural purposes has resulted in the presence of their residues in various environmental matrices. The occurrence of pesticides and their metabolite transported in rivers, channels, lakes, sea, air, soils, groundwater, and even drinking water, proves the high risk of these chemicals to human health and the environment. Therefore, pesticide removal is of an increasing concern. In this study, a review of the published literature dealing with pesticides removal process is presented. Firstly, pesticide removal by conventional means is briefly considered. Secondly, the use of the low‐cost sorbent through biosorption process is discussed comprehensively. The effect of factors such as pH, contact time, sorbent dosage, initial pesticide concentration, and optimization of biosorption conditions is also discussed. Kinetic, thermodynamic, and mechanism studies are also given. This study shows that both microorganisms and other materials with biological origin like agricultural by‐products may be used to this end. There is a significant potential for pesticide uptake by the use of various pristine and especially modified biosorbents. In the case of living organisms used as removal agents, degradation may also play a role in the total removal observed. 相似文献
10.
This study evaluates the performance of two low cost and high performance adsorption materials, i.e., activated carbon produced from two natural waste products: Bamboo and coconut shell, in the removal of three pesticides from drinking water sources. Due to the fact that bamboo and coconut shell are abundant and inexpensive materials in many parts of the world, they respond to the “low‐cost” aspect. The adsorption capacities of two local adsorbents have been compared with commercial activated carbon to explore their potential to respond to the “high quality” aspect. Two pesticides were selected, namely dieldrin and chlorpyrifos, because they are commonly used in agriculture activities, and may remain in high concentrations in surface water used as drinking water sources. The results indicate that the adsorption of pesticides on activated carbons is influenced by physico‐chemical properties of the activated carbon and the pesticides such as the presence of an aromatic ring, and their molar mass. The activated carbon produced from bamboo can be employed as low‐cost and high performance adsorbent, alternative to commercial activated carbon for the removal of pesticides during drinking water production. The performance of activated carbon from bamboo was better due to its relatively large macroporosity and planar surface. The effect of adsorbent and pesticide characteristics on the performance was derived from batch experiments in which the adsorption behavior was studied on the basis of Freundlich isotherms. 相似文献
11.
Hydrogeologic and ground water quality data obtained from a gas-driven multilevel sampler system and a polyvinyl chloride (PVC) monitoring well nest with the same aquifer communication intervals are compared. All monitoring points are in close proximity to each other. The study was conducted at an eight-acre uncontrolled hazardous waste site. The site is located in an alluvial valley composed of approximately 40 feet of alluvium overlying shale bedrock. The ground water at the site is contaminated with various organic constituents. A ground water monitoring network consisting of 26 conventional monitoring wells, nine observation well points, and six multilevel gas-driven samplers was established to characterize the hydrogeologic regime and define the vertical and horizontal extent of contamination in the vicinity of the abandoned chemical plant. As part of this study, a multilevel monitoring system was installed adjacent to a well nest. The communication zones of the multilevel samplers were placed at the same elevation as the sand packs of the well nest. The multilevel sampler system and well nest are located in a contaminated area directly downgradient of the site. A comparison of the vertical head distribution and ground water quality was performed between the well nest and the multilevel sampling system. The gas-driven multilevel sampling system consists of three gas-driven samplers that monitor separate intervals in the unconsolidated materials. The well nest, composed of two PVC monitoring wells in separate boreholes, has the same communication interval as the other two gas-driven samplers. Hydraulic head information for each multilevel sampler was obtained using capillary tubing. This was compared with heads obtained from the well nest utilizing an electric water level indicator. Chemical analyses from the PVC and multilevel sampler wells were performed and compared with one another. The analyses included organic acids, base neutrals, pesticides, PCBs, metals, volatile organics, TOX, TOC, CN, pH and specific conductance. 相似文献
12.
Previous research has shown that the most commonly used well casing materials-stainless steel. polyvinyl chloride (PVC). and polytetra-fluoroethylene (PTFE)-are not suited for all monitoring environments and applications. This study is part of a series of experiments that were conducted to determine the suitability of four other polymeric well casing materials-acrylonitrile butadiene styrene (ABS), fluorinalcd ethylene propylene (FHP), fiberglass-reinlorced epoxy (FRE), and fiberglass-reinforced plastic (FRP)- for use in ground water monitoring wells. In these studies, these four materials were compared with two other commonly used polymeric well casings, PVC and PTFE. Part I of these studies examines the resistance of these materials to degradation by chemicals. Future reports will consider sorption and leaching of organic and metal contaminants.
In this study, the six materials were exposed to 28 neat organic compounds (including one acid) and to extremely acidic and alkaline aqueous solutions for up to 112 days. This was done to simulate the most aggressive environments to which monitoring well casings may be exposed. The casings were observed for changes in weight and signs of physical degradation (swelling, softening, deterioration, or dissolution).
The two fluorinated polymers (FEP and PTFE) were not degraded by any of the lest chemicals. Among the nonfluorinated products tested. FRE was the most inert. Three organic chemicals caused the glass fibers to separate. and two organic solvents caused weight gains exceeding 10 percent. ABS was the most readily degraded material tested. By the end of the study, only the acid and alkaline solutions had little effect on ABS. FRP was more severely degraded by the organic chemicals than FRH but was less affected than PVC. FRP and FRE. lost weight when exposed to the highly acidic conditions. 相似文献
In this study, the six materials were exposed to 28 neat organic compounds (including one acid) and to extremely acidic and alkaline aqueous solutions for up to 112 days. This was done to simulate the most aggressive environments to which monitoring well casings may be exposed. The casings were observed for changes in weight and signs of physical degradation (swelling, softening, deterioration, or dissolution).
The two fluorinated polymers (FEP and PTFE) were not degraded by any of the lest chemicals. Among the nonfluorinated products tested. FRE was the most inert. Three organic chemicals caused the glass fibers to separate. and two organic solvents caused weight gains exceeding 10 percent. ABS was the most readily degraded material tested. By the end of the study, only the acid and alkaline solutions had little effect on ABS. FRP was more severely degraded by the organic chemicals than FRH but was less affected than PVC. FRP and FRE. lost weight when exposed to the highly acidic conditions. 相似文献
13.
A simple, inexpensive sampling pump has lately come into use in ground water monitoring. The pump is referred to as an inertial pump; its only downhole components are a foot valve connected to a length of tubing or pipe. The operating principle of the pump is based on the inertia of a column of water within the riser tubing. Ground water is drawn through the foot valve and up the riser tubing by rapid up and down movements of the tubing. This pumping method is not new, but has only recently been applied to monitoring wells. Foot valves are available in a variety of materials and sizes and can be used in monitoring wells as small as 19mm (3/4 inch) I.D. Flexible polyethylene or Teflon® tubing, and in some cases stainless steel tubing or rigid PVC pipe, is used as the riser. The inertial pump satisfies most of the criteria normally cited for an "ideal" sampling device. The pump is easy to operate, reliable, durable, portable, and virtually maintenance-free. It can be operated manually from as deep as 40m or from as deep as 60m using a motor drive. The pump is inexpensive, and therefore suitable for use as a dedicated sampling pump. Recent tests have shown the pump to be suitable for sampling volatile organics. The inertial pump has a high flow capacity and performs well in silty/sandy environments, which makes it useful for developing and purging monitoring wells. It may also be used to perform field hydraulic conductivity tests. 相似文献
14.
W. Hrtig 《洁净——土壤、空气、水》1993,21(4):197-202
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
15.
Joel M. Hubbell Thomas R. Wood Brian Higgs Allan H. Wylie Deborah L. McElroy 《Ground Water Monitoring & Remediation》1998,18(3):151-157
Waste disposal sites with volatile organic compounds (VOCs) frequently contain contaminants that are present in both the ground water and vadose zone. Vertical sampling is useful where transport of VOCs in the vadose zone may effect ground water and where steep vertical gradients in chemical concentrations are anticipated. Designs for combination ground water and gas sampling wells place the tubing inside the casing with the sample port penetrating the casing for sampling. This physically interferes with pump or sampler placement. This paper describes a well design that combines a ground water well with gas sampling ports by attaching the gas sampling tubing and ports to the exterior of the casing. Placement of the tubing on the exterior of the casing allows exact definition of gas port depth, reduces physical interference between the various monitoring equipment, and allows simultaneous remediation and monitoring in a single well. The usefulness and versatility of this design was demonstrated at the Idaho National Engineering and Environmental Laboratory (INEEL) with the installation of seven wells with 53 gas ports, in a geologic formation consisting of deep basalt with sedimentary interbeds at depths from 7.2 to 178 m below land surface. The INEEL combination well design is easy to construct, install, and operate. 相似文献
16.
Pesticides in Nebraska's Ground Water 总被引：1，自引：0，他引：1
《Ground Water Monitoring & Remediation》1989,9(4):126-133
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
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
17.
Environmental fate of fungicides and other current-use pesticides in a central California estuary 总被引：2，自引：0，他引：2
Kelly L. Smalling Kathryn M. Kuivila James L. Orlando Bryn M. Phillips Brian S. Anderson Katie Siegler John W. Hunt Mary Hamilton 《Marine pollution bulletin》2013
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
18.
Barry J. Allred 《Ground Water Monitoring & Remediation》2012,32(2):81-95
Agricultural subsurface drainage waters containing nutrients (nitrate/phosphate) and pesticides are discharged into neighboring streams and lakes, frequently producing adverse environmental impacts on local, regional, and national scales. On‐site drainage water filter treatment systems can potentially prevent the release of agricultural contaminants into adjacent waterways. Zero valent iron (ZVI) and sulfur‐modified iron (SMI) are two types of promising filter materials that could be used within these treatment systems. Therefore, water treatment capabilities of three ZVI and three SMI filter materials were evaluated in the laboratory. Laboratory evaluation included saturated falling‐head hydraulic conductivity tests, contaminant removal batch tests, and saturated solute transport column experiments. The three ZVI and the three SMI filter materials, on average, all had a sufficient hydraulic conductivity greater than 1 × 10–3 cm/s. Batch test results showed a phosphate decrease of at least 94% for all tests conducted with the ZVI and SMI. Furthermore, the three SMI filter materials removed at least 86% of the batch test nitrate originally present, while batch tests for one of the ZVI filter materials exhibited an 88% decrease in the pesticide, atrazine. Saturated solute transport column experiments were carried on the best ZVI filter material, or the best SMI filter material, or both together, in order to better evaluate drainage water treatment effectiveness and efficiency. Results from these column tests additionally document the drainage water treatment ability of both ZVI and SMI to remove the phosphate, the ability of SMI to remove nitrate, and the ability of a select ZVI material to remove atrazine. Consequently, these findings support further investigation of ZVI and SMI subsurface drainage water treatment capabilities, particularly in regard to small‐ and large‐scale field tests. 相似文献
19.
M. Kruhm-Pimpl 《洁净——土壤、空气、水》1993,21(3):145-152
The results of a series of investigations are presented, performed by the governmental chemical laboratory Karlsruhe (CLUA) in order to determine pesticides in drinking water for purposes of food monitoring. 231 samples of 8 municipal water supplies (groundwater wells/no bank filtrate) and 34 private water supplies close to the bank of the river Rhine (groundwater wells/partly bank filtrate) were analysed. The sampling sites were located between Mannheim and Greffern, Germany. In 1986 high amounts of atrazine and simazine were determined in the drinking water wells of several private water supplies, especially at the sampling sites in the south. The likewise high chloride content of the samples was taken as a proof of bank filtrate contributing to the water. The decrease of atrazine load in the river water of the Rhine since 1987 has its parallel in the analytical results for the concerned drinking water wells. Obviously the pesticide contamination of water from bank filtrate pumping wells is mainly depending on the pesticide load of the river water. The application of fertilizers and pesticides in the fields seems not to be a significant source of the pesticide contamination of dringing waters derived from bank filtrate water. For reasons of public health a monitoring of pesticide content in bank filtrate pumping wells of private water supplies is recommended. 相似文献
20.
Analytical Model for Contaminant Mass Removal by Air Sparging 总被引：2，自引：0，他引：2
An analytical model was developed lo predict the removal of volatile organic compounds (VOCs) from ground water by air sparging (AS). The model treats the air sparging zone as a completely mixed reactor subject to the removal of dissolved contaminants by volatilization, advection, and first-order decay Nonequilibrium desorption is approximated as a first-order mass transfer process. The model reproduces the tailing and rebound behavior often observed at AS sites, and would normally require the estimation of three site-specific parameters. Dimensional analysis demonstrates that predicted tailing can be interpreted in terms of kinetic desorption or diffusion of aqueous phase contaminants into discrete air channels. Related work is ongoing to test the model against field data. 相似文献