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1.
Antibiotics are widely used, and there is a serious concern about its adverse impacts on the environment and human health. To our knowledge, prior to this work, there was no evidence of the potential presence of antibiotics in groundwater in China, despite populous speculations. This study reported the detection of 35 target antibiotics of 6 groups (chloramphenicois, lincosamides, marcrolides, quinolones, sulfonamides, and tetracyclines), in shallow groundwater samples collected in northern and southwestern China. Thirty‐four of thirty‐five target antibiotics were detected in the groundwater samples; 73 of 74 monitoring wells contained at least one antibiotic; and at least two antibiotics were detected in 72 of the 74 wells. Ofloxacin (1199.7 ng/L), lincomycin (860.7 ng/L), and norfloxacin (441.9 ng/L) as well as antibiotics with the highest detection frequency such as sulfapyridine (70%), norfloxacin (69%), and lincomycin (64%) were detected at elevated concentrations. The highest detection frequency and concentration of lincosamides were observed in those groundwater samples, but no clear distribution patterns were observed for the six antibiotic groups. Moreover, shallow groundwater in southwestern China seemed to contain most antibiotics, likely due to the high antibiotics discharge and frequent exchange of groundwater with surface matrices. The findings from this work suggest that groundwater in China has been widely contaminated by antibiotics, and presumably other pharmaceutical compounds that have not been investigated to date.  相似文献   

2.
A pioneering investigation of semi‐volatile organic compounds (SVOCs) in shallow groundwater in China was hereby reported. Representative groundwater samples were collected from three selected regions: Eastern Hai River Plain, Yangtze River Delta, and Yunnan‐Guizhou Plateau, and analyzed for 103 SVOCs linked to agricultural and industrial practices. Analytical results showed that 70 of the 103 SVOCs were present in the groundwater samples, a detection frequency of approximately 86%. Compounds detected most frequently included P,P′‐DDT (53.49%, MDL 0.0007 µg/L), 2,4‐dinitrotoluene (51.16%, MDL 0.02 µg/L), and phenol (51.16%, MDL 0.02 µg/L). Fifteen SVOCs, such as P,P′‐DDT, 2,4‐dinitrotoluene, heptachlor, and aldrin, were detected at concentrations exceeding the USA National Recommended Water Quality Criteria‐2009 (USNRWQC‐2009). Most of these 15 SVOCs belong to polycyclic aromatic hydrocarbons and organochlorine pesticides. The detection of SVOCs in the Yunnan‐Guizhou Plateau warrants special concern, since this region has limited human activities and been assumed as an environmentally pristine area. The data from this work are expected to contribute to the database of contemporary groundwater quality in China.  相似文献   

3.
In situ chemical oxidation involves the introduction of a chemical oxidant into the subsurface for the purpose of transforming groundwater contaminants into harmless by‐products. Owing to oxidant persistence, groundwater samples collected at hazardous waste sites may contain both the contaminant(s) and the oxidant in a “binary mixture.” Binary mixtures composed of sodium persulfate (2.5 g/L; 10.5 mM) and volatile organic compounds (VOCs) (benzene, toluene, m‐xylene, perchloroethylene, trichloroethylene) were analyzed to assess the impact on the quality of the sample. A significant decline (49 to 100%) in VOC concentrations was measured in binary mixtures using gas chromatography (GC) purge and trap, and GC mass spectroscopy headspace methods. Preservation of the binary mixture samples was achieved through the addition of ascorbic acid (99 to 100% VOC average recovery). High concentrations of ascorbic acid (42 to 420 mM) did not interfere in the measurement of the VOCs and did not negatively impact the analytical instruments. High concentrations of ascorbic acid favored the reaction between persulfate and ascorbic acid while limiting the reaction between persulfate and VOCs. If an oxidant is detected and the binary sample is not appropriately preserved, the quality of the sample is likely to be compromised.  相似文献   

4.
This research demonstrates that groundwater contaminated by a relatively dilute but persistent concentration of 1,4‐dioxane (1,4‐D), approximately 60 μg/L, and chlorinated aliphatic co‐contaminants (1.4 to 10 μg/L) can be efficiently and reliably treated by in situ aerobic cometabolic biodegradation (ACB). A field trial lasting 265 days was conducted at Operable Unit D at the former McClellan Air Force Base and involved establishing an in situ ACB reactor through amending recirculated groundwater with propane and oxygen. The stimulated indigenous microbial population was able to consistently degrade 1,4‐D to below 3 μg/L while the co‐contaminants trichloroethene (TCE) and 1,2‐dichloroethane (1,2‐DCA) were decreased to below 1 μg/L and 0.18 μg/L, respectively. A stable treatment efficiency of more than 95% removal for 1,4‐D and 1,2‐DCA and of more than 90% removal for TCE was achieved. High treatment efficiencies for 1,4‐D and all co‐contaminants were sustained even without propane and oxygen addition for a 2‐week period.  相似文献   

5.
The southern coastal plain of Laizhou Bay, which is the area most seriously affected by salt water intrusion in north China, is a large alluvial depression, which represents one of the most important hydrogeological units in the coastal region of northern China. Chlorofluorocarbons (CFCs, including CFC‐11, CFC‐12 and CFC‐113) and tritium were used together for dating groundwater up to 50 years old in the study area. There are two cones of depression, caused by intensive over‐exploitation of fresh groundwater in the south and brine water in the north. The assigned CFC apparent ages for shallow groundwater range from 8 a to >50 a. A binary mixing model based on CFC‐113 and CFC‐12 concentrations in groundwater was used to estimate fractions of young and pre‐modern water in shallow aquifers and to identify groundwater mixing processes during saltwater intrusion. Discordance between concentrations of different CFC compounds indicate that shallow groundwater around the Changyi cone of depression is vulnerable to contamination. Pumping activities, CFC contamination, mixing and/or a large unsaturated zone thickness (e.g. >20 m) may be reasons for some groundwater containing CFCs without tritium. Saline intrusion mainly occurs because of large head gradients between fresh groundwater in the south and saline water bodies in the north, forming a wedge of saline water below/within fresh aquifer layers. Both CFC and tritium dates indicate that the majority of the saline water is from >50 a, with little or no modern seawater component. Based on the distribution of CFC apparent ages, tritium contents plus chemical and physical data, a conceptual model of groundwater flow along the investigated Changyi‐Xiaying transect has been developed to describe the hydrogeological processes. Three regimes are identified from south to north: (i) fresh groundwater zone, with a mixing fraction of 0.80–0.65 ‘young’ water calculated with the CFC binary mixing model (groundwater ages <34 a) and 1.9–7.8TU of tritium; (ii) mixing zone characterized by a mixing fraction of 0.05–0.65 young groundwater (ages of 23–44 a), accompanied by local vertical recharge and upward leakage of older groundwater; and (iii) salt water zone, mostly comprising waters with ages beyond the dating range of both CFCs and tritium. Some shallow groundwater in the north of the Changyi groundwater depression belongs to the >50a water group (iii), indicating slow velocity of groundwater circulation and possible drawing in of saline or deep groundwater that is tracer‐free. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

6.
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7.
Adaptive site management and aggressive bioremediation in the source zone of a complex chlorinated dense nonaqueous phase liquid (DNAPL) site reduced total chlorinated hydrocarbon mass discharge by nearly 80%. Successful anaerobic bioremediation of chlorinated hydrocarbons can be impaired by inadequate concentrations of electron donors, competing electron acceptors, specific inhibitors such as chloroform, and potentially by high contaminant concentrations associated with residual DNAPL. At the study site, the fractured bedrock aquifer was impacted by a mixture of chlorinated solvents and associated daughter products. Concentrations of 1,1,2,2‐tetrachloroethane (1,1,2,2‐TeCA), 1,1,2‐trichloroethane (1,1,2‐TCA), and 1,2‐dichloroethane (1,2‐DCA) were on the order of 100 to 1000 mg/L. Chloroform was present as a co‐contaminant and background sulfate concentrations were approximately 400 mg/L. Following propylene glycol injections, concentrations of organohalide‐respiring bacteria including Dehalococcoides and Dehalogenimonas spp. increased by two to three orders of magnitude across most of the source area. Statistical analysis indicated that reaching volatile fatty acid concentrations greater than 1000 mg/L and depleting sulfate to concentrations less than 50 mg/L were required to achieve a Dehalococcoides concentration greater than the 104 cells/mL recommended for generally effective reductive dechlorination. In a limited area, chloroform concentrations greater than 5 mg/L inhibited growth of Dehalococcoides populations despite the availability of electron donor and otherwise appropriate geochemical conditions. After implementing a groundwater recirculation system targeting the inhibited area, chloroform concentrations decreased permitting significant increases in concentrations of Dehalococcoides and vinyl chloride reductase gene copies.  相似文献   

8.
The potential discharge of groundwater contaminated by oil sands process‐affected water (OSPW) is a concern for aquatic ecosystems near tailings ponds. Groundwater in the area, but unaffected by OSPW, may contain similar compounds, complicating the assessment of potential ecological impacts. In this study, 177 shallow groundwater samples were collected from riparian areas along the Athabasca River and tributaries proximate to oil sands developments. For “pond‐site” samples (71; adjacent to study tailings pond), Canadian aquatic life guidelines were exceeded for 11 of 20 assessed compounds. However, “non‐pond” samples (54; not near any tailings pond) provided similar exceedances. Statistical analyses indicate that pond‐site and non‐pond samples were indistinguishable for all but seven parameters assessed, including salts, many trace metals, and fluorescence profiles of aromatic naphthenic acids (ANA). This suggests that, regarding the tested parameters, groundwater adjacent to the study tailings pond generally poses no greater ecological risk than other nearby groundwaters at this time. Multivariate analyses applied to the groundwater data set separated into 11 smaller zones support this conclusion, but show some variation between zones. Geological and potential OSPW influences could not be distinguished based on major ions and metals concentrations. However, similarities in indicator parameters, namely ANA, F, Mo, Se, and Na‐Cl ratio, were noted between a small subset of samples from two pond‐site zones and two OSPW samples and two shallow groundwater samples documented as likely OSPW affected. This indicator‐based screening suggests that OSPW‐affected groundwater may be reaching Athabasca River sediments at a few locations.  相似文献   

9.
A comprehensive study aimed at evaluating the occurrence, significance of concentrations and spatial distribution of priority pollutants (PPs) along the Comunidad Valenciana coastal waters (Spain) was carried out in order to fulfil the European Water Framework Directive (WFD). Additionally, PP concentrations were also analysed in the effluent of 28 WWTPs distributed along the studied area. In coastal waters 36 organic pollutants of the 71 analysed, including 26 PPs were detected although many of them with low frequency of occurrence. Only 13 compounds, which belong to four different classes (VOCs, organochlorinated pesticides, phthalates and tributyltin compounds (TBT)) showed a frequency of occurrence above 20% in coastal waters. In the results obtained until now, octylphenol, pentachlorobenzene, DEHP and TBT exceeded the annual average concentration (EQS-AAC), and only TBT surpassed the maximum allowable concentration (EQS-MAC). The most frequent contaminants determined in coastal waters were also present in WWTP effluents.  相似文献   

10.
On-site analysis of trichloroethylene (TCE) in aqueous samples by head- space sample preparation and gas chromatography (HS/GC) provides for quick and precise concentration estimates. This analytical approach is well suited for the on-site determination of volatile organic compounds (VOCs) in a variety of sample matrices, including ground water and saturated and unsatured soils. For these reasons, HS/GC can be used to establish analyte concentrations on a near real time basis to help select appropriate casing material during monitoring well installation. This application and the collection of multiple well samples during sampling events facilitates the hydrogeological site interpretation and the formulation of remediation strategies.  相似文献   

11.
This paper provides a summary of a number of indoor air quality studies reporting concentrations of volatile organic compounds (VOCs) in indoor air samples collected from residential properties in North America and provides average values for certain statistics (percentiles, detection frequency, maximum). This compilation includes several VOCs that are commonly assessed in studies of subsurface vapor intrusion to indoor air, but may also be attributable to consumer products, building materials, or even outdoor air (ambient) sources, specifically benzene, carbon tetrachloride, chloroform, 1,1-dichloroethane, 1,1-dichloroethene, 1,2-dichloroethane, cis and trans-1,2-dichloroethene, ethylbenzene, methyl tert-butyl ether, methylene chloride, tetrachloroethene, trichloroethene, toluene, trichloro-1,2,2-trifluoroethane, 1,1,1-trichloroethane, vinyl chloride, and meta, para, and ortho-xylene. In studies spanning 1990 through 2005, eleven of these compounds were detected in more than 50% of samples collected, and for several compounds (benzene, carbon tetrachloride, chloroform, ethylbenzene, and tetrachloroethene) the lower and upper quintiles of the indoor air concentrations are within the range of typical risk-based target levels. These summary statistics may help interpret data collected during a vapor intrusion investigation and communicate the findings of indoor air quality studies to building occupants and other stakeholders. Similar studies have been published in the past, but there has been a gradual change in indoor air quality over time and a large amount of new data has been collected, so this paper provides more relevant information for current use than previous compilations.  相似文献   

12.
Chahardouly basin is located in the western part of Iran and is characterized by semi‐arid climatic conditions and scarcity in water resources. The main aquifer systems are developed within alluvial deposits. The availability of groundwater is rather erratic owing to the occurrence of hard rock formation and a saline zone in some parts of the area. The aquifer systems of the area show signs of depletion, which have taken place in recent years due to a decline in water levels. Groundwater samples collected from shallow and deep wells were analysed to examine the quality characteristics of groundwater. The major ion chemistry of groundwater is dominated by Ca2+ and HCO3?, while higher values of total dissolved solids (TDS) in groundwater are associated with high concentrations of all major ions. An increase in salinity is recorded in the down‐gradient part of the basin. The occurrence of saline groundwater, as witnessed by the high electrical conductivity (EC), may be attributed to the long residence time of water and the dissolution of minerals, as well as evaporation of rainfall and irrigation return flow. Based on SAR values and sodium content (%Na), salinity appears to be responsible for the poor groundwater quality, rendering most of the samples not suitable for irrigation use. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

13.
Drinking water supply in Lithuania is entirely based on groundwater. Wellfields of Vilnius develop intermorainic ca. 50 m deep (in average) aquifer which is locally contaminated by chlorinated hydrocarbons— volatile organic compounds (VOCs). Groundwater abstraction activates VOCs migration from an abandoned factory into the pumping wells of one wellfield named “Vingis.” However monitoring data testify that only traces of VOCs were detected on the territory of this factory. Subsequent studies revealed the “secret”: dense VOCs have migrated from the territory of the polluter and have accumulated in lowermost places of pumped aquifer inside the wellfield. An attempt to ensure low concentration of VOCs in pumped water manipulating by pumping rates of more or less contaminated abstraction wells was not effective. Finally, an acceptable concentration of VOCs in supplied drinking water was ensured by permanent pumping out of the most polluted groundwater from some abstraction wells of the wellfield and diverting this water to the Neris River.  相似文献   

14.
Based on stable isotopes in stream water, groundwater, and meltwater in the Kaidu River Basin, NW China, we estimated the evaporation enrichment of stable oxygen isotopes in different types of water and separated the contribution of each streamflow component in river run‐off. Our results indicated that δ18O and δ2H in stream water did not vary with altitude regularly but with seasons, with low concentrations in spring and high concentrations in summer. However, the seasonal variations of δ18O and δ2H in groundwater were not as obvious. The mean evaporation enrichment was between 26% and 44% for δ18O. Of the various water types under investigation, we found glaciers were influenced the most, showing an evaporation enrichment of 44%, followed by oasis groundwater (37%), stream water (36%), and mountain groundwater (26%). Overall, meltwater and groundwater were the predominant streamflow components, with their contributions were governed by temperature, and varied both temporally and specially. In the oasis region, groundwater was the predominant contributor (64% in spring, 50% in summer, and 66% in autumn), whereas in the mountains, groundwater was the dominant in spring (53%) and autumn (51%), and meltwater contributed the most in summer (52%). Precipitation contributed less than 15% to the streamflow.  相似文献   

15.
Arsenic Removal from Natural Groundwater Using Cupric Oxide   总被引：1，自引：0，他引：1  
Groundwater is a main source of drinking water for some rural areas. People in these rural areas are potentially at risk from elevated levels of arsenic (As) due to a lack of water treatment facilities. The objectives of this study were to (1) measure As concentrations in approximately 50 groundwater samples from rural domestic wells in the western United States, (2) explore the potential of cupric oxide (CuO) particles in removal of As from groundwater samples under natural conditions (i.e., without adding competing anions and adjusting the pH or oxidation state), and (3) determine the effects of As removal on the chemistry of groundwater samples. Forty‐six groundwater well samples from rural domestic areas were tested in this study. More than 50% of these samples exceeded the U.S. Environmental Protection Agency Maximum Contaminant Limit (US EPA MCL) of 10 µg/L for As. CuO particles effectively removed As from groundwater samples across a wide range of pH (7.11 and 8.95) and concentrations of competing anions including phosphate (<0.05 to 3.06 mg/L), silica (<1 to 54.5 mg/L), and sulfate (1.3 to 735 mg/L). Removal of As showed minor effects on the chemistry of groundwater samples, therefore most of the water quality parameters remained within the US EPA MCLs. Overall, results of this study could help develop a simple one‐step process to remove As from groundwater.  相似文献   

16.
The concentrations of chlorofluorocarbons (CFC‐11, CFC‐12 and CFC‐113) and tritium (3H) content in groundwater were used to date groundwater age, delineate groundwater flow systems and estimate flow velocity in the Hohhot basin. The estimated young groundwater age is fallen in the bracket of 21 ~ 50 a and indicates the presence of two different age profiles and flow systems in the shallow groundwater system. Older age waters occur under the topographically low areas, where the aquifer is double‐layer aquifer system consisting of shallow unconfined‐semi‐confined aquifer and deep confined aquifer. This reflects long flow paths associated with regional flow. Groundwater (range from 21 to 34 years) in the north piedmont and east hilly areas, where the aquifer is a single‐layer aquifer consisting of alluvial fans, are typically younger than those in the low areas. The combination of CFCs dating with hydrogeological information indicates that both local and regional flow systems are present at the basin. The regional groundwater flow mainly flows from the north and east to the southwest, the local groundwater flow system occurs nearby the Hohhot city. The mean regional groundwater flow velocity of the shallow groundwater is estimated about 0.73 km/a. These findings can aid in refining hydrogeological conceptual model of the study area. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

17.
Vertical flow filters are containers filled with porous medium that are recharged from top and drained at the bottom, and are operated at partly saturated conditions. They have recently been suggested as treatment technology for groundwater containing volatile organic compounds (VOCs). Numerical reactive transport simulations were performed to investigate the relevance of different filter operation modes on biodegradation and/or volatilization of the contaminants and to evaluate the potential limitation of such remediation mean due to volatile emissions. On the basis of the data from a pilot‐scale vertical flow filter intermittently fed with domestic waste water, model predictions on the system’s performance for the treatment of contaminated groundwater were derived. These simulations considered the transport and aerobic degradation of ammonium and two VOCs, benzene and methyl tertiary butyl ether (MTBE). In addition, the advective‐diffusive gas‐phase transport of volatile compounds as well as oxygen was simulated. Model predictions addressed the influence of depth and frequency of the intermittent groundwater injection, degradation rate kinetics, and the composition of the filter material. Simulation results show that for unfavorable operation conditions significant VOC emissions have to be considered and that operation modes limiting VOC emissions may limit aerobic biodegradation. However, a suitable combination of injection depth and composition of the filter material does facilitate high biodegradation rates while only little VOC emissions take place. Using such optimized operation modes would allow using vertical flow filter systems as remediation technology suitable for groundwater contaminated with volatile compounds.  相似文献   

18.
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19.
Twenty-seven black guillemot eggs and 39 livers were analysed for polychlorinated biphenyls (PCBs), chlorinated pesticides including chlordane-related compounds and toxaphene, and polybrominated diphenylethers (PBDEs). The samples were collected at Qeqertarsuaq (Godhavn, West Greenland) and Ittoqqortoormiit (Scoresbysund, East Greenland). The concentrations of halogenated organic compounds in samples from East Greenland were somewhat higher than the corresponding concentrations from West Greenland. Differences in compound patterns were found between West and East Greenland, with higher percentages of the heavier PCB molecules, p,p(')-DDE and alpha-HCH in the samples from Ittoqqortoormiit. Similarly, different levels and different compositions were observed for eggs and livers. The eggs had generally higher concentrations of all compounds as well as higher percentages of CHB-50, CHB-62 and alpha-HCH than liver samples from the same area. Dividing the liver samples into age groups revealed increasing concentrations with age.  相似文献   

20.
Compound‐specific standardized sampling and storage methods are not available for artificial sweeteners found in groundwater. This study aimed to understand: (1) the appropriate length of storage time for samples containing acesulfame (ACE), sucralose (SUC), saccharin (SAC), and cyclamate (CYC) in simulated groundwater (SGW); (2) conditions of their stability; and (3) which sampling materials are appropriate for sample collection. The evaluated storage conditions included acidification, headspace, exposure to light, and refrigeration; the evaluated sampling materials included steel, stainless steel, aluminum, polyvinyl chloride, polyamide (nylon), polypropylene (PharMed BPT?) tubing, styrene‐ethylene‐butylene co‐polymer (MasterFlex?) tubing, and polytetrafluoroethylene (Teflon?) tubing. All compounds evaluated were stable in storage at 4 °C for 241 d (8 months). Concentrations of artificial sweeteners were consistently within 60% to 120% of original concentrations, except ACE and SAC that were substantially lower under acidified conditions at 25 °C after 241 d. Artificial sweetener concentrations remained nearly constant while in contact with all sampling materials except steel. SEM and TEM images showed oxidation of steel occurred; moreover, removal of all artificial sweetener compounds from aqueous solution had occurred after 289 d. These results suggest artificial sweetener analyses conducted within 14 d of sample collection produce optimal results; however, longer storage times may be acceptable under certain conditions. The results also suggest concentrations of artificial sweeteners in SGW are not affected by contact with typical well casing, sampling, and storage materials, with the exception of steel. The findings from this study will improve the use of artificial sweeteners as tracers in environmental studies.  相似文献   

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