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1

Groundwater Contamination  

NSDL National Science Digital Library

This site by the Michigan Environmental Education Curriculum presents an interactive module that provides an introduction to groundwater quality issues. The information is presented as a series of slides with text, animations, quiz questions and interactive features. Topics include types of aquifers, groundwater movement, sources of contamination, the concentration and dispersion of contaminants, plumes and remediation.

Babcock, Matthew; Mayer, Alex; Curriculum, Michigan E.

2

Groundwater Contamination  

NSDL National Science Digital Library

The Groundwater Foundation's sources of ground water contamination page discusses common contaminates, how they get to ground water, sources of pollution along with cleanup and prevention practices. The site's focal point is a detailed map of contaminants as they enter the water cycle.

2008-10-13

3

Groundwater Contamination  

NSDL National Science Digital Library

This lesson addresses groundwater contamination from leakage of underground gasoline, oil, or other hazardous chemical tanks. Students read two short articles and investigate causes, effects, solutions, and prevention measures.

Mclelland, Christine

4

Groundwater Contamination  

NSDL National Science Digital Library

This investigation consists of two parts, in which students first model the effects of groundwater contamination and then track the flow of the contamination. However, Part I does not have to be done in order to do Part II. This Teacher Information sectio

Van Faasen, Carl; Peaslee, Graham; Soukhome, Jennifer; Statema, William

2009-04-01

5

EPA (Environmental Protection Agency) activities related to sources of ground-water contamination  

SciTech Connect

The report contains a listing of EPA programs and activities, as of October 1986, that address 33 sources of potential ground-water contamination. The information on each activity is presented in a matrix format that is organized by type of contamination source. The following information is presented for each program and activity listed: title, lead office, contact person, type of activity (study, regulation, guidance, strategy, etc.) status, and a summary of the activity. The 33 sources of ground-water contamination are discussed in the 1984 EPA Office of Technology report: Protecting the Nations Ground Water from Contamination.

Black-Coleman, W.

1987-02-01

6

Development of a microbial contamination susceptibility model for private domestic groundwater sources  

NASA Astrophysics Data System (ADS)

Groundwater quality analyses were carried out on samples from 262 private sources in the Republic of Ireland during the period from April 2008 to November 2010, with microbial quality assessed by thermotolerant coliform (TTC) presence. Assessment of potential microbial contamination risk factors was undertaken at all sources, and local meteorological data were also acquired. Overall, 28.9% of wells tested positive for TTC, with risk analysis indicating that source type (i.e., borehole or hand-dug well), local bedrock type, local subsoil type, groundwater vulnerability, septic tank setback distance, and 48 h antecedent precipitation were all significantly associated with TTC presence (p < 0.05). A number of source-specific design parameters were also significantly associated with bacterial presence. Hierarchical logistic regression with stepwise parameter entry was used to develop a private well susceptibility model, with the final model exhibiting a mean predictive accuracy of >80% (TTC present or absent) when compared to an independent validation data set. Model hierarchies of primary significance are source design (20%), septic tank location (11%), hydrogeological setting (10%), and antecedent 120 h precipitation (2%). Sensitivity analysis shows that the probability of contamination is highly sensitive to septic tank setback distance, with probability increasing linearly with decreases in setback distance. Likewise, contamination probability was shown to increase with increasing antecedent precipitation. Results show that while groundwater vulnerability category is a useful indicator of aquifer susceptibility to contamination, its suitability with regard to source contamination is less clear. The final model illustrates that both localized (well-specific) and generalized (aquifer-specific) contamination mechanisms are involved in contamination events, with localized bypass mechanisms dominant. The susceptibility model developed here could be employed in the appropriate location, design, construction, and operation of private groundwater wells, thereby decreasing the contamination risk, and hence health risk, associated with these sources.

Hynds, Paul D.; Misstear, Bruce D.; Gill, Laurence W.

2012-12-01

7

Investigation of Isotopic Signatures for Sources of Groundwater Contamination at the Hanford Site  

Microsoft Academic Search

The Hanford Site Groundwater Monitoring Project at Pacific Northwest National Laboratory (PNNL) investigated selected isotopic signature techniques to aid interpretation of contaminant plumes in Hanford Site groundwater. The main approach was to select groundwater samples expected to exhibit a variety of contaminant characteristics and then develop inductively coupled plasma mass spectrometry (ICP-MS) analytical methods for the groundwater matrix. Initial broad

P Evan Dresel; John C. Evans; Orville T. Farmer

2002-01-01

8

Toxic fluoride and arsenic contaminated groundwater in the Lahore and Kasur districts, Punjab, Pakistan and possible contaminant sources.  

PubMed

The present study is the first attempt to put forward possible sources of As, F- and SO4(2-) contaminated groundwater in the Kalalanwala area, Punjab, Pakistan. Five rainwater and 24 groundwater samples from three different depths were analyzed. Shallow groundwater from 24 to 27 m depth contained high F- (2.47-21.1mg/L), while the groundwater samples from the deeper depth were free from fluoride contamination. All groundwater samples contained high As (32-1900 microg/L), in excess of WHO drinking water standards. The SO4(2-) ranges from 110 to 1550 mg/L. Delta34S data indicate three sources for SO4(2-) air pollutants (5.5-5.7 per thousand), fertilizers (4.8 per thousand), and household waste (7.0 per thousand). Our important finding is the presence of SO4(2-), As and F- in rainwater, indicating the contribution of these elements from air pollution. We propose that pollutants originate, in part, from coal combusted at brick factories and were mobilized promotionally by the alkaline nature of the local groundwater. PMID:16777300

Farooqi, Abida; Masuda, Harue; Firdous, Nousheen

2007-02-01

9

The Relationship Between Partial Contaminant Source Zone Remediation and Groundwater Plume Attenuation  

NASA Astrophysics Data System (ADS)

Analytical solutions are developed that relate changes in the contaminant mass in a source area to the behavior of biologically reactive dissolved contaminant groundwater plumes. Based on data from field experiments, laboratory experiments, numerical streamtube models, and numerical multiphase flow models, the chemical discharge from a source region is assumed to be a nonlinear power function of the fraction of contaminant mass removed from the source zone. This function can approximately represent source zone mass discharge behavior over a wide range of site conditions ranging from simple homogeneous systems, to complex heterogeneous systems. A mass balance on the source zone with advective transport and first order decay leads to a nonlinear differential equation that is solved analytically to provide a prediction of the time-dependent contaminant mass discharge leaving the source zone. The solution for source zone mass discharge is coupled semi-analytically with a modified version of the Domenico (1987) analytical solution for three-dimensional reactive advective and dispersive transport in groundwater. The semi-analytical model then employs the BIOCHLOR (Aziz et al., 2000; Sun et al., 1999) transformations to model sequential first order parent-daughter biological decay reactions of chlorinated ethenes and ethanes in the groundwater plume. The resulting semi-analytic model thus allows for transient simulation of complex source zone behavior that is fully coupled to a dissolved contaminant plume undergoing sequential biological reactions. Analyses of several realistic scenarios show that substantial changes in the ground water plume can result from the partial removal of contaminant mass from the source zone. These results, however, are sensitive to the nature of the source mass reduction-source discharge reduction curve, and to the rates of degradation of the primary contaminant and its daughter products in the ground water plume. Aziz, C.E., C.J. Newell, J.R. Gonzales, P. Haas, T.P. Clement, and Y. Sun, 2000, BIOCHLOR Natural Attenuation Decision Support System User's Manual Version 1.0, US EPA Report EPA/600/R-00/008 Domenico, P.A., 1987, An analytical model for multidimensional transport of a decaying contaminant species, J. Hydrol., 91: 49-58. Sun, Y., J.N. Petersen, T.P. Clement, and R.S. Skeen, 1999, A new analytical solution for multi-species transport equations with serial and parallel reactions, Water Resour. Res., 35(1): 185-190.

Falta, R. W.

2004-05-01

10

Stable lead isotopes reveal a natural source of high lead concentrations to gasoline-contaminated groundwater  

USGS Publications Warehouse

Concentrations of total lead as high as 1,600 ??g/L were detected in gasoline-contaminated and uncontaminated groundwater at three gasoline-release sites in South Carolina. Total lead concentrations were highest in turbid groundwater samples from gasoline-contaminated and uncontaminated wells, whereas lower turbidity groundwater samples (collected using low-flow methods) had lower total lead concentrations. Dissolved lead concentrations in all wells sampled, however, were less than 15 ??g total lead/L, the current United States Environmental Protection Agency (US EPA) maximum contaminant level (MCL). Because many total lead concentrations exceeded the MCL, the source of lead to the groundwater system at two of the three sites was investigated using a stable lead isotope ratio approach. Plots of the stable isotope ratios of lead (Pb) in groundwater as 207Pb/206Pb versus 208Pb/206Pb, and 208Pb/204Pb versus 206Pb/204Pb were similar to ratios characteristic of lead-based minerals in local rocks of the southeastern US, and were not similar to the stable lead isotopes ratios characteristic of distant lead ore deposits such as Broken Hill, Australia, used to produce tetraethyl lead in gasoline products prior to its phase-out and ban in the United States. Moreover, the isotopic composition of dissolved lead was equivalent to the isotopic composition of total lead in turbid samples collected from the same well, suggesting that the majority of the lead detected in the groundwater samples was associated with sediment particulates of indigenous aquifer material, rather than lead associated with spilled leaded gasoline. The results of this investigation indicate that (1) lead detected at some gasoline-release sites may be derived from the local aquifer material, rather than the gasoline release, and consequently may affect site-specific remediation goals; (2) non-low flow groundwater sampling methods, such as a disposable bailer, may result in turbid groundwater samples and high total lead concentrations, and; (3) stable lead isotopes can be used to clarify the source of lead detected above permissible levels in gasoline-contaminated groundwater systems.

Landmeyer, J. E.; Bradley, P. M.; Bullen, T. D.

2003-01-01

11

Groundwater Contamination in Urban Areas  

Microsoft Academic Search

Groundwater has been used everywhere in the world for a long time because of its easy accessibility and good quality. In urban\\u000a areas, groundwater as a source of domestic, commercial and industrial water has greatly contributed to the development of\\u000a cities. Groundwater in urban areas is sometimes contaminated with multiple contaminants at higher concentrations than in rural\\u000a areas. For example,

Keisuke Kuroda; Tetsuo Fukushi

12

Influence of carbon source on nitrate removal of contaminated groundwater in a denitrifying submerged filter  

Microsoft Academic Search

The effectiveness of three selected carbon sources (sucrose, ethanol and methanol) on submerged filters for the removal of nitrate from contaminated groundwater (100mg NO3?\\/litre), was studied. Process yields, nitrite accumulation, biomass production and growth of denitrifying bacteria were compared. Process yields, represented as ratio C\\/N were 2.5, 1.08 and 1.1 for sucrose, ethanol and methanol assays, respectively, making sucrose the

M. A. Gómez; J. González-López; E. Hontoria-Garc??a

2000-01-01

13

Sources of nitrate and ammonium contamination in groundwater under developing Asian megacities.  

PubMed

The status of nitrate (NO(3)(-)), nitrite (NO(2)(-)) and ammonium (NH(4)(+)) contamination in the water systems, and the mechanisms controlling their sources, pathways, and distributions were investigated for the Southeast Asian cities of Metro Manila, Bangkok, and Jakarta. GIS-based monitoring and dual isotope approach (nitrate delta(15)N and delta(18)O) suggested that human waste via severe sewer leakage was the major source of nutrient contaminants in Metro Manila and Jakarta urban areas. Furthermore, the characteristics of the nutrient contamination differed depending on the agricultural land use pattern in the suburban areas: high nitrate contamination was observed in Jakarta (dry fields), and relatively lower nutrients consisting mainly of ammonium were detected in Bangkok (paddy fields). The exponential increase in NO(3)(-)-delta(15)N along with the NO(3)(-) reduction and clear delta(18)O/delta(15)N slopes of NO(3)(-) ( approximately 0.5) indicated the occurrence of denitrification. An anoxic subsurface system associated with the natural geological setting (e.g., the old tidal plain at Bangkok) and artificial pavement coverage served to buffer NO(3)(-) contamination via active denitrification and reduced nitrification. Our results showed that NO(3)(-) and NH(4)(+) contamination of the aquifers in Metro Manila, Bangkok, and Jakarta was not excessive, suggesting low risk of drinking groundwater to human health, at present. However, the increased nitrogen load and increased per capita gross domestic product (GDP) in these developing cities may increase this contamination in the very near future. Continuous monitoring and management of the groundwater system is needed to minimize groundwater pollution in these areas, and this information should be shared among adjacent countries with similar geographic and cultural settings. PMID:18533227

Umezawa, Yu; Hosono, Takahiro; Onodera, Shin-ichi; Siringan, Fernando; Buapeng, Somkid; Delinom, Robert; Yoshimizu, Chikage; Tayasu, Ichiro; Nagata, Toshi; Taniguchi, Makoto

2008-10-15

14

Erratum to "Sources of nitrate and ammonium contamination in groundwater under developing Asian megacities".  

PubMed

The status of nitrate (NO3-), nitrite (NO2-) and ammonium (NH4 +) contamination in the water systems, and the mechanisms controlling their sources, pathways, and distributions were investigated for the Southeast Asian cities of Metro Manila, Bangkok, and Jakarta. GIS-based monitoring and dual isotope approach (nitrate delta15N and delta18O) suggested that human waste via severe sewer leakage was the major source of nutrient contaminants in Metro Manila and Jakarta urban areas. Furthermore, the characteristics of the nutrient contamination differed depending on the agricultural land use pattern in the suburban areas: high nitrate contamination was observed in Jakarta (dry fields), and relatively lower nutrients consisting mainly of ammonium were detected in Bangkok (paddy fields). The exponential increase in NO3--delta15N along with the NO3- reduction and clear delta18O/delta15N slopes of NO3- (approximately 0.5) indicated the occurrence of denitrification. An anoxic subsurface system associated with the natural geological setting (e.g., the old tidal plain at Bangkok) and artificial pavement coverage served to buffer NO3- contamination via active denitrification and reduced nitrification. Our results showed that NO3- and NH4+ contamination of the aquifers in Metro Manila, Bangkok, and Jakarta was not excessive, suggesting low risk of drinking groundwater to human health, at present. However, the increased nitrogen load and increased per capita gross domestic product (GDP) in these developing cities may increase this contamination in the very near future. Continuous monitoring and management of the groundwater system is needed to minimize groundwater pollution in these areas, and this information should be shared among adjacent countries with similar geographic and cultural settings. PMID:19437606

Umezawa, Yu; Hosono, Takahiro; Onodera, Shin-ichi; Siringan, Fernando; Buapeng, Somkid; Delinom, Robert; Yoshimizu, Chikage; Tayasu, Ichiro; Nagata, Toshi; Taniguchi, Makoto

2009-04-15

15

A spatial analysis of pit latrine density and groundwater source contamination.  

PubMed

This study aims to assess the relationship between chemical and microbial contamination of groundwater sources and a range of potential hazards in two peri-urban areas of Kisumu, Kenya where shallow wells and pit latrines are widely used. From 1998 to 2004, 263 samples were taken from 61 groundwater sources and tested for thermotolerant coliforms. Eighteen of these sources were also tested for chemical contaminants, including nitrate, chloride and fluoride. The locations of all water sources, buildings and pit latrines in the study area were surveyed. Local pit latrine densities were calculated using a geographic information system. Ten out 18 samples were above the World Health Organization guideline values for nitrate, 236 out of 263 were positive for thermotolerant coliforms, and all were above the guideline values for fluoride. There was neither a relationship between thermotolerant coliform levels and daily rainfall patterns nor with sanitary risk inspection scores for samples from shallow wells (r = 0.01, p = 0.91, n = 191). The density of pit latrines within a 100-m radius was significantly correlated with nitrate and chloride levels (r = 0.64, p = 0.004 and r = 0.46, p = 0.05, respectively) but not with thermotolerant coliforms (r = 0.22, p = 0.11). These results illustrate both the public health risks associated with shallow groundwater sources, on-site sanitation and high population density. These findings have implications for current policies that promote latrine construction, especially in peri-urban areas of high population density. More comprehensive studies of larger communities should be commissioned to extend this analysis of the links between latrine density and groundwater contamination and so identify the contingent policy risks. PMID:22976120

Wright, Jim A; Cronin, Aidan; Okotto-Okotto, Joseph; Yang, Hong; Pedley, Steve; Gundry, Stephen W

2013-05-01

16

Sewers as a source and sink of chlorinated-solvent groundwater contamination, Marine Corps Recruit Depot, Parris Island, South Carolina  

USGS Publications Warehouse

Groundwater contamination by tetrachloroethene and its dechlorination products is present in two partially intermingled plumes in the surficial aquifer near a former dry-cleaning facility at Site 45, Marine Corps Recruit Depot, Parris Island, South Carolina. The northern plume originates from the vicinity of former above-ground storage tanks. Free-phase tetrachloroethene from activities in this area entered the groundwater. The southern plume originates at a nearby, new dry-cleaning facility, but probably was the result of contamination released to the aquifer from a leaking sanitary sewer line from the former dry-cleaning facility. Discharge of dissolved groundwater contamination is primarily to leaking storm sewers below the water table. The strong influence of sanitary sewers on source distribution and of storm sewers on plume orientation and discharge at this site indicates that groundwater-contamination investigators should consider the potential influence of sewer systems at their sites. ?? 2011, National Ground Water Association.

Vroblesky, D. A.; Petkewich, M. D.; Lowery, M. A.; Landmeyer, J. E.

2011-01-01

17

Development of Real-Time PCR to Monitor Groundwater Contaminated by Fecal Sources and Leachate from the Carcass  

NASA Astrophysics Data System (ADS)

The 2010 outbreak of foot and mouth disease (FMD) in South Korea caused about 4,054 carcass burial sites to dispose the carcasses. Potential environmental impacts by leachate of carcass on groundwater have been issued and it still needs to be studied. Therefore, we tried to develop robust and sensitive tool to immediately determine a groundwater contamination by the leachate from carcass burial. For tracking both an agricultural fecal contamination source and the leachate in groundwater, competitive real-time PCR and PCR method were developed using various PCR primer sets designed to detect E. Coli uidA gene and mtDNA(cytochrome B, cytB) of the animal species such as ovine, porcine, caprine, and bovine. The designed methods were applied to tract the animal species in livestock wastewater and leachate of carcass under appropriate PCR or real-time PCR condition. In the result, mtDNA primer sets for individual (Cow or Pig) and multiple (Cow and Pig) amplification, and E. Coli uidA primers for fecal source amplification were specific and sensitive to target genes. To determine contamination source, concentration of amplified mtDNA and uidA was competitively quantified in Livestock wastewater, leachate of carcass, and groundwater. The highest concentration of mtDNA and uidA showed in leachate of carcass and livestock wastewater, respectively. Groundwater samples possibly contaminated by leachate of carcass were analyzed by this assay and it was able to prove contamination source.

Park, S.; Kim, H.; Kim, M.; Lee, Y.; Han, J.

2011-12-01

18

Groundwater contamination in Japan  

NASA Astrophysics Data System (ADS)

Problems on groundwater contamination in Japan are briefly summarized in this paper. Although normal physical conditions in Japan restrict the possibilities of groundwater contamination, human activities are threatening groundwater resources. A survey by the Environment Agency of Japan showed nationwide spreading of organic substances, such as trichloroethylene as well as nitrogen compounds. Synthetic detergents have also been detected even in rural areas and in deep confined aquifers, although their concentrations are not as high. Public awareness of agrichemical or pesticides abuse, especially from golf courses, is apparent. Other problems such as nitrate-nitrogen, leachate from landfills, and the leaking of underground storage tanks are also discussed.

Tase, Norio

1992-07-01

19

Sources and controls of Arsenic contamination in groundwater of Rajnandgaon and Kanker District, Chattisgarh Central India  

NASA Astrophysics Data System (ADS)

SummaryA high concentration of Arsenic (As) contamination in ground water has been reported in the village of Kaudikasa in Rajnandgaon district, wherein around 10% of the population is suffering from As-borne diseases. The region does not share any demographic or geological similarity with the sedimentary aquifers of the Bengal Delta Plain in Eastern India, but represents an igneous terrain with elevated As concentrations in groundwater. There is limited information about the source of As in groundwater and its mobility constraints. In this area, almost all the wells are located in the granitic terrain with pegmatitic intrusions. Most of these wells are characterized by As concentration above the World Health Organization ( WHO, 1999) and the BIS (Bureau of Indian Standards) standards, with the highest being found in a well with more than 250 ?g/L of As. Here we report petrographic studies of the granitic host rock and X-ray diffraction results that indicate that altered realgar (?-As 4S 4), para realgar (AsS), and/or tennantite (Cu 12As 4S 13), are the main mineral that contain As. This element is leached during the weathering and water-rock interactions. Microprobe analysis of the altered realgar grains of in pegmatitic intrusions of the host granite indicate 23-27 wt.% As. Remote sensing is useful to delineate the source of this contaminant, which appears to lie at the intersection of a mineralized NW-SE and N-S lineaments associated with the Kotri rift zone. These lineaments are structurally controlled as rifting followed by thrusting and other types of faulting caused left-lateral displacement of N-S Kotri lineament along a NW-SE fault plane showing sinistral shearing. This process caused water drainage in the areas to flow along these highly mineralized weak zones. Thus, the water becomes highly contaminated due to leaching of minerals at the intersection of these lineaments, clearly visible at two areas of high contamination that lie very near to this intersection over granitic rock. The source of As affecting the Rajnandgaon district is located in granites that have pegmatitic intrusions likely generated by hydrothermal activity.

Shukla, Dericks Praise; Dubey, C. S.; Singh, Ningthoujam P.; Tajbakhsh, M.; Chaudhry, M.

20

Groundwater pollution and remediation options for multi-source contaminated aquifers (Bitterfeld\\/Wolfen, Germany)  

Microsoft Academic Search

Large-scale contaminated megasites like Bitterfeld\\/Wolfen in the eastern part of Germany are characterized by a regional pollution of soil, surface water and groundwater due to the long and varied history of the chemical industry on location. The pollutants in groundwater may spread to uncontaminated areas and endanger receptors like surface water and drinking water wells according to the site-specific hydrologic

P. Wycisk; H. Weiss; A. Kaschl; S. Heidrich; K. Sommerwerk

2003-01-01

21

Quantifying the loss of available groundwater resource associated with point-source contamination in unused aquifers  

NASA Astrophysics Data System (ADS)

Cost-benefit analysis can be used to identify the optimum remedial strategy for contaminated groundwater, but requires that the benefits of remedial action be quantified. When the groundwater is located in an unused part of an aquifer, it can be difficult to estimate the economic loss of resource. `Option values', which represent the value placed on groundwater for possible future use, may be used. Calculation of the overall loss requires consideration of the spatial (physical) extent of an aquifer where groundwater use is constrained by the presence of contamination and economic elements. An approach is presented for estimating the spatial element, represented as the annualised abstraction loss from the groundwater resource. Two distinct components have been identified based on the potential restriction on location of a new abstraction well: (1) the direct resource loss, which relates to the contaminated zone of the aquifer within which new abstraction is no longer an option, and, (2) the indirect location loss, which relates to the loss of an opportunity to site a new abstraction well in the surrounding uncontaminated aquifer due to the presence of the plume. Methods are presented for their calculation and the approach is illustrated with a case study.

Bartlett, T. W.; Smith, J. W. N.; Hardisty, P. E.

2014-06-01

22

Bioremediation of contaminated groundwater  

DOEpatents

An apparatus and method are described for in situ remediation of contaminated subsurface soil or groundwater contaminated by chlorinated hydrocarbons. A nutrient fluid is selected to stimulate the growth and reproduction of indigenous subsurface microorganisms that are capable of degrading the contaminants. An oxygenated fluid is selected to create a generally aerobic environment for these microorganisms to degrade the contaminants, leaving only pockets that are anaerobic. The nutrient fluid is injected periodically while the oxygenated fluid is injected continuously and both are extracted so that both are drawn across the plume. The nutrient fluid stimulates microbial colony growth. Withholding it periodically forces the larger, healthy colony of microbes to degrade the contaminants. Treatment is continued until the subsurface concentration of contaminants is reduced to an acceptable, preselected level. The nutrient fluid can be methane and the oxygenated fluid air for stimulating production of methanotrophs to break down chlorohydrocarbons, especially trichloroethylene (TCE) and tetrachloroethylene. 3 figures.

Hazen, T.C.; Fliermans, C.B.

1995-01-24

23

Identification of Unknown Groundwater Pollution Sources Using Feedback Based Linked simulation-Optimization model at a Contaminated site  

Microsoft Academic Search

Abstract A feedback,based methodology,has been developed,for identifying the unknown,pollution sources in groundwater contaminated,aquifers. The methodology,consists of models within an iterative feedback system, with the capacity of feeding back real-time measurements of pollutant concentrations,for the sequential optimal,designs,and,characterization of the contaminated,aquifer study area. The resulting linked-simulation optimization model considers the delineation of the contaminant plume, optimally characterizing the site in terms of

Sreenivasulu Chadalavada; Bithin Datta; Ravi Naidu

24

Bioremediation of contaminated groundwater  

DOEpatents

Disclosed is an apparatus and method for in situ remediation of contaminated subsurface soil or groundwater contaminated by chlorinated hydrocarbons. A nutrient fluid (NF) is selected to simulated the growth and reproduction of indigenous subsurface microorganisms capable of degrading the contaminants; an oxygenated fluid (OF) is selected to create an aerobic environment with anaerobic pockets. NF is injected periodically while OF is injected continuously and both are extracted so that both are drawn across the plume. NF stimulates microbial colony growth; withholding it periodically forces the larger, healthy colony of microbes to degrade the contaminants. Treatment is continued until the subsurface concentration of contaminants is acceptable. NF can be methane and OF be air, for stimulating production of methanotrophs to break down chlorohydrocarbons, especially TCE and tetrachloroethylene.

Hazen, T.C.; Fliermans, C.B.

1994-01-01

25

Sources, pathways, and relative risks of contaminants in surface water and groundwater: a perspective prepared for the Walkerton inquiry.  

PubMed

On a global scale, pathogenic contamination of drinking water poses the most significant health risk to humans, and there have been countless numbers of disease outbreaks and poisonings throughout history resulting from exposure to untreated or poorly treated drinking water. However, significant risks to human health may also result from exposure to nonpathogenic, toxic contaminants that are often globally ubiquitous in waters from which drinking water is derived. With this latter point in mind, the objective of this commission paper is to discuss the primary sources of toxic contaminants in surface waters and groundwater, the pathways through which they move in aquatic environments, factors that affect their concentration and structure along the many transport flow paths, and the relative risks that these contaminants pose to human and environmental health. In assessing the relative risk of toxic contaminants in drinking water to humans, we have organized our discussion to follow the classical risk assessment paradigm, with emphasis placed on risk characterization. In doing so, we have focused predominantly on toxic contaminants that have had a demonstrated or potential effect on human health via exposure through drinking water. In the risk assessment process, understanding the sources and pathways for contaminants in the environment is a crucial step in addressing (and reducing) uncertainty associated with estimating the likelihood of exposure to contaminants in drinking water. More importantly, understanding the sources and pathways of contaminants strengthens our ability to quantify effects through accurate measurement and testing, or to predict the likelihood of effects based on empirical models. Understanding the sources, fate, and concentrations of chemicals in water, in conjunction with assessment of effects, not only forms the basis of risk characterization, but also provides critical information required to render decisions regarding regulatory initiatives, remediation, monitoring, and management. Our discussion is divided into two primary themes. First we discuss the major sources of contaminants from anthropogenic activities to aquatic surface and groundwater and the pathways along which these contaminants move to become incorporated into drinking water supplies. Second, we assess the health significance of the contaminants reported and identify uncertainties associated with exposures and potential effects. Loading of contaminants to surface waters, groundwater, sediments, and drinking water occurs via two primary routes: (1) point-source pollution and (2) non-point-source pollution. Point-source pollution originates from discrete sources whose inputs into aquatic systems can often be defined in a spatially explicit manner. Examples of point-source pollution include industrial effluents (pulp and paper mills, steel plants, food processing plants), municipal sewage treatment plants and combined sewage-storm-water overflows, resource extraction (mining), and land disposal sites (landfill sites, industrial impoundments). Non-point-source pollution, in contrast, originates from poorly defined, diffuse sources that typically occur over broad geographical scales. Examples of non-point-source pollution include agricultural runoff (pesticides, pathogens, and fertilizers), storm-water and urban runoff, and atmospheric deposition (wet and dry deposition of persistent organic pollutants such as polychlorinated biphenyls [PCBs] and mercury). Within each source, we identify the most important contaminants that have either been demonstrated to pose significant risks to human health and/or aquatic ecosystem integrity, or which are suspected of posing such risks. Examples include nutrients, metals, pesticides, persistent organic pollutants (POPs), chlorination by-products, and pharmaceuticals. Due to the significant number of toxic contaminants in the environment, we have necessarily restricted our discussion to those chemicals that pose risks to human health via exposure through drinking water. A comprehensive and judicious

Ritter, Len; Solomon, Keith; Sibley, Paul; Hall, Ken; Keen, Patricia; Mattu, Gevan; Linton, Beth

2002-01-11

26

Identifying sources of groundwater nitrate contamination in a large alluvial groundwater basin with highly diversified intensive agricultural production.  

PubMed

Groundwater quality is a concern in alluvial aquifers underlying agricultural areas worldwide. Nitrate from land applied fertilizers or from animal waste can leach to groundwater and contaminate drinking water resources. The San Joaquin Valley, California, is an example of an agricultural landscape with a large diversity of field, vegetable, tree, nut, and citrus crops, but also confined animal feeding operations (CAFOs, here mostly dairies) that generate, store, and land apply large amounts of liquid manure. As in other such regions around the world, the rural population in the San Joaquin Valley relies almost exclusively on shallow domestic wells (?150 m deep), of which many have been affected by nitrate. Variability in crops, soil type, and depth to groundwater contribute to large variability in nitrate occurrence across the underlying aquifer system. The role of these factors in controlling groundwater nitrate contamination levels is examined. Two hundred domestic wells were sampled in two sub-regions of the San Joaquin Valley, Stanislaus and Merced (Stan/Mer) and Tulare and Kings (Tul/Kings) Counties. Forty six percent of well water samples in Tul/Kings and 42% of well water samples in Stan/Mer exceeded the MCL for nitrate (10mg/L NO3-N). For statistical analysis of nitrate contamination, 78 crop and landuse types were considered by grouping them into ten categories (CAFO, citrus, deciduous fruits and nuts, field crops, forage, native, pasture, truck crops, urban, and vineyards). Vadose zone thickness, soil type, well construction information, well proximity to dairies, and dominant landuse near the well were considered. In the Stan/Mer area, elevated nitrate levels in domestic wells most strongly correlate with the combination of very shallow (?21 m) water table and the presence of either CAFO derived animal waste applications or deciduous fruit and nut crops (synthetic fertilizer applications). In Tulare County, statistical data indicate that elevated nitrate levels in domestic well water are most strongly associated with citrus orchards when located in areas with a very shallow (?21 m) water table. Kings County had relatively few nitrate MCL exceedances in domestic wells, probably due to the deeper water table in Kings County. PMID:23800783

Lockhart, K M; King, A M; Harter, T

2013-08-01

27

Simulated annealing based simulation-optimization approach for identification of unknown contaminant sources in groundwater aquifers  

Microsoft Academic Search

The exact location and release history of groundwater pollutant sources is often unknown. Identification of unknown release histories is usually carried out by inversion of the equations governing flow and transport over time and space. This is an ill posed problem. Solution of this ill-posed inversion is complicated due to the inherent non-uniqueness of solutions, uncertainties in modelling the flow

Manish K. Jha; Bithin Datta

2011-01-01

28

Groundwater contamination and its effect on health in Turkey  

Microsoft Academic Search

The sources of groundwater pollution in Turkey are identified, and pathways of contaminants to groundwater are first described.\\u000a Then, the effects of groundwater quality on health in Turkey are evaluated. In general, sources of groundwater contamination\\u000a fall into two main categories: natural and anthropogenic sources. Important sources of natural groundwater pollution in Turkey\\u000a include geological formations, seawater intrusion, and geothermal

Alper Baba; Gokmen Tayfur

29

The oxygen isotope composition of dissolved chromate: a new tool for determining sources of chromium contamination in groundwater  

NASA Astrophysics Data System (ADS)

Hexavalent chromium (Cr(VI)) is a widespread carcinogen in groundwater, derived from both anthropogenic and natural sources. A large range of chromium isotope composition has been demonstrated for dissolved Cr(VI) in groundwater, resulting from the large isotope fractionation accompanying reduction of Cr(VI) to trivalent chromium (Cr(III)). As a result, the isotopic composition of chromium in dissolved chromate is beginning to prove useful for determining the sources of chromium in contaminated groundwater, but considered alone can likewise be non-diagnostic due to overlapping compositional ranges of potential anthropogenic and natural sources. Based on the strong Cr-O bond in the chromate molecule implied by the large chromium isotope fractionation accompanying Cr(VI) reduction, we have proposed that oxygen will remain closely linked to chromium in the chromate molecule and thus can be used to better constrain chromate sources through a Cr-O "multi-tracer" approach. In a series of laboratory experiments using isotopically "enriched" water and "normal" chromate, we have demonstrated that there is insignificant isotopic exchange between oxygen in chromate and water for residence times as long as one year, and thus chromate will retain the oxygen isotope composition of its source during extended transport in groundwater. We have likewise demonstrated that sufficient chromate for oxygen isotope analysis can be successfully isolated from a chemically complex groundwater sample through a series of precipitation, ion exchange and heating procedures. Although our current approach of measuring 100 micromolar samples of chromate using TCEA- gas mass spectrometry is straightforward and robust, we are also developing a negative-ion thermal ionization mass spectrometry technique in order to greatly reduce the sample size requirement. We are currently applying this novel technique at an electric power facility in California and a metal plating facility in France in order to better determine chromate sources at those sites.

Bullen, T.; Widory, D.

2009-05-01

30

Delineating Fecal Contaminant Sources and Travel Times in a Karst Groundwater Basin, Inner Bluegrass Region, Kentucky  

Microsoft Academic Search

Because of preferential flowpaths via features such as sinkholes and conduits, karst aquifers are susceptible to non-point-source pollution from agricultural and urban drainage. With many karst aquifers being drinking- water sources, pathogens are contaminants of public health concern. Monitoring of microbial parameters (total coliforms [TC], atypical colonies [AC] and fecal coliform bacteria [FC]) transpired biweekly from December 2002 March 2004

J. W. Ward; T. M. Reed; A. E. Fryar; G. M. Brion

2006-01-01

31

ZVI-Clay remediation of a chlorinated solvent source zone, Skuldelev, Denmark: 2. Groundwater contaminant mass discharge reduction  

NASA Astrophysics Data System (ADS)

The impact of source mass depletion on the down-gradient contaminant mass discharge was monitored for a 19-month period as a part of a field demonstration of the ZVI-Clay soil mixing remediation technology. Groundwater samples were collected from conventional monitoring wells (120 samples) and a dense network of multilevel samplers (640 samples). The hydraulic gradient and conductivity were determined. Depletion of the contaminant source is described in the companion paper (Fjordbøge et al., 2012). Field data showed four distinct phases for PCE mass discharge: (1) baseline conditions, (2) initial rapid reduction, (3) temporary increase, and (4) slow long-term reduction. Numerical modeling was utilized to develop a conceptual understanding of the four phases and to identify the governing processes. The initial rapid reduction of mass discharge was a result of the changed hydraulic properties in the source zone after soil mixing. The subsequent phases depended on the changed accessibility of the contaminant mass after mixing, the rate of source depletion, and the concentration gradient at the boundaries of the mixed source zone. Overall, ZVI-Clay soil mixing resulted in a significant down-gradient contaminant mass discharge reduction (76%) for the parent compound (PCE), while the overall reduction of chlorinated ethenes was smaller (21%).

Fjordbøge, Annika S.; Lange, Ida V.; Bjerg, Poul L.; Binning, Philip J.; Riis, Charlotte; Kjeldsen, Peter

2012-10-01

32

ZVI-Clay remediation of a chlorinated solvent source zone, Skuldelev, Denmark: 2. Groundwater contaminant mass discharge reduction.  

PubMed

The impact of source mass depletion on the down-gradient contaminant mass discharge was monitored for a 19-month period as a part of a field demonstration of the ZVI-Clay soil mixing remediation technology. Groundwater samples were collected from conventional monitoring wells (120 samples) and a dense network of multilevel samplers (640 samples). The hydraulic gradient and conductivity were determined. Depletion of the contaminant source is described in the companion paper (Fjordbøge et al., 2012). Field data showed four distinct phases for PCE mass discharge: (1) baseline conditions, (2) initial rapid reduction, (3) temporary increase, and (4) slow long-term reduction. Numerical modeling was utilized to develop a conceptual understanding of the four phases and to identify the governing processes. The initial rapid reduction of mass discharge was a result of the changed hydraulic properties in the source zone after soil mixing. The subsequent phases depended on the changed accessibility of the contaminant mass after mixing, the rate of source depletion, and the concentration gradient at the boundaries of the mixed source zone. Overall, ZVI-Clay soil mixing resulted in a significant down-gradient contaminant mass discharge reduction (76%) for the parent compound (PCE), while the overall reduction of chlorinated ethenes was smaller (21%). PMID:23010547

Fjordbøge, Annika S; Lange, Ida V; Bjerg, Poul L; Binning, Philip J; Riis, Charlotte; Kjeldsen, Peter

2012-10-01

33

Technical options for the remediation of contaminated groundwater.  

National Technical Information Service (NTIS)

This report provides a description of the nature and extent of problems related to radioactive groundwater contamination by outlining the environmental impacts, the sources of contamination and the contaminants of concern radionuclides and their associate...

1999-01-01

34

Evaluation of early life stage fall chinook salmon exposed to hexavalent chromium from a contaminated groundwater source.  

PubMed

We conducted a laboratory evaluation to assess the risk to early life stage (i.e., eyed egg to swim up) fall Chinook salmon (Oncorhynchus tshawytscha) for exposure to hexavalent chromium from a contaminated groundwater source. Local populations of fall Chinook salmon were exposed to Hanford Site source groundwater that was diluted with Columbia River water. Specific endpoints included survival, development rate, and growth. Tissue burdens of fish were also measured to estimate uptake and elimination rates of chromium. Survival, development, and growth of early life stage fall Chinook salmon were not adversely affected by extended exposures (i.e., 98 day) to hexavalent chromium ranging from 0.79 to 260 microg/l. Survival for all treatment levels and controls exceeded 98% at termination of the test. In addition, there were no differences among the mean lengths and weights of fish among all treatment groups. Whole-body concentrations of chromium in early life stage fall Chinook salmon had a typical dose-response pattern; i.e., those subjected to highest exposure concentrations and longest exposure intervals had higher tissue concentrations. Given the spatial extent of chromium concentrations at the Hanford Site, and the dynamics of the groundwater-river water interface, the current cleanup criterion of 10 microg/l chromium appear adequate to protect early life stage fall Chinook salmon. These findings, together with previous research indicate low risk to these populations. PMID:17294282

Patton, Gregory; Dauble, Dennis; McKinstry, Craig

2007-10-01

35

Application of phage typing to the identification of sources of groundwater contamination  

NASA Astrophysics Data System (ADS)

Phage typing of Escherichia coli populations was used as a "fingerprinting" tool to identify the source(s) of fecal coliform contamination of a drinking water well, PW- 12. Group discriminate analysis was used to evaluate the data and determine the relative distance of population centroids from the centroid of the PW- 12 population. The phage typing patterns were compared to serological results and correlations noted. Phage typing patterns were shown to be stable following 32-days incubation of E. coli isolates in garden soil, tap water and neutralized tertiary effluent, with and without the presence of autochthonous flora.

Rusin, Patricia A.; Sinclair, Norval A.; Gerba, Charles P.; Gershman, Melvin

1992-10-01

36

Using Nitrogen and Oxygen Isotope Compositions of Nitrate to Distinguish Contaminant Sources in Hanford Soil and Groundwater  

SciTech Connect

The nitrogen ({delta}{sup 15}N) and oxygen ({delta}{sup 18}O) isotopic compositions of nitrate in the environment are primarily a function of the source of the nitrate. The ranges of isotopic compositions for nitrate resulting from common sources are outlined in Figure 1 from Kendall (1998). As noted on Figure 1, processes such as microbial metabolism can modify the isotopic compositions of the nitrate, but the effects of these processes are generally predictable. At Hanford, nitrate and other nitrogenous compounds were significant components of most of the chemical processes used at the site. Most of the oxygen in nitrate chemicals (e.g., nitric acid) is derived from atmospheric oxygen, giving it a significantly higher {delta}{sup 18}O value (+23.5{per_thousand}) than naturally occurring nitrate that obtains most of its oxygen from water (the {delta}{sup 18}O of Hanford groundwater ranges from -14{per_thousand} to -18{per_thousand}). This makes it possible to differentiate nitrate from Hanford site activities from background nitrate at the site (including most fertilizers that might have been used prior to the Department of Energy plutonium production activities at the site). In addition, the extreme thermal and chemical conditions that occurred during some of the waste processing procedures and subsequent waste storage in select single-shell tanks resulted in unique nitrate isotopic compositions that can be used to identify those waste streams in soil and groundwater at the site (Singleton et al., 2005; Christensen et al., 2007). This report presents nitrate isotope data for soil and groundwater samples from the Hanford 200 Areas and discusses the implications of that data for potential sources of groundwater contamination.

Conrad, Mark; Bill, Markus

2008-08-01

37

Contamination and restoration of groundwater aquifers.  

PubMed Central

Humans are exposed to chemicals in contaminated groundwaters that are used as sources of drinking water. Chemicals contaminate groundwater resources as a result of waste disposal methods for toxic chemicals, overuse of agricultural chemicals, and leakage of chemicals into the subsurface from buried tanks used to hold fluid chemicals and fuels. In the process, both the solid portions of the subsurface and the groundwaters that flow through these porous structures have become contaminated. Restoring these aquifers and minimizing human exposure to the parent chemicals and their degradation products will require the identification of suitable biomarkers of human exposure; better understandings of how exposure can be related to disease outcome; better understandings of mechanisms of transport of pollutants in the heterogeneous structures of the subsurface; and field testing and evaluation of methods proposed to restore and cleanup contaminated aquifers. In this review, progress in these many different but related activities is presented.

Piver, W T

1993-01-01

38

Effects of selected sources of contamination on ground-water quality at seven sites in Connecticut  

USGS Publications Warehouse

The introduction of contaminants has altered the quality of ground water at several places in Connecticut. This investigation of the hydrogeologic environment and the quality of water in stratified-drift aquifers underlying seven probable contaminant sources in Connecticut shows some effects at each site. Water from test wells downgradient from septage-disposal facilities in Old Saybrook and Clinton contains elevated concentrations of sodium, chloride, manganese, iron, detergent (as MBAS), dissolved organic carbon, and some trace metals. The effects are most pronounced at shallow depths close to the septage lagoons, where concentrations of some constituents exceed Connecticut Department of Health drinking water standards. Fly-ash disposal at Wallingford has contributed chromium, manganese, and dissolved organic carbon to water in the underlying aquifer, but the low hydraulic conductivity of the fine-grained surficial materials have kept effects to a minimum. Road salt leached from a storage area in the Tylerville section of Haddam has increased the sodium and chloride concentrations in ground water to the extent that it is unsuitable for drinking water. The effect diminishes in wells 1000 feet downgradient from the storage site. Water from some wells adjacent to landfills in Bristol and Southington has elevated sodium, chloride, manganese, and dissolved organic carbon concentrations, and samples from two wells near industrial-sludge disposal pits in the Bristol landfill contain cyanide and phenols. Gasoline odor is present in water samples from a test well 175 feet from a ruptured buried tank in Fairfield. The gasoline odor from this well was also detectable during well construction and sampling.

Handman, Elinor H.; Bingham, James W.

1980-01-01

39

Investigation of the potential source area, contamination pathway, and probable release history of chlorinated-solvent-contaminated groundwater at the Capital City Plume Site, Montgomery, Alabama, 2008-2010  

USGS Publications Warehouse

Detection of the organic solvent perchloroethylene (PCE) in a shallow public-supply well in 1991 and exposure of workers in 1993 to solvent vapors during excavation activities to depths near the water table provided evidence that the shallow aquifer beneath the capital city of Montgomery, Alabama, was contaminated. Investigations conducted from 1993 to 1999 by State and Federal agencies confirmed the detection of PCE in the shallow aquifer, as well as the detection of the organic solvent trichloroethylene (TCE) and various inorganic compounds, but the source of the groundwater contamination was not determined. In May 2000 the U.S. Environmental Protection Agency proposed that the site, called the Capital City Plume (CCP) Site, be a candidate for the National Priorities List. Between 2000 and 2007, numerous site-investigation activities also did not determine the source of the groundwater contamination. In 2008, additional assessments were conducted at the CCP Site to investigate the potential source area, contamination pathway, and the probable release history of the chlorinated-solvent-contaminated groundwater. The assessments included the collection of (1) pore water in 2008 from the hyporheic zone of a creek using passive-diffusion bag samplers; (2) tissue samples in 2008 and 2009 from trees growing in areas of downtown Montgomery characterized by groundwater contamination and from trees growing in riparian zones along the Alabama River and Cypress Creek; and (3) groundwater samples in 2009 and 2010. The data collected were used to investigate the potential source area of contaminants detected in groundwater, the pathway of groundwater contamination, and constraints on the probable contaminant-release history. The data collected between 2008 and 2010 indicate that the PCE and TCE contamination of the shallow aquifer beneath the CCP Site most likely resulted from the past use and disposal of industrial wastewater from printing operations containing chlorinated solvents into the sanitary sewer and (or) stormwater systems of Montgomery. Moreover, chlorinated-solvent use and disposal occurred at least between the 1940s and 1970s at several locations occupied by printing operations. The data also indicate that PCE and TCE contamination continues to occur in the shallow subsurface near potential release areas and that PCE and TCE have been transported to the intermediate part of the shallow aquifer.

Landmeyer, James E.; Miller, Scott; Campbell, Bruce G.; Vroblesky, Don A.; Gill, Amy C.; Clark, Athena P.

2011-01-01

40

Source, Transport, and Fate of Groundwater Contamination at Site 45, Marine Corps Recruit Depot, Parris Island, South Carolina  

USGS Publications Warehouse

Groundwater contamination by tetrachloroethene and its dechlorination products is present in two partially intermingled plumes in the surficial aquifer near a former dry-cleaning facility at Site 45, Marine Corps Recruit Depot, Parris Island, South Carolina. The northern plume originates from the vicinity of former above-ground storage tanks. Free-phase tetrachloroethene from activities in this area entered the groundwater and the storm sewer. The southern plume originates at a nearby new dry-cleaning facility, but probably was the result of contamination released to the aquifer from a leaking sanitary sewer line from the former dry-cleaning facility. Discharge of dissolved groundwater contamination is primarily to leaking storm sewers below the water table. Extensive biodegradation of the contamination takes place in the surficial aquifer; however, the biodegradation is insufficient to reduce trichloroethene to less than milligram-per-liter concentrations prior to discharging into the storm sewers. The groundwater volatile organic compounds entering the storm sewers are substantially diluted by tidal flushing upon entry and are subject to volatilization as they are transported through the storm sewer to a discharge point in a tributary to Ballast Creek. TCE concentrations of about 2-6 micrograms per liter were present in storm-sewer water near the discharge point (sampled at manhole STS26). On three out of four sampling events at manhole STS14, the storm-sewer water contained no vinyl chloride. During a time of relatively high groundwater levels, however, 20 micrograms per liter of vinyl chloride was present in STS14 storm-sewer water. Because groundwater leaks into that storm sewer and because the storm sewer upgradient from manhole STS14 is adjacent to part of the aquifer where 2,290 micrograms per liter of vinyl chloride have been detected, there is a potential for substantially increased concentrations of vinyl chloride to discharge at the storm-sewer outfall under conditions of high groundwater levels and low tidal flushing. In addition, the observation that free-phase tetrachloroethene may have entered the storm-sewer system during the 1994 discharge means that dense nonaqueous phase liquid tetrachloroethene could have leaked from various parts of the storm sewer or discharged to surface water at the storm-sewer outfall.

Vroblesky, Don A.; Petkewich, Matthew D.; Landmeyer, James E.; Lowery, Mark A.

2009-01-01

41

Identification of the nitrate contamination sources of the Brusselian sands groundwater body (Belgium) using a dual-isotope approach.  

PubMed

Isotopic fingerprinting is an advanced technique allowing the classification of the nitrate source pollution of groundwater, but needs further development and validation. In this study, we performed measurements of natural stable isotopic composition of nitrate ((15)N and (18)O) in the groundwater body of the Brussels sands (Belgium) and studied the spatial and temporal dynamics of the isotope signature of this aquifer. Potential nitrogen sources sampled in the region had isotopic signatures that fell within the corresponding typical ranges found in the literature. For a few monitoring stations, the isotopic data strongly suggest that the sources of nitrate are from mineral fertiliser origin, as used in agriculture and golf courses. Other stations suggest that manure leaching from unprotected stockpiles in farms, domestic gardening practices, septic tanks and probably cemeteries contribute to the nitrate pollution of this groundwater body. For most monitoring stations, nitrate originates from a mixing of several nitrogen sources. The isotopic signature of the groundwater body was poorly structured in space, but exhibited a clear temporal structure. This temporal structure could be explained by groundwater recharge dynamics and cycling process of nitrogen in the soil-nitrogen pool. PMID:21892890

Mattern, Samuel; Sebilo, Mathieu; Vanclooster, Marnik

2011-09-01

42

Identifying and Quantifying transient groundwater fluxes and fluxes of contaminated sources of recharge into complex groundwater reservoir by Mixing Cells Modeling approach.  

NASA Astrophysics Data System (ADS)

Groundwater reservoirs are rarely isolated. Usually production aquifers are affected by hydraulically connected to neighboring sub-aquifers units and nearby water baring formations with different water qualities and dissolved mineral contents. These results long term special and temporal variations in groundwater quality of production aquifers. Phreatic aquifers are prone to on-surface anthropogenic activities, although it is clear that even confined aquifers are negatively affected down the years by percolation of contaminants that gradually percolate into groundwater reservoirs over the recharge area. Even massive groundwater abstraction reveals almost a steady flow system after several years. However the differential fluxes from neighboring sub-aquifers attracted into the production aquifer cause long-term temporal distribution of the groundwater quality. The main issue is how to firmly identify the hydraulic connectivity among the various sub aquifers, and to draw the solid pathways among the connected active water bearing units. Beyond that, these processes often prevail under announcing a non-steady aquifers environment as function of massive groundwater abstraction. This results gradual yet substantial spatial and temporal variations in chemical and dissolved minerals distribution, all which suggest on transient flow and mass transport distribution. For such complex aquifers system, where the hydrologic conditions along the boundaries cannot be well-defined, the transient Mixing Cells Modeling approach MCMusf (unsteady flow) is proposed to illuminate on the active flow paths and to assess the transient groundwater fluxes within the aquifer. The presentation will elaborate on the mathematical set up of the newly developed MCMusf code for transient flow system, and on a feasible solution which is based on linear optimization scheme.

Adar, Eilon; Massoth, Sylvie

2013-04-01

43

Kinetics of scheelite dissolution in groundwater: defining the release rate of tungsten contamination from a natural source  

NASA Astrophysics Data System (ADS)

Tungsten, an emerging contaminant, has no EPA standard for its permissible levels in drinking water. At sites in California, Nevada, and Arizona there may be a correlation between elevated levels of tungsten in drinking water and clusters of childhood acute lymphocytic leukemia (ALL). Developing a better understanding of how tungsten is released from rocks into surface and groundwaters is therefore of growing environmental interest. Knowledge of tungstate ore mineral weathering processes, particularly the rates of dissolution of scheelite (CaWO4) in groundwater, could improve models of how tungsten is released and transported in natural waters. Our research is focusing on experimental determination of the rates and products of tungstate mineral dissolution in synthetic groundwater, as a function of temperature, pH and mineral surface area. The initial rate method is being used to develop rate laws. Batch reactor experiments are conducted within constant temperature circulation baths over a pH range of 2-9. Cleaned scheelite powder with grain diameters of 106-150um is placed between two screens in a sample platform and then placed inside a two liter Teflon vessel filled with synthetic groundwater. Ports on the vessel allow sample extraction, temperature and pH measurement, gas inflow, and water circulation. Aliquots of solution are taken periodically for product analysis by ICP -MS. Changes in mineral surface characteristics are monitored using SEM and EDS methods. Results so far reveal that the dissolution of scheelite is incongruent at both neutral and low pH. Solid tungstic acid forms on scheelite mineral surfaces under acidic conditions, implying that this phase controls the dissolution rate in acidic environments. The influence of dissolved CO2 and resultant calcium carbonate precipitation on the dissolution of scheelite at higher pH is also being investigated. The rate law being developed for scheelite dissolution will be useful in reactive-transport computer codes designed to model tungsten contamination in a variety of surface and groundwater settings.

Montgomery, S. D.; Mckibben, M. A.

2011-12-01

44

Radionuclides in groundwaters: contaminants and tracers  

Microsoft Academic Search

As groundwaters serve for drinking-water purposes, radionuclides in groundwater are generally considered as contaminants. Some of the radionuclides contributing to natural radioactivity in groundwater and some of the manmade atmospheric radionuclides, however, have become good tracers for the assessment of residence times (groundwater age) and mixing. Controlled experiments with artificial radionuclides, on the other hand, are restricted to a few

EDUARD HOEHN

45

Situ treatment of contaminated groundwater  

DOEpatents

A system for treating dissolved halogenated organic compounds in groundwater that relies upon electrolytically-generated hydrogen to chemically reduce the halogenated compounds in the presence of a suitable catalyst. A direct current is placed across at least a pair, or an array, of electrodes which are housed within groundwater wells so that hydrogen is generated at the cathode and oxygen at the anode. A pump is located within the well housing in which the cathode(s) is(are) located and draws in groundwater where it is hydrogenated via electrolysis, passes through a well-bore treatment unit, and then transported to the anode well(s) for reinjection into the ground. The well-bore treatment involves a permeable cylinder located in the well bore and containing a packed bed of catalyst material that facilitates the reductive dehalogenation of the halogenated organic compounds by hydrogen into environmentally benign species such as ethane and methane. Also, electro-osmatic transport of contaminants toward the cathode also contributes to contaminant mass removal. The only above ground equipment required are the transfer pipes and a direct circuit power supply for the electrodes. The electrode wells in an array may be used in pairs or one anode well may be used with a plurality of cathode wells. The DC current flow between electrode wells may be periodically reversed which controls the formation of mineral deposits in the alkaline cathode well-bore water, as well as to help rejuvenate the catalysis.

McNab, Jr., Walt W. (Concord, CA); Ruiz, Roberto (Tracy, CA); Pico, Tristan M. (Livermore, CA)

2001-01-01

46

Risk Assessment for the Protection from and the Prevention of Groundwater Contamination.  

National Technical Information Service (NTIS)

A methodological framework is presented for dealing with uncertainty associated with sources of groundwater contamination. The framework describes how risks (due to groundwater contamination and resulting from these uncertainties) can be assessed for any ...

Y. Y. Haimes V. Chankong

1987-01-01

47

A model for evaluating the three-dimensional groundwater dividing pathline between a contaminant source and a partially penetrating water-supply well  

NASA Astrophysics Data System (ADS)

Effluent from septic tank-drainfields can degrade groundwater quality and contaminate nearby water-supply wells. Such groundwater contamination is a problem in the unsewered subdivisions of the sand plain of central Wisconsin, for example. To help planners minimize the risk of direct contamination of a water-supply well by a septic system, a model was developed to estimate the location of the critical dividing pathline between a rectangular contaminant source (the septic tank drainfield) and a partially penetrating pumping well. The model is capable of handling three-dimensional, transient flow in an unconfined, homogeneous, anisotropic aquifer of infinite areal extent, under a regional horizontal hydraulic gradient. Model results are in very good agreement with several other numerical and analytical models. Examples are given for which the safe, horizontal and vertical separation distances to avoid well water contamination are determined for typical central Wisconsin sand plain conditions. A companion paper (Harmsen et al., 1991) describes the application of this model, using a Monte-Carlo analysis, to study the variation of these separation distances in the Wisconsin sand plain. The model can also be applied to larger scale problems and, therefore, could be useful in implementing the U.S. Environmental Protection Agency's new well head protection program.

Harmsen, Eric W.; Converse, James C.; Anderson, Mary P.; Hoopes, John A.

1991-09-01

48

Natural biodegradation of organic contaminants in groundwater  

SciTech Connect

There has recently been a growing awareness that natural processes are degrading contaminants of concern, and that the contribution these natural processes make to achieving cleanup goals needs to be formally considered during site-specific cleanup. Historical case data from a large number of releases has been used to evaluate the expectation for natural attenuation to contribute to the cleanup of petroleum hydrocarbons and chlorinated solvents. The use of historical case data has several advantages, among them: 1) sites can reduce characterization costs by sharing information on key hydrogeologic parameters controlling contaminant fate and transport, and 2) standard reference frameworks can be developed that individual sites can use as a basis of comparison regarding plume behavior. Definition of cleanup times must take into account basic constraints imposed by natural laws governing the transport and natural degradation process of petroleum hydrocarbons. The actual time to reach groundwater cleanup goals is determined by these laws and the limitations on residual subsurface contamination attenuation rates, through either active or natural biological processes. These limitations will practically constrain the time to achieve low concentration cleanup goals. Recognition is needed that sites will need to be transitioned to remediation by natural processes at some point following implementation of active remediation options. The results of an analysis of approximately 1800 California and 600 Texas fuel hydrocarbon (FHC) releases and 2.50 chlorinated volatile organic compound (CVOC) plumes will be summarized. Plume lengths and natural biodegradation potential were evaluated. For FHC releases, 90% of benzene groundwater plumes were less than 280 feet in length and evidence of natural biodegradation was found to be present at all sites studied in detail. For CVOC releases, source strength and groundwater flow velocity are dominant factors controlling groundwater plume lengths. After adjusting for these factors, biodegradation also appears to limit the length of CVOC plumes in many instances. The application of natural biodegradation processes as a remediation approach will depend on the time frame for anticipated beneficial use of the affected groundwater.

McNab, W W; Rice, D W

1998-09-23

49

Groundwater contamination and its effect on health in Turkey.  

PubMed

The sources of groundwater pollution in Turkey are identified, and pathways of contaminants to groundwater are first described. Then, the effects of groundwater quality on health in Turkey are evaluated. In general, sources of groundwater contamination fall into two main categories: natural and anthropogenic sources. Important sources of natural groundwater pollution in Turkey include geological formations, seawater intrusion, and geothermal fluid(s). The major sources of anthropogenic groundwater contamination are agricultural activities, mining waste, industrial waste, on-site septic tank systems, and pollution from imperfect well constructions. The analysis results revealed that natural contamination due to salt and gypsum are mostly found in Central and Mediterranean regions and arsenic in Aegean region. Geothermal fluids which contain fluoride poses a danger for skeleton, dental, and bone problems, especially in the areas of Denizli, Isparta, and Ayd?n. Discharges from surface water bodies contaminate groundwater by infiltration. Evidence of such contamination is found in Upper K?z?l?rmak basin, Gediz basin, and Büyük Melen river basin and some drinking water reservoirs in ?stanbul. Additionally, seawater intrusion causes groundwater quality problems in coastal regions, especially in the Aegean coast. Industrial wastes are also polluting surface and groundwater in industrialized regions of Turkey. Deterioration of water quality as a result of fertilizers and pesticides is another major problem especially in the regions of Mediterranean, Aegean, Central Anatolia, and Marmara. Abandoned mercury mines in the western regions of Turkey, especially in Çanakkale, ?zmir, Mu?la, Kütahya, and Bal?kesir, cause serious groundwater quality problems. PMID:21336483

Baba, Alper; Tayfur, Gokmen

2011-12-01

50

Reactive transport modeling of a groundwater contamination by ammoniacal liquor  

Microsoft Academic Search

A reactive transport modeling study was carried out to assess the fate of a groundwater contamination by ammoniacal liquor from a former coking plant and the associated geochemical response. The simulations over a 45-year period provide a conclusive explanation and quantitative description of all measured data from observation wells down gradient of the contaminant source. It is shown that cation

Bruno Haerens; Henning Prommer; David N. Lerner; Alain Dassargues; CSIRO Land

51

History of ground-water contamination and summary of ground-water investigations through 1985 at four industrial sites, Logan Township, New Jersey  

SciTech Connect

Investigations of potential sources of groundwater contamination conducted by various regulatory agencies and consultants at four industrial sites in Logan Township, New Jersey found groundwater contamination at all four sites and at properties adjoining two of the sites. The four sites directly overlie the Potomac-Raritan-Magothy aquifer system, the Township's sole source of potable water. One site was a waste-oil processing and storage facility. The major source of groundwater contamination at the site is a lagoon containing waste oil. Groundwater within 1,000 ft of the lagoon is contaminated. The second site is used to maintain, dispatch, and clean chemical-transportation tanks. Potential sources of groundwater contamination at the site include former wastewater lagoons, leaking storage drums, and leaking tank trucks. Groundwater at and immediately north of the property is contaminated. Organic compounds are manufactured at the third site. Potential sources of groundwater contamination at this site include landfilled industrial wastes. Groundwater underlying the property is contaminated, but there is no evidence of offsite groundwater contamination from this source. The fourth site is used to treat and dispose of hazardous wastes. The major source of groundwater contamination at this site is landfilled residue from waste-treatment processes. Groundwater underlying the property is contaminated, but there is no evidence of off-site groundwater contamination from this source.

Lewis, J.C.; Hochreitner, J.J. (Geological Survey, Trenton, NJ (United States))

1990-01-01

52

Assessing groundwater vulnerability to agrichemical contamination in the Midwest US  

USGS Publications Warehouse

Agrichemicals (herbicides and nitrate) are significant sources of diffuse pollution to groundwater. Indirect methods are needed to assess the potential for groundwater contamination by diffuse sources because groundwater monitoring is too costly to adequately define the geographic extent of contamination at a regional or national scale. This paper presents examples of the application of statistical, overlay and index, and process-based modeling methods for groundwater vulnerability assessments to a variety of data from the Midwest U.S. The principles for vulnerability assessment include both intrinsic (pedologic, climatologic, and hydrogeologic factors) and specific (contaminant and other anthropogenic factors) vulnerability of a location. Statistical methods use the frequency of contaminant occurrence, contaminant concentration, or contamination probability as a response variable. Statistical assessments are useful for defining the relations among explanatory and response variables whether they define intrinsic or specific vulnerability. Multivariate statistical analyses are useful for ranking variables critical to estimating water quality responses of interest. Overlay and index methods involve intersecting maps of intrinsic and specific vulnerability properties and indexing the variables by applying appropriate weights. Deterministic models use process-based equations to simulate contaminant transport and are distinguished from the other methods in their potential to predict contaminant transport in both space and time. An example of a one-dimensional leaching model linked to a geographic information system (GIS) to define a regional metamodel for contamination in the Midwest is included.

Burkart, M. R.; Kolpin, D. W.; James, D. E.

1999-01-01

53

Strontium-Isotope Studies Of Chloride-Contaminated Groundwater, Denmark  

NASA Astrophysics Data System (ADS)

Saline groundwater has three principal origins in Denmark: 1) Seawater infiltration into nearcoastal aquifers, 2) saline formation water in aquifers of marine sedimentary origin, and 3) intrusion of brines from deep saline formation waters and evaporitic deposits in the subsurface. Strontium-isotope studies of chloride-contaminated groundwater from a Quaternary sandy aquifer at Stautrup Waterworks, Denmark, indicate that the groundwater is heavily influenced by saline formation water from underlying Oligocene marine mica clay. Thus, strontium isotopic hydrochemical criteria were successfully used to identify the sources of saline groundwater.

Jørgensen, N. O.; Holm, P. M.

1995-02-01

54

Microbiological Cleanup of Pentachlorophenol-Contaminated Groundwater.  

National Technical Information Service (NTIS)

The study demonstrated the feasibility of microbiological cleanup of pentachlorophenol-contaminated groundwater. A 200 liter packed bed bioreactor was constructed and colonized with a microbial consortia which degrade pentachlorophenol. The bioreactor eff...

T. D. Frick R. L. Crawford

1986-01-01

55

Can antibiotic resistance analysis be a useful tool for tracking population sources of contamination in Yucatan groundwater?  

NASA Astrophysics Data System (ADS)

Antibiotic resistance patterns have been widely used in scientific studies conducted to identify sources of water contamination. However, the methods of resistance determination have not been standardized; therefore, the data on antibiotic resistance in the environment come from studies that have used a range of media types, antibiotic concentrations, and incubation periods, making it difficult to compare results between environments. Over two years, we assessed antibiotic sensitivity of Gram-positive and Gram-negative bacteria isolated from Yucatan water sources, to identify unique resistance patterns and assess the potential for antibiotic resistance analysis as a tool to discriminate between fecal pollution from two population sources (tourist and local). Though resistance to erythromycin, streptomycin, and ciprofloxacin showed some differences between populations, natural bacterial resistance (in isolates from pristine sources) was very high and confounded the research findings. This study highlights the need among the research community involved in tracking of environmental antibiotic resistance to develop a standardized and rigorously validated suite of methods that address background resistance and that can be used across environments, to accurately inform source tracking studies.

McLain, J. E.; Lenczewski, M.; Leal-Bautista, R. M.

2013-05-01

56

Impact Of Groundwater Discharge On Contaminant Behavior In Sediments  

EPA Science Inventory

The discharge of groundwater into surface water may influence the concentrations and availability of contaminants in sediments. There are three predominant pathways by which groundwater may affect the characteristics of contaminated sediments: 1) direct contribution of contamin...

57

Groundwater pumping effects on contaminant loading management in agricultural regions.  

PubMed

Groundwater pumping changes the behavior of subsurface water, including the location of the water table and characteristics of the flow system, and eventually affects the fate of contaminants, such as nitrate from agricultural fertilizers. The objectives of this study were to demonstrate the importance of considering the existing pumping conditions for contaminant loading management and to develop a management model to obtain a contaminant loading design more appropriate and practical for agricultural regions where groundwater pumping is common. Results from this study found that optimal designs for contaminant loading could be determined differently when the existing pumping conditions were considered. This study also showed that prediction of contamination and contaminant loading management without considering pumping activities might be unrealistic. Motivated by these results, a management model optimizing the permissible on-ground contaminant loading mass together with pumping rates was developed and applied to field investigation and monitoring data from Icheon, Korea. The analytical solution for 1-D unsaturated solute transport was integrated with the 3-D saturated solute transport model in order to approximate the fate of contaminants loaded periodically from on-ground sources. This model was further expanded to manage agricultural contaminant loading in regions where groundwater extraction tends to be concentrated in a specific period of time, such as during the rice-growing season, using a method that approximates contaminant leaching to a fluctuating water table. The results illustrated that the simultaneous management of groundwater quantity and quality was effective and appropriate to the agricultural contaminant loading management and the model developed in this study, which can consider time-variant pumping, could be used to accurately estimate and to reasonably manage contaminant loading in agricultural areas. PMID:24681649

Park, Dong Kyu; Bae, Gwang-Ok; Kim, Seong-Kyun; Lee, Kang-Kun

2014-06-15

58

AGRICULTURAL CONTAMINANTS REMOVAL FROM GROUNDWATER BY CARBON AND REVERSE OSMOSIS  

EPA Science Inventory

The groundwater of Suffolk County, New York, is designated as a sole source aquifer and in recent years there have been increasing concerns about the contamination of this water by agricultural chemicals. Two parallel treatment systems were evaluated for a one-year period: granul...

59

Probabilistic screening tool for ground-water contamination assessment  

Microsoft Academic Search

This paper presents a methodology for assessing the effects of source-, chemical-, and aquifer-related parameter uncertainty on the response of a semianalytical transport model using first- and second-order reliability methods. A probabilistic model is developed by coupling the deterministic transport model with a general-purpose probability analysis program. Ground-water contamination risk is addressed by evaluating the probability that a given contaminant

Maged M. Hamed; Joel P. Conte; Philip B. Bedient

1995-01-01

60

[Groundwater organic pollution source identification technology system research and application].  

PubMed

Groundwater organic pollutions are found in large amount of locations, and the pollutions are widely spread once onset; which is hard to identify and control. The key process to control and govern groundwater pollution is how to control the sources of pollution and reduce the danger to groundwater. This paper introduced typical contaminated sites as an example; then carried out the source identification studies and established groundwater organic pollution source identification system, finally applied the system to the identification of typical contaminated sites. First, grasp the basis of the contaminated sites of geological and hydrogeological conditions; determine the contaminated sites characteristics of pollutants as carbon tetrachloride, from the large numbers of groundwater analysis and test data; then find the solute transport model of contaminated sites and compound-specific isotope techniques. At last, through groundwater solute transport model and compound-specific isotope technology, determine the distribution of the typical site of organic sources of pollution and pollution status; invest identified potential sources of pollution and sample the soil to analysis. It turns out that the results of two identified historical pollution sources and pollutant concentration distribution are reliable. The results provided the basis for treatment of groundwater pollution. PMID:23668138

Wang, Xiao-Hong; Wei, Jia-Hua; Cheng, Zhi-Neng; Liu, Pei-Bin; Ji, Yi-Qun; Zhang, Gan

2013-02-01

61

Method to remove uranium/vanadium contamination from groundwater  

DOEpatents

A process for removing uranium/vanadium-based contaminants from groundwater using a primary in-ground treatment media and a pretreatment media that chemically adjusts the groundwater contaminant to provide for optimum treatment by the primary treatment media.

Metzler, Donald R. (DeBeque, CO); Morrison, Stanley (Grand Junction, CO)

2004-07-27

62

Methyl Tertiary Butyl Ether (MTBE) Groundwater Contamination  

NSDL National Science Digital Library

Methyl tertiary-butyl ether (MTBE), a fuel additive, is highly mobile in groundwater, dissolving and traveling faster than the other petroleum constituents which tend to biodegrade and adsorb to soil particles. This unit will introduce the problem of pollutants as they move through the various soil layers and contaminate the groundwater and challenge the students to investigate the effects of MTBE spills in the environment by researching the available literature on fuel oxygenates and learning their mode of transport through the soil. Experimentally determined data, obtained in lab activities, will facilitate building models of the contamination process of the groundwater. Mathematics modeling will involve the use of spreadsheet analysis of real-world-data obtained online.

63

A Guide for Assessing Biodegradation and Source Identification of Organic Groundwater Contaminants Using Compound Specific Isotope Analysis (CSIA)  

EPA Science Inventory

When organic contaminants are degraded in the environment, the ratio of stable isotopes will often change, and the extent of degradation can be recognized and predicted from the change in the ratio of stable isotopes. Recent advances in analytical chemistry make it possible to p...

64

[Risk assessment of quaternary groundwater contamination in Beijing Plain].  

PubMed

Firstly, advances in investigation and evaluation of groundwater pollution in China in the last decade were presented, and several issues in the field which hinder the development of groundwater environment were pointed out. Then, four key concepts in risk assessment of groundwater pollution were briefly described with more emphasis on the difference between groundwater pollution assessment and groundwater quality assessment in this paper. After that, a method on risk assessment of groundwater pollution which included four indicators, the pollution assessment, the quality assessment, the vulnerability and the pollution load of groundwater, was presented based on the regional characteristics of Beijing Plain. Also, AHP and expert scoring method were applied to determine the weight of the four evaluation factors. Finally, the application of this method in Beijing Plain showed the area with high, relative high, medium, relative low and low risk of groundwater contamination was 1 232.1 km2, 699.3 km2, 1 951.4 km, 2 644 km2, and 133.2 km2, respectively. The study results showed that the higher risk in the western region was likely caused by the higher pollution load and its higher vulnerability, while the relatively high risk in the southeast of Beijing plain area, the Tongzhou District, is mainly caused by historical pollution sources. PMID:24812948

Guo, Gao-Xuan; Li, Yu; Xu, Liang; Li, Zhi-Ping; Yang, Qing; Xu, Miao-Juan

2014-02-01

65

Groundwater Contamination. Instructor Guide. Working for Clean Water: An Information Program for Advisory Groups.  

ERIC Educational Resources Information Center

Described is a presentation and learning session on groundwater, which is intended to educate advisory groups interested in improving water quality decision making. Among the areas addressed are the importance of groundwater, sources of contamination, and groundwater pollution control programs. These materials are part of the Working for Clean…

Cole, Charles A.

66

NUTRIENT, BACTERIAL, AND VIRUS CONTROL AS RELATED TO GROUND-WATER CONTAMINATION  

EPA Science Inventory

A general introduction provides something of the history of groundwater, its present use, and the means by which it can become contaminated. A priority listing of sources of ground-water contamination is presented for four geographical areas of the United States. Phosphorus is di...

67

Using Nitrogen and Oxygen Isotope Compositions of Nitrate to Distinguish Contaminant Sources in Hanford Soil and Groundwater  

Microsoft Academic Search

The nitrogen (¹N) and oxygen (¹O) isotopic compositions of nitrate in the environment are primarily a function of the source of the nitrate. The ranges of isotopic compositions for nitrate resulting from common sources are outlined in Figure 1 from Kendall (1998). As noted on Figure 1, processes such as microbial metabolism can modify the isotopic compositions of the nitrate,

Mark Conrad; Markus Bill

2008-01-01

68

Migration of wood-preserving chemicals in contaminated groundwater in a sand aquifer at Pensacola, Florida  

USGS Publications Warehouse

Operation of a wood-preserving facility for nearly 80 years at Pensacola, FL, contaminated the near-surface groundwater with creosote and pentachlorophenol. The major source of aquifer contamination was unlined surface impoundments that were in direct hydraulic contact with the groundwater. Episodes of overtopping the impoundments and overland flow of treatment liquor and waste were also significant to the migration and contamination of the groundwater. Solutes contaminating the ground-water are mainly naphthalene and substituted phenols. Sorption did not influence retardation of solutes in transport in the groundwater. Phenol and the mono substituted methylphenols appear to be undergoing bio-transformation. Pentachlorophenol (PCP) was not found in significant concentrations in the groundwater possibly because the solubility of PCP is approximately 5 mg/L at pH 6, near the average acidity for the groundwater.

Goerlitz, D. F.; Troutman, D. E.; Godsy, E. M.; Franks, B. J.

1985-01-01

69

Groundwater contamination downstream of a contaminant penetration site. I. Extension-expansion of the contaminant plume.  

PubMed

This study concerns the possible use of boundary layer (BL) approach for the analysis and evaluation of contaminant transport in groundwater due to contaminant penetration into the groundwater aquifer through a site of limited size. The contaminant penetration may occur through either the upper (surface) or lower (bedrock) boundary of the aquifer. Two general cases of contaminant penetration mechanisms are considered: (1) the contaminant is transferred through an interface between a contaminating and freshwater fluid phases, and (2) the contaminant arrives at groundwater by leakage and percolation. For the purpose of BL evaluation the contaminant plume is divided into three different sections: (1) the penetration section, (2) the extension-expansion section, and (3) the spearhead section. In each section a different BL method approach yields simple analytical expressions for the description of the contaminant plume migration and contaminant transport. Previous studies of the BL method can be directly applied to the evaluation of contaminant transport at the contaminant penetration section. The present study extends those studies and concerns the contaminant transport in the two other sections, which are located downstream of the penetration section. This study shows that the contaminant concentration profiles in sections 2 and 3 incorporate two BLs: (1) an inner BL adjacent to the aquifer bottom or surface boundary, and (2) an outer BL, which develops above or below the inner one. The method developed in the present study has been applied to practical issues concerning salinity penetration into groundwater in south central Kansas. PMID:12413210

Rubin, Hillel; Buddemeier, Robert W

2002-11-01

70

Nitrate contamination of groundwater: A conceptual management framework  

SciTech Connect

In many countries, public concern over the deterioration of groundwater quality from nitrate contamination has grown significantly in recent years. This concern has focused increasingly on anthropogenic sources as the potential cause of the problem. Evidence indicates that the nitrate (NO{sub 3}) levels routinely exceed the maximum contaminant level (MCL) of 10 mg/l NO{sub 3}-N in many aquifer systems that underlie agriculture-dominated watersheds. Degradation of groundwater quality due to nitrate pollution along with the increasing demand for potable water has motivated the adoption of restoration actions of the contaminated aquifers. Restoration efforts have intensified the dire need for developing protection alternatives and management options such that the ultimate nitrate concentrations at the critical receptors are below the MCL. This paper presents a general conceptual framework for the management of groundwater contamination from nitrate. The management framework utilizes models of nitrate fate and transport in the unsaturated and saturated zones to simulate nitrate concentration at the critical receptors. To study the impact of different management options considering both environmental and economic aspects, the proposed framework incorporates a component of a multi-criteria decision analysis. To enhance spatiality in model development along with the management options, the utilization of a land use map is depicted for the allocation and computation of on-ground nitrogen loadings from the different sources.

Almasri, Mohammad N. [Water and Environmental Studies Institute, An-Najah National University, Nablus, Palestine (Country Unknown)]. E-mail: mnmasri@najah.edu

2007-04-15

71

Arsenic contamination in groundwater of Samta, Bangladesh.  

PubMed

In March 1997, we analyzed the water of all tubewells used for drinking in Samta village in the Jessore district, Bangladesh. It has been confirmed from the survey that the arsenic contamination in Samta was one of the worst in the Ganges basin including West Bengal, India. 90% of the tubewells had arsenic concentrations above the Bangladesh standard of 0.05 mg/l. Tubewells with higher arsenic concentrations of over 0.50 mg/l were distributed in the southern area with a belt-like shape from east to west, and the distribution of arsenic concentration showed gradual decreasing toward northern area of the village. In order to examine the characteristics of the arsenic distribution in Samta, we have performed investigations such as: 1) the characteristics of groundwater flow, 2) the distribution of arsenic in the ground, 3) the concentration of arsenic and the other dissolved materials in groundwater, and 4) the distribution of arsenic concentration of trivalence and pentavalence. This paper examines the mechanism of arsenic release to groundwater and explains the above-mentioned characteristics of the arsenic contamination in Samta through the investigations of the survey results for these years. PMID:12523781

Yokota, H; Tanabe, K; Sezaki, M; Yano, Y; Hamabe, K; Yabuuchi, K; Tokunaga, H

2002-01-01

72

Treatment of Leachate-Contaminated Groundwater with an Interception Trench.  

National Technical Information Service (NTIS)

A study was conducted to evaluate the effectiveness of a groundwater-interception trench for treating potential groundwater contamination originating from a solid-waste landfill operation and to evaluate the long-term impact of landfill operations on grou...

J. N. Dornbush

1984-01-01

73

Modeling In Situ Bioremediation of Perchlorate-Contaminated Groundwater  

Microsoft Academic Search

Perchlorate-contaminated groundwater is a significant national problem. An innovative technology was recently developed which uses a pair of dual-screened treatment wells to mix an electron donor into perchlorate- contaminated groundwater in order to effect in situ bioremediation of the perchlorate by indigenous perchlorate reducing bacteria (PRB) without the need to extract the contaminated water from the subsurface. The two treatment

M. N. Goltz; R. E. Secody; J. Huang; P. B. Hatzinger

2007-01-01

74

Groundwater and Contaminant Transport Modelling at the Sydney Tar Ponds  

Microsoft Academic Search

The Muggah Creek estuary has accumulated contaminants from 100 years of iron, steel and coke manufacturing in its contributing watershed. The estuary, locally known as the Tar Ponds, contains sediments contaminated with PAHs and PCBs. A program of groundwater modelling was aimed at estimating current contaminant fluxes to the estuary and site streams, via groundwater. The conceptual model developed for

Mark King

75

Intrinsic bioremediation in a solvent-contaminated alluvial groundwater.  

PubMed

An industrial site contaminated with a mixture of volatile organic compounds in its subsurface differed from previously reported locations in that the contamination consisted of a mixture of chlorinated, brominated, and non-halogenated aromatic and aliphatic solvents in an alluvial aquifer. The source area was adjacent to a river. Of the contaminants present in the aquifer, benzene, toluene, and chlorobenzene (BTC) were of primary concern. Studies of the physical, chemical, and microbiological characteristics of site groundwater were conducted. The studies concentrated on BTC, but also addressed the fate of the other aquifer VOCs. Gas chromatographic analyses performed on laboratory microcosms demonstrated that subsurface microorganisms were capable of BTC degradation. Mineralization of BTC was demonstrated by the release of 14CO2 from radiolabelled BTC. In the field, distribution patterns of nutrients and electron acceptors were consistent with expression of in situ microbial metabolic activity: methane, conductivity, salinity and o-phosphate concentrations were all positively correlated with contaminant concentration; while oxidation-reduction potential, nitrate, dissolved oxygen and sulfate concentrations were negatively correlated. Total aerobes, aerotolerant anaerobes, BTC-specific degraders, and acridine orange direct microscopic microorganism counts were strongly and positively correlated with field contaminant concentrations. The relative concentrations of benzene and toluene were lower away from the core of the plume compared to the less readily metabolized compound, chlorobenzene. Hydrodynamic modeling of electron-acceptor depletion conservatively estimated that 450 kg of contaminant have been removed from the subsurface yearly. Models lacking a biodegradation term predicted that 360 kg of contaminant would reach the river annually, which would result in measurable contaminant concentrations. River surveillance, however, has only rarely detected these compounds in the sediment and then only at trace concentrations. Thus, the combination of field modeling, laboratory studies, and site surveillance data confirm that significant in situ biodegradation of the contaminants has occurred. These studies establish the presence of intrinsic bioremediation of groundwater contaminants in this unusual industrial site subsurface habitat. PMID:9134765

Williams, R A; Shuttle, K A; Kunkler, J L; Madsen, E L; Hooper, S W

1997-01-01

76

Impact of trichloroethylene contaminated groundwater discharged to the main canal and Indian River Lagoon, Vero Beach, Florida  

Microsoft Academic Search

Contamination of groundwater by organic pollutants is now widely recognized as a serious threat to the integrity of many municipal and rural water supplies (Burmaster 1982; Wilson and McNabb 1983; Hansen 1983). The source of this contamination includes various waste disposal activities (e.g. industrial impoundments, landfills, accidental spills, underground storage tank leaks, pesticides and fertilizer application). Groundwater highly contaminated with

T. Wang; R. Lenahan; M. Kanik

1985-01-01

77

Investigation of contaminant sources at Navarre, Kansas.  

SciTech Connect

The results of the 2006 investigation of contaminant sources at Navarre, Kansas, clearly demonstrate the following: {sm_bullet} Sources of carbon tetrachloride contamination were found on the Navarre Co-op property. These sources are the locations of the highest concentrations of carbon tetrachloride found in soil and groundwater at Navarre. The ongoing groundwater contamination at Navarre originates from these sources. {sm_bullet} The sources on the Co-op property are in locations where the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) never conducted grain storage operations. {sm_bullet} No definitive sources of carbon tetrachloride were identified on the portion of the current Co-op property formerly used by the CCC/USDA. {sm_bullet} The source areas on the Co-op property are consistent with the locations of the most intense Co-op operations, both historically and at present. The Co-op historically stored carbon tetrachloride for retail sale and used it as a grain fumigant in these locations. {sm_bullet} The distribution patterns of other contaminants (tetrachloroethene and nitrate) originating from sources on the Co-op property mimic the carbon tetrachloride plume. These other contaminants are not associated with CCC/USDA operations. {sm_bullet} The distribution of carbon tetrachloride at the Co-op source areas, particularly the absence of contamination in soils at depths less than 20 ft below ground level, is consistent with vertical migration into the subsurface through a conduit (well Co-op 2), with subsequent lateral migration through the subsurface. {sm_bullet} The groundwater flow direction, which is toward the west-northwest, is not consistent with migration of carbon tetrachloride in groundwater from the former CCC/USDA property to the source areas on the Co-op property. {sm_bullet} The absence of soil and groundwater contamination along surface drainage pathways on the former CCC/USDA property is not consistent with migration of carbon tetrachloride in surface water runoff from the former CCC/USDA property to the source areas on the Co-op property. {sm_bullet} The contamination detected in soil and groundwater samples collected along the northern boundary of the former CCC/USDA facility can be attributed to migration from the Co-op sources or to operations of the Co-op on the property after CCC/USDA operations ended. {sm_bullet} The southern boundary of the Co-op property has expanded over time, so that the Co-op has operated for a lengthy period in all areas previously leased by the CCC/USDA (Figure S.1). The Co-op began expanding onto the former CCC/USDA property in 1969 and has operated on that property longer than the CCC/USDA did. The use of carbon tetrachloride as a grain fumigant was standard industry practice until 1985, when the compound was banned by the U.S. Environmental Protection Agency. {sm_bullet} Petroleum-related contamination was detected on the southern part of the former CCC/USDA property. This contamination is associated with aboveground storage tanks that are owned and operated by the Co-op. The major findings of the 2006 investigations are summarized in greater detail below. The 2006 investigation was implemented by the Environmental Science Division of Argonne National Laboratory on behalf of the CCC/USDA.

LaFreniere, L. M.; Environmental Science Division

2007-11-05

78

Biotreatment of TCE-contaminated groundwater  

SciTech Connect

A trickle-bed bioreactor containing a consortium of microorganisms using methane as the primary carbon source was used to treat a synthetic groundwater containing trichloroethylene (TCE) and trans-1,2-dichloroethylene (DCE). With influent concentrations of TCE and DCE of 1 mg/L each and an average residence time of about 50 min, >50% of the TCE and >90% of the DCE was degraded. The reactor exhibited first-order kinetics with respect to TCE degradation. 5 refs., 1 tab.

Donaldson, T.L.; Strandberg, G.W.; Palumbo, A.V.

1989-01-01

79

Magnetic properties changes due to hydrocarbon contaminated groundwater table fluctuations  

NASA Astrophysics Data System (ADS)

This study aims to understand the mechanisms and conditions which control the formation and transformation of ferro(i)magnetic minerals caused by hydrocarbon contaminated groundwater, in particular in the zone of fluctuating water levels. The work extends previous studies conducted at the same site. The study area is a former military air base at Hrad?any, Czech Republic (50°37'22.71"N, 14°45'2.24"E). The site was heavily contaminated with petroleum hydrocarbons, due to leaks in petroleum storage tanks and jet fuelling stations over years of active use by the Soviet Union, which closed the base in 1991. The site is one of the most important sources of high quality groundwater in the Czech Republic. In a previous study, Rijal et al. (2010) concluded that the contaminants could be flushed into the sediments as the water level rose due to remediation processes leading to new formation of magnetite. In this previous study three different locations were investigated; however, from each location only one core was obtained. In order to recognize significant magnetic signatures versus depth three cores from each of these three locations were drilled in early 2012, penetrating the unsaturated zone, the groundwater fluctuation (GWF) zone and extending to about one meter below the groundwater level (~2.3 m depth at the time of sampling). Magnetic susceptibility (MS) profiles combined with other magnetic properties were analyzed to obtain a significant depth distribution of the ferro(i)magnetic concentration. Sediment properties, hydrocarbon content and bacterial activity were additionally studied. The results show that the highest ferrimagnetic mineral concentrations exist between 1.4-1.9 m depth from the baseline which is interpreted as the top of the GWF zone. Spikes of MS detected in the previous studies turned out to represent small-scale isolated features, but the trend of increasing MS values from the lowermost position of the groundwater table upward was verified. Mineral magnetic parameters indicate that magnetite is responsible for the MS signal which confirms the previous results (Rijal et al., 2010). The so far existing uncertainty of the groundwater level position could be solved. Bacterial activity is studied at particular depth horizons as it is assumed to be responsible for iron mineralogy changes. References: Rijal M.L., Appel E., Petrovský E. and Blaha U., 2010. Change of magnetic properties due to fluctuations of hydrocarbon contaminated groundwater in unconsolidated sediments. Environ.Pollut., 158, 1756-1762.

Ameen, Nawrass

2013-04-01

80

Hydrocarbon Contamination in Groundwaters: Removal by Alcohol Flooding.  

National Technical Information Service (NTIS)

Present pump-and-treat remediation strategies employed to remove hydrocarbon contaminants that exist in groundwater as nonaqueous phase liquids (NAPLs) can displace only a fraction of the contaminant due to the trapping effects of capillary forces. These ...

K. J. Farley G. R. Boyd S. Patwardhan

1992-01-01

81

Arsenic contaminated groundwater and its treatment options in Bangladesh.  

PubMed

Arsenic (As) causes health concerns due to its significant toxicity and worldwide presence in drinking water and groundwater. The major sources of As pollution may be natural process such as dissolution of As-containing minerals and anthropogenic activities such as percolation of water from mines, etc. The maximum contaminant level for total As in potable water has been established as 10 µg/L. Among the countries facing As contamination problems, Bangladesh is the most affected. Up to 77 million people in Bangladesh have been exposed to toxic levels of arsenic from drinking water. Therefore, it has become an urgent need to provide As-free drinking water in rural households throughout Bangladesh. This paper provides a comprehensive overview on the recent data on arsenic contamination status, its sources and reasons of mobilization and the exposure pathways in Bangladesh. Very little literature has focused on the removal of As from groundwaters in developing countries and thus this paper aims to review the As removal technologies and be a useful resource for researchers or policy makers to help identify and investigate useful treatment options. While a number of technological developments in arsenic removal have taken place, we must consider variations in sources and quality characteristics of As polluted water and differences in the socio-economic and literacy conditions of people, and then aim at improving effectiveness in arsenic removal, reducing the cost of the system, making the technology user friendly, overcoming maintenance problems and resolving sludge management issues. PMID:23343979

Jiang, Jia-Qian; Ashekuzzaman, S M; Jiang, Anlun; Sharifuzzaman, S M; Chowdhury, Sayedur Rahman

2013-01-01

82

Groundwater contamination from an inactive uranium mill tailings pile: 1. Application of a chemical mixing model  

Microsoft Academic Search

Low-pH process waters contained in a number of inactive and abandoned uranium mill tailings in the United States represent potential sources of radionuclide and trace metal contamination of groundwater. Detailed investigations at a typical site at Riverton, Wyoming, indicate that chemical transport occurs from initial dewatering of the tailings, downward infiltration due to precipitation, and groundwater intrusion into the base

A. F. White; J. M. Delany; T. N. Narasimhan; A. Smith

1984-01-01

83

TREATMENT OF HIGHLY CONTAMINATED GROUNDWATER: A SITE DEMONSTRATION PROJECT  

EPA Science Inventory

From 9-11/1994, the USEPA conducted a field demonstration of the remediation of highly contaminated groundwater at the Mascolite Superfund site located in Millville, NJ. Besides high concentrations of the major contaminant, methyl methacrylate (MMA), the groundwater also containe...

84

Potential of groundwater contamination by polybrominated diphenyl ethers (PBDEs) in a sensitive bedrock aquifer (Canada)  

NASA Astrophysics Data System (ADS)

It is necessary to understand the presence, movement, and persistence of contaminants in aquifers to develop adequate groundwater protection plans. Fractured bedrock aquifers with thin overburden cover are very sensitive to contamination, and little is known about transport processes from the ground surface to depth in this setting. This study was undertaken to investigate the potential of groundwater contamination by polybrominated diphenyl ethers (PBDEs), which are flame retardants, in a natural fractured bedrock aquifer in Canada proven to be sensitive to contamination. PBDEs, which had not been previously measured in groundwater in detail, were detected in the study aquifer at concentrations greater than those observed in surface-water bodies. Potential sources include manure, septic tanks, and the atmosphere. From this scoping study, it is evident that additional surveys of PBDE concentrations in groundwater are warranted, especially in settings with high potential source concentrations coupled with sensitive aquifers.

Levison, Jana; Novakowski, Kent; Reiner, Eric J.; Kolic, Terry

2012-03-01

85

Monitoring Groundwater Contaminant Plumes Using Airborne Geophysical Data  

NASA Astrophysics Data System (ADS)

Under the European Union Water Framework Directive, Member States are required to assess water quality across both surface water and groundwater bodies. Subsurface pollution plumes, originating from a variety of sources, pose a significant direct risk to water quality. The monitoring and characterisation of groundwater contaminant plumes is generally invasive, time consuming and expensive. In particular, adequately capturing the contaminant plume with monitoring installations, when the extent of the feature is unknown and the presence of contamination is only evident from indirect observations, can be prohibitively expensive. This research aims to identify the extent and nature of subsurface contaminant plumes using airborne geophysical survey data. This data was collected across parts of the island of Ireland within the scope of the original Tellus and subsequent Tellus Border projects. The rapid assessment of the airborne electro-magnetic (AEM) data allowed the identification of several sites containing possible contaminant plumes. These AEM anomalies were assessed through the analysis of existing site data and field site inspections, with areas of interest being examined for metallic structures that could affect the AEM data. Electrical resistivity tomography (ERT), ground penetrating radar (GPR) and ground-based electro-magnetic (EM) surveys were performed to ground-truth existing airborne data and to confirm the extent and nature of the affected area identified using the airborne data. Groundwater and surface water quality were assessed using existing field site information. Initial results collected from a landfill site underlain by basalt have indicated that the AEM data, coupled with ERT and GPR, can successfully be used to locate possible plumes and help delineate their extent. The analysis of a range of case study sites exhibiting different geological and environmental settings will allow for the development of a consistent methodology for examining the airborne data for the detection of groundwater contaminant plumes. This will provide a basis for assessing the influence that drift and bedrock geology exert on the feasibility of using Tellus airborne data as a plume monitoring tool. This research will facilitate a conjunctive approach for the detection and monitoring of pollution sources adversely affecting water bodies, as well as improve the targeting of costly intrusive monitoring and restoration efforts.

Robinson, Martin; Oftendinger, Ulrich; Ruffell, Alastair; Cowan, Marie; Cassidy, Rachel; Comte, Jean-Christophe; Wilson, Christopher; Desissa, Mohammednur

2013-04-01

86

PILOT TESTING OF A BIOREACTOR FOR PERCHLORATE CONTAMINATED GROUNDWATER TREATMENT  

Microsoft Academic Search

Groundwater at the Crafton-Redlands site in Redlands, California is contaminated with perchlorate in addition to chlorinated volatile organic compounds (VOCs). VOCs are removed from extracted groundwater using granular activated carbon, which is ineffective for perchlorate removal. Side-by-side pilot-scale bioreactors for perchlorate removal from extracted groundwater were tested at the site. Preliminary results showed that perchlorate was consistently removed from groundwater

Patrick Evans; Allyson Chu; Stephen Liao; Mieko Moody; Booki Min; Bruce Logan

2002-01-01

87

What should be done to mitigate groundwater contamination?  

PubMed Central

Groundwater contamination is a serious problem that is growing in the United States, but its true extent is not known and it is difficult to determine because of the complexities of contaminants, their transformation, and fate in groundwater systems. It is also difficult to predict their movement in groundwater. Since we know that the problem is serious and that our needs for groundwater will grow, the mitigation of groundwater contamination, despite the high cost, is necessary. Furthermore, it is very difficult to predict effects on human health because they have not been defined for many of the chemicals. Antagonism and synergistic effects of interacting chemicals have not been determined because they are complicated by many factors, for example, volatile organic compounds. The effects of leachates in groundwaters entering streams on the riverine environment and aquatic life have not been determined. Successful mitigation requires that we determine which microbial and chemical contaminants are the most serious threats to human health, develop the technology to biologically, chemically, and physically transform hazardous waste into nonhazardous materials; develop the technology to properly contain hazardous materials and to remediate contamination, and determine the effects of those hazardous materials on soils and water microorganisms and macroorganisms. Our challenge is how can we immobilize or destroy groundwater contaminants so that they will not enter groundwater, or if they enter groundwater, are confined and destroyed.

Patrick, R

1990-01-01

88

Review of risk from potential emerging contaminants in UK groundwater.  

PubMed

This paper provides a review of the types of emerging organic groundwater contaminants (EGCs) which are beginning to be found in the UK. EGCs are compounds being found in groundwater that were previously not detectable or known to be significant and can come from agricultural, urban and rural point sources. EGCs include nanomaterials, pesticides, pharmaceuticals, industrial compounds, personal care products, fragrances, water treatment by-products, flame retardants and surfactants, as well as caffeine and nicotine. Many are relatively small polar molecules which may not be effectively removed by drinking water treatment. Data from the UK Environment Agency's groundwater screening programme for organic pollutants found within the 30 most frequently detected compounds a number of EGCs such as pesticide metabolites, caffeine and DEET. Specific determinands frequently detected include pesticides metabolites, pharmaceuticals including carbamazepine and triclosan, nicotine, food additives and alkyl phosphates. This paper discusses the routes by which these compounds enter groundwater, their toxicity and potential risks to drinking water and the environment. It identifies challenges that need to be met to minimise risk to drinking water and ecosystems. PMID:22209399

Stuart, Marianne; Lapworth, Dan; Crane, Emily; Hart, Alwyn

2012-02-01

89

A controlled field experiment on groundwater contamination by a multicomponent DNAPL: creation of the emplaced-source and overview of dissolved plume development.  

PubMed

A unique field experiment has been undertaken at the CFB Borden research site to investigate the development of dissolved chlorinated solvent plumes from a residual dense non-aqueous phase liquid (DNAPL) source. The "emplaced-source" tracer test methodology involved a controlled emplacement of a block-shaped source of sand containing chlorinated solvents below the water table. The gradual dissolution of this residual DNAPL solvent source under natural aquifer conditions caused dissolved solvent plumes of trichloromethane (TCM), trichloroethene (TCE) and perchloroethene (PCE) to continuously develop down gradient. Source dissolution and 3-D plume development were successfully monitored via 173 multilevel samplers over a 475-day tracer test period prior to site remediation research being initiated. Detailed groundwater level and hydraulic conductivity data were collected. Development of plumes with concentrations spanning 1-700,000 micrograms/1 is described and key processes controlling their migration identified. Plumes were observed to be narrow due to the weakness of transverse dispersion processes and long due to advection and significant longitudinal dispersion, very limited sorptive retardation and negligible, if any, attenuation due to biodegradation or abiotic reaction. TCM was shown to be essentially conservative, TCE very nearly conservative and PCE, consistent with its greater hydrophobicity, more retarded yet having a greater mobility than observed in previous Borden field tests. The absence of biodegradation was ascribed to the prevailing aerobic conditions and lack of any additional biodegradable carbon substrates. The transient groundwater flow regime caused significant transverse lateral plume movement, plume asymmetry and was likely responsible for most of the, albeit limited, transverse horizontal plume spreading. In agreement with the widespread incidence of extensive TCE and PCE plumes throughout the industrialized world, the experiment indicates such solvent plumes are likely to be highly mobile and persistent, at least in aquifers that are aerobic and have low sorption potential (low foc content). PMID:11351512

Rivett, M O; Feenstra, S; Cherry, J A

2001-05-01

90

A controlled field experiment on groundwater contamination by a multicomponent DNAPL: creation of the emplaced-source and overview of dissolved plume development  

NASA Astrophysics Data System (ADS)

A unique field experiment has been undertaken at the CFB Borden research site to investigate the development of dissolved chlorinated solvent plumes from a residual dense non-aqueous phase liquid (DNAPL) source. The "emplaced-source" tracer test methodology involved a controlled emplacement of a block-shaped source of sand containing chlorinated solvents below the water table. The gradual dissolution of this residual DNAPL solvent source under natural aquifer conditions caused dissolved solvent plumes of trichloromethane (TCM), trichloroethene (TCE) and perchloroethene (PCE) to continuously develop down gradient. Source dissolution and 3-D plume development were successfully monitored via 173 multilevel samplers over a 475-day tracer test period prior to site remediation research being initiated. Detailed groundwater level and hydraulic conductivity data were collected. Development of plumes with concentrations spanning 1-700,000 ?g/l is described and key processes controlling their migration identified. Plumes were observed to be narrow due to the weakness of transverse dispersion processes and long due to advection and significant longitudinal dispersion, very limited sorptive retardation and negligible, if any, attenuation due to biodegradation or abiotic reaction. TCM was shown to be essentially conservative, TCE very nearly conservative and PCE, consistent with its greater hydrophobicity, more retarded yet having a greater mobility than observed in previous Borden field tests. The absence of biodegradation was ascribed to the prevailing aerobic conditions and lack of any additional biodegradable carbon substrates. The transient groundwater flow regime caused significant transverse lateral plume movement, plume asymmetry and was likely responsible for most of the, albeit limited, transverse horizontal plume spreading. In agreement with the widespread incidence of extensive TCE and PCE plumes throughout the industrialized world, the experiment indicates such solvent plumes are likely to be highly mobile and persistent, at least in aquifers that are aerobic and have low sorption potential (low foc content).

Rivett, Michael O.; Feenstra, Stanley; Cherry, John A.

2001-05-01

91

A regional flux-based risk assessment approach for multiple contaminated sites on groundwater bodies.  

PubMed

In the context of the Water Framework Directive (EP and CEU, 2000), management plans have to be set up to monitor and to maintain water quality in groundwater bodies in the EU. In heavily industrialized and urbanized areas, the cumulative effect of multiple contaminant sources is likely and has to be evaluated. In order to propose adequate measures, the calculated risk should be based on criteria reflecting the risk of groundwater quality deterioration, in a cumulative manner and at the scale of the entire groundwater body. An integrated GIS- and flux-based risk assessment approach for groundwater bodies is described, with a regional scale indicator for evaluating the quality status of the groundwater body. It is based on the SEQ-ESO currently used in the Walloon Region of Belgium which defines, for different water uses and for a detailed list of groundwater contaminants, a set of threshold values reflecting the levels of water quality and degradation with respect to each contaminant. The methodology is illustrated with first results at a regional scale on a groundwater body-scale application to a contaminated alluvial aquifer which has been classified to be at risk of not reaching a good quality status by 2015. These first results show that contaminants resulting from old industrial activities in that area are likely to contribute significantly to the degradation of groundwater quality. However, further investigations are required on the evaluation of the actual polluting pressures before any definitive conclusion be established. PMID:22036196

Jamin, P; Dollé, F; Chisala, B; Orban, Ph; Popescu, I-C; Hérivaux, C; Dassargues, A; Brouyère, S

2012-01-01

92

Assessing Groundwater Contamination Vulnerability at Public Water Supply Wells in California  

Microsoft Academic Search

The California Aquifer Susceptibility project, sponsored by the California State Water Resources Control Board, uses a probabilistic approach to assess the vulnerability of public water supply wells to contamination by anthropogenic compounds. Sources of contamination to groundwater occur near the earth's surface, and have been present mostly since WWII. Therefore, wells that receive water that has recharged in the recent

J. E. Moran; B. Hudson; B. P. Dooher; R. Leif; G. F. Eaton; L. Davisson

2001-01-01

93

Assessment of diesel contamination in groundwater using electromagnetic induction geophysical techniques  

SciTech Connect

Determining hydrocarbon plumes in groundwater is typically accomplished through the installation of extensive monitoring wells. Issues of scale and site heterogeneities tend to introduce errors in delineating the extent of contamination and environmental impact. In this study, electromagnetic induction survey was investigated as an alternative technique for mapping petroleum contaminants in the subsurface. The surveys were conducted at a coal mining site near Gillette, Wyoming, using the EM34-XL ground conductivity meter. Data from this survey were validated with known concentrations of diesel compounds detected in groundwater from the study site. Groundwater data correlated well with the electromagnetic survey data, which was used to generate a site model to identify subsurface diesel plumes. To our knowledge, this is one of the first studies to use electromagnetic survey techniques for mapping hydrocarbon contamination in groundwater. Results from this study indicate that this geophysical technique can be an effective tool for assessing subsurface petroleum hydrocarbon sources and plumes at contaminated sites.

Jin, S.; Fallgren, P.; Cooper, J.; Morris, J; . Urynowicz, M. [Western Research Institute, Laramie, WY (United States)

2008-07-01

94

Contaminated site remedial investigation and feasibility removal of chlorinated volatile organic compounds from groundwater by activated carbon fiber adsorption  

Microsoft Academic Search

Groundwater contaminated by dense, non-aqueous phase liquids (DNAPLs) such as chlorinated solvents has become a serious problem in some regions of Taiwan. The sources of these contaminants are due to industrial discharges. These chlorinated volatile organic compounds (VOCs) have been proven to be carcinogenic to humans. The groundwater is used for domestic drinking water supply in some cities of Taiwan

Jya-Jyun Yu; Shinn-Yow Chou

2000-01-01

95

Groundwater Arsenic Contamination in Kopruoren Basin (Kutahya), Turkey  

NASA Astrophysics Data System (ADS)

Groundwater quality in the Kopruoren Basin located to the west of Kutahya city in western Anatolia was investigated. Kopruoren Basin is about 275 km2 with about 6,000 residents, but the surface and ground-water quality in this basin impacts a much larger population since the area is located upstream of Kutahya and Eskisehir plains. Groundwater occurs under confined conditions in the limestones of Pliocene units. The only silver deposit of Turkey is developed in the metamorphic basement rocks, Early Miocene volcanics and Pliocene units near Gumuskoy. The amount of silver manufactured annually comprises about 1% of the World's Silver Production. The cyanide-rich wastes of the Eti Gumus silver plant is stored in waste pools. There have been debates about the safety of this facility after a major collapse occurred in one of the pools in May 2011. In this study samples from 31 wells and 21 springs were collected in July and October 2011 and May 2012. The groundwaters are of Ca-Mg-HCO3 type, with arsenic, zinc and antimony occurring at high concentrations. Dissolved arsenic concentrations are as high as 48 ug/L in springs and 734 ug/L in well water. Arsenic in 57% of the springs and 68% of the wells exceeded the WHO guideline value (10 ug/L). Natural sources of arsenic in the area include the dissolution of arsenic-rich minerals such as realgar and orpiment associated with the mineral deposits in the southern part of the study area. In the northern part, arsenic is enriched due to the dissolution of arsenic-bearing coal deposits. Besides these natural sources of contamination, the silver mining activity could be an important anthropogenic source. The leakage of cyanide and arsenic, together with other trace elements to the environment from the waste pools, will continue to poison the environment if necessary precautions are not taken immediately.

Arslan, S.; Dokuz, U.; Celik, M.; Cheng, Z.

2012-12-01

96

Risk assessment of groundwater contamination: a multilevel fuzzy comprehensive evaluation approach based on DRASTIC model.  

PubMed

Groundwater contamination is a serious threat to water supply. Risk assessment of groundwater contamination is an effective way to protect the safety of groundwater resource. Groundwater is a complex and fuzzy system with many uncertainties, which is impacted by different geological and hydrological factors. In order to deal with the uncertainty in the risk assessment of groundwater contamination, we propose an approach with analysis hierarchy process and fuzzy comprehensive evaluation integrated together. Firstly, the risk factors of groundwater contamination are identified by the sources-pathway-receptor-consequence method, and a corresponding index system of risk assessment based on DRASTIC model is established. Due to the complexity in the process of transitions between the possible pollution risks and the uncertainties of factors, the method of analysis hierarchy process is applied to determine the weights of each factor, and the fuzzy sets theory is adopted to calculate the membership degrees of each factor. Finally, a case study is presented to illustrate and test this methodology. It is concluded that the proposed approach integrates the advantages of both analysis hierarchy process and fuzzy comprehensive evaluation, which provides a more flexible and reliable way to deal with the linguistic uncertainty and mechanism uncertainty in groundwater contamination without losing important information. PMID:24453883

Zhang, Qiuwen; Yang, Xiaohong; Zhang, Yan; Zhong, Ming

2013-01-01

97

Modeling In Situ Bioremediation of Perchlorate-Contaminated Groundwater.  

National Technical Information Service (NTIS)

Perchlorate-contaminated groundwater is a significant problem for the Department of Defense and the United States Air Force. An innovative technology was recently developed which uses dual-screened treatment wells to mix an electron donor into perchlorate...

R. E. Secody

2007-01-01

98

APPLICABILITY OF UV/OXIDATION TECHNOLOGIES TO TREAT CONTAMINATED GROUNDWATER  

EPA Science Inventory

This paper presents information useful in evaluating the applicability of UV/Oxidation treatment technologies for groundwater contaminated with organics. he information presented includes a description of the technologies, factors affecting the technologies, and results from two ...

99

ADVANCED OXIDATION TECHNOLOGIES FOR THE TREATMENT OF CONTAMINATED GROUNDWATER  

EPA Science Inventory

This paper presents information on two pilot-field applications of advanced oxidation technologies for contaminated groundwater with organics. he two UV/oxidation technologies were developed by Ultrox International of Santa Ana, California and Peroxidation Systems, Inc. of Tucson...

100

ADVANCED OXIDATION TECHNOLOGIES FOR THE TREATMENT OF CONTAMINATED GROUNDWATER  

EPA Science Inventory

This paper presents information on two pilot-field appliations of advanced oxidation technologies for contaminated groundwater with organis. The two UV/oxidation technologies were developed by Ultrox International of Santa Ana, California and Peroxidatrion Systems, Inc. of Tucso...

101

Superfund Record of Decision (EPA Region 9): Newmark Groundwater Contamination Site, San Bernardino, CA., August 1993.  

National Technical Information Service (NTIS)

This decision document presents the selected remedial action for the Newmark Operable Unit, Newmark Groundwater Contamination Superfund site. EPA has selected an interim remedy for the Newmark plume of groundwater contamination in the Newmark Groundwater ...

1993-01-01

102

In Situ Permeable Reactive Barriers for Groundwater Contamination  

Microsoft Academic Search

In situ permeable reactive barriers (PRBs) consist of zones of reactive material, such as granular iron or other typically reduced metal, lime, electron donor-releasing compounds, or electron acceptor-releasing compounds, installed in the path of a plume of contaminated groundwater. As the groundwater flows through this zone, contaminants are degraded to innocuous components through chemical and\\/or biological reactions, adsorbed, or chemically

John P. Richardson; John W. Nicklow

2002-01-01

103

Groundwater pollution by airborne toxic contaminants: a factor to be considered in groundwater management?  

Microsoft Academic Search

The atmosphere contains various amounts of contaminants which may be dry scavenged or flushed by rain and eventually arrive in groundwater. In Israel, like many other industrial countries, most atmospheric contaminants originate from the coastal city complex, which also provides energy for the introduction of the contaminants into the atmosphere. Coastal breezes and other movements of masses of air transport

A. J. MELLOUL

1994-01-01

104

Investigating a Real-Life Groundwater Contamination Event  

NSDL National Science Digital Library

This assignment is designed as a final project for students in my undergraduate 3 credit non lab elective geohydrology course. Students work in pairs to analyze an actual, local contaminated site (Delphi) and use raw data from consulting reports (boring logs, water levels, chemical water analyses) to prepare a geologic cross-section, water table map and contaminant plume map. Students are assigned different lines of cross section, water level dates and contaminant types. Students examine the variety of different figures and maps to better characterize hydrogeologic and water quality conditions over the entire site and answer some assigned questions. This project is an opportunity for students to apply skills they learned in the course (contouring, groundwater flow) to investigate an existing groundwater contamination event. It also provides the kind of "practical" experience the students can highlight in a job interview. Key words: Groundwater contamination, case study, TCE

Riemersma, Peter

105

Application of particle methods to reliable identification of groundwater pollution sources  

Microsoft Academic Search

An alternative strategy for identifying sources of contamination in groundwater systems is presented. Under the assumption that the remediation cost is affected by the level of contamination, the proposed scheme provides probabilistic estimates of source locations and spill-time histories. Moreover, the method successfully assesses the relative importance of each potential source.

Amvrossios C. Bagtzoglou; David E. Dougherty; Andrew F. B. Tompson

1992-01-01

106

Assessment of Groundwater Vulnerability for Antropogenic and Geogenic Contaminants in Subwatershed  

NASA Astrophysics Data System (ADS)

Groundwater is an important natural resource that providing drinking water to more than five million people in Korea. Nonpoint source nitrate was frequently observed contaminant and the investigation result for small potable water supply system that mainly consisted of 70 percent groundwater showed that about 5 percent of water samples exceeded potable water quality standards of Korea. The geogenic contanminants such as arsenic and fluoride also frequently observed contaminants in Korea. In order to protect groundwater and to supply safe water to public, we need to assess groundwater vulnerability and to know the cause of occurrence of contaminants. To achieve this goal, we executed groundwater investigation and assessment study for Keumsan subwatershed with 600km2 in Keum-river watershed. The geostatistical and GIS technique were applied to map the spatial distribution of each contaminants and to calculate vulnerability index. The results of logistic regression for nitrate indicated the close relationship with land use. The results of hydrogeochemical analyses showed that nitrates in groundwater are largely influenced by land use and had high values in granitic region with dense agricultural field and resident. The high nitrates are closely related to groundwater of greenhouse area where large amount of manure and fertilizer were usually introduced in cultural land. The soil in granitic region had high contents of permeable sand of weathered products of granite that play as a role of pathway of contaminants in agricultural land and resident area. The high values of bicarbonate are originated from two sources, limestone dissolution of Ogcheon belt and biodegradation organic pollutants from municipal wastes in granitic region with dense agriculture and residence. It is considered that the anomalous distribution of arsenic and fluoride is related to limestone and metasedimentry rock of Ogcheon belt with high contents of sulfide minerals and F bearing minerals. The ubiquitous old fluorite and coal mines in Ogcheon belt are considered the main source of arsenic and fluoride in groundwater.

Ko, K.; Koh, D.; Chae, G.; Cheong, B.

2007-12-01

107

Evaluation of organic contamination in urban groundwater surrounding a municipal landfill, Zhoukou, China.  

PubMed

This paper investigates the organic pollution status of shallow aquifer sediments and groundwater around Zhoukou landfill. Chlorinated aliphatic hydrocarbons, monocylic aromatic hydrocarbons, halogenated aromatic hydrocarbons, organochlorine pesticides and other pesticides, and polycyclic aromatic hydrocarbons (PAHs) have been detected in some water samples. Among the detected eleven PAHs, phenanthrene, fluorine, and fluoranthene are the three dominant in most of the groundwater samples. Analysis of groundwater samples around the landfill revealed concentrations of PAHs ranging from not detected to 2.19 ?g/L. The results show that sediments below the waste dump were low in pollution, and the shallow aquifer, at a depth of 18-30 m, was heavily contaminated, particularly during the wet season. An oval-shaped pollution halo has formed, spanning 3 km from west to east and 2 km from south to north, and mainly occurs in groundwater depths of 2-4 m. For PAH source identification, both diagnostic ratios of selected PAHs and principal component analysis were studied, suggesting mixed sources of pyro- and petrogenic derived PAHs in the Zhoukou landfill. Groundwater table fluctuations play an important role in the distribution of organic pollutants within the shallow aquifer. A conceptual model of leachate migration in the Quaternary aquifers surrounding the Zhoukou landfill has been developed to describe the contamination processes based on the major contaminant (PAHs). The groundwater zone contaminated by leachate has been identified surrounding the landfill. PMID:22872511

Han, D M; Tong, X X; Jin, M G; Hepburn, Emily; Tong, C S; Song, X F

2013-04-01

108

Nitrate contamination of groundwater in the catchment of Gocza?kowice reservoir  

NASA Astrophysics Data System (ADS)

Gocza?kowice dammed reservoir (area - 26 km2 , volume - 100 million m3 at a typical water level) is a very important source of drinking water for Upper Silesian agglomeration. At the catchment of the reservoir there are many potential sources of groundwater pollution (agriculture, bad practices in wastewater management, intensive fish farming). Thus local groundwater contamination, mainly by nitrogen compounds. The paper presents groundwater monitoring system and preliminary results of the research carried on at Gocza?kowice reservoir and its catchment in 2010 - 2014 within the project "Integrated system supporting management and protection of dammed reservoir (ZiZoZap)'. The main objective for hydrogeologists in the project is to assess the role of groundwater in total water balance of the reservoir and the influence of groundwater on its water quality. During research temporal variability of groundwater - surface water exchange has been observed. Monitoring Network of groundwater quality consists of 22 observation wells (nested piezometers included) located around the reservoir - 13 piezometers is placed in two transects on northern and southern shore of reservoir. Sampling of groundwater from piezometers was conducted twice - in autumn 2011 and spring 2012. Maximum observed concentrations of nitrate, nitrite and ammonium were 255 mg/L, 0,16 mg/L and 3,48 mg/L, respectively. Surface water in reservoir (8 points) has also been sampled. Concentrations of nitrate in groundwater are higher than in surface water. Nitrate and ammonium concentrations exceeding standards for drinking water were reported in 18% and 50% of monitored piezometers, respectively. High concentration of nitrate (exceeding more than 5 times maximal admissible concentration) have been a significant groundwater contamination problem in the catchment of the reservoir. Periodically decrease of surface water quality is possible. Results of hydrogeological research indicate substantial spatial variability in concentrations of nitrogen compounds in groundwater of the Quaternary aquifer. To determine an origin of nitrate in groundwater the study of isotopic composition of nitrogen and oxygen in nitrate was conducted.

Czekaj, Joanna; Witkowski, Andrzej J.

2014-05-01

109

Probabilistic assessment of ground-water contamination. 1: Geostatistical framework  

Microsoft Academic Search

Characterizing the extent and severity of ground-water contamination at waste sites is expensive and time-consuming. A probabilistic approach, based on the acceptance of uncertainty and a finite probability of making classification errors (contaminated relative to a regulatory threshold vs. uncontaminated), is presented as an alternative to traditional site characterization methodology. The approach utilizes geostatistical techniques to identify and model the

Christopher A. Rautman; Jonathan D. Istok

1996-01-01

110

Seismic and Tilt Data Processing for Monitoring Groundwater Contamination  

NASA Astrophysics Data System (ADS)

We are conducting a feasibility study to see if we can detect changes in the state of saturation in groundwater by seismic means. This field study is based on laboratory experiments that show large changes in seismic attenuation when contaminants change the wettability of porous rocks. Three tiltmeters and three seismometers were installed at different distances from a controlled irrigation site near Maricopa, AZ. The research site has a facility to controllably irrigate a 50 m by 50 m area with water and chemical surfactants. The instruments are used to record naturally-occurring, low frequency strain and seismic signals before, during and after irrigations. The purpose of the data analysis is to develop techniques for looking for the differences in station response due to local differences, such as contamination in the vadose zone and groundwater. Ours is not a conventional way of data processing for our non-traditional use of the data, since the variations in instrument response caused by the trace amount of contaminants are very small. We are looking for small changes in the relative response between the instruments. For the seismic data, not only do we examine large events, such as Earthquakes, but also microseisms. We use microseisms as our source and the related processing is an attempt to measure the tiny changes in instrument response caused by differences in irrigation and contamination at the three different locations. In tilt data processing, the large events caused by regional water pumping, oil productions, and Earthquakes, etc. need to be removed, since we wish to use the Earth solid tide as our strain source. The key issue during the process of removing the large events is to make sure that the tide signals are not also removed or greatly distorted. A method and corresponding codes were developed for automatically removing data at the three stations induced by large events. After completing this processing, the signal left is the local Earth tide data. Through comparing these observed data with the theoretical tide amplitudes specific to our field location we can find the relative responses of the three instruments and influences induced by the contaminations.

Zhang, J.; Spetzler, H. A.

2003-12-01

111

Groundwater contaminant model of chemical mass loading and discharge in the Great Lakes Basin  

SciTech Connect

With numerous point and non-point groundwater contaminant sources found throughout the Great Lakes Basin, the potential loading and migration of contaminants into the Great Lakes via subsurface pathways represents a serious cause for concern. A regional scale study of contaminant sources and chemical mass loadings with the Greater Toronto area was conducted. This area was chosen because its diverse contaminant sources and range of land use makes it an ideal area to be used as a model for developed areas throughout North America. A 2-D steady state flow model was used to simulate the groundwater flow regime using representative transmissivities and recharge rates. To calibrate the model, simulated heads were compared to over 8,000 static water levels contained in water well records. A reverse particle tracking routine was invoked in the flow model to provide a visual aid in understanding the movement and discharge of contaminants with time. This routine permits particle travel times to be plotted along their groundwater flow paths. In turn, isochrones [lines of equal travel times from surface water discharge points] were constructed for contaminants that range from relatively conservative inorganic ions to chemically retarded organics. The isochrones formed the basis for predicting long-term contaminant loading of selected chemical parameters from point and non-point sources on receiving streams and Lake Ontario.

Livingstone, S.; Howard, K.W.F. (Univ. of Toronto, Scarborough, Ontario (Canada). Groundwater Research Group)

1992-01-01

112

Managing ground-water contamination from agricultural nitrates  

SciTech Connect

Ground-water contamination from agricultural nitrates poses potential adverse health effects to a large segment of the rural population of the United States. Contamination is especially prevalent in livestock intensive areas, which produce large quantities of animal waste with substantial nitrogen content. In this study, potential management strategies for reducing nitrate contamination of ground water from agricultural sources were examined using an economic-physical model of representative dairy farm in Rockingham County, Virginia. A mixed-integer programming model with stochastic constraints on nitrate loading to ground water and silage production was used. Results of the model indicate that substantial reductions in current nitrate loadings are possible with relatively minor impacts on farmers' net returns through the use of currently practiced approaches of cost sharing for manure storage facility construction and nutrient management planning. Study results indicate that a wide range of policy options exist for reducing nitrate loading to ground water; these reductions, while varying in cost, do no appear to come at the expense of eliminating the economic viability of the county dairy sector.

Halstead, J.M.

1989-01-01

113

Validity of the Latest Research Findings on Causes of Groundwater Arsenic Contamination in Bangladesh  

Microsoft Academic Search

The groundwater arsenic contamination problem in Bangladesh is the worst in the world. Two hypotheses are prevailing as the cause (mobilization) of groundwater arsenic contamination in Bangladesh. One is called “pyrite oxidation” and the other is “oxy-hydroxide reduction.” According to the first hypothesis, groundwater arsenic contamination is human-made, which has a relationship with excessive groundwater withdrawal. On the other hand,

Toshihiko Kawachi; Eiji Ichion

2001-01-01

114

Environmental contamination of groundwater in the Gaza Strip  

NASA Astrophysics Data System (ADS)

Environmental problems of groundwater contamination in the Gaza Strip are summarized in this paper. The Gaza Strip is a very narrow and highly populated area along the coast of the Mediterranean Sea (360 km2). Human activities greatly threaten the groundwater resources in the area, while the unconfined nature of some parts of the coastal main aquifer favors groundwater contamination. Recent investigations show contamination of the aquifer with organic substances from detergents, agrochemicals, sewage (cesspools), and waste degradation. These effects enhance each other because there is no recycling industry, sewage system, or any type of environmental protection management at present. Inorganic contamination results from overpumping, which increases the salinity of the groundwater. Seawater intrusion also increases the salinity of the groundwater that are used for drinking and agricultural purposes. Consequently, at present about 80 percent of the groundwater in the Gaza Strip is unfit for both human and animal consumption. Solutions are very urgently needed for these problems in order to prevent the spread of dangerous diseases.

Al-Agha, M. R.

1995-03-01

115

Virus occurrence in municipal groundwater sources in Quebec, Canada.  

PubMed

A 1 year study was undertaken on groundwater that was a source of drinking water in the province of Quebec, Canada. Twelve municipal wells (raw water) were sampled monthly during a 1 year period, for a total of 160 samples. Using historic data, the 12 sites were categorized into 3 groups: group A (no known contamination), group B (sporadically contaminated by total coliforms), and group C (historic and continuous contamination by total coliforms and (or) fecal coliforms). Bacterial indicators (total coliform, Escherichia coli, enteroccoci), viral indicators (somatic and male-specific coliphages), total culturable human enteric viruses, and noroviruses were analyzed at every sampling site. Total coliforms were the best indicator of microbial degradation, and coliform bacteria were always present at the same time as human enteric viruses. Two samples contained human enteric viruses but no fecal pollution indicators (E. coli, enterococci, or coliphages), suggesting the limited value of these microorganisms in predicting the presence of human enteric viruses in groundwater. Our results underline the value of historic data in assessing the vulnerability of a well on the basis of raw water quality and in detecting degradation of the source. This project allowed us to characterize the microbiologic and virologic quality of groundwater used as municipal drinking water sources in Quebec. PMID:17668028

Locas, Annie; Barthe, Christine; Barbeau, Benoit; Carrière, Annie; Payment, Pierre

2007-06-01

116

Probabilistic assessment of ground-water contamination. 1: Geostatistical framework  

SciTech Connect

Characterizing the extent and severity of ground-water contamination at waste sites is expensive and time-consuming. A probabilistic approach, based on the acceptance of uncertainty and a finite probability of making classification errors (contaminated relative to a regulatory threshold vs. uncontaminated), is presented as an alternative to traditional site characterization methodology. The approach utilizes geostatistical techniques to identify and model the spatial continuity of contamination at a site (variography) and to develop alternate plausible simulations of contamination fields (conditional simulation). Probabilistic summaries of many simulations provide tools for (a) estimating the range of plausible contaminant concentrations at unsampled locations, (b) identifying the locations of boundaries between contaminated and uncontaminated portions of the site and the degree of certainty in those locations, and (c) estimating the range of plausible values for total contaminant mass. The first paper in the series presents the geostatistical framework and illustrates the approach using synthetic data for a hypothetical site. The second paper presents an application of the proposed methodology to the probabilistic assessment of ground-water contamination at a site involving ground-water contamination by nitrate and herbicide in a shallow, unconfined alluvial aquifer in an agricultural area in eastern Oregon.

Rautman, C.A. [Sandia National Labs., Albuquerque, NM (United States). Geohydrology Dept.; Istok, J.D. [Oregon State Univ., Corvallis, OR (United States). Dept. of Civil Engineering

1996-09-01

117

Potassium ferrate treatment of RFETS' contaminated groundwater.  

National Technical Information Service (NTIS)

The potassium ferrate treatment study of Rocky Flats Environmental Technology Site (RFETS) groundwater was performed under the Sitewide Treatability Studies Program (STSP). This study was undertaken to determine the effectiveness of potassium ferrate in a...

1995-01-01

118

REMOVAL OF AGRICULTURAL CONTAMINANTS FROM GROUNDWATER  

EPA Science Inventory

As analytical testing of community and individual homeowner wells has intensified, more drinking water contamination has been identified. In some instances, this contamination can be attributed to agricultural practices. Of special concern are those locations where no community t...

119

Hydrogeochemistry of alluvial groundwaters in an agricultural area: an implication for groundwater contamination susceptibility.  

PubMed

Alluvial groundwaters in the area where intensive agricultural activity takes place were geochemically investigated to evaluate factors regulating groundwater quality of alluvial aquifers. For this study, 55 groundwater samples were taken from the uniformly distributed irrigation wells and were classified into three distinct groups according to their geochemical characteristics. This study reveals that the groundwater quality and the geochemical characteristics of the clustered groups are consistent with the geology of the area. The samples collected from the area where a thick silt bed overlies the sand aquifer are clustered into Group II and show water quality that is only slightly affected by the contaminants originating from the land surface. However, groundwaters of this group are very high in Fe and Mn levels due to strong anoxic condition caused by the thick silt bed. In contrast, Group I shows water quality largely influenced by agricultural activities (i.e., fertilization, liming) and occurs in the area adjacent to the river where the silt bed is not observed and the sand aquifer is covered with sandy soils. Group III mostly occurs in the upgradient of Group I where a thin, silty soil covers the sand aquifer. In overall, the results show that the clustered groups closely reflect the groundwater susceptibility to the contaminants originated from the land surface. This suggests that groundwater clustering based on water chemistry could be applied to the contamination susceptibility assessment for groundwaters in the agricultural area. PMID:14987935

Chae, Gi-Tak; Kim, Kangjoo; Yun, Seong-Taek; Kim, Kyoung-Ho; Kim, Soon-Oh; Choi, Byoung-Young; Kim, Hyoung-Soo; Rhee, Chul Woo

2004-04-01

120

Groundwater contamination from an inactive uranium mill tailings pile: 1. Application of a chemical mixing model  

NASA Astrophysics Data System (ADS)

Low-pH process waters contained in a number of inactive and abandoned uranium mill tailings in the United States represent potential sources of radionuclide and trace metal contamination of groundwater. Detailed investigations at a typical site at Riverton, Wyoming, indicate that chemical transport occurs from initial dewatering of the tailings, downward infiltration due to precipitation, and groundwater intrusion into the base of the tailings pile. Except for elevated uranium and molybdenum concentrations, current radionuclide and trace metal transport is limited by the near-neutral pH conditions of the groundwater. Significant reactions include the dissolution of calcite, production of CO2, and precipitation of gypsum and the hydroxides of iron and aluminum. A geochemical mixing model employing the PHREEQE computer code is used to estimate current rates of the groundwater contamination by tailings water. A maximum mixing of 1.7% of pore water is a factor of 2 less than steady state estimates based on hydraulic parameters.

White, A. F.; Delany, J. M.; Narasimhan, T. N.; Smith, A.

1984-11-01

121

Enhanced detection of groundwater contamination from a leaking waste disposal site by microbial community profiles  

NASA Astrophysics Data System (ADS)

Groundwater biogeochemistry is adversely impacted when municipal solid waste leachate, rich in nutrients and anthropogenic compounds, percolates into the subsurface from leaking landfills. Detecting leachate contamination using statistical techniques is challenging because well strategies or analytical techniques may be insufficient for detecting low levels of groundwater contamination. We sampled profiles of the microbial community from monitoring wells surrounding a leaking landfill using terminal restriction fragment length polymorphism (T-RFLP) targeting the 16S rRNA gene. Results show in situ monitoring of bacteria, archaea, and the family Geobacteraceae improves characterization of groundwater quality. Bacterial T-RFLP profiles showed shifts correlated to known gradients of leachate and effectively detected changes along plume fringes that were not detected using hydrochemical data. Experimental sediment microcosms exposed to leachate-contaminated groundwater revealed a shift from a ?-Proteobacteria and Actinobacteria dominated community to one dominated by Firmicutes and ?-Proteobacteria. This shift is consistent with the transition from oxic conditions to an anoxic, iron-reducing environment as a result of landfill leachate-derived contaminants and associated redox conditions. We suggest microbial communities are more sensitive than hydrochemistry data for characterizing low levels of groundwater contamination and thus provide a novel source of information for optimizing detection and long-term monitoring strategies at landfill sites.

Mouser, Paula J.; Rizzo, Donna M.; Druschel, Gregory K.; Morales, Sergio E.; Hayden, Nancy; O'Grady, Patrick; Stevens, Lori

2010-12-01

122

Fluorine contamination in groundwater: a major challenge.  

PubMed

Fluoride in high concentration in groundwater has been reported from many parts of India. However, a systematic study is required to understand the behavior of fluoride in natural water in terms of local hydrogeological setting, climatic conditions, and agricultural practices. The present study is an attempt to assess hydrogeochemistry of groundwater in parts of Palar river basin pertaining to Kancheepuram district Tamil Nadu to understand the fluoride abundance in groundwater and to deduce the chemical parameters responsible for the dissolution activity of fluoride. The study area is geologically occupied by partly sedimentary and partly crystalline formations. A total of 50 dug cum borewell-water samples, representing an area of 2,628.92 km2. The results of the chemical analyses in September 2009 show fluoride abundance in the range of 1 to 3.24 mg/l with 86% of the samples in excess of the permissible limit of 1.5 mg/l. Presence of fluoride-bearing minerals in the host rock, chemical properties like decomposition, dissociation, and dissolution, and their interaction with water are considered to be the main causes for fluoride in groundwater. Chemical weathering with relatively high alkalinity favors high concentration of fluoride in groundwater. Villagers who consume nonpotable high fluoride water may suffer from yellow, cracked teeth; joint pains; and crippled limbs and also age rapidly. PMID:20364310

Dar, Mithas Ahmad; Sankar, K; Dar, Imran A

2011-02-01

123

Assessing Ground-Water Vulnerability to Contamination: Providing Scientifically Defensible Information for Decision Makers  

NSDL National Science Digital Library

A new report from the US Geological Survey has been made available entitled Assessing Ground-Water Vulnerability to Contamination: Providing Scientifically Defensible Information for Decision Makers. The report provides a look at the common approaches used to scientifically determine the factors controlling the vulnerability of groundwater resources to contamination. The introduction states that it also discusses the strengths and weaknesses of the various approaches as sources of scientifically defensible information for the water-resource management decision-making process. Viewed online or downloadable, the freely accessed publication covers everything from methods and examples to conclusions and references.

Focazio, Michael J.; Helsel, Dennis R.; Reilly, Thomas E.; Rupert, Michael G.

124

The new potential for understanding groundwater contaminant transport.  

PubMed

The groundwater remediation field has been changing constantly since it first emerged in the 1970s. The remediation field has evolved from a dissolved-phase centric conceptual model to a DNAPL-dominated one, which is now being questioned due to a renewed appreciation of matrix diffusion effects on remediation. Detailed observations about contaminant transport have emerged from the remediation field, and challenge the validity of one of the mainstays of the groundwater solute transport modeling world: the concept of mechanical dispersion (Payne et al. 2008). We review and discuss how a new conceptual model of contaminant transport based on diffusion (the usurper) may topple the well-established position of mechanical dispersion (the status quo) that is commonly used in almost every groundwater contaminant transport model, and evaluate the status of existing models and modeling studies that were conducted using advection-dispersion models. PMID:24224536

Hadley, Paul W; Newell, Charles

2014-01-01

125

Anthropogenic groundwater contamination by selenium at Suchomasty Village (Prague Basin, Czech Republic)  

Microsoft Academic Search

The aim of the project is to clarify and characterize the probable sources of increased selenium contamination in groundwater at Suchomasty Village located 35 km SW of Prague. The village is supplied by drinking water from a 25 m deep bore-hole with catchment formed by Ordovician to Devonian mostly sedimentary rocks of the Prague Basin. The selenium concentrations have suddenly

Renata Kadlecova; Jiri Bruthans; Frantisek Buzek; Barbora Dousova; Stanislava Konecna; Ondrej Zeman

2010-01-01

126

Assessment of pesticide contamination of groundwater in New Zealand 1. Ranking of regions for potential contamination  

Microsoft Academic Search

Groundwater contamination by pesticides may be affected by the amounts of pesticide used, the mobility and degradation characteristics of the pesticides, and the vulnerability of an area to pollution. An index of potential pollution was developed based on these factors, with the groundwater vulnerability being measured using the DRASTIC ranking method. Seventeen regions were selected from throughout New Zealand where

MURRAY E. CLOSE

127

Quantifying Groundwater and Contaminant Flux in Fractured Rock Systems  

NASA Astrophysics Data System (ADS)

Complex hydrogeologic conditions such as fractured and karst bedrock settings pose substantial economic and technical challenges both to the characterization and remediation of DNAPL source zones. The objective of this project is to demonstrate and validate the fractured rock passive flux meter (FRPFM) as new technology for measuring the magnitudes and directions of cumulative water and contaminant fluxes in fractured rock aquifers. The sensor consists of an inflatable core that compresses a reactive fabric against the wall of a borehole and to any water-filled fractures intersected by a borehole. The reactive fabric is designed to intercept and retain target groundwater contaminants (e.g. TCE, DCE, VC); in addition, the fabric releases non-toxic tracers, some of which visibly indicate active fracture location, aperture, orientation, and direction of fracture flow along a borehole, while others quantify cumulative groundwater discharge within the fractures. Field demonstration tests are ongoing at a site in Guelph, Ontario and at the Naval Air Warfare Center (NAWC) in West Trenton, NJ. The tests are comparing multiple technologies including fractured rock passive flux meters, hydrophysical logging, temperature logging, and borehole dilution tests. The technologies are being evaluated based upon their ability to: identify flowing fractures, determine flow direction, and quantify both water and contaminant mass flux in flowing fractures. Laboratory tests comparing the capabilities of each technology were previously performed in two separate flow simulators representing a range of likely field conditions: a planar single fracture simulator (fracture aperture = 0.5 mm; specific discharge range 25 - 2500 cm/day) and a large-scale three-dimensional aquifer box with layered high contrast flow zones simulating fractured zones (physical flow domain 2 m length, 0.5 m width, and 1 m height; specific discharge range 25 to 4000 cm/day (per layer)). Based upon initial field and laboratory tests sampling procedures have been developed for multiple scenarios depending upon the composition of fractured media and orientation of fractures encountered. These conditions have been found to be both site and sub-site specific depending upon multiple factors such as geology (rock composition) and the amount of weathering. At the Guelph site observed conditions have included discrete fractures, fractured zones exhibiting bulk conductivity, and washout zones more similar to karst dissolution channels. In each case the visual indications of flow intercepting the FRPFM are distinctive and unique, which allows for condition specific sampling of the sorbent for resident tracers and target contaminants.

Cho, J.; Newman, M. A.; Klammler, H.; Hatfield, K.; Annable, M. D.; Parker, B. L.; Cherry, J.; Kroeker, R.; Pedler, W. H.

2011-12-01

128

Catalytic destruction of groundwater contaminants in reactive extraction wells  

DOEpatents

A system for remediating groundwater contaminated with halogenated solvents, certain metals and other inorganic species based on catalytic reduction reactions within reactive well bores. The groundwater treatment uses dissolved hydrogen as a reducing agent in the presence of a metal catalyst, such a palladium, to reduce halogenated solvents (as well as other substituted organic compounds) to harmless species (e.g., ethane or methane) and immobilize certain metals to low valence states. The reactive wells function by removing water from a contaminated water-bearing zone, treating contaminants with a well bore using catalytic reduction, and then reinjecting the treated effluent into an adjacent water-bearing zone. This system offers the advantages of a compact design with a minimal surface footprint (surface facilities) and the destruction of a broad suite of contaminants without generating secondary waste streams.

McNab, Jr., Walt W. (Concord, CA); Reinhard, Martin (Stanford, CA)

2002-01-01

129

Brines as Sources of Long-term Subsurface Contamination  

NASA Astrophysics Data System (ADS)

Concentrated salt solutions, i.e. brines, are source terms for environmental contaminants released into surface waters and groundwaters. Brines arise from both natural and industrial processes such as natural salt deposits, solid rocket fuel production, landfill leachates, nuclear fuel reprocessing, and acid rock drainage. Additionally, many of the in-situ remediation fluids that have been implemented at the pilot or the field scale are also classified as brines. While brines are miscible with water, mixing processes are slow in the subsurface and this constrains the dilution of contaminants present within brines and the delivery of remediation fluids to sites where reactions are needed. The mixing of brines during their vertical migration through aquifers is determined by aquifer permeability as well as differences in density and viscosity between the brine and the ambient groundwater. The stability criterion for brine displacement was predicted in 1952 by Hill and the resulting dispersion at the mixing front is quantified by a compilation of literature data and the acquisition of new experimental data. As brines sink through aquifers, they become emplaced in less accessible locations where mass transfer models predict that contaminants within brines are slowly released into flowing groundwater. For radioactive wastes and environmental contaminants with very low acceptable concentrations, groundwater quality can be impacted for decades. Field data from a cooling water disposal site suggest that a dense brine is likely still present as a source term 40 years after waste disposal was stopped. Overall, analysis of pollution sources, quantification of transport processes, generalization of laboratory data, and limited evaluation of field data indicate that brines represent long-term sources of groundwater contamination and that source control has not been seriously addressed.

Flowers, T. C.; Hunt, J. R.

2004-12-01

130

Prioritization and accelerated remediation of groundwater contamination in the 200 Areas of the Hanford Site, Washington  

SciTech Connect

The Hanford Site, operated by the US Department of Energy (DOE), occupies about 1,450 km{sup 2} (560 mi{sup 2}) of the southeastern part of Washington State north of the confluence of the Yakima and Columbia Rivers. The Hanford Site is organized into numerically designated operational areas. The 200 Areas, located near the center of the Hanford Site, encompasses the 200 West, East and North Areas and cover an area of over 40 km{sup 2}. The Hanford Site was originally designed, built, and operated to produce plutonium for nuclear weapons using production reactors and chemical reprocessing plants. Operations in the 200 Areas were mainly related to separation of special nuclear materials from spent nuclear fuel and contain related chemical and fuel processing and waste management facilities. Large quantities of chemical and radioactive waste associated with these processes were often disposed to the environment via infiltration structures such as cribs, ponds, ditches. This has resulted in over 25 chemical and radionuclide groundwater plumes, some of which have reached the Columbia River. An Aggregate Area Management Study program was implemented under the Hanford Federal Facility Agreement and Consent Order to assess source and groundwater contamination and develop a prioritized approach for managing groundwater remediation in the 200 Areas. This included a comprehensive evaluation of existing waste disposal and environmental monitoring data and the conduct of limited field investigations (DOE-RL 1992, 1993). This paper summarizes the results of groundwater portion of AAMS program focusing on high priority contaminant plume distributions and the groundwater plume prioritization process. The objectives of the study were to identify groundwater contaminants of concern, develop a conceptual model, refine groundwater contaminant plume maps, and develop a strategy to expedite the remediation of high priority contaminants through the implementation of interim actions.

Wittreich, C.D.; Ford, B.H.

1993-04-01

131

Vulnerability of deep groundwater in the Bengal Aquifer System to contamination by arsenic  

USGS Publications Warehouse

Shallow groundwater, the primary water source in the Bengal Basin, contains up to 100 times the World Health Organization (WHO) drinking-water guideline of 10g l 1 arsenic (As), threatening the health of 70 million people. Groundwater from a depth greater than 150m, which almost uniformly meets the WHO guideline, has become the preferred alternative source. The vulnerability of deep wells to contamination by As is governed by the geometry of induced groundwater flow paths and the geochemical conditions encountered between the shallow and deep regions of the aquifer. Stratification of flow separates deep groundwater from shallow sources of As in some areas. Oxidized sediments also protect deep groundwater through the ability of ferric oxyhydroxides to adsorb As. Basin-scale groundwater flow modelling suggests that, over large regions, deep hand-pumped wells for domestic supply may be secure against As invasion for hundreds of years. By contrast, widespread deep irrigation pumping might effectively eliminate deep groundwater as an As-free resource within decades. Finer-scale models, incorporating spatial heterogeneity, are needed to investigate the security of deep municipal abstraction at specific urban locations. ?? 2010 Macmillan Publishers Limited. All rights reserved.

Burgess, W. G.; Hoque, M. A.; Michael, H. A.; Voss, C. I.; Breit, G. N.; Ahmed, K. M.

2010-01-01

132

Effect of Particles on Fenton Oxidation of Organic Contaminated Groundwater  

NASA Astrophysics Data System (ADS)

Fenton oxidation has been widely applied for a variety of water treatment due to non-selectively oxidative capability at a high reaction rate and cost effectiveness. Even though wide and deep range of studies were conducted for understanding the Fenton reaction with various contaminants, effect of particles on Fenton reaction has been little studied. This study explored the performance of Fenton oxidation for organic contaminated groundwater treatment in the presence of particles. The contaminated groundwater was a free oil separated groundwater obtained from a pilot scale bioslurping process for LNAPL treatment. The groundwater was characterized by a high suspended solid (SS) concentration relative to total organic carbon (TOC) concentration varying from 4 to 7.3. It was found that the optimum ratio of Fenton’s reagent (Fe2+:H2O2) was 1:10 in terms of TOC removal efficiency. Presence of solid particles significantly affected the TOC removal efficiency by Fenton’s reaction accounting for 37% for raw groundwater and 61% for soluble groundwater. Particles larger than 5 µm could be effectively settled out by a quiescent settling for 3 hr based on particle size distribution analysis. The TOC removal efficiency for the supernatant after settling was a similar to that of soluble sample. Total petroleum hydrocarbon (TPH) was mostly present in the adsorbed form to the particles in the groundwater and was potentially persistent to Fenton oxidation. TPH removal efficiency by Fenton oxidation was 24% which was less than that of the total groundwater indicating that hydroxyl radicals generated from Fenton oxidation did not directly attack the adsorbed organic carbon and removal of the adsorbed organic carbon was dependent on its mass transfer to bulk region. The concept for particle effect on Fenton oxidation was confirmed in another experiment spiking washed soil to the soluble groundwater. TOC removal efficiency was lowered by addition of the soil probably because the substantial amount of organic carbon moved toward and then was adsorbed to the soil and consequently they were not significantly oxidized by Fenton. This study suggests that a pretreatment process such as settling or floatation is need for enhancing the performance of Fenton oxidation of organic contaminated groundwater containing particles.

Lee, J.; Kim, Y.; Gwak, J.; Lee, C.; Ha, J.

2009-12-01

133

OASIS: A GRAPHICAL DECISION SUPPORT SYSTEM FOR GROUNDWATER CONTAMINANT MODELING  

EPA Science Inventory

Three new software technologies were applied to develop an efficient and easy to use decision support system far ground-water contaminant modeling. raphical interfaces create a more intuitive and effective form of communication with the computer compared to text-based interfaces....

134

Toxicity reduction associated with bioremediation of gasoline-contaminated groundwaters  

Microsoft Academic Search

In-situ biodegradation has received increasing attention as a method to remediate gasoline-contaminated soils and groundwaters. Typically, oxygen is added to enhance aerobic biodegradation. However, since oxygen is not very soluble in water and is difficult to distribute uniformly throughout an aquifer, nitrate has been investigated as an alternate electron acceptor. Nitrate has recently been used to stimulate BTX (benzene, toluene

M. J. Carroquino; R. M. Gersberg; W. J. Dawsey; M. D. Bradley

1992-01-01

135

Distribution of Land Use to Purify Contaminated Groundwater by Nitrate  

NASA Astrophysics Data System (ADS)

Groundwater contamination by nitrate results from over-fertilizing and/or inadequate disposal of livestock excreta has been large-scale problem in agricultural area. Because nitrate is primarily transported to streams via ground water flow, explaining actual condition of groundwater is needed to propose an effective measure for the conservation and restoration of sound nitrogen cycle in agricultural river catchments. The purpose of this research was to clarify a triangular relationship between the groundwater quality and flow system, river water quality and land use. The experimental field is located on a slope from Tsukuba tableland to bottomland, which is a part of Nishi- Yata River watershed in Ibaraki Prefecture, Japan. The site area is about 0.0675 square kilometers and the altitude varies from 24 m to 19 m. Land use of tableland, bottomland and intermediate between them are forestland, paddy field and cropland, respectively. Groundwater quality and level were monitored for the year 2004. During the study period significant differences were not observed in groundwater ionic concentrations. Relative high concentrations of dissolved nitrate were detected in cropland (3 - 43 mg/l) and forestland (74 - 179 mg/l). It revealed that there was a purification zone in the paddy field and the area around its 2-4m and denitrification eliminates nitrate-nitrogen. The pressure head converted into hydraulics head, and the groundwater flow were calculated. According to the results, it seems that groundwater flow from tableland to the riverbed through bottomland. It is presumed that groundwater cultivated in cropland with chemical fertilizer pass through the purification zone of nitrate. On the other hand, it is assumed that groundwater containing nitrate originated from inadequate disposal of livestock excreta discharge from forestland does not pass through the depth of this spot. It is suggested that considering flow system of groundwater to manage distribution of land use and conservation of bottomland are important to conserve river water quality.

Iizumi, Y.; Tanaka, T.; Kinouchi, T.; Tase, N.; Fukami, K.

2006-12-01

136

Arsenic contamination of groundwater: Mitigation strategies and policies  

NASA Astrophysics Data System (ADS)

Contamination of groundwater by arsenic from natural geochemical sources is at present a most serious challenge in the planning of large-scale use of groundwater for drinking and other purposes. Recent improvements in detection limits of analytical instruments are allowing the correlation of health impacts such as cancer with large concentrations of arsenic in groundwater. However, there are at present no known large-scale technological solutions for the millions of people-mostly rural-who are potentially affected in developing countries. An overall framework of combating natural resource degradation is combined with case studies from Chile, Mexico, Bangladesh and elsewhere to arrive at a set of strategic recommendations for the global, national and local dimensions of the arsenic ``crisis''. The main recommendations include: the need for flexibility in the elaboration of any arsenic mitigation strategy, the improvement and large-scale use of low-cost and participatory groundwater quality testing techniques, the need to maintain consistent use of key lessons learned worldwide in water supply and sanitation and to integrate arsenic as just one other factor in providing a sustainable water supply, and the following of distinct but communicable tracks between arsenic-related developments and enhanced, long-term, sustainable water supplies. La contamination des eaux souterraines par l'arsenic provenant de sources naturelles est actuellement un sujet des plus graves dans l'organisation d'un recours à grande échelle des eaux souterraines pour la boisson et d'autres usages. De récentes améliorations dans les limites de détection des équipements analytiques permettent de corréler les effets sur la santé tels que le cancer à de fortes concentrations en arsenic dans les eaux souterraines. Toutefois, il n'existe pas actuellement de solutions technologiques à grande échelle connues pour des millions de personnes, surtout en zones rurales, qui sont potentiellement affectées dans les pays en développement. Un cadre d'ensemble pour lutter contre la dégradation naturelle des ressources est associé à des études de cas au Chili, au Mexique, au Bangladesh et ailleurs afin d'établir un ensemble de recommandations stratégiques pour les dimensions globale, nationale et locale de la «crise» de l'arsenic. Les principales recommandations sont les suivantes: le besoin d'une flexibilité pour élaborer une stratégie de diminution de l'arsenic, l'amélioration et l'utilisation à grande échelle de techniques peu coûteuses et associant les populations pour tester la qualité de l'eau souterraine, le besoin de maintenir un usage logique des leçons clés acquises de par le monde pour l'alimentation en eau et la santé publique, celui d'intégrer l'arsenic simplement comme un autre facteur pour assurer une alimentation durable en eau, et pour suivre des pistes distinctes mais communicables entre les développements liés à l'arsenic et les alimentations durables en eau mises en valeurs à long terme. La contaminación de las aguas subterráneas con arsénico procedente de fuentes geoquímicas naturales es actualmente uno de los retos principales de la planificación a gran escala de las aguas subterráneas para uso de boca y otros fines. Las recientes mejoras en los límites de detección del instrumental analítico permiten correlacionar impactos en la salud tales como el cáncer con concentraciones elevadas de arsénico en las aguas subterráneas. Sin embargo, a fecha de hoy no existen soluciones tecnológicas de gran escala para millones de personas-población principalmente rural-que están potencialmente afectadas en los países en vías de desarrollo. Se combina un enfoque general para combatir la degradación de los recursos naturales con estudios concretos de Chile, México, Bangladesh y cualquier otro lugar que permita obtener un conjunto de recomendaciones estratégicas para las dimensiones global, nacional y local de la ``crisis'' del arsénico. Las recomendaciones principales incluyen la necesidad de flexibilizar l

Alaerts, Guy J.; Khouri, Nadim

137

Preliminary Application of Microseisms into Groundwater Contamination Monitoring  

NASA Astrophysics Data System (ADS)

Microseisms, one scientist¡_s annoying noise are another¡_s diagnostic tool. We are conducting a controlled field experiments with the aim of detecting the infiltration of a contaminant - a biosurfactant - into groundwater. Three sets of instruments are placed 3m, 13m and 32m respectively from a 50m by 50m irrigation site. Each set of instruments consists of a 3-component seismometer and a tilt meter. We are seeking to detect temporal changes in local station corrections that are caused by the irrigation. We use natural signals, such as microseisms as seismic sources and solid Earth tides as sources for the tilt signals. Seasonal changes in the amplitude ratios (horizontal to vertical HZ) of signals from microseisms have been found in California. These seasonal changes are likely to be caused by rather shallow changes in the water table as well as a partial saturated level in the vadose zone. In our field experiment we control the influx of water and monitor it as it percolates down to the ground water. This represents a near ideal arrangement to experimentally check if the HZ ratio can indeed be changed by changes in the local groundwater, or if the cause for the observed seasonal variations has to be found elsewhere. In the laboratory we have found that small additions of some chemicals to water can drastically change the surface energies and thus the wettability of solid surfaces. Surface energy changes in a partially saturated porous rock lead to large changes in complex elastic moduli. In the field experiment we are changing the wettability of the subsurface and are analyzing seismic and tilt data at varying distance from the irrigation site for contaminant caused changes in the moduli. Tilt data show a pronounced change between the three stations during the summer months, probably caused by the differential heating that occurs between the covered irrigation site and the bare ground surrounding it. The observed effect trails off as the instrument¡_s distance from the irrigation site increases. In the seismic data we clearly see the microseismic energy and are now looking for changes in the HZ ratios at the three stations. We keenly anticipate getting and analyzing the seismic records from before, during and following the irrigation of biosurfactants which commences in mid October, 2004.

Zhang, J.; Tanimoto, T.; Spetzler, H.

2004-12-01

138

Studies in geophysics groundwater contamination by Geophysics Study Committee  

SciTech Connect

The book cites the massive application of chemicals to the land and the possibility of groundwater contamination and the extent of contamination on the natural scale. Movement by microscopic and macroscopic processes is discussed together with a description of chemical processes involved. This is followed by description of shallow land disposal of municipal waste and deep well injection. Several specific examples are then described and discussed. For example, the section on the Love Canal discusses a modeling system and recommendations for receiving the problem. Each section includes an abstract and a comprehensive set of references. It is well written, comprehensive and a valuable addition to the library of anyone working on the environmental problems of groundwater contamination.

Not Available

1984-01-01

139

DRINKING WATER FROM AGRICULTURALLY CONTAMINATED GROUNDWATER  

EPA Science Inventory

Sharp increases in fertilizer and pesticide use throughout the 1960s and 1970s along with generally less attachment to soil particles may result in more widespread contamination of drinking water supplies. he purpose of this study was to highlight the use of agricultural chemical...

140

Passive treatment of wastewater and contaminated groundwater  

DOEpatents

A bioremediation system using inorganic oxide-reducing microbial consortia for the treatment of, inter alia coal mine and coal yard runoff uses a containment vessel for contaminated water and a second, floating phase for nutrients. Biodegradable oils are preferred nutrients.

Phifer, Mark A. (N. Augusta, SC); Sappington, Frank C. (Dahlonega, GA); Millings, Margaret R. (N. Augusta, SC); Turick, Charles E. (Aiken, SC); McKinsey, Pamela C. (Aiken, SC)

2007-11-06

141

Remediation alternatives for low-level herbicide contaminated groundwater  

SciTech Connect

In early 1995, an evaluation of alternatives for remediation of a shallow groundwater plume containing low-levels of an organic herbicide was conducted at BASF Corporation, a petrochemical facility located in Ascension Parish, Louisiana. The contaminated site is located on an undeveloped portion of property within 1/4 mile of the east bank of the Mississippi River near the community of Geismar. Environmental assessment data indicated that about two acres of the thirty acre site had been contaminated from past waste management practices with the herbicide bentazon. Shallow soils and groundwater between 5 to 15 feet in depth were affected. Maximum concentrations of bentazon in groundwater were less than seven parts per million. To identify potentially feasible remediation alternatives, the environmental assessment data, available research, and cost effectiveness were reviewed. After consideration of a preliminary list of alternatives, only two potentially feasible alternatives could be identified. Groundwater pumping, the most commonly used remediation alternative, followed by carbon adsorption treatment was identified as was a new innovative alternative known as vegetative transpiration. This alternative relies on the natural transpiration processes of vegetation to bioremediate organic contaminants. Advantages identified during screening suggest that the transpiration method could be the best remediation alternative to address both economic and environmental factors. An experiment to test critical factors of the vegetatived transpiration alternative with bentazon was recommended before a final decision on feasibility can be made.

Conger, R.M. [BASF Corp., Geismar, LA (United States)

1995-10-01

142

Investigation of groundwater flow zones and contaminant transport in Solid Waste Storage Area 5 at Oak Ridge National Laboratory, Oak Ridge, Tennessee. Environmental Restoration Program  

Microsoft Academic Search

An understanding of subsurface transport processes is essential to produce realistic predictions of future contaminant discharge from Solid Waste Storage Areas (SWSAs) at Oak Ridge National Laboratory (ORNL). Locating groundwater flow zones (permeable pathways) and determining the relative contributions of primary vs secondary contaminant sources are critical to the proper selection and evaluation of remedial actions. Because groundwater discharge from

D. S. Hicks; D. K. Solomon; N. D. Farrow

1992-01-01

143

Investigation of groundwater flow zones and contaminant transport in Solid Waste Storage Area 5 at Oak Ridge National Laboratory, Oak Ridge, Tennessee  

Microsoft Academic Search

An understanding of subsurface transport processes is essential to produce realistic predictions of future contaminant discharge from Solid Waste Storage Areas (SWSAs) at Oak Ridge National Laboratory (ORNL). Locating groundwater flow zones (permeable pathways) and determining the relative contributions of primary vs secondary contaminant sources are critical to the proper selection and evaluation of remedial actions. Because groundwater discharge from

D. S. Hicks; D. K. Solomon; N. D. Farrow

1992-01-01

144

A controlled field experiment on groundwater contamination by a multicomponent DNAPL: creation of the emplaced-source and overview of dissolved plume development  

Microsoft Academic Search

A unique field experiment has been undertaken at the CFB Borden research site to investigate the development of dissolved chlorinated solvent plumes from a residual dense non-aqueous phase liquid (DNAPL) source. The “emplaced-source” tracer test methodology involved a controlled emplacement of a block-shaped source of sand containing chlorinated solvents below the water table. The gradual dissolution of this residual DNAPL

Michael O Rivett; Stanley Feenstra; John A Cherry

2001-01-01

145

A pilot plant to treat chromium-contaminated groundwater  

SciTech Connect

The groundwater at a site in California is contaminated with hexavalent chromium. Different treatment options were tested. The options tested included: carbon adsorption, ion exchange, chemical treatment, reverse osmosis, and in-place fixation. Electrochemical treatment was the treatment of choice. Treatment operations were designed with turn down flexibility to allow operation at variable flow rates. Metal reduction is the first treatment step after collection of the groundwater and lowering of the pH to 3 in an on-line acid tank. Soluble ferrous ions are produced in an off-line electrochemical cell using sacrificial electrodes.

El-Shoubary, Y.; Speizer, N.; Seth, S.; Savoia, H. [Merck Mfg. Div., Somerset, NJ (United States)

1998-12-31

146

Nebraska's groundwater legacy: Nitrate contamination beneath irrigated cropland  

NASA Astrophysics Data System (ADS)

31 year record of ˜44,000 nitrate analyses in ˜11,500 irrigation wells was utilized to depict the decadal expansion of groundwater nitrate contamination (N ? 10 mg/L) in the irrigated corn-growing areas of eastern and central Nebraska and analyze long-term nitrate concentration trends in 17 management areas (MAs) subject to N fertilizer and budgeting requirements. The 1.3 M contaminated hectares were characterized by irrigation method, soil drainage, and vadose zone thickness and lithology. The areal extent and growth of contaminated groundwater in two predominately sprinkler-irrigated areas was only ˜20% smaller beneath well-drained silt loams with thick clayey-silt unsaturated layers and unsaturated thicknesses >15 m (400,000 ha and 15,000 ha/yr) than beneath well and excessively well-drained soils with very sandy vadose zones (511,000 ha and 18,600 ha/yr). Much slower expansion (3700 ha/yr) occurred in the 220,000 contaminated hectares in the central Platte valley characterized by predominately gravity irrigation on thick, well-drained silt loams above a thin (˜5.3 m), sandy unsaturated zone. The only reversals in long-term concentration trends occurred in two MAs (120,500 ha) within this contaminated area. Concentrations declined 0.14 and 0.20 mg N/L/yr (p < 0.02) to ˜18.3 and 18.8 mg N/L, respectively, during >20 years of management. Average annual concentrations in 10 MAs are increasing (p < 0.05) and indicate that average nitrate concentrations in leachates below the root zone and groundwater concentrations have not yet reached steady state. While management practices likely have slowed increases in groundwater nitrate concentrations, irrigation and nutrient applications must be more effectively controlled to retain nitrate in the root zone.

Exner, Mary E.; Hirsh, Aaron J.; Spalding, Roy F.

2014-05-01

147

Bioremediation of trichloroethylene contaminated groundwater using anaerobic process.  

PubMed

Anaerobic remediation of trichloroethylene (TCE) contaminated soil and groundwater was studied in laboratory setups. In this process fermentation of polymeric organic materials (POMS) produced volatile fatty acids (VFAs) that were electron donors in reductive dechlorination of TCE. Shredded peanut shell was selected as low cost POM and the experiments were set up in 500 ml Erlenmeyer flasks. In the setups, approximately 25 mg of leachate contaminated soil was used as the main source of microorganisms and about 5 g of shredded peanut shell (0.5-2.36 mm) was added to produce VFAs for dechlorination of TCE. In the first set of experiments, fermentation of soil and shredded peanut shell was studied and it was found that VFAs were produced continuously with increasing concentration (5.63 mM as CH3COOH from the first day to 17.17 in the 10th day of the experiment). During the fermentation, concentration of ammonia-nitrogen was 22-50 mg/L, the ratio of VFA to NH3 was 15.29-23.44 and pH was 5.24-6.00. These results show that the system was appropriate for microorganism activities. In the second set of experiments, TCE (approximately 48 mg/L) was added to the fermentation system and remediation of TCE by reductive dechlorination was studied. It was found that 0.04(+/-0.01) mg TCE adsorbed to a gram of soil and peanut shells at the beginning of the experiment and based on mass balance of the system, TCE concentration in water was linearly reduced at the rate of 0.0098 mg/hr. PMID:19092188

Chomsurin, Cheema; Kajorntraidej, Juthathip; Luangmuang, Kongrit

2008-01-01

148

Estimation of emission from an LNAPL contaminated zone considering groundwater recharge  

NASA Astrophysics Data System (ADS)

The aim of this work was to develop an easy to handle semi-analytical method to estimate the temporal development of emission from a multi-component LNAPL pool considering groundwater recharge. The presented approach allows the estimation of the total mass flux out of an LNAPL pool into the gas and the water phase, the latter including the mass fluxes from groundwater recharge, advection through and diffusion out of the LNAPL zone. Therefore, the known set of constitutive relationships to determine fluid saturation profiles of 2- and 3-phase systems is extended in this work to account for dynamic conditions due to groundwater recharge. The methodology is applied to a kerosene pool at a former military airfield and it is found that the mass flux due to groundwater recharge dominates the aqueous mass flux from the kerosene contaminated zone. A sensitivity study using field parameters shows, that the apparent kerosene thicknesses observed in monitoring wells and the lithology control mass flux into the gas phase, whereas the mass flux into groundwater mainly depends on the groundwater recharge rate. For the kerosene found at the site, source emission into the soil gas is estimated to last longer than the emission into groundwater, the latter varying between less than 100 and 400 years.

Peter, A.; Miles, B.; Teutsch, G.

2008-07-01

149

Contamination of groundwater under cultivated fields in an arid environment, central Arava Valley, Israel  

USGS Publications Warehouse

The purpose of this study is to obtain a better understanding of groundwater contamination processes in an arid environment (precipitation of 50 mm/year) due to cultivation. Additional aims were to study the fate of N, K, and other ions along the whole hydrological system including the soil and vadose zone, and to compare groundwater in its natural state with contaminated groundwater (through the drilling of several wells). A combination of physical, chemical, and isotopic analyses was used to describe the hydrogeological system and the recharge trends of water and salts to the aquifers. The results indicate that intensive irrigation and fertilization substantially affected the quantity and quality of groundwater recharge. Low irrigation efficiency of about 50% contributes approximately 3.5-4 millionm3/year to the hydrological system, which corresponds to 0.65 m per year of recharge in the irrigated area, by far the most significant recharge mechanism. Two main contamination processes were identified, both linked to human activity: (1) salinization due to circulation of dissolved salts in the irrigation water itself, mainly chloride, sulfate, sodium and calcium, and (2) direct input of nitrate and potassium mainly from fertilizers. The nitrate concentrations in a local shallow groundwater lens range between 100 and 300 mg/l and in the upper sub-aquifer are over 50 mg/l. A major source of nitrate is fertilizer N in the excess irrigation water. The isotopic compositions of ??15N- NO3 (range of 4.9-14.8???) imply also possible contributions from nearby sewage ponds and/or manure. Other evidence of contamination of the local groundwater lens includes high concentrations of K (20-120 mg/l) and total organic carbon (about 10 mg/l). ?? 2004 Elsevier B.V. All rights reserved.

Oren, O.; Yechieli, Y.; Bohlke, J. K.; Dody, A.

2004-01-01

150

Optimal Identification of Groundwater Pollution Sources Using Feedback Monitoring Information: A Case Study  

Microsoft Academic Search

A feedback-based methodology has been developed for identifying the unknown pollution sources in groundwater-contaminated aquifers. The methodology consists of models within an iterative feedback system, with the capacity of feeding back real-time measurements of pollutant concentrations for the sequential optimal designs and characterization of the contaminated aquifer study area. The resulting linked-simulation optimization model considers the delineation of the contaminant

Sreenivasulu Chadalavada; Bithin Datta; Ravi Naidu

2012-01-01

151

Storage and Release of Contaminants in Low Flow Zones in Source and Plumes  

Microsoft Academic Search

Through a rich body of published research and recent studies at Colorado State University it has been shown that dissolved and sorbed phase contaminants in low flow zones can act as persistent sources of groundwater contamination. This occurs both in source zones and plumes. Examples of low flow zones included silt beds bounded by sand and sand layers bounded by

T. C. Sale; L. A. Doner; E. S. Seger

2006-01-01

152

Superfund record of decision (EPA Region 9): Newmark Groundwater Contamination Site, San Bernardino, CA, August 1993  

SciTech Connect

This decision document presents the selected remedial action for the Newmark Operable Unit, Newmark Groundwater Contamination Superfund site. EPA has selected an interim remedy for the Newmark plume of groundwater contamination in the Newmark Groundwater Contamination Superfund Site. This portion of the site cleanup is referred to as the Newmark Operable Unit (OU). The Newmark OU is an interim action focusing on contamination in the undergound water supply in the Bunker Hill Basin of San Bernardino, north and east of the Shandin Hills.

Not Available

1993-08-04

153

ModBack - simplified contaminant source zone delineation using backtracking  

NASA Astrophysics Data System (ADS)

Contaminated groundwater poses a serious threat to drinking water resources all over the world. Even though contaminated water might be detected in observation wells, a proper clean up is often only successful if the source of the contamination is detected and subsequently removed, contained or remediated. The high costs of groundwater remediation could be possibly significantly reduced if, from the outset, a focus is placed on source zone detection. ModBack combines several existing modelling tools in one easy to use GIS-based interface helping to delineate potential contaminant source zones in the subsurface. The software is written in Visual Basic 3.5 and uses the ArcObjects library to implement all required GIS applications. It can run without modification on any Microsoft Windows based PC with sufficient RAM and at least Microsoft .NET Framework 3.5. Using ModBack requires additional installation of the following software: Processing Modflow Pro 7.0, ModPath, CSTREAM (Bayer-Raich et al., 2003), Golden Software Surfer and Microsoft Excel. The graphical user interface of ModBack is separated into four blocks of procedures dealing with: data input, groundwater modelling, backtracking and analyses. Geographical data input includes all georeferenced information pertaining to the study site. Information on subsurface contamination is gathered either by conventional sampling of monitoring wells or by conducting integral pumping tests at control planes with a specific sampling scheme. Hydraulic data from these pumping tests together with all other available information are then used to set up a groundwater flow model of the study site, which provides the flow field for transport simulations within the subsequent contamination backtracking procedures, starting from the defined control planes. The backtracking results are then analysed within ModBack. The potential areas of contamination source presence or absence are determined based on the procedure used by Jarsjö et al. (2005). The contaminant plume length can be estimated using plume length statistics, first order rate degradation equations or calculations based on site specific hydraulic and chemical parameters. Furthermore, an analytical tool is included to identify the distribution of contaminants across a control plane. All relevant output can be graphically displayed and saved as vector data to be later used in GIS software. ModBack has been already used to delimit the zones of source presence or absence at several test sites. With ModBack, a tool is now available which enables environmental consultants, engineers and environmental agencies to delineate possible sources of contamination already at the planning stage of site investigation and remediation measures, helping to significantly reduce costs of contaminated site management. Bayer-Raich, M., Jarsjö, J., Holder, T. and Ptak, T. (2003): "Numerical estimations of contaminant mass flow rate based on concentration measurements in pumping wells", ModelCare 2002: A Few Steps Closer to Reality, IAHS Publication No. 277, 10-16. Jarsjö, J., Bayer-Raich, M., Ptak, T. (2005): "Monitoring groundwater contamination and delineating source zones at industrial sites: Uncertainty analyses using integral pumping tests", Journal of Contaminant Hydrology, 79, 107-134

Thielsch, K.; Herold, M.; Ptak, T.

2012-12-01

154

Assessment of groundwater contamination resulting from a major accident in land nuclear power plants (LNPP), I: Concepts and methodology  

NASA Astrophysics Data System (ADS)

Hydrological site suitability is examined on the basis of potential groundwater pollution associated with major hypothetical accidents of reasonable probability. Loss of Coolant Accident (LOCA) is considered here as the Maximum Design Basis Event in nuclear power plants. Two alternative nuclide paths, resulting in groundwater contamination are considered: (a) core penetration through the basement, bringing possibly a major part of the nuclide inventory of the reactor into a direct contact with underlying groundwaters, or alternatively (b) major nuclide releases to the atmosphere, resulting in their wide spread as fallout, thus endangering the exploitability of underlying aquifers over large areas. These are referred to commonly as point-source and diffused-source contamination, respectively. Contamination analyses, related to the point-source scenario, are derived according to known analytical solutions of the convection-dispersion differential equation for absorbable and decaying species.

Mercado, Abraham

1989-12-01

155

Distinguishing sources of groundwater nitrate by 1H NMR of dissolved organic matter  

Microsoft Academic Search

Dissolved organic matter (DOM) originating from a certain source usually carries characteristic marks in its molecular structures that can be recognized by spectroscopic analysis. Sources of water-borne contaminants, such as nitrate, can be identified by recognition of the characteristics of DOM entrained in the water. In this study, DOM in groundwaters sampled from a dairy\\/crop production area (Chino Basin, CA)

Jianhang Lu; Andrew C Chang; Laosheng Wu

2004-01-01

156

Remediation of Nitrate-contaminated Groundwater by a Mixture of Iron and Activated Carbon  

Microsoft Academic Search

Nitrate contamination in groundwater has become a major environmental and health problem worldwide. The aim of the present study is to remediate groundwater contaminated by nitrate and develop potential reactive materials to be used in PRBs (Permeable Reactive Barriers). A new approach was proposed for abiotic groundwater remediation by reactive materials of iron chips and granular activated carbon particles. Batch

Guoxin Huang; Fei Liu; Aifang Jin; Xiaopeng Qin

2010-01-01

157

In situ bioremediation of perchlorate-contaminated groundwater using a multi-objective parallel evolutionary algorithm  

Microsoft Academic Search

Combining horizontal flow treatment wells (HFTWs) with in situ biodegradation is an innovative approach with the potential to remediate perchlorate-contaminated groundwater. A model has been developed that combines the groundwater flow induced by HFTWs with biodegradation processes that result from using the HFTWs to mix electron donor into perchlorate-contaminated groundwater. The model can be used to select engineering design parameters

Mark R. Knarr; Mark N. Goltz; Gary B. Lamont; Junqi Huang

2003-01-01

158

Arsenic and Other Metal Contamination of Groundwater in the Mekong River Delta, Vietnam  

Microsoft Academic Search

High levels of arsenic (As) contamination are found in the groundwater of Vietnam. To determine the distribution of arsenic and other metal contami- nation in the groundwater of the Mekong River Delta, we examined the contamination status of As and other metals in two regions, Tien Giang Province and Dong Thap Province. The concentration of total As in the groundwater,

Yasuhiro Shinkai; Duong Van Truc; Daigo Sumi; Doan Canh; Yoshito Kumagai

2007-01-01

159

Sulfate contamination in groundwater from a carbonate-hosted mine  

NASA Astrophysics Data System (ADS)

Sulfide oxidation in a carbonate environment produces groundwater contamination with high sulfate making the water unsuitable for drinking supplies. The zinc-lead mines near Shullsburg, Wisconsin are located in the Galena-Platteville Formation, a carbonate aquifer that was dewatered during mining. Sulfate levels have reached as high as 40 nmol/l in some local wells and eleven wells were abandoned. Geochemical modeling of chemical reactions and isotope effects using the USGS computer program PHREEQE showed the importance of dolomite, calcite, CO 2, and siderite or iron hydroxide in controlling the water chemistry. The decrease in sulfate levels with time indicated that dilution by incoming recharge water was an ongoing process. The results of carbon isotope reaction modeling are consistent with dilution of contaminated water. The evidence for localization of contamination and dilution means that area farmers have seen the worst of the contamination. The mechanism of contamination was further examined by microbiological sampling and sulfur isotope determinations, which indicated that bacteria of the Thiobacillus species that thrive under neutral pH conditions may have catalyzed sulfide oxidation. Research into the chemical evolution of contamination in this environment not only explains how sulfide oxidation causes contamination despite buffering by carbonate rocks, but also suggests how oxidation is initiated in the case of acid mine drainage.

Toran, Laura

1987-09-01

160

Chronic exposure to aldicarb-contaminated groundwater and human immune function.  

PubMed

Aldicarb, a carbamate pesticide, has been a known groundwater contaminant in Wisconsin since 1981. To assess the effects of chronic ingestion of low-level aldicarb-contaminated groundwater (less than 61 ppb) on the immune function of humans, we identified 50 women, ages 18 to 70, with no known underlying reason for immunodysfunction. Twenty-three of these women (exposed group) consumed groundwater with detectable levels of aldicarb, and 27 (unexposed group) consumed water from a source with no detectable levels of aldicarb. Data were collected on each woman's health status, immune function, and fluid intake. Exposed women as compared with unexposed women showed an elevated stimulation assay response to the antigen Candida (P less than 0.02, t test). The exposed group had increased numbers of T8 cells (P less than 0.05, t test), an increased percentage of total lymphocytes as T8 cells (P less than 0.02, t test), and a decreased ratio of T4:T8 cells (P less than 0.02, t test). Our results suggest an association between consumption of aldicarb-contaminated groundwater and abnormalities in T-cell subsets in women with otherwise intact immune systems. PMID:3490967

Fiore, M C; Anderson, H A; Hong, R; Golubjatnikov, R; Seiser, J E; Nordstrom, D; Hanrahan, L; Belluck, D

1986-12-01

161

Chronic exposure to aldicarb-contaminated groundwater and human immune function  

SciTech Connect

Aldicarb, a carbamate pesticide, has been a known groundwater contaminant in Wisconsin since 1981. To assess the effects of chronic ingestion of low-level aldicarb-contaminated groundwater (less than 61 ppb) on the immune function of humans, we identified 50 women, ages 18 to 70, with no known underlying reason for immunodysfunction. Twenty-three of these women (exposed group) consumed groundwater with detectable levels of aldicarb, and 27 (unexposed group) consumed water from a source with no detectable levels of aldicarb. Data were collected on each woman's health status, immune function, and fluid intake. Exposed women as compared with unexposed women showed an elevated stimulation assay response to the antigen Candida (P less than 0.02, t test). The exposed group had increased numbers of T8 cells (P less than 0.05, t test), an increased percentage of total lymphocytes as T8 cells (P less than 0.02, t test), and a decreased ratio of T4:T8 cells (P less than 0.02, t test). Our results suggest an association between consumption of aldicarb-contaminated groundwater and abnormalities in T-cell subsets in women with otherwise intact immune systems.

Fiore, M.C.; Anderson, H.A.; Hong, R.; Golubjatnikov, R.; Seiser, J.E.; Nordstrom, D.; Hanrahan, L.; Belluck, D.

1986-12-01

162

Logistic regression modeling to assess groundwater vulnerability to contamination in Hawaii, USA  

NASA Astrophysics Data System (ADS)

Capture zone analysis combined with a subjective susceptibility index is currently used in Hawaii to assess vulnerability to contamination of drinking water sources derived from groundwater. In this study, we developed an alternative objective approach that combines well capture zones with multiple-variable logistic regression (LR) modeling and applied it to the highly-utilized Pearl Harbor and Honolulu aquifers on the island of Oahu, Hawaii. Input for the LR models utilized explanatory variables based on hydrogeology, land use, and well geometry/location. A suite of 11 target contaminants detected in the region, including elevated nitrate (> 1 mg/L), four chlorinated solvents, four agricultural fumigants, and two pesticides, was used to develop the models. We then tested the ability of the new approach to accurately separate groups of wells with low and high vulnerability, and the suitability of nitrate as an indicator of other types of contamination. Our results produced contaminant-specific LR models that accurately identified groups of wells with the lowest/highest reported detections and the lowest/highest nitrate concentrations. Current and former agricultural land uses were identified as significant explanatory variables for eight of the 11 target contaminants, while elevated nitrate was a significant variable for five contaminants. The utility of the combined approach is contingent on the availability of hydrologic and chemical monitoring data for calibrating groundwater and LR models. Application of the approach using a reference site with sufficient data could help identify key variables in areas with similar hydrogeology and land use but limited data. In addition, elevated nitrate may also be a suitable indicator of groundwater contamination in areas with limited data. The objective LR modeling approach developed in this study is flexible enough to address a wide range of contaminants and represents a suitable addition to the current subjective approach.

Mair, Alan; El-Kadi, Aly I.

2013-10-01

163

Uranium removal from contaminated groundwater by synthetic resins.  

PubMed

Synthetic resins are shown to be effective in removing uranium from contaminated groundwater. Batch and field column tests showed that strong-base anion-exchange resins were more effective in removing uranium from both near-neutral-pH (6.5)- and high-pH (8)-low-nitrate-containing groundwaters, than metal-chelating resins, which removed more uranium from acidic-pH (5)-high-nitrate-containing groundwater from the Oak Ridge Reservation (ORR) Y-12 S-3 Ponds area in Tennessee, USA. Dowex 1-X8 and Purolite A-520E anion-exchange resins removed more uranium from high-pH (8)-low-nitrate-containing synthetic groundwater in batch tests than metal-chelating resins. The Dowex 21K anion-exchange resin achieved a cumulative loading capacity of 49.8 mg g(-1) before breakthrough in a field column test using near-neutral-pH (6.5)-low-nitrate-containing groundwater. However, in an acidic-pH (5)-high-nitrate-containing groundwater, metal-chelating resins Diphonix and Chelex-100 removed more uranium than anion-exchange resins. In 15 m L of acidic-pH (5)-high-nitrate-containing groundwater spiked with 20 mg L(-1) uranium, the uranium concentrations ranged from 0.95 mg L(-1) at 1-h equilibrium to 0.08 mg L(-1) at 24-h equilibrium for Diphonix and 0.17 mg L(-1) at 1-h equilibrium to 0.03 mg L(-1) at 24-h equilibrium for Chelex-100. Chelex-100 removed more uranium in the first 10 min in the 100mL of acidic-(pH 5)-high-nitrate-containing groundwater ( approximately 5 mg L(-1) uranium); however, after 10 min, Diphonix equaled or out-performed Chelex-100. This study presents an improved understanding of the selectivity and sorption kenetics of a range of ion-exchange resins that remove uranium from both low- and high-nitrate-containing groundwaters with varying pHs. PMID:17697694

Phillips, D H; Gu, B; Watson, D B; Parmele, C S

2008-01-01

164

Prevalence of anaerobic ammonium-oxidizing bacteria in contaminated groundwater.  

PubMed

Anaerobic ammonium-oxidizing (anammox) bacteria perform an important step in the global nitrogen cycle: anaerobic oxidation of ammonium and reduction of nitrite to form dinitrogen gas (N(2)). Anammox organisms appear to be widely distributed in natural and artificial environments. However, their roles in groundwater ammonium attenuation remain unclear and only limited biomarker-based data confirmed their presence prior to this study. We used complementary molecular and isotope-based methods to assess anammox diversity and activity occurring at three ammonium-contaminated groundwater sites: quantitative PCR, denaturing gradient gel electrophoresis, sequencing of 16S rRNA genes, and (15)N-tracer incubations. Here we show that anammox performing organisms were abundant bacterial community members. Although all sites were dominated by Candidatus Brocadia-like sequences, the community at one site was particularly diverse, possessing four of five known genera of anammox bacteria. Isotope data showed that anammox produced up to 18 and 36% of N(2) at these sites. By combining molecular and isotopic results we have demonstrated the diversity, abundance, and activity of these autotrophic bacteria. Our results provide strong evidence for their important biogeochemical role in attenuating groundwater ammonium contamination. PMID:21786759

Moore, Tara A; Xing, Yangping; Lazenby, Brent; Lynch, Michael D J; Schiff, Sherry; Robertson, William D; Timlin, Robert; Lanza, Sadia; Ryan, M Cathryn; Aravena, Ramon; Fortin, Danielle; Clark, Ian D; Neufeld, Josh D

2011-09-01

165

Comparative efficiency of microbial systems for destroying carbon tetrachloride contamination in Hanford groundwater  

Microsoft Academic Search

Past waste disposal practices at the US Department of Energy`s (DOE) Hanford site have resulted in carbon tetrachloride (CClâ) and nitrate contamination in the groundwater. In situ bioremediation is currently being investigated as a cost effective means to destroy these groundwater contaminants. The cost effectiveness of bioremediation is significantly influenced by the nutrient amendments required to sustain the contaminant destruction

M. J. Truex; R. S. Skeen; S. M. Caley; D. J. Workman

1993-01-01

166

Substrate Injection Treatment for a Chlorinated Solvent Groundwater Source Area  

Microsoft Academic Search

An industrial facility was found to have contamination from chlorinated solvents in surface, shallow and deep groundwater systems in the early 1990s, with perchlorate found in 2001. In situ anaerobic bioremediation pilot tests were implemented beginning in August 2002 to address both the residual chlorinated solvents (primarily tetrachloroethene) and perchlorate in soil and shallow groundwater simultaneously at and adjacent to

Kevin A. Morris; William Smith

167

Optimal Environmental Management Strategy and Implementation for Groundwater Contamination Prevention and Restoration  

Microsoft Academic Search

An innovative management strategy is proposed for optimized and integrated environmental management for regional or national\\u000a groundwater contamination prevention and restoration allied with consideration of sustainable development. This management\\u000a strategy accounts for availability of limited resources, human health and ecological risks from groundwater contamination,\\u000a costs for groundwater protection measures, beneficial uses and values from groundwater protection, and sustainable development.\\u000a Six

Mingyu Wang; Robert S. Kerr

2006-01-01

168

Environmental application of nanomaterials and metal-reducing bacteria to remediate arsenic-contaminated groundwater.  

PubMed

The objective of this study was to remediate As-contaminated groundwater using both nanomaterials and metal-reducing bacteria. In the batch experiment, a set of Pd-akaganeite in combination with the bacteria removed 95% of the arsenic from the contaminated groundwater. This result suggested that nanotechnology and biotechnology has the potential to create novel and effective treatment technologies for arsenic-contaminated groundwater. PMID:21456243

Sun, Eun-Young; Kim, Yumi; Park, Byungno; Roh, Yul

2011-02-01

169

Natural Attenuation Software (NAS): A computer program for estimating remediation times of contaminated groundwater  

USGS Publications Warehouse

This paper describes the development and application of a modeling system called Natural Attenuation Software (NAS). NAS was designed as a screening tool to estimate times of remediation (TORs), associated with monitored natural attenuation (MNA), to lower groundwater contaminant concentrations to regulatory limits. Natural attenuation processes that NAS models include advection, dispersion, sorption, biodegradation, and non-aqueous phase liquid (NAPL) dissolution. This paper discusses the three main interactive components of NAS: 1) estimation of the target source concentration required for a plume extent to contract to regulatory limits, 2) estimation of the time required for NAFL contaminants in the source area to attenuate to a predetermined target source concentration, and 3) estimation of the time required for a plume extent to contract to regulatory limits after source reduction. The model's capability is illustrated by results from a case study at a MNA site, where NAS time of remediation estimates compared well with observed monitoring data over multiple years.

Mendez, E.; Widdowson, M.; Brauner, S.; Chapelle, F.; Casey, C.

2004-01-01

170

Groundwater contamination by Temik Aldicarb pesticide: The first 8 months  

NASA Astrophysics Data System (ADS)

In 1979, Temik aldicarb pesticide was detected in the groundwater of Suffolk County, New York. Concentrations detected in drinking water supplies exceeded health guidelines, causing concern among thousands of residents. In spite of suggestive evidence prior to detection and inquiries from local investigators, EPA did not consider contamination a likely event. Upon detection of the contamination, EPA officials instituted an emergency response. Then, when they were sure there was no acute hazard, they left the situation in the hands of local health authorities, who struggled without adequate resources or sufficient in-house expertise. The local officials' failure to acknowledge these limitations led to public mistrust and discontent. From this case study one sees the consequences of limited implementation of the federal pesticide regulatory system. More stringent requirements would have likely prevented the contamination. In addition, an integrated response from agencies at many levels of government would have helped prevent similar contamination elsewhere and provided more comprehensive management of this episode on Long Island. Openness by government officials on the limitations of the health data would have helped defuse public animosity and encouraged a more satisfactory resolution of the contamination.

Wartenberg, Daniel

1988-02-01

171

Major Ion Chemistry and Mixing Proportions of Nitrate Sources in Urban Groundwater  

NASA Astrophysics Data System (ADS)

Working with Dr. Gilbert Hanson has allowed me to apply general mixing equations to identification of nonpoint sources of groundwater contamination. These methods have not commonly been used in hydrologic studies, as they involve a more classical petrologic approach, one which Dr. Hanson has pioneered. Our drinking water supplies are becoming more susceptible to contamination and knowing the chemistry of contaminate sources will yield precise determination of potential sources to groundwater and allow government agencies to adopt policies to reduce or prevent contamination. The geochemistry of soil water from below fertilized turfgrass sites and of sewage from septic tank/cesspools was used to place constraints on the sources of nitrate in groundwater of an unconsolidated aquifer in Suffolk County, Long Island, New York, USA. Twenty four sewage samples were acquired from Suffolk County Public Works. Soil water samples, from suction lysimeters, were acquired monthly during 2003, totaling 70 samples. We found that soil water concentrations were elevated in Ca, Mg and SO4 relative to sewage and sewage had higher concentrations of Cl, N-NO3, PO4, Na and K. This difference in the major ion chemistry allows identification of the source signatures in groundwater. We then compared the source signatures to 28 groundwater wells on binary ion diagrams of SO4, Cl and N- NO3 and created a cation sorption model for Na, Ca, Mg and K, in order to model cation concentrations on binary ion diagrams. These diagrams allow estimates of the relative contributions of each source to each well. Groundwater wells plotted according to their major land use and show that wells of similar land use have similar geochemistry and similar source contributions. The estimates of source contributions show that the proportions of soil water and sewage increase as residential land use increases. Although volumetric source proportions to groundwater wells are similar for soil water and sewage within a given land use, sewage contributes a greater proportion to the nitrate concentration in groundwater wells. For example, sewage contributes between 86-100% of the nitrate in wells sourced in medium density residential land use, even when accounting for a 50% reduction in nitrate concentrations from the septic tank/cesspool system. Our results indicate that to decrease the nitrate concentrations in groundwater one must reduce the load from septic tank/cesspool systems.

Munster, J.; Hanson, G. N.; Bokuniewicz, H.

2007-05-01

172

Evaluation of groundwater contamination beneath an urban environment: the Besòs river basin (Barcelona, Spain).  

PubMed

The urban groundwater of the central Besòs river basin (the La Llagosta aquifer) has become contaminated due to the infiltration of wastewater from septic tanks and sewage networks, and by industrial activities located in urban areas. The groundwater hydrogeochemistry of the La Llagosta aquifer was characterized using isoconcentration maps, hydrogeochemical diagrams (Piper, Schoeller-Berkaloff) and by analyzing hydrogeochemical changes along a flow-path that crosses an urban and peripheral industrial area in the main alluvial aquifer (the La Llagosta unit). The evolution of cations, anions and heavy metals along the flow path and the use of the PHREEQC numerical code indicate a complex set of geochemical processes, which result from the interaction between the sources of pollution, the groundwater flow and the mineral composition of the aquifer materials. The contaminated groundwater below the urban areas shows high contents of NO(3)(-) (90-100 mg/L) and an increase in the concentrations of Ca(2+) and Mg(2+) which coincides with a decrease in pH. The Eh shows greater variation than the pH along the flow line studied, with values ranging between 56 mV in the industrial area and 370 mV in the urban area. The area with the lowest Eh value coincides with the highest concentrations of dissolved Fe (4.7 mg/L) and Mn (0.22 mg/L). PMID:17223248

Navarro, Andrés; Carbonell, Montserrat

2007-10-01

173

Nitrate contamination of groundwater in two areas of the Cameroon Volcanic Line (Banana Plain and Mount Cameroon area)  

NASA Astrophysics Data System (ADS)

Water containing high concentrations of nitrate is unfit for human consumption and, if discharging to freshwater or marine habitats, can contribute to algal blooms and eutrophication. The level of nitrate contamination in groundwater of two densely populated, agro-industrial areas of the Cameroon Volcanic Line (CVL) (Banana Plain and Mount Cameroon area) was evaluated. A total of 100 samples from boreholes, open wells and springs (67 from the Banana Plain; 33 from springs only, in the Mount Cameroon area) were collected in April 2009 and January 2010 and analyzed for chemical constituents, including nitrates. The average groundwater nitrate concentrations for the studied areas are: 17.28 mg/l for the Banana Plain and 2.90 mg/l for the Mount Cameroon area. Overall, groundwaters are relatively free from excessive nitrate contamination, with nitrate concentrations in only 6 % of groundwater resources in the Banana Plain exceeding the maximum admissible concentration for drinking water (50 mg/l). Sources of NO3 - in groundwater of this region may be mainly anthropogenic (N-fertilizers, sewerage, animal waste, organic manure, pit latrines, etc.). Multivariate statistical analyses of the hydrochemical data revealed that three factors were responsible for the groundwater chemistry (especially, degree of nitrate contamination): (1) a geogenic factor; (2) nitrate contamination factor; (3) ionic enrichment factor. The impact of anthropogenic activities, especially groundwater nitrate contamination, is more accentuated in the Banana Plain than in the Mount Cameroon area. This study also demonstrates the usefulness of multivariate statistical analysis in groundwater study as a supplementary tool for interpretation of complex hydrochemical data sets.

Ako, Andrew Ako; Eyong, Gloria Eneke Takem; Shimada, Jun; Koike, Katsuaki; Hosono, Takahiro; Ichiyanagi, Kimpei; Richard, Akoachere; Tandia, Beatrice Ketchemen; Nkeng, George Elambo; Roger, Ntankouo Njila

2013-11-01

174

Nitrate contamination of groundwater in two areas of the Cameroon Volcanic Line (Banana Plain and Mount Cameroon area)  

NASA Astrophysics Data System (ADS)

Water containing high concentrations of nitrate is unfit for human consumption and, if discharging to freshwater or marine habitats, can contribute to algal blooms and eutrophication. The level of nitrate contamination in groundwater of two densely populated, agro-industrial areas of the Cameroon Volcanic Line (CVL) (Banana Plain and Mount Cameroon area) was evaluated. A total of 100 samples from boreholes, open wells and springs (67 from the Banana Plain; 33 from springs only, in the Mount Cameroon area) were collected in April 2009 and January 2010 and analyzed for chemical constituents, including nitrates. The average groundwater nitrate concentrations for the studied areas are: 17.28 mg/l for the Banana Plain and 2.90 mg/l for the Mount Cameroon area. Overall, groundwaters are relatively free from excessive nitrate contamination, with nitrate concentrations in only 6 % of groundwater resources in the Banana Plain exceeding the maximum admissible concentration for drinking water (50 mg/l). Sources of NO3 - in groundwater of this region may be mainly anthropogenic (N-fertilizers, sewerage, animal waste, organic manure, pit latrines, etc.). Multivariate statistical analyses of the hydrochemical data revealed that three factors were responsible for the groundwater chemistry (especially, degree of nitrate contamination): (1) a geogenic factor; (2) nitrate contamination factor; (3) ionic enrichment factor. The impact of anthropogenic activities, especially groundwater nitrate contamination, is more accentuated in the Banana Plain than in the Mount Cameroon area. This study also demonstrates the usefulness of multivariate statistical analysis in groundwater study as a supplementary tool for interpretation of complex hydrochemical data sets.

Ako, Andrew Ako; Eyong, Gloria Eneke Takem; Shimada, Jun; Koike, Katsuaki; Hosono, Takahiro; Ichiyanagi, Kimpei; Richard, Akoachere; Tandia, Beatrice Ketchemen; Nkeng, George Elambo; Roger, Ntankouo Njila

2014-06-01

175

Surfactant-Altered Zeolites as Permeable Barriers for In-Situ Treatment of Contaminated Groundwater.  

National Technical Information Service (NTIS)

We characterized surfactant-modified zeolite (SMZ) for its ability to sorb organic and inorganic contaminants from water. Our ultimate objective is to use SMZ as a permeable barrier to prevent migration of contaminants in groundwater. This paper summarize...

R. S. Bowman

2005-01-01

176

Analysis for remedial alternatives of unregulated municipal solid waste landfills leachate-contaminated groundwater  

NASA Astrophysics Data System (ADS)

A groundwater flow and solute transport model was developed using Visual Modflow for forecasting contaminant transport and assessing effects of remedial alternatives based on a case study of an unregulated landfill leachate-contaminated groundwater in eastern China. The results showed that arsenic plume was to reach the pumping well in the downstream farmland after eight years, and the longest lateral and longitudinal distance of arsenic plume was to reach 200 m and 260 m, respectively. But the area of high concentration region of arsenic plume was not to obviously increase from eight years to ten years and the plume was to spread to the downstream river and the farmland region after 20 years; while the landfill's ground was hardened, the plume was not to reach the downstream farmland region after eight years; when the pumping well was installed in the plume downstream and discharge rate was 200m3/d, the plume was to be effectively restrained; for leakage-proof barriers, it might effectively protect the groundwater of sensitive objects within an extent time range. But for the continuous point source, the plume was still to circle the leakage-proof barrier; when discharge rate of drainage ditches was 170.26 m3/d, the plume was effectively controlled; the comprehensive method combining ground-harden with drainage ditches could get the best effect in controlling contaminant diffusion, and the discharge rate was to be reduced to 111.43 m3/d. Therefore, the comprehensive remedial alternative combining ground-harden with drainage ditch will be recommended for preventing groundwater contamination when leachate leakage has happened in unregulated landfills.

An, Da; Jiang, Yonghai; Xi, Beidou; Ma, Zhifei; Yang, Yu; Yang, Queping; Li, Mingxiao; Zhang, Jinbao; Bai, Shunguo; Jiang, Lei

2013-09-01

177

Urban groundwater contamination by residues of UV filters.  

PubMed

The occurrence and fate of UV filters (UV F) in an urban aquifer in correlation with (1) the spatial distribution of UV F in Barcelona's groundwater, (2) the depth of the groundwater sample, (3) the physicochemical properties of the target compounds, (4) the recharge sources, and (5) the redox conditions of the Barcelona aquifers, were studied for the first time. The highest groundwater concentrations and the largest number of detected UV F were observed in an aquifer recharged by a polluted river (around 55 ng/L in SAP-4). In contrast, the urbanized areas had lower concentrations (around 20 ng/L in MPSP-1). Two pathways can be identified for UV F to enter the aquifers: (1) leakage of row sewage from the sewage network in urbanized areas and (2) wastewater treatment plant (WWTP) effluents discharged into the river. Measured concentrations of UV F were significantly much lower than those estimated from the waste water proportion in groundwater samples suggesting that UV F might undergo transformation processes in both reducing and oxidizing conditions. PMID:24632366

Jurado, Anna; Gago-Ferrero, Pablo; Vàzquez-Suñé, Enric; Carrera, Jesus; Pujades, Estanislao; Díaz-Cruz, M Silvia; Barceló, Damià

2014-04-30

178

Arsenic and other toxic elemental contamination of groundwater, surface water and soil in Bangladesh and its possible effects on human health  

Microsoft Academic Search

The problems of contamination caused by arsenic (As) and other toxic metals in groundwater, surface water and soils in the Bengal basin of Bangladesh have been studied. Altogether 10 groundwater, seven surface water and 31 soil samples were collected from arsenic-affected areas and analysed chemically. The geologic and anthropogenic sources of As and other toxic metals are discussed in this

Reijo Salminen; Pertti W. Lahermo

2000-01-01

179

Arsenic Contamination in Food-chain: Transfer of Arsenic into Food Materials through Groundwater Irrigation  

PubMed Central

Arsenic contamination in groundwater in Bangladesh has become an additional concern vis-à-vis its use for irrigation purposes. Even if arsenic-safe drinking-water is assured, the question of irrigating soils with arsenic-laden groundwater will continue for years to come. Immediate attention should be given to assess the possibility of accumulating arsenic in soils through irrigation-water and its subsequent entry into the food-chain through various food crops and fodders. With this possibility in mind, arsenic content of 2,500 water, soil and vegetable samples from arsenic-affected and arsenic-unaffected areas were analyzed during 1999–2004. Other sources of foods and fodders were also analyzed. Irrigating a rice field with groundwater containing 0.55 mg/L of arsenic with a water requirement of 1,000 mm results in an estimated addition of 5.5 kg of arsenic per ha per annum. Concentration of arsenic as high as 80 mg per kg of soil was found in an area receiving arsenic-contaminated irrigation. A comparison of results from affected and unaffected areas revealed that some commonly-grown vegetables, which would usually be suitable as good sources of nourishment, accumulate substantially-elevated amounts of arsenic. For example, more than 150 mg/kg of arsenic has been found to be accumulated in arum (kochu) vegetable. Implications of arsenic ingested in vegetables and other food materials are discussed in the paper.

Joardar, J.C.; Parvin, S.; Correll, Ray; Naidu, Ravi

2006-01-01

180

Assessing ground-water vulnerability to contamination: Providing scientifically defensible information for decision makers  

USGS Publications Warehouse

Throughout the United States increasing demands for safe drinking water and requirements to maintain healthy ecosystems are leading policy makers to ask complex social and scientific questions about how to assess and manage our water resources. This challenge becomes particularly difficult as policy and management objectives require scientific assessments of the potential for ground-water resources to become contaminated from anthropogenic, as well as natural sources of contamination. Assessments of the vulnerability of ground water to contamination range in scope and complexity from simple, qualitative, and relatively inexpensive approaches to rigorous, quantitative, and costly assessments. Tradeoffs must be carefully considered among the competing influences of the cost of an assessment, the scientific defensibility, and the amount of acceptable uncertainty in meeting the objectives of the water-resource decision maker.

Focazio, Michael J.; Reilly, Thomas E.; Rupert, Michael G.; Helsel, Dennis R.

2002-01-01

181

Modeling nitrate contamination of groundwater in agricultural watersheds  

NASA Astrophysics Data System (ADS)

SummaryThis paper presents and implements a framework for modeling the impact of land use practices and protection alternatives on nitrate pollution of groundwater in agricultural watersheds. The framework utilizes the national land cover database (NLCD) of the United State Geological Survey (USGS) grid and a geographic information system (GIS) to account for the spatial distribution of on-ground nitrogen sources and corresponding loadings. The framework employs a soil nitrogen dynamic model to estimate nitrate leaching to groundwater. These estimates were used in developing a groundwater nitrate fate and transport model. The framework considers both point and non-point sources of nitrogen across different land use classes. The methodology was applied for the Sumas-Blaine aquifer of Washington State, US, where heavy dairy industry and berry plantations are concentrated. Simulations were carried out using the developed framework to evaluate the overall impacts of current land use practices and the efficiency of proposed protection alternatives on nitrate pollution in the aquifer.

Almasri, Mohammad N.; Kaluarachchi, Jagath J.

2007-09-01

182

Protection of public water supplies from ground-water contamination. Seminar publication  

SciTech Connect

The publication contains material from technology transfer seminars presented for the water-supply community. The document provides utility managers and operators, regulators and technical specialists with guidance for preventing contamination and alternatives for treating public ground-water supplies that are contaminated. An understanding of the processes that affect the movement and degradation of contaminants in the subsurface is essential for effective ground-water quality management. Knowledge can be gained from chapters on Ground-Water Hydrology, Classification of Ground-Water Regions and Ground-Water--Surface Water Relationship.

Graham, L.L.; Heath, R.C.; Hinkle, L.; Love, O.T.; McNabb, J.F.

1985-09-01

183

A calcite permeable reactive barrier for the remediation of Fluoride from spent potliner (SPL) contaminated groundwater  

Microsoft Academic Search

The use of calcite (CaCO3) as a substrate for a permeable reactive barrier (PRB) for removing fluoride from contaminated groundwater is proposed and is illustrated by application to groundwater contaminated by spent potliner leachate (SPL), a waste derived from the aluminium smelting process. The paper focuses on two issues in the implementation of calcite permeable reactive barriers for remediating fluoride

Brett D. Turner; Philip J. Binning; Scott W. Sloan

2008-01-01

184

PERMEABLE REACTIVE BARRIER STRATEGIES FOR REMEDIATION OF ARSENIC-CONTAMINATED GROUNDWATER  

EPA Science Inventory

Results are presented from laboratory batch tests using zero-valent iron to treat arsenic-contaminated groundwater. The laboratory tests were conducted using near- neutral pH groundwater from a contaminated aquifer located adjacent to a custom smelting facility. Experiments we...

185

Enhanced detection of groundwater contamination from a leaking waste disposal site by microbial community profiles  

Microsoft Academic Search

Groundwater biogeochemistry is adversely impacted when municipal solid waste leachate, rich in nutrients and anthropogenic compounds, percolates into the subsurface from leaking landfills. Detecting leachate contamination using statistical techniques is challenging because well strategies or analytical techniques may be insufficient for detecting low levels of groundwater contamination. We sampled profiles of the microbial community from monitoring wells surrounding a leaking

Paula J. Mouser; Donna M. Rizzo; Gregory K. Druschel; Sergio E. Morales; Nancy Hayden; Patrick O'Grady; Lori Stevens

2010-01-01

186

The Use of Atmospheric Contaminants to Estimate the Minimum Age of Environmental Releases Impacting Groundwater  

Microsoft Academic Search

Numerous age-dating techniques are available to estimate the time frame of contaminant releases impacting groundwater. One method, historically used in the hydrology field to assess recharge ages and rates of groundwater flow, can be applied to estimating the age of contaminant releases. Chlorofluorocarbons (CFCs) and tritium are anthropogenic substances present in the atmosphere over the past half century. These atmospheric

Gil Oudijk

2005-01-01

187

Source screening module for contaminant transport analysis through vadose and saturated zones.  

PubMed

At complex sites there may be many potential sources of contaminants within the vadose zone. Screening-level analyses are useful to identify which potential source areas should be the focus of detailed investigation and analysis. A source screening module (SSM) has been developed to support preliminary evaluation of the threat posed by vadose zone waste sites on groundwater quality. This tool implements analytical solutions to simulate contaminant transport through the unsaturated and saturated zones to predict time-varying concentrations at potential groundwater receptors. The SSM integrates several transport processes in a single simulation that is implemented within a user-friendly, Microsoft Excel™ - based interface. PMID:22716000

Bedekar, Vivek; Neville, Christopher; Tonkin, Matthew

2012-01-01

188

Biofouling of contaminated ground-water recovery wells: Characterization of microorganisms  

SciTech Connect

The taxonomy and physiology of microorganisms isolated from contaminated ground-water recovery wells prone to biofouling are characterized for an industrial site in Rochester, New York. Principal aquifer contaminants include acetone, cyclohexane, dichloroethane, dichloromethane, 1,4-dioxane, isopropanol, methanol, and toluene. These contaminants represent a significant fraction (up to 95%) of the total organic carbon in the ground water. Ground-water samples from 12 recovery wells were used to isolate, quantify, and identify aerobic and anaerobic bacterial populations. Samples from selected wells were also characterized geochemically to assess redox conditions and availability of essential and trace nutrients. Dominant bacteria, listed in order of descending numbers, including sulfate-reducers (Desulfovibrio desulfuricans), anaerobic heterotrophs (Actinomyces, Bacteriodes, Bacillus, Agrobacterium), aerobic heterotrophs (Pseudomonas, Flavobacterium, Nocardia, Citrobacter), iron-oxidizers (Gallionella ferruginea, Crenothrix polyspora), iron-reducers (Shewanella), and sulfur-oxidizers (Thiobacillus ferrooxidans). Fungi were also recovered in low numbers. Both aerobic and anaerobic heterotrophs were able to utilize all principal contaminants as sole carbon and energy sources except 1,4-dioxane. The prevalence of heterotrophic bacteria and their ability to use the available anthropogenic carbon suggests that aerobic and anaerobic heterotrophs contribute to the biofouling of wells at this site, in addition to the often cited fouling due to iron-oxidizing bacteria and sulfate-reducing bacteria.

Taylor, S.W. [Bechtel Environmental, Inc., Oak Ridge, TN (United States); Lange, C.R. [Auburn Univ., AL (United States). Dept. of Civil Engineering; Lesold, E.A. [State Univ. of New York, Buffalo, NY (United States)

1997-11-01

189

Detection of Septic System Waste in the Groundwaters of Southern California Using Emerging Contaminants and Isotopic Tracers  

NASA Astrophysics Data System (ADS)

In California, groundwater supplies 30-40% of the State's water and in rapidly growing regions like the Inland Empire, groundwater makes up 80-90% of the municipal water supply. However, anthropogenic contamination could adversely affect groundwater quality and thereby reduce available supplies. Appropriate tracers are needed to identify groundwater contamination and protect human health. Stable isotopes ?15N and ? 18O offer unique information about the importance of nitrate sources and processes affecting nitrate in aquifers. We investigated the influence of septic systems on groundwater quality in and around the city of Beaumont, CA during 2010-11. Groundwater samples were collected from 38 active wells and 10 surface water sites in the region (urban and natural streams, agricultural drainage and groundwater recharge basins supplied by the California State Water Project). Stable isotopes and pharmaceuticals and personal care products (PPCPs) were analyzed for all the water samples. The variations of ?15N and ? 18O of nitrate were 2 - 21 per mil and -4 - 9 per mil respectively. ?15N-NO3 values greater than 10 per mil have been associated with nitrate inputs from sewage and animal waste, but in the Beaumont wells, PPCP concentrations were at or below the detection limit in most wells with high isotope ratios. We also observed a strong linear relationship between ?15N and ? 18O of nitrate (slope of~ 0.5) in the vast majority of our samples including those with high isotope ratios. Our results suggest that denitrification was widespread in the Beaumont aquifer and strongly affected the isotope composition of nitrate. In some wells, PPCPs (carbamazepine, sulfamethoxazole, primidone, meprobamate and diuron) and isotope measurements indicated inputs from human waste, but these sites were affected primarily by local waste-water treatment plant effluent. A mixing model was developed using multiple tracers to determine sources and contributions of groundwater contamination.

Huang, W.; Conkle, J.; Sickman, J. O.; Lucero, D.; Pang, F.; Gan, J.

2011-12-01

190

Modeling uranium transport in acidic contaminated groundwater with base addition.  

PubMed

This study investigates reactive transport modeling in a column of uranium(VI)-contaminated sediments with base additions in the circulating influent. The groundwater and sediment exhibit oxic conditions with low pH, high concentrations of NO(3)(-), SO(4)(2-), U and various metal cations. Preliminary batch experiments indicate that additions of strong base induce rapid immobilization of U for this material. In the column experiment that is the focus of the present study, effluent groundwater was titrated with NaOH solution in an inflow reservoir before reinjection to gradually increase the solution pH in the column. An equilibrium hydrolysis, precipitation and ion exchange reaction model developed through simulation of the preliminary batch titration experiments predicted faster reduction of aqueous Al than observed in the column experiment. The model was therefore modified to consider reaction kinetics for the precipitation and dissolution processes which are the major mechanism for Al immobilization. The combined kinetic and equilibrium reaction model adequately described variations in pH, aqueous concentrations of metal cations (Al, Ca, Mg, Sr, Mn, Ni, Co), sulfate and U(VI). The experimental and modeling results indicate that U(VI) can be effectively sequestered with controlled base addition due to sorption by slowly precipitated Al with pH-dependent surface charge. The model may prove useful to predict field-scale U(VI) sequestration and remediation effectiveness. PMID:21531075

Zhang, Fan; Luo, Wensui; Parker, Jack C; Brooks, Scott C; Watson, David B; Jardine, Philip M; Gu, Baohua

2011-06-15

191

Technetium-99 removal from process solutions and contaminated groundwater  

SciTech Connect

The predominant form of technetium under oxic conditions is the pertechnetate anion (TcO{sub 4}{sup {minus}}), which is highly soluble in water and readily mobile in the environment. Technetium-99 is of particular concern because of its persistence and mobility. Various equipment decontamination and uranium recovery operations at the Portsmouth Gaseous Diffusion Plant generate a `raffinate` waste stream characterized by toxic heavy metals, high concentration of nitric acid, and low levels of radionuclides ({sup 235}U and {sup 99}Tc). Dilution and adjustment of solution pH to a value of 8.2 to 8.5 precipitates a heavy-metals-sludge and a filtrate. The removal of {sup 99}Tc from these waste streams and from contaminated groundwater can be accomplished using anionic ion-exchange resins. Batch equilibrium and packed column breakthrough and regeneration studies were performed using inorganic sorbents and organic ion-exchange resins (Dowex SRB-OH and Reillex resins). These studies were performed on actual and surrogate raw raffinates, filtrates, and surrogate groundwater samples. The experimental conditions were chosen to closely represent the actual process.

Del Cul, G.D.; Bostick, W.D.; Trotter, D.R.; Osborne, P.E. [Oak Ridge K-25 Site, TN (United States)

1993-01-01

192

Predicting geogenic arsenic contamination in shallow groundwater of South louisiana, United States.  

PubMed

Groundwater contaminated with arsenic (As) threatens the health of more than 140 million people worldwide. Previous studies indicate that geology and sedimentary depositional environments are important factors controlling groundwater As contamination. The Mississippi River delta has broadly similar geology and sedimentary depositional environments to the large deltas in South and Southeast Asia, which are severely affected by geogenic As contamination and therefore may also be vulnerable to groundwater As contamination. In this study, logistic regression is used to develop a probability model based on surface hydrology, soil properties, geology, and sedimentary depositional environments. The model is calibrated using 3286 aggregated and binary-coded groundwater As concentration measurements from Bangladesh and verified using 78 As measurements from south Louisiana. The model's predictions are in good agreement with the known spatial distribution of groundwater As contamination of Bangladesh, and the predictions also indicate high risk of As contamination in shallow groundwater from Holocene sediments of south Louisiana. Furthermore, the model correctly predicted 79% of the existing shallow groundwater As measurements in the study region, indicating good performance of the model in predicting groundwater As contamination in shallow aquifers of south Louisiana. PMID:24779344

Yang, Ningfang; Winkel, Lenny H E; Johannesson, Karen H

2014-05-20

193

Characterization of Persistent Volatile Contaminant Sources in the Vadose Zone  

SciTech Connect

Remediation activities over time will alter the subsurface distribution of contaminants and likely create significant changes in the source-zone architecture. A field method was demonstrated for use of data collected from multiple individual soil vapor extraction (SVE) system well tests to locate and characterize the distribution of persistent VOC sources in the vadose zone. Operational data collected at the Department of Energy’s Hanford site were used to examine source zone alteration over time due to SVE operation and to illustrate the source-zone characterization approach. Individual well test results confirmed a heterogeneous distribution of permeability and contaminant mass discharge throughout the vadose zone. The trends in mass discharge and concentration were analyzed to determine the location and extent of the primary source zone within a lower-permeability unit at the site. This information is useful to evaluate the performance of SVE operations, and support decisions concerning system alteration or closure based on risk assessments of the impact of vadose-zone sources on groundwater contamination or vapor intrusion.

Carroll, Kenneth C.; Truex, Michael J.; Brusseau, Mark L.; Parker, Kyle R.; Mackley, Rob D.; Rohay, Virginia J.

2013-05-01

194

Volatilized tritiated water vapor in the vicinity of exposed tritium contaminated groundwater  

SciTech Connect

Water vapor tritium concentrations in air above a known source of tritiated water can be estimated. Estimates should account for the mechanisms of evaporation and condensation at the water surface and water species exchange, and are typically applicable under a broad range of wind, temperature and humidity conditions. An estimate of volatilized tritium water vapor was made for a known outcropping of tritium contaminated groundwater at the Savannah River Site (SRS) old F-Area effluent stream. In order to validate this estimate and the associated dose calculation, sampling equipment was fabricated, tested, and installed at the effluent stream. The estimate and the dose calculation were confirmed using data from samples collected.

Dunn, D.L.; Carlton, B.; Hunter, C.; McAdams, T.

1994-06-01

195

Risk Management of Groundwater Contamination in a Multiobjective Framework  

NASA Astrophysics Data System (ADS)

This paper addresses the issue of uncertainty in groundwater contamination by applying risk analysis concepts to the problem of industrial chemical spills. A hypothetical aquifer system is considered that includes a factory and two water supply wells. Accidental spills of solvent at the factory enter the aquifer, causing well solute concentrations to exceed a mandated limit. Regulation forces the company owning the factory to reduce the frequency and magnitude of the spills. Its managers need to determine the optimal levels of investment in spill control technologies that will achieve three objectives: minimize the cost of contamination prevention, minimize the proportion (ratio) of time in which a maximum contaminant limit (MCL) is exceeded, and minimize the sensitivity of the MCL exceedance ratio to uncertainties in aquifer dispersivity. Simulation with a stochastic time series of spills gives sample values of the MCL exceedance ratio for values of the investment decision variables and dispersivity; the investment decisions determine the statistics of the time series. Use of regression enables calculation of a continuous function relating the contamination time ratio objective to investments and dispersivity. The third objective is an approximation to the standard deviation of the MCL exceedance ratio and is computed through the risk dispersion index method (RDIM). The RDIM incorporates the surrogate worth trade-off method for optimizing the resulting multiple objectives. The simulations assume that the aquifer is in a steady state and behaves linearly. The concentration impulse response at the wells for a single spill is computed via a mass transport model. The well solute concentration over time, which is determined from the convolution of a series of spills, provides the basis for calculating the exceedance ratio. This ratio is defined as the portion of time that the pollution concentration limit is exceeded in some chosen time span. To obtain credible values of the exceedance ratio, several simulations, each encompassing a 20-year planning horizon, are run for each scenario (policy option).

Kaunas, John R.; Haimes, Yacov Y.

1985-11-01

196

Efficient Bayesian experimental design for contaminant source identification  

NASA Astrophysics Data System (ADS)

In this study, an efficient full Bayesian approach is developed for the optimal sampling well location design and source parameter identification of groundwater contaminants. An information measure, i.e., the relative entropy, is employed to quantify the information gain from indirect concentration measurements in identifying unknown source parameters such as the release time, strength and location. In this approach, the sampling location that gives the maximum relative entropy is selected as the optimal one. Once the sampling location is determined, a Bayesian approach based on Markov Chain Monte Carlo (MCMC) is used to estimate unknown source parameters. In both the design and estimation, the contaminant transport equation is required to be solved many times to evaluate the likelihood. To reduce the computational burden, an interpolation method based on the adaptive sparse grid is utilized to construct a surrogate for the contaminant transport. The approximated likelihood can be evaluated directly from the surrogate, which greatly accelerates the design and estimation process. The accuracy and efficiency of our approach are demonstrated through numerical case studies. Compared with the traditional optimal design, which is based on the Gaussian linear assumption, the method developed in this study can cope with arbitrary nonlinearity. It can be used to assist in groundwater monitor network design and identification of unknown contaminant sources. Contours of the expected information gain. The optimal observing location corresponds to the maximum value. Posterior marginal probability densities of unknown parameters, the thick solid black lines are for the designed location. For comparison, other 7 lines are for randomly chosen locations. The true values are denoted by vertical lines. It is obvious that the unknown parameters are estimated better with the desinged location.

Zhang, J.; Zeng, L.

2013-12-01

197

Groundwater  

NSDL National Science Digital Library

Groundwater plays a central role in the environment and many communities around the world depend on it. This radio broadcast explores the importance of groundwater in our lives. Most freshwater resources are stored naturally as groundwater, a substantial portion of the public water supply is taken from this source, and in drier regions, many communities are totally dependent upon it. Although totally hidden from view, groundwater plays a central role in the environment, maintaining wetlands and river flows through prolonged dry periods. However, to many people who rely upon it, groundwater remains a subject of mystery. How does groundwater occur and where can it be found? How is it used and how do people care for it? Is the way that people behave on the land posing a huge risk to its natural pristine quality and how can science and technology help in the way we treat, use, and preserve groundwater? The broadcast is 30 minutes in length.

198

Prediction of contamination potential of groundwater arsenic in Cambodia, Laos, and Thailand using artificial neural network.  

PubMed

The arsenic (As) contamination of groundwater has increasingly been recognized as a major global issue of concern. As groundwater resources are one of most important freshwater sources for water supplies in Southeast Asian countries, it is important to investigate the spatial distribution of As contamination and evaluate the health risk of As for these countries. The detection of As contamination in groundwater resources, however, can create a substantial labor and cost burden for Southeast Asian countries. Therefore, modeling approaches for As concentration using conventional on-site measurement data can be an alternative to quantify the As contamination. The objective of this study is to evaluate the predictive performance of four different models; specifically, multiple linear regression (MLR), principal component regression (PCR), artificial neural network (ANN), and the combination of principal components and an artificial neural network (PC-ANN) in the prediction of As concentration, and to provide assessment tools for Southeast Asian countries including Cambodia, Laos, and Thailand. The modeling results show that the prediction accuracy of PC-ANN (Nash-Sutcliffe model efficiency coefficients: 0.98 (traning step) and 0.71 (validation step)) is superior among the four different models. This finding can be explained by the fact that the PC-ANN not only solves the problem of collinearity of input variables, but also reflects the presence of high variability in observed As concentrations. We expect that the model developed in this work can be used to predict As concentrations using conventional water quality data obtained from on-site measurements, and can further provide reliable and predictive information for public health management policies. PMID:21917287

Cho, Kyung Hwa; Sthiannopkao, Suthipong; Pachepsky, Yakov A; Kim, Kyoung-Woong; Kim, Joon Ha

2011-11-01

199

A model for managing sources of groundwater pollution  

Microsoft Academic Search

The waste disposal capacity of a groundwater system can be maximized maintaining water quality at specified locations by using a groundwater pollutant source management model that is based upon linear programing and numerical simulation. The decision variables of the management model are solute waste disposal rates at various facilities distributed over space. A concentration response matrix is used in the

Steven M. Gorelick

1982-01-01

200

Thermal sustainability of groundwater-source cooling in Winnipeg, Manitoba  

Microsoft Academic Search

Groundwater from the Carbonate Rock Aquifer is extensively used for cooling purposes in Winnipeg, Mani- toba. This paper examines the factors affecting the magnitude and timing of temperature increases at production wells in groundwater-source cooling applications through numerical modeling and observations at a case study site. Generic simulations carried out using typical hydrogeologic parameters for the Carbonate Rock Aquifer suggested

Grant Ferguson; Allan D. Woodbury

2005-01-01

201

Biofouling of contaminated ground-water recovery wells: Characterization of microorganisms  

Microsoft Academic Search

The taxonomy and physiology of microorganisms isolated from contaminated ground-water recovery wells prone to biofouling are characterized for an industrial site in Rochester, New York. Principal aquifer contaminants include acetone, cyclohexane, dichloroethane, dichloromethane, 1,4-dioxane, isopropanol, methanol, and toluene. These contaminants represent a significant fraction (up to 95%) of the total organic carbon in the ground water. Ground-water samples from 12

Stewart W. Taylor; Clifford R. Lange; Elizabeth A. Lesold

1997-01-01

202

There Must Be Something in the Water: Investigating How Underground Pollutants Contaminate the Water Supply  

NSDL National Science Digital Library

In this lesson, students explore how groundwater contamination can spread through aquifers by participating in a groundwater plume simulation. They will learn how to determine the source of groundwater contamination, explore the possible contamination of Nevada groundwater by a major nuclear test site, and write a persuasive essay from the point of view of a Nevada resident living close to a groundwater contamination source.

203

Ammonium transport and reaction in contaminated groundwater: Application of isotope tracers and isotope fractionation studies  

USGS Publications Warehouse

Ammonium (NH4+) is a major constituent of many contaminated groundwaters, but its movement through aquifers is complex and poorly documented. In this study, processes affecting NH4+ movement in a treated wastewater plume were studied by a combination of techniques including large-scale monitoring of NH4+ distribution; isotopic analyses of coexisting aqueous NH4+, NO3-, N2, and sorbed NH 4+; and in situ natural gradient 15NH 4+ tracer tests with numerical simulations of 15NH4+, 15NO3-, and 15N2 breakthrough data. Combined results indicate that the main mass of NH4+ was moving downgradient at a rate about 0.25 times the groundwater velocity. Retardation factors and groundwater ages indicate that much of the NH4+ in the plume was recharged early in the history of the wastewater disposal. NO3- and excess N2 gas, which were related to each other by denitrification near the plume source, were moving downgradient more rapidly and were largely unrelated to coexisting NH 4+. The ??15N data indicate areas of the plume affected by nitrification (substantial isotope fractionation) and sorption (no isotope fractionation). There was no conclusive evidence for NH 4+-consuming reactions (nitrification or anammox) in the anoxic core of the plume. Nitrification occurred along the upper boundary of the plume but was limited by a low rate of transverse dispersive mixing of wastewater NH4+ and O2 from overlying uncontaminated groundwater. Without induced vertical mixing or displacement of plume water with oxic groundwater from upgradient sources, the main mass of NH4+ could reach a discharge area without substantial reaction long after the more mobile wastewater constituents are gone. Multiple approaches including in situ isotopic tracers and fractionation studies provided critical information about processes affecting NH4+ movement and N speciation.

Bohlke, J. K.; Smith, R. L.; Miller, D. N.

2006-01-01

204

Geohydrologic reconnaissance of a ground-water contamination problem in the Argonne Road area near Spokane, Washington  

USGS Publications Warehouse

Three domestic wells that withdraw groundwater from an alluvium-filled trough cut into granite were found to be contaminated with the organic solvents tetrachloroethene, trichloroethene, 1,1,1-trichloroethane, and 1 ,2-trans-dichloroethene. The suspected source of contamination is a nearby septic-tank sludge disposal area. There is concern that the affected aquifer is tributary to the Spokane aquifer, which has been accorded ' sole source ' status by the U.S. Environmental Protection Agency. Preliminary estimates suggest that groundwater in the area is moving toward the Spokane aquifer and that the transit time may range from 2.5 to 25 years. Because of longitudinal dispersion, however, the plume of contaminants may move at a faster rate than the ambient groundwater and may arrive at given destinations more quickly than calculated above. A literature search has indicated that the dissolved solute phase of the contaminants will not be significantly affected by sorption, volatilization, chemical activity, or biodegradation. Because of the preliminary nature of the investigation, many questions relating to the extent of contamination remain unanswered. A list of suggested additional studies to answer those questions and to refine and confirm the findings of this investigation is presented. (Author 's abstract)

Dion, N. P.

1987-01-01

205

A Discovery-Based Experiment Illustrating How Iron Metal Is Used to Remediate Contaminated Groundwater  

Microsoft Academic Search

In this article, we describe an experiment for undergraduate general chemistry in which students investigate the chemistry behind iron-permeable reactive barriers (iron PRBs), a new technology that is widely used to remediate contaminated groundwater. Contaminant remediation involving iron PRBs is a redox process: the iron metal undergoes oxidative dissolution while the contaminant is reduced. The reaction is complicated, however, by

Barbara A. Balko; Paul G. Tratnyek

2001-01-01

206

In situ source zone sediment mixing coupled to groundwater biostimulation to enhance phenol natural attenuation.  

PubMed

Phenol is an industrially key compound that has a wide range of applications and also one of the most commonly found toxic pollutants in wastewaters and groundwater. This paper demonstrates the applicability of in situ remediation at a deactivated industrial site using source zone excavation and sediment mixing associated with nutrients delivery into groundwater. Sediment excavation and mixing displaced the entrapped source zone enhancing mass transfer into groundwater and contaminant bioavailability. A nutrient solution prepared with nitrate, phosphate, sodium hydroxide and hydrogen peroxide was continuously delivered into groundwater to stimulate biodegradation and restrict plume migration. The observed correlation between phenol-dependent Enterobacteriaceae concentrations throughout the remediation time frame supported circumstantial evidence of biodegradation. Phenol concentration in groundwater (up to 1,300 mg/L) was reduced >99% after 5 months following remediation and remained under the established site specific target level (4 mg/L). Nitrate and phosphate concentrations returned to background concentrations levels at the end of the remediation. Overall, the proposed in situ remediation scheme was effective to remediate this particular aquifer contaminated with phenol for over 20 years. PMID:22678209

da Silva, Marcio Luis Busi; Wendt, Marcos Felipe; de Oliveira, José Carlos Silveira; Schneider, Marcio Roberto

2012-01-01

207

Biotreatment of groundwater contaminated with MTBE: interaction of common environmental co-contaminants.  

PubMed

Contamination of groundwater with the gasoline additive methyl tert-butyl ether (MTBE) is often accompanied by many aromatic components such as benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene (BTEX). In this study, a laboratory-scale biotrickling filter for groundwater treatment inoculated with a microbial consortium degrading MTBE was studied. Individual or mixtures of BTEX compounds were transiently loaded in combination with MTBE. The results indicated that single BTEX compound or BTEX mixtures inhibited MTBE degradation to varying degrees, but none of them completely repressed the metabolic degradation in the biotrickling filter. Tert-butyl alcohol (TBA), a frequent co-contaminant of MTBE had no inhibitory effect on MTBE degradation. The bacterial consortium was stable and showed promising capabilities to remove TBA, ethylbenzene and toluene, and partially degraded benzene and xylenes without significant lag time. The study suggests that it is feasible to deploy a mixed bacterial consortia to degrade MTBE, BTEX and TBA at the same time. PMID:16733621

Wang, Xiaolin; Deshusses, Marc A

2007-02-01

208

Evidence for Groundwater Contamination Vulnerability in California's Central Valley.  

National Technical Information Service (NTIS)

The California Water Resources Control Board, in collaboration with the US Geological Survey and Lawrence Livermore National Laboratory, has implemented a program to assess the susceptibility of groundwater resources. Advanced techniques such as groundwat...

J. E. Morgan R. Leif B. K. Esser M. J. Singleton

2005-01-01

209

Edible Oil Barriers for Treatment of Perchlorate Contaminated Groundwater.  

National Technical Information Service (NTIS)

This final technical report documents the demonstration of emulsified edible oils for remediation of perchlorate in groundwater. The demonstration was conducted at a confidential site in Maryland with a mixed perchlorate and 1,1,1-TCA groundwater plume. T...

R. C. Borden C. Zawtocki T. M. Lieberman

2006-01-01

210

APPLYING MEMBRANE PROCESSES TO GROUNDWATER SOURCES FOR TRIHALOMETHANE PRECURSOR CONTROL  

EPA Science Inventory

The use of membrane processes for controlling trihalomethanes (THMs) was investigated for Florida groundwater sources and one surface water source. All of the sources were used for public supply and had excessive THMs (>300 micrograms/L) in the finished water. The performance and...

211

Migration of contaminants in groundwater at a landfill: A case study. 2. Groundwater monitoring devices  

NASA Astrophysics Data System (ADS)

Six types of devices for groundwater monitoring were used on an experimental basis in the investigation of the plume of contamination in the unconfined sandy aquifer at the Borden landfill. These include: standpipe piezometers, water-table standpipes, an auger-head sampler, suction-type and positive-displacement-type multilevel point-samplers, and bundle-piezometers. With the exception of the first two, each of these devices provides a means of obtaining vertical sample profiles of groundwater from a single borehole. The auger-head sampler, which is a device that is attached to the cutting head of conventional continuous-flight hollow-stem augers, yields samples from relatively undisturbed aquifer zones as the augers are advanced downward in the borehole from one depth of sampling to another. This method is a rapid means of aquiring water-quality profiles for mapping the distribution of a contaminant plume. The other three profiling devices can be used to establish permanent networks for groundwater-quality monitoring. A suction-type multilevel sampler consists of twenty or more narrow polyethylene or polypropylene tubes contained in a PVC casing that is capped at the bottom. Each tube extends to a different depth and is attached to a small screened sampling point that extends through the casing to draw water from the aquifer when suction is applied. A positive-displacement multilevel sampler is similar except that each sampling point is connected to a positive-displacement pumping device located inside the PVC casing adjacent to the screen. Use of the suction-type multilevel sampler is limited to zones where the water table is less than the suction-lift depth of 8 or 9 m. The positive-displacement sampler can be used even if the water table is at a much greater depth. A bundle-piezometer consists of 1.2-cm O.D. flexible polyethylene tubes, each with a short screened section at the bottom, fastened as a bundle around a semi-rigid center-piezometer constructed of thick-walled 2-cm O.D. PVC pipe. In shallow water-table areas water is withdrawn from each of the tubes and from the PVC piezometer by suction. In areas with a deep water table, samples are obtained by bailing with a narrow tube with a check valve on the bottom or by displacement using a double- or triple-tube gas-drive sampler. The positive-displacement multilevel sampler or use of the gas-drive samplers in the bundle-piezometers provide the best opportunities for collecting samples that can be filtered and have preservatives added without the water being influenced excessively by degassing or by oxygen invasion. Networks of these three types of devices for multilevel groundwater monitoring were installed in the Borden aquifer by means of hollow-stem augers. The devices are particularly well suited for use in aquifers composed of cohesionless sand or gravel that have little or no clay and groundwater flow that is primarily horizontal. When 8-cm diameter hollow-stem augers are used, as many as eight polyethylene tubes are included conveniently in each bundle-piezometer. If augers with a larger hollow-stem are used, more tubes can be assembled in each bundle.

Cherry, J. A.; Gillham, R. W.; Anderson, E. G.; Johnson, P. E.

1983-05-01

212

Tracking the sources of nitrate in groundwater using coupled nitrogen and boron isotopes: a synthesis.  

PubMed

Nitrate (NO3) is one of the world's major pollutants of drinking water resources. Although recent European Directives have reduced input from intensive agriculture, NO3 levels in groundwater are approaching the drinking water limit of 50 mg L(-1) almost everywhere. Determining the sources of groundwater contamination is an important first step toward improving its quality by emission control. It is with this aim that we review here the benefit of using a coupled isotopic approach (delta15N and delta11B), in addition to conventional hydrogeological analyses, to trace the origin of NO3 in water. The studied watersheds include both fractured bedrock and alluvial (subsurface and deep) hydrogeological contexts. The joint use of nitrogen and boron isotope systematics in each context deciphers the origin of NO3 in the groundwater and allows a semi-quantification of the contributions of the respective pollution sources (mineral fertilizers, wastewater, and animal manure). PMID:15707054

Widory, David; Petelet-Giraud, Emmanuelle; Négrel, Philippe; Ladouche, Bernard

2005-01-15

213

Susceptibility of ground water to surface and shallow sources of contamination, Orange County, North Carolina  

USGS Publications Warehouse

In 1998, the relative susceptibility of ground water in Orange County, North Carolina,to contamination from surface and shallow sources was evaluated. A geographic information system was used to build three county-wide layers--soil permeability, land use/land cover, and land-surface slope. The harmonic mean permeability of soil layers was used to estimate a location's capacity to transmit water through the soil. Values for each of these three factors were categorized and ranked from 1 to 10 according to relative potential for contamination. Each factor was weighted to reflect its relative potential contribution to ground-water contamination, then the factors were combined to create a relative susceptibility index. The relative susceptibility index was categorized to reflect lowest, low, moderate, high, and highest potential for ground-water contamination. The relative susceptibility index for about 12 percent of the area in Orange County was categorized as high or highest. The high and highest range areas have highly permeable soils, land cover or land-use activities that have a high contamination potential, and low to moderate slopes. Most of the county is within the moderate category of relative susceptibility to ground-water contamination. About 21 percent of the county is ranked as low or lowest relative susceptibility to ground-water contamination.

Terziotti, Silvia; Eimers, J. L.

1999-01-01

214

Investigation of Contaminated Groundwater at Solid Waste Management Unit 12, Naval Weapons Station Charleston, North Charleston, South Carolina, 2008  

USGS Publications Warehouse

The U.S. Geological Survey and the Naval Facilities Engineering Command Southeast investigated natural and engineered remediation of chlorinated volatile organic compound (VOC) groundwater contamination at Solid Waste Management Unit 12 at the Naval Weapons Station Charleston, North Charleston, South Carolina, beginning in 2000. The primary contaminants of interest in the study are tetrachloroethene, 1,1,1-trichloroethane, trichloroethene, cis-1,2-dichloroethene, vinyl chloride, 1,1-dichloroethane, and 1,1-dichloroethene. Engineered remediation aspects at the site consist of a zero-valent-iron permeable reactive barrier (PRB) installed in December 2002 intercepting the contamination plume and a phytoremediation test stand of loblolly pine trees planted in the source area in May 2003. The U.S. Geological Survey planted an additional phytoremediation test stand of loblolly pine trees on the upgradient side of the southern end of the PRB in February 2008. At least once during the summer, however, the trees were inadvertently mowed during lawn cutting activity. The PRB along the main axis of the contaminant plume appears to be actively removing contamination. In contrast to the central area of the PRB, the data from the southern end of the PRB indicate that contaminants are moving around the PRB. Concentrations in wells upgradient from the PRB showed a general decrease in VOC concentrations. VOC concentrations in some wells in the forest downgradient from the PRB showed a sharp increase in 2005, followed by a decrease in 2006. Farther downgradient in the forest, the VOC concentrations began to increase in 2007 and continued to increase into 2008. The VOC-concentration changes in groundwater beneath the forest appear to indicate movement of a groundwater-contaminant pulse through the forest. It also is possible that the data may represent lateral shifting of the plume in response to changes in groundwater-flow direction.

Vroblesky, Don A.; Petkewich, Matthew D.

2009-01-01

215

Laboratory study on sequenced permeable reactive barrier remediation for landfill leachate-contaminated groundwater  

Microsoft Academic Search

Permeable reactive barrier (PRB) was a promising technology for groundwater remediation. Landfill leachate-polluted groundwater riches in various hazardous contaminants. Two lab-scale reactors (reactors A and B) were designed for studying the feasibility of PRB to remedy the landfill leachate-polluted groundwater. Zero valent iron (ZVI) and the mixture of ZVI and zeolites constitute the first section of the reactors A and

Dong Jun; Zhao Yongsheng; Zhang Weihong; Hong Mei

2009-01-01

216

Chemometric evaluation of nitrate contamination in the groundwater of a hard rock area in Dharapuram, south India  

NASA Astrophysics Data System (ADS)

This paper presents the results of investigations on groundwater nitrate contamination in the Dharapuram area of Tamil Nadu in south India as a primary step to initiate denitrification. Groundwater samples were collected from 26 selected locations during the pre-monsoon season in July 2010 and analysed for nitrate and other water quality parameters. Two important water types were identified, viz. Ca-Na-HCO3 and mixed Ca-Mg-Cl. It is found that the majority of samples possess high nitrate concentration; 57 % of samples exceeded the permissible limit of Indian (45 mg/L) and WHO (50 mg/L) drinking water standard. Spatial distribution map of NO3 suggested that major contamination was observed in the SW and NW parts of the study area. This result was in agreement with the corresponding land-use pattern in this study area. Denitrification process at greater depths was evident from the negative correlation between NO3 and well depth. The sources and controlling factors of high nitrate were investigated using cross plots of NO3 with other selected hydrochemical parameters. Positive correlation for NO3 was observed with EC, K, Cl and SO4. This analysis was capable of differentiating the various sources of nitrate in groundwater. The major sources of nitrate contamination are identified as areas of high fertilizer application, sewages and animal waste dumping yards. Regulation of these pollutant sources with appropriate and cost-effective denitrification process can restore the water quality in this area.

Sajil Kumar, P. J.; Jegathambal, P.; James, E. J.

2014-02-01

217

Application of Horizontal Flow Treatment Wells for In Situ Treatment of Perchlorate Contaminated Groundwater.  

National Technical Information Service (NTIS)

Groundwater contamination by perchlorate has recently been recognized as a significant environmental problem across the United States, and especially at Department of Defense facilities. In this study, a model is used to evaluate the potential of a innova...

J. C. Parr

2002-01-01

218

Effects of natural attenuation processes on groundwater contamination caused by abandoned waste sites in Berlin  

NASA Astrophysics Data System (ADS)

The aim of this research project is to identify, characterize and quantify natural attenuation (NA) processes in groundwater affected by emissions of abandoned waste disposal sites in Berlin-Kladow/Gatow, Germany. It is part of the funding priority called KORA established by the Federal Ministry for Education and Research (BMBF) to explore the extent to which NA can be used for remedial purposes for varied forms of soil and groundwater contamination. Information on the emission behaviour of individual parameters is generated on the basis of hydrogeochemical comparison of 20 years old and new data. Using groundwater-modelling and CFC-analysis, information on the transport and retention of pollutants in groundwater is compiled. The microbial colonization of contaminated aquifers is characterized by molecular biological methods [polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE)] to differentiate between contaminated and not contaminated zones.

Kerndorff, Helmut; Kühn, Stephan; Minden, Thomas; Orlikowski, Dagmar; Struppe, Thomas

2008-07-01

219

Abiotic Remediation of Nitro-Aromatic Groundwater Contaminants by Zero- Valent Iron.  

National Technical Information Service (NTIS)

Recent laboratory and field experiments have shown that some halogenated hydrocarbons undergo rapid reductive dehalogenation with zero-valent iron and the application of this process is being developed for in-situ remediation of contaminated groundwater. ...

A. Agrawal P. G. Tratnyek

1994-01-01

220

IDENTIFYING AND PREDICTING DIVING PLUME BEHAVIOR AT GROUNDWATER SITES CONTAMINATED WITH MTBE: PART 1  

EPA Science Inventory

In EPA Region 5, MTBE from leaking underground storage tanks (LUST) has contaminated groundwater. In some cases, drinking water supply wells have been impacted, which forced local communities to adopt expensive alternatives. Traditionally, LUST site characterizations have focus...

221

Site Characterization To Support Use Of Monitored Natural Attentuation For Remediation Of Inorganic Contaminants In Groundwater  

EPA Science Inventory

Technical recommendations have recently been published by the U.S. Environmental Protection Agency to address site characterization needed to support selection of Monitored Natural Attenuation (MNA) for cleanup of inorganic contaminant plumes in groundwater. Immobilization onto ...

222

PERMEABLE REACTIVE BARRIER STRATEGIES FOR REMEDIATION OF ARSENIC-CONTAMINATED GROUNDWATER: ABSTRACT  

EPA Science Inventory

NRMRL-ADA-01152 Wilkin*, R.T., and Paul*, C.J. "Permeable Reactive Barrier Strategies for Remediation of Arsenic- Contaminated Groundwater." In: Geological Society of America, Abstracts with programs., Geological Society of America Annua...

223

RAPID ASSESSMENT OF POTENTIAL GROUND-WATER CONTAMINATION UNDER EMERGENCY RESPONSE CONDITIONS  

EPA Science Inventory

Emergency response actions at chemical spills and abandoned hazardous waste sites often require rapid assessment of the potential for groundwater contamination by the chemical or waste compound. This manual provides a rapid assessment methodology for performing such an evaluation...

224

TAILORING CATALYSTS FOR HYDRODECHLORINATING CHLORINATED HYDROCARBON CONTAMINANTS IN GROUNDWATER. (R825689C078)  

EPA Science Inventory

Abstract A palladium-on-zeolite catalyst has been optimized for treating groundwater contaminated with halogenated hydrocarbon compounds (HHCs) by hydrodechlorination with dissolved hydrogen. Aqueous sulfite was used as the model poison and the dechlorination of 1,2-di...

225

TAILORING CATALYSTS FOR HYDRODECHLORINATING CHLORINATED HYDROCARBON CONTAMINANTS IN GROUNDWATER. (R825689C093)  

EPA Science Inventory

Abstract A palladium-on-zeolite catalyst has been optimized for treating groundwater contaminated with halogenated hydrocarbon compounds (HHCs) by hydrodechlorination with dissolved hydrogen. Aqueous sulfite was used as the model poison and the dechlorination of 1,2-di...

226

PERMEABLE REACTIVE BARRIERS FOR IN-SITU TREATMENT OF ARSENIC-CONTAMINATED GROUNDWATER  

EPA Science Inventory

Laboratory and field research has shown that permeable reactive barriers (PRBs) containing a variety of materials can treat arsenic (As) contaminated groundwater. Sites where these PRBs are located include a mine tailings facility, fertilizer and chemical manufacturing sites, a...

227

Investigation of Ground-Water Contamination at Solid Waste Management Unit 12, Naval Weapons Station Charleston, North Charleston, South Carolina  

USGS Publications Warehouse

The U.S. Geological Survey and the Naval Facilities Engineering Command Southeast investigated natural and engineered remediation of chlorinated volatile organic compound ground-water contamination at Solid Waste Management Unit 12 at the Naval Weapons Station Charleston, North Charleston, South Carolina. The primary contaminants of interest are tetrachloroethene, 1,1,1-trichloroethane, trichloroethene, cis-1,2-dichloroethene, vinyl chloride, 1,1-dichloroethane, and 1,1-dichloroethene. In general, the hydrogeology of Solid Waste Management Unit 12 consists of a surficial aquifer, composed of sand to clayey sand, overlain by dense clay that extends from about land surface to a depth of about 8 to 10 feet and substantially limits local recharge. During some months in the summer, evapotranspiration and limited local recharge result in ground-water level depressions in the forested area near wells 12MW-12S and 12MW-17S, seasonally reflecting the effects of evapotranspiration. Changes in surface-water levels following Hurricane Gaston in 2004 resulted in a substantial change in the ground-water levels at the site that, in turn, may have caused lateral shifting of the contaminant plume. Hydraulic conductivity, determined by slug tests, is higher along the axis of the plume in the downgradient part of the forests than adjacent to the plume, implying that there is some degree of lithologic control on the plume location. Hydraulic conductivity, hydraulic gradient, sulfur-hexafluoride measurements, and historical data indicate that ground-water flow rates are substantially slower in the forested area relative to upgradient areas. The ground-water contamination, consisting of chlorinated volatile organic compounds, extends eastward in the surficial aquifer from the probable source area near a former underground storage tank. Engineered remediation approaches include a permeable reactive barrier and phytoremediation. The central part of the permeable reactive barrier along the main axis of the contaminant plume appears to be actively removing contamination; however, ground-water contamination is moving around the southern end of the permeable reactive barrier. Changes in the contaminant concentrations along the path of ground-water transport reflect a complex variety of influences. Potential influences include dechlorination, sorption and desorption, transpirative removal by trees, lateral shifting of the plume, and the presence of zones of differing concentrations possibly reflecting one or more pulse releases of contamination from the source area. Near the source area at well 12MW-10S, volatile organic compound concentrations of cis-1,2-dichlorothene, vinyl chloride, 1,1-dichloroethane, and 1,1,1-trichloroethane continued an irregular decline, while tetrachloroethene and 1,1-dichloroethene showed marked fluctuations in concentration during 2005 and 2006. Volatile organic compound concentrations at well 12MW-03S continued to show decreasing concentrations with the June 2006 concentrations being the lowest yet recorded at that well for several volatile organic compounds. Concentration and delta carbon 13 data indicate that in the upgradient part of the plume, tetrachloroethene is being degraded to trichloroethene, which is being degraded to cis-1,2-dichloroethene, and cis-1,2-dichloroethene is accumulating faster than it is being depleted. Ground-water volatile organic compound concentrations also changed in some wells in the forested area in the midpart of the plume. Increasing tetrachloroethene and decreasing trichloroethene and 1,1-dichloroethene concentrations were observed at wells 12MW-05S and 12MW-29S, possibly reflecting a lateral shift in the axis of the contamination plume or an advancing contamination pulse. Substantial decreases in contamination occur in the forested area downgradient from well 12MW-05S. Probable major loss mechanisms in this area include evapotranspiration and sorption.

Vroblesky, Don A.; Casey, Clifton C.; Petkewich, Matthew D.; Lowery, Mark A.; Conlon, Kevin J.; Harrelson, Larry G.

2007-01-01

228

Development of a decision support system for groundwater pollution control at coal-mining contaminated sites  

Microsoft Academic Search

Groundwater contamination is one of the major environmental concerns at coal-mining sites. Highly saline or highly acidic water from coal-mining can introduce serious pollution to groundwater and adversely affect its quality. This impact may last a long time even after the mining activity has ceased. Identification of an appropriate remediation technique is critical for effective pollution control. However, due to

Xiaodong Zhang; Christine W. Chan; Gordon Huang

2005-01-01

229

A pragmatic approach for estimation of source-zone emissions at LNAPL contaminated sites  

NASA Astrophysics Data System (ADS)

When considering natural attenuation as a remediation strategy at a site contaminated by a light non-aqueous phase liquid (LNAPL), it is important to consider the emission of contaminants from the source zone. A quantification of source-zone emissions is essential both for comparison with down-gradient mass fluxes to provide an estimate of fractional mass flux reduction, as well as for estimating the source lifetime. Because the spatial distribution of LNAPL at a field site is strongly dependent on both the spill circumstances and the heterogeneity of the geologic materials, which can be problematic for in-situ determination, alternative methods for estimating source-zone emissions are needed. In this work, a three-dimensional multiphase flow and transport modelling approach is used to investigate the relationship between the lateral extent of an LNAPL body and the emission of contaminants to groundwater at a contaminated site. For simulations involving an LNAPL release in an aquifer comprised of heterogeneous porosity and permeability distributions that were generated geostatistically, it is shown that a simple linear relationship exists between the lateral extent of the LNAPL body in the capillary fringe and the emission to the aqueous phase. The parameters describing the relationship are found to be linear functions of the groundwater flow velocity and the vertical infiltration rate. This site-specific relationship provides a simple method to estimate contaminant emissions to groundwater at LNAPL contaminated sites.

Miles, B.; Maji, R.; Sudicky, E. A.; Teutsch, G.; Peter, A.

2008-02-01

230

A pragmatic approach for estimation of source-zone emissions at LNAPL contaminated sites.  

PubMed

When considering natural attenuation as a remediation strategy at a site contaminated by a light non-aqueous phase liquid (LNAPL), it is important to consider the emission of contaminants from the source zone. A quantification of source-zone emissions is essential both for comparison with down-gradient mass fluxes to provide an estimate of fractional mass flux reduction, as well as for estimating the source lifetime. Because the spatial distribution of LNAPL at a field site is strongly dependent on both the spill circumstances and the heterogeneity of the geologic materials, which can be problematic for in-situ determination, alternative methods for estimating source-zone emissions are needed. In this work, a three-dimensional multiphase flow and transport modelling approach is used to investigate the relationship between the lateral extent of an LNAPL body and the emission of contaminants to groundwater at a contaminated site. For simulations involving an LNAPL release in an aquifer comprised of heterogeneous porosity and permeability distributions that were generated geostatistically, it is shown that a simple linear relationship exists between the lateral extent of the LNAPL body in the capillary fringe and the emission to the aqueous phase. The parameters describing the relationship are found to be linear functions of the groundwater flow velocity and the vertical infiltration rate. This site-specific relationship provides a simple method to estimate contaminant emissions to groundwater at LNAPL contaminated sites. PMID:18022279

Miles, B; Maji, R; Sudicky, E A; Teutsch, G; Peter, A

2008-02-19

231

Modeling approaches to management of nitrate contamination of groundwater in a heavily cultivated area  

NASA Astrophysics Data System (ADS)

A three-dimensional variably-saturated groundwater flow and reactive transport modeling framework was implemented to simulate nitrate contamination in a heavily cultivated area in Jeju volcanic Island. In the study area, two localized aquifer systems (perched and regional groundwater) exist due to distributions of impermeable clay layers beneath the perched groundwater. The approximate application rate of chemical fertilizers was surveyed to be 627.9 kg-N/ha per year, which is much higher than the average annual chemical fertilizer usage in Jeju Island, 172 kg-N/ha per year. Severe nitrate contamination has been observed in the perched groundwater system and such perched groundwater has influenced regional groundwater quality, through poorly cemented wall of the distributed throughout the region wells. For a part of managing plan of nitrate contamination in the island, a numerical modeling framework was developed for various scenarios associated with the factors affecting nitrate contamination in the study area (i.e., usage amount of chemical fertilizers, cultivated methods, grouting condition of wells). This work provides useful information to suggest effective ways to manage nitrate contamination of groundwater in the agricultural field. Acknowledgements: This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2011-0001120) and by BK21 project of Korean Government.

Koh, E.; Park, Y.; Lee, K.

2011-12-01

232

The Use of Permeable Reactive Barriers for In-situ Remediation of Groundwater Contaminants  

Microsoft Academic Search

The treatment of contaminated groundwater is among the most difficult and expensive environmental problems and often the primary factor limiting closure of contaminated sites. The most common technology used historically for remediation of groundwater has been ex-situ pump-and-treat systems. Pump and treat systems are still suited for certain site-specific remediation scenarios; however, the limitations of pump-and-treat technologies have also been

Keith J. Mountjoy; Eric K. Pringle; Michael Choi; William Gowdy

233

Optimum P levels for arsenic removal from contaminated groundwater by Pteris vittata L. of different ages  

Microsoft Academic Search

Optimization of arsenic uptake by Pteris vittata may reduce the remediation time and cost of arsenic-contaminated groundwater. This greenhouse experiment evaluated the effects of five doses of P (0, 150, 300, 450 and 600?M P) and two fern ages (45 and 90d old) on the effectiveness of arsenic removal using 18L of contaminated groundwater per plant. Arsenic-depletion was monitored weekly

Jorge A. G. Santos; Maria I. Silva Gonzaga; Lena Q. Ma

2010-01-01

234

Signal Analysis on Pumping Source Identification in Groundwater Modeling  

NASA Astrophysics Data System (ADS)

In this paper, we introduce Independent Component Analysis (ICA) to groundwater modeling. ICA is combined with a groundwater simulation and optimization model to solve the pumping source identification problem. ICA has been successfully applied for source separation and feature extraction in signal processing. ICA is applied here to decompose the observed head at monitoring wells into a linear combination of head fluctuation caused by each pumping source, thus, creating an ideal situation that only one well is pumping with all monitoring wells are observing. Moreover, the decomposed head fluctuation at monitoring wells provides useful characteristics of pumping sources, including starting time, ending time, and relative distance among sources and observations. A hypothetical case is presented to test the proposed identification method and to demonstrate the potential of ICA in pumping source identification. The results clearly show that with ICA, adding characteristics and decreasing the number of unknowns, the source identification problem is solved correctly and efficiently. The maximum number of pumping sources could be identified is extended to the number of monitoring wells. The results obtained thus far show that signal analysis technique is a viable method which can be used for pumping source identification in groundwater modeling. Keywords: Independent Component Analysis, Pumping Source Identification, Groundwater Modeling

Liu, H.; Hsu, N.; Yeh, W. W.

2012-12-01

235

Identifying the sources of subsurface contamination at the Hanford Site in Washington using high-precision uranium isotopic measurements.  

PubMed

In the mid-1990s, a groundwater plume of uranium (U) was detected in monitoring wells in the B-BX-BY Waste Management Area at the Hanford Site in Washington. This area has been used since the late 1940s to store high-level radioactive waste and other products of U fuel-rod processing. Using multiple-collector ICP source magnetic sector mass spectrometry, high-precision uranium isotopic analyses were conducted of samples of vadose zone contamination and of groundwater. The isotope ratios 236U/238U, 234U/238U, and 238U/235U are used to distinguish contaminant sources. On the basis of the isotopic data, the source of the groundwater contamination appears to be related to a 1951 overflow event at tank BX-102 that spilled high-level U waste into the vadose zone. The U isotopic variation of the groundwater plume is a result of mixing between contaminant U from this spill and natural background U. Vadose zone U contamination at tank B-110 likely predates the recorded tank leak and can be ruled out as a significant source of groundwater contamination, based on the U isotopic composition. The locus of vadose zone contamination is displaced from the initial locus of groundwater contamination, indicating that lateral migration in the vadose zone was at least 8 times greater than vertical migration. The time evolution of the groundwater plume suggests an average U migration rate of approximately 0.7-0.8 m/day showing slight retardation relative to a groundwater flow of approximately 1 m/day. PMID:15260332

Christensen, John N; Dresel, P Evan; Conrad, Mark E; Maher, Kate; DePaolo, Donald J

2004-06-15

236

Identifying the Sources of Subsurface Contamination at the Hanford Site in Washington using High-precision Uranium Istopic Measurements  

SciTech Connect

In the mid-1990s, a groundwater plume of uranium (U) was detected in monitoring wells in the B-BX-BY Waste Management Area at the Hanford Site in Washington. This area has been used since the late 1940s to store high level radioactive waste and other products of U fuel-rod processing. Using multiple-collector ICP source magnetic sector mass spectrometry, high-precision uranium isotopic analyses were conducted of samples of vadose zone contamination and of groundwater. The isotope ratios 236U/238U, 234U/238U, and 238U/235U are used to distinguish contaminant sources. On the basis of the isotopic data, the source of the groundwater contamination appears to be related to a 1951 overflow event at tank BX-102 that spilled high-level U waste into the vadose zone. The U isotopic variation of the groundwater plume is a result of mixing between contaminant U from this spill and natural background U. Vadose zone U contamination at tank B-110 likely predates the recorded tank leak and can be ruled out as a significant source of groundwater contamination, based on the U isotopic composition. The locus of vadose zone contamination is displaced from the initial locus of groundwater contamination, indicating that lateral migration in the vadose zone was at least 8 times greater than vertical migration. The time evolution the groundwater plume suggests an average U migration rate of {approx}0.7-0.8 m/day showing slight retardation relative a groundwater flow of {approx}1 m/day.

Christensen, John N.; Dresel, P Evan; Conrad, Mark E.; Maher, Katharine; DePaolo, Donald J.

2004-06-15

237

A model for managing sources of groundwater pollution.  

USGS Publications Warehouse

The waste disposal capacity of a groundwater system can be maximized while maintaining water quality at specified locations by using a groundwater pollutant source management model that is based upon linear programing and numerical simulation. The decision variables of the management model are solute waste disposal rates at various facilities distributed over space. A concentration response matrix is used in the management model to describe transient solute transport and is developed using the US Geological Survey solute transport simulation model. The management model was applied to a complex hypothetical groundwater system. -from Author

Gorelick, S. M.

1982-01-01

238

Hydrogen sulphide production tests and the detection of groundwater faecal contamination by septic seepage.  

PubMed

The 'H2S test' is being advanced for microbiological water quality testing where conventional coliform based methods are impractical or too expensive. It involves ambient temperature incubation of water samples with nutrient formulated to generate hydrogen sulphide when 'faecal' bacteria are present. Recently a WHO review identified several concerns including the limited number of comparative studies, formulation variability, and false positives and negatives. In response we have compared the H2S test's ability to detect and quantify faecal contamination in an aquifer impacted by septic tank leachfields with measurements obtained concurrently using conventional bacterial indicators, coliphages, faecal sterol biomarkers, Cryptosporidium and Giardia. Like these other analytes, H2S testing detected a contamination gradient ranging from high (septic liquid) to moderate (exfiltration zones), to background (e.g. domestic bores), corresponding to indicator removal + dilution by factors > 10(6). Presence/absence tests could not distinguish between heavily and slightly contaminated waters, whereas multi-tube testing (e.g. 10 x 10 mL arrays) did. It was concluded that while the WHO review concerns are justified, the H2S test performance shows promise in sanitary survey work, can be improved by employing an mpn approach and has potential to aid in the protection of source water and identifying contaminated groundwater. PMID:16104433

Roser, D J; Ashbolt, N; Ho, G; Mathew, K; Nair, J; Ryken-Rapp, D; Toze, S

2005-01-01

239

How Groundwater Discharge Influences the Time Scales of Contaminant Release From Streambed Sediments  

NASA Astrophysics Data System (ADS)

Streambed sediments can act as long-term storage zones for organic contaminants originating from the stream water. Although contamination levels in German rivers have generally declined in recent years, streambed sediments might still be considerably contaminated. Groundwater discharge through the sediments can induce an advective contaminant transport so that contaminants are released back from the sediment to the stream water. In our study, groundwater fluxes were quantified along a reach of 220m length of a small man-made stream in the industrial area of Bitterfeld (Germany). The stream was used for waste water discharge from the chemical industry nearby until the early 1990s. The study focuses on the long-term behaviour of chlorinated benzenes (MCB, DCBs) which are the major contaminants at the study site. The groundwater fluxes were obtained with fine spatial resolution using streambed temperatures. Groundwater discharge ranged from 11.0 to 455.0 Lm-2 d-1. According to locations with high and low groundwater discharge, time-integrating passive samplers were installed in the streambed to monitor the vertical distribution of current contaminant concentrations. Batch experiments were conducted to obtain the kinetic parameters of the desorption process and the water-sediment distribution coefficients as input data for a transport model of the streambed. We applied a numerical one-dimensional advective transport model to simulate the timescales of contaminant release and their dependence on the magnitude of groundwater discharge. As initial condition a homogeneous contaminant distribution in the streambed sediment layer was assumed. The mass fluxes from the streambed to the water are determined by the flow velocity of the groundwater and the sediment water distribution coefficient of the specific substance. The long-term predictive modeling indicated that the time required to reduce the concentrations and the resulting mass fluxes to the water by 90% of the initial values will be in the scale of decades for high-discharge locations and centuries for low-discharge locations, respectively.

Schmidt, C.; Kalbus, E.; Martienssen, M.; Schirmer, M.

2007-12-01

240

Long term (1960-2010) trends in groundwater contamination and salinization in the Ogallala aquifer in Texas  

NASA Astrophysics Data System (ADS)

Although numerous studies have expounded on depletion of the Ogallala aquifer, very few researchers have studied groundwater quality therein which relates to the ‘usability’ of available groundwater resources. The objective of this study was to elucidate regional trends in groundwater quality and salinization in the Ogallala aquifer, underlying 49 counties and two Groundwater Management Areas (GMA 1 and 2) in Texas, on a decadal scale between 1960 and 2010. Contrasting groundwater quality distinguished GMA 1 (northern Ogallala) from GMA 2 (southern Ogallala), and shallow wells (depth <50 m) from deep (>50 m) wells. The GMA 2 was characterized by pronounced groundwater nitrate (NO3-) contamination accompanied by elevated levels of sulfate (SO42-), chloride (Cl-) and salinity (TDS), marked by an abundance of mixed cation SO4-Cl and Na-Cl facies. In contrast, Ca-Mg-HCO3 and Ca-HCO3 facies prevailed in GMA 1 with substantially lower salinization, SO42-, Cl- and NO3 contamination. In shallow wells, more abundant in GMA 2, about 80% and 32% of observations exceeded the United State Environmental Protection Agency’s Secondary Maximum Contaminant Level (SMCL, 500 mg L-1) for total dissolved solids (TDS) and MCL (44 mg L-1) for NO3, respectively in the 2000s (2000-2010), with progressive increases in both parameters since the 1960s (1960-1969). Majority (>60%) of the shallow observations since the 1980s (1980-1989) have exceeded the natural background of 11 mg L-1 of NO3- indicating anthropogenic sources, The NO3- contamination was more apparent in domestic wells indicating substantial human health risk. Groundwater salinization in this aquifer resulted from a combination of natural (e.g. upwelling of highly mineralized groundwater from the underlying formations, seepage from playas and saline plumes, and evaporative enrichment) and anthropogenic processes (irrigated agriculture and hydrocarbon exploration activities). Natural processes were largely aggravated by anthropogenic practices such as lowering of hydraulic heads in the Ogallala aquifer due to prolonged irrigational pumping, inducing cross-formational flow from underlying highly mineralized older formations (Edwards Trinity (High Plains)) which led to groundwater mixing between the formations and rise in salinity levels in the Ogallala aquifer over time.

Chaudhuri, Sriroop; Ale, Srinivasulu

2014-05-01

241

ESTIMATING RESIDENTIAL INDOOR AIR IMPACTS DUE TO GROUNDWATER CONTAMINATION  

Microsoft Academic Search

ABSTRACT Key words: chlorinated, decisions, groundwater, residential, risk The reliability of making,risk-based corrective action (RBCA) decisions using ASTM methods was evaluated. Indoor air quality (IAQ) testing results for 153 residential homes in 1998 at a site in Denver, Colo., were evaluated in this study. Decisions regarding groundwater remediation and indoor air mitigation in resi- dences located over a shallow groundwater,plume

D. w. Kurz

242

U.S. Geological Survey toxic Waste-Groundwater Contamination Program, fiscal year 1985  

USGS Publications Warehouse

In fiscal year 1982, the U S Geological Survey began an interdisciplinary research thrust entitled Toxic Waste-Groundwater Contamination Program The objective of the thrust was to provide earth sciences information necessary to evaluate and mitigate existing groundwater contamination problems resulting from the planned or inadvertant disposal of wastes and from certain land-use practices, and to improve future waste disposal and land-use practices The program supports process-oriented and interdisciplinary field research, and regional groundwater quality studies This article provides an overview of the current (Fiscal Year 1985) activities of the Toxic Waste Program ?? 1986 Springer-Verlag New York Inc.

Ragone, S. E.

1986-01-01

243

Identification of Pollution Sources in Transient Groundwater Systems  

Microsoft Academic Search

A methodology using a nonlinear optimization model is presentedfor estimating unknown magnitude, location and duration ofgroundwater pollution sources under transient flow and transportconditions. The proposed optimization model incorporates thegoverning equations of flow and solute transport as binding equalityconstraints, and thus essentially simulates the physical processes oftransient flow and transient transport in the groundwater systems.The proposed inverse model identifies unknown sources

Pooran S. Mahar; Bithin Datta

2000-01-01

244

Perched-Water Analysis Related to Deep Vadose Zone Contaminant Transport and Impact to Groundwater  

SciTech Connect

Perched-water conditions have been observed in the vadose zone above a fine-grained zone that is located just a few meters above the water table beneath the B-complex at the Hanford Site. The perched water, containing elevated concentrations of uranium and technetium-99, is important to consider in evaluating the future flux of contaminated water into the groundwater. A study was conducted to examine the perched-water conditions and quantitatively evaluate 1) factors that control perching behavior, 2) contaminant flux toward groundwater, and, 3) associated groundwater impact. Based on the current vertical transport pathways and large areal extent of the perched system, the evaluation was conducted using a one-dimensional (1-D) analysis. Steady-state scoping calculations showed that the perching-layer hydraulic conductivity is likely to be up to two orders of magnitude less than the base case value obtained from Hanford site literature. Numerical flow and transport simulations provided both steady-state and transient system estimates of water and contaminant behavior and were used to further refine the range of conditions consistent with current observations of perched water height and to provide estimates of future water and contaminant flux to groundwater. With a recharge rate of 6 cm/yr, representative of current disturbed surface conditions, contaminant flux from the perched water occurs over a time interval of tens of years. However, if the recharge rate is 0.35 cm/yr, representative of returning recharge to pre-Hanford Site levels, the contaminant flux into the groundwater is spread over hundreds of years. It was also demonstrated that removal of perched water by pumping would reduce the flux of water (and associated contaminants) to the groundwater, thereby impacting the long-term rate of contaminant movement to the groundwater.

Oostrom, Martinus; Truex, Michael J.; Carroll, KC; Chronister, Glen B.

2013-11-15

245

Conceptual Models for Migration of Key Groundwater Contaminants Through the Vadose Zone and Into the Upper Unconfined Aquifer Below the B-Complex  

SciTech Connect

The B-Complex contains 3 major crib and trench disposal sites and 3 SST farms that have released nearly 346 mega-liters of waste liquids containing the following high groundwater risk drivers: ~14,000 kg of CN, 29,000 kg of Cr, 12,000 kg of U and 145 Ci of Tc-99. After a thorough review of available vadose zone sediment and pore water, groundwater plume, field gamma logging, field electrical resistivity studies, we developed conceptual models for which facilities have been the significant sources of the contaminants in the groundwater and estimated the masses of these contaminants remaining in the vadose zone and currently present in the groundwater in comparison to the totals released. This allowed us to make mass balance calculations on how consistent our knowledge is on the current deep vadose zone and groundwater distribution of contaminants. Strengths and weaknesses of the conceptual models are discussed as well as implications on future groundwater and deep vadose zone remediation alternatives. Our hypothesized conceptual models attribute the source of all of the cyanide and most of the Tc-99 currently in the groundwater to the BY cribs. The source of the uranium is the BX-102 tank overfill event and the source of most of the chromium is the B-7-A&B and B-8 cribs. Our mass balance estimates suggest that there are much larger masses of U, CN, and Tc remaining in the deep vadose zone within ~20 ft of the water table than is currently in the groundwater plumes below the B-Complex. This hypothesis needs to be carefully considered before future remediation efforts are chosen. The masses of these groundwater risk drivers in the the groundwater plumes have been increasing over the last decade and the groundwater plumes are migrating to the northwest towards the Gable Gap. The groundwater flow rate appears to flucuate in response to seasonal changes in hydraulic gradient. The flux of contaminants out of the deep vadose zone from the three proposed sources also appears to be transient such that the evolution of the contaminant plumes is transient.

Serne, R. Jeffrey; Bjornstad, Bruce N.; Keller, Jason M.; Thorne, Paul D.; Lanigan, David C.; Christensen, J. N.; Thomas, Gregory S.

2010-07-01

246

Source identification study of heavy metal contamination in the industrial hub of Unnao, India.  

PubMed

India's Unnao region is home to many leather-treatment facilities and related industries. Industrial and agricultural waste leads to heavy metal contamination that infiltrates groundwater and leads to human health hazards. This work measured the amount of heavy metal in groundwater at specific sites near the industrial facilities in Unnao and identified potential sources of contamination as anthropogenic or lithogenic. Groundwater samples were taken from 10 bore well sites chosen for depth and proximity to industry. Data obtained from sample sites was interpreted using a multivariate statistical analytical approach, i.e., principal component analysis, clustering analysis, and correlation analysis. The results of the multivariate analysis showed that cadmium, copper, manganese, nickel, lead, and zinc were correlated with anthropogenic sources, while iron and chromium were associated with lithogenic sources. These findings provide information on the possible sources of heavy metal contamination and could be a model for assessing and monitoring heavy metal pollution in groundwater in other locales. This study analyzed a selection of heavy metals chosen on the basis of industries located in the study area, which might not provide a complete range of information about the sources and availability of all heavy metals. Therefore, an extended investigation on heavy metal fractions will be developed in further studies. PMID:24488365

Dwivedi, Ashish Kr; Vankar, Padma S

2014-06-01

247

Tracing nitrate pollution sources and transformation in surface- and ground-waters using environmental isotopes.  

PubMed

Water pollution in the form of nitrate nitrogen (NO3(-)-N) contamination is a major concern in most agricultural areas in the world. Concentrations and nitrogen and oxygen isotopic compositions of nitrate, as well as oxygen and deuterium isotopic compositions of surface and groundwater from a typical irrigated region in the North China Plain (NCP) collected from May to October in 2012 were analyzed to examine the major nitrate sources and transformations. Concentrations of NO3(-)-N ranged from 0.2 to 29.6mg/L (mean of 11.2mg/L) in surface water, and from 0.1 to 19.4mg/L (mean of 2.8mg/L) in groundwater. Approximately 46.7% of the surface water samples and 10% of the groundwater samples exceeded the World Health Organization (WHO) drinking water standard for NO3(-)-N. Surface water samples that exceeded the standard were collected mainly in the dry season (May and October), while groundwater samples that exceeded the standard were collected in the wet season (June). Overall, the highest nitrate levels were observed in surface water in May and in groundwater in June, indicating that fertilizer application, precipitation, and irrigation strongly influence the NO3(-)-N concentrations. Analyses of isotopic compositions suggest that the main sources of nitrate are nitrification of fertilizer and sewage in surface water, in contrast, mineralization of soil organic N and sewage is the groundwater sources during the dry season. When fertilizers are applied, nitrate will be transported by precipitation through the soil layers to the groundwater in the wet season (June). Denitrification only occurred in surface water in the wet season. Attempts should be made to minimize overuse of nitrogen fertilizers and to improve nitrogen use efficiency in irrigated agricultural regions. PMID:24858219

Zhang, Yan; Li, Fadong; Zhang, Qiuying; Li, Jing; Liu, Qiang

2014-08-15

248

Modeling Three-Dimensional Groundwater Flow and Advective Contaminant Transport at a Heterogeneous Mountainous Site in Support of Remediation Strategy  

SciTech Connect

A calibrated groundwater flow model for a contaminated site can provide substantial information for assessing and improving hydraulic measures implemented for remediation. A three-dimensional transient groundwater flow model was developed for a contaminated mountainous site, at which interim corrective measures were initiated to limit further spreading of contaminants. This flow model accounts for complex geologic units that vary considerably in thickness, slope, and hydrogeologic properties, as well as large seasonal fluctuations of the groundwater table and flow rates. Other significant factors are local recharge from leaking underground storm drains and recharge from steep uphill areas. The zonation method was employed to account for the clustering of high and low hydraulic conductivities measured in a geologic unit. A composite model was used to represent the bulk effect of thin layers of relatively high hydraulic conductivity found within bedrock of otherwise low conductivity. The inverse simulator ITOUGH2 was used to calibrate the model for the distribution of rock properties. The model was initially calibrated using data collected between 1994 and 1996. To check the validity of the model, it was subsequently applied to predicting groundwater level fluctuation and groundwater flux between 1996 and 1998. Comparison of simulated and measured data demonstrated that the model is capable of predicting the complex flow reasonably well. Advective transport was approximated using pathways of particles originating from source areas of the plumes. The advective transport approximation was in good agreement with the trend of contaminant plumes observed over the years. The validated model was then refined to focus on a subsection of the large system. The refined model was subsequently used to assess the efficiency of hydraulic measures implemented for remediation.

Zhou, Quanlin; Birkholzer, Jens T.; Javandel, Iraj; Jordan, Preston D.

2004-01-14

249

DEMONSTRATION OF THE HIPOX ADVANCED OXIDATION TECHNOLOGY FOR THE TREATMENT OF MTBE-CONTAMINATED GROUNDWATER  

EPA Science Inventory

The HiPOx technology is an advanced oxidation process that incorporates high-precision delivery of ozone and hydrogen peroxide to chemically destroy organic contaminants with the promise of minimizing bromate formation. A MTBE-contaminated groundwater from the Ventura County Nav...

250

A Stochastic Approach To Human Health Risk Assessment Due To Groundwater Contamination  

Microsoft Academic Search

We present a probabilistic framework to addressing adverse human health effects due to groundwater contamination. One of the main challenges in health risk assessment is in relating it to subsurface data acquisition and to improvement in our understanding of human physiological responses to contamination. In this paper we propose to investigate this problem through an approach that integrates flow, transport

F. P. de Barros; Y. Rubin

2006-01-01

251

Probabilistic assessment of ground-water contamination. 2: Results of case study  

Microsoft Academic Search

The first paper in this series presented a geostatistical framework for obtaining a probabilistic assessment of ground-water contamination. This paper presents the results of a case study that applies this framework to define the spatial extent and severity of nitrate and Dacthal (dimethyl tetrachloroterephthalate or DCPA, a herbicide) contamination in the unsaturated and saturated zones for a 150 km² site

Jonathan D. Istok; Christopher A. Rautman

1996-01-01

252

DEMONSTRATION OF THE HIPOX ADVANCED OXIDATION TECHNOLOGY FOR THE TREATMENT OF MTBE-CONTAMINATED GROUNDWATER  

EPA Science Inventory

The HiPOx technology is an advanced oxidation process that incorporates high-precision delivery of ozone and hydrogen peroxide to chemically destroy organic contaminants with the promise of minimizing bromate formation. A MTBE-contaminated groundwater from the Ventura County Nava...

253

IN SITU TREATMENT OF SOIL AND GROUNDWATER CONTAMINATED WITH CHROMIUM - TECHNICAL RESOURCE GUIDE  

EPA Science Inventory

New information and treatment approaches have been developed for chromium-contaminated soil and groundwater treatment. The prupose of this report is to bring together the most current information pertaining to the science of chromium contamination and the insitu treatment and co...

254

Modeling to Support Groundwater Contaminant Boundaries for the Shoal Underground Nuclear Test  

SciTech Connect

The purpose of this work is to characterize groundwater flow and contaminant transport at the Shoal underground nuclear test through numerical modeling using site-specific hydrologic data. The ultimate objective is the development of a contaminant boundary, a model-predicted perimeter defining the extent of radionuclide-contaminated groundwater from the underground test throughout 1,000 years at a prescribed level of confidence. This boundary will be developed using the numerical models described here, after they are approved for that purpose by DOE and NDEP.

K. Pohlmann; G. Pohll; J. Chapman; A. Hassan; R. Carroll; C. Shirley

2004-03-01

255

Nonpoint Source Groundwater Solute Transport Using Unit Response Functions  

NASA Astrophysics Data System (ADS)

Deterministic nonpoint source solute transport modeling in groundwater is traditionally a process that consumes a large amount of computational resources. Here, a three dimensional finite element groundwater flow model is coupled with a one dimensional finite element advection dispersion model. Using particle tracking and assuming long-term steady state flow conditions, we develop unit response functions that characterize the solute transport (such as nitrate and salinity) to spatially distributed production wells (including domestic wells) from solute leaching underneath spatially distributed surface sources. Individual surface sources include fields, septic systems, animal holding areas, impoundments, and waste water treatment plant recharge facilities. With known source-specific input functions, these unit response functions can be used to directly calculate time variant solute concentrations in wells deterministically, without the need for further numerical calculations. Alternative source management scenarios and their impact to regional groundwater quality can be computed quickly even with highly temporally and spatially variable surface solute loading, as one would expect to encounter in nonpoint source pollution problems. The unit response function method will be compared with a three dimensional solute transport model using an equivalent groundwater flow model and equivalent solute transport parameters. The advantages and potential applications of the Unit Response Function method will be discussed.

Klein, F.; Harter, T.

2009-12-01

256

Groundwater arsenic contamination affecting different geologic domains in India - a review: influence of geological setting, fluvial geomorphology and Quaternary stratigraphy  

SciTech Connect

Arsenic contamination in groundwater is pervasive within lowland organic-rich Bengal Delta and narrow entrenched channels in the Middle Ganga floodplains. Local areas of Damodar fan-delta and isolated areas within the Dongargarh Proterozoic rift-zone in central India are also contaminated. In this rift-zone, arsenic is enriched in felsic magmatic rocks and weathered rocks and soils from local areas are enriched further in arsenic and iron. Late Quaternary stratigraphy, geomorphology and sedimentation have influenced groundwater arsenic contamination in alluvium that aggraded during the Holocene sea-level rise. No specific source of arsenic could be identified, although Himalaya is the main provenance for the Ganga floodplain and the Bengal Delta. Gondwana coal seams and other Peninsular Indian rocks might be sources for arsenic in the Damodar fan-delta. As-bearing pyrite or any As-mineral is nearly absent in the aquifer sediments. Arsenic mainly occurs adsorbed on hydrated-iron-oxide (HFO), which coat sediment grains and minerals. Arsenic and iron are released to groundwater by bio-mediated reductive dissolution of HFO with corresponding oxidation of organic matter.

Acharyya, S.K.; Shah, B.A. [Jadavpur University, Calcutta (India). Dept. of Geological Science

2007-10-15

257

Long Term Remote Monitoring of TCE Contaminated Groundwater at Savannah River Site  

SciTech Connect

The purpose of this study was to develop a mobile self powered remote monitoring system enhanced for field deployment at Savannah River Site (SRS). The system used a localized power source with solar recharging and has wireless data collection, analysis, transmission, and data management capabilities. The prototype was equipped with a Hydrolab's DataSonde 4a multi-sensor array package managed by a Supervisory Control and Data Acquisition (SCADA) system, with an adequate pumping capacity of water samples for sampling and analysis of Trichloroethylene (TCE) in contaminated groundwater wells at SRS. This paper focuses on a study and technology development efforts conducted at the Hemispheric Center for Environmental Technology (HCET) at Florida International University (FIU) to automate the sampling of contaminated wells with a multi-sensor array package developed using COTS (Commercial Off The shelf) parts. Bladder pumps will pump water from different wells to the sensors array, water quality TCE indicator parameters are measured (i.e. pH, redox, ORP, DO, NO3 -, Cl-). In order to increase user access and data management, the system was designed to be accessible over the Internet. Remote users can take sample readings and collect data remotely over a web. Results obtained at Florida International University in-house testing and at a field deployment at the Savannah River Site indicate that this long term monitoring technique can be a feasible solution for the sampling of TCE indicator parameters at remote contaminated sites.

Duran, C.; Gudavalli, R.; Lagos, L.; Tansel, B.; Varona, J.; Allen, M.

2004-10-06

258

BENEFITS OF REDUCING DOMESTIC WELL NITRATE CONTAMINATION FROM CONCENTRATED ANIMAL FEEDING OPERATIONS: A NATIONAL MODEL OF GROUNDWATER CONTAMINATION  

Microsoft Academic Search

This paper presents an analysis of benefits to private drinking water well users from regulatory changes for concentrated animal feeding operations (CAFOs). Combining a statistical model of groundwater quality with benefit estimates based on values available from the literature, we develop aggregate national benefit estimates for reduced well water contamination from changes in CAFO regulations. The statistical model is developed

Jeffrey K. Lazo; Donald M. Waldman; Thomas D. Ottem; William J. Wheeler

2003-01-01

259

Edible Oil Barriers for Treatment of Perchlorate Contaminated Groundwater.  

National Technical Information Service (NTIS)

This Technical Report Addendum documents longevity and continued effectiveness of emulsified edible oil substrate for remediation of perchlorate and chlorinated solvents in groundwater. The project was funded by the Environmental Security Technology Certi...

M. T. Lieberman R. C. Borden

2008-01-01

260

QUALITY ASSURANCE IN COMPUTER SIMULATIONS OF GROUNDWATER CONTAMINATION  

EPA Science Inventory

In the development of policies and regulations for groundwater protection, in permitting, and in planning monitoring and remedial actions, the role of mathematical models is growing rapidly. Because water-resource management decisions should be based on technically and scientific...

261

Vulnerability of groundwater in Quaternary aquifers to organic contaminants: a case study in Wuhan City, China  

NASA Astrophysics Data System (ADS)

More than 30 organic contaminants were detected in shallow groundwaters at Wuhan, the largest city in central China. Seriously contaminated groundwaters were from densely populated, industrial and commercial areas. Abnormal concentrations were found in groundwater from Hankou, downtown Wuhan: trimethylbenzene up to 29 ?g/L, tetramethylbenzene up to 866 ?g/L, and trichloroethene up to 9.5 ?g/L. Benzene, Toluene, Ethylene and Xylene (BTEX) contamination of groundwater is serious and widespread at Wuhan, ranging between 0.14 and 25.0 ?g/L. Considering the hydrogeological conditions of most Chinese cities, DRAMIC, a modified version of the widely used DRASTIC model, was proposed by the authors for assessing vulnerability of groundwater to contamination. The factors D, R, A and I in DRAMIC model are the same as in DRASTIC. The factor topography is ignored. The factor soil media is substituted by a new factor aquifer thickness ( M) and the factor hydraulic conductivity of the aquifer by a new factor impact of contaminant ( C). The equation for determining the DRAMIC Index is: DRAMIC = 5 D R + 3 R R + 4 A R + 2 M R + 5 I R + 1 C R. The calculated DRAMIC Index can be used to identify areas that are more likely to be susceptible to groundwater contamination relative to each other. The higher the DRAMIC Index is, the greater the groundwater pollution potential. Applying DRAMIC, a GIS-based vulnerability map for Wuhan city was prepared. Interestingly, places such as downtown Hankou, where enhanced concentrations of BTEX have been detected, correspond quite well with those with higher DRAMIC ratings.

Wang, Yanxin; Merkel, Broder J.; Li, Yilian; Ye, Hui; Fu, Surong; Ihm, Dana

2007-11-01

262

Distinguishing sources of groundwater nitrate by 1H NMR of dissolved organic matter.  

PubMed

Dissolved organic matter (DOM) originating from a certain source usually carries characteristic marks in its molecular structures that can be recognized by spectroscopic analysis. Sources of water-borne contaminants, such as nitrate, can be identified by recognition of the characteristics of DOM entrained in the water. In this study, DOM in groundwaters sampled from a dairy/crop production area (Chino Basin, CA) was analyzed by 1H nuclear magnetic resonance (1H NMR). Results showed that DOM derived from natural soil organic matter has a characteristic resonance at a chemical shift region of 4.0-4.3 ppm, while DOM derived from dairy wastes has a characteristic resonance at a lower chemical shift region of 3.2-3.6 ppm. These signature resonances were then used to distinguish the origins of nitrate in the groundwater. It was found that disposal of dairy wastes on croplands is the primary source of nitrate contamination in groundwater underlying the Chino Basin dairy area. PMID:15312948

Lu, Jianhang; Chang, Andrew C; Wu, Laosheng

2004-11-01

263

Statistical Estimation and Visualization of Ground-Water Contamination Data.  

National Technical Information Service (NTIS)

This work presents methods of visualizing and animating statistical estimates of ground water and/or soil contamination over a region from observations of the contaminant for that region. The primary statistical methods used to produce the regional estima...

R. K. Boeckenhauer D. D. Cox K. B. Ensor P. B. Bedient A. W. Holder

2000-01-01

264

Determination of 90Sr and Pu isotopes in contaminated groundwater samples by inductively coupled plasma mass spectrometry  

NASA Astrophysics Data System (ADS)

A sensitive analytical method for determining the artificial radionuclides 90Sr, 239Pu and 240Pu at the ultratrace level in groundwater samples from the Semipalatinsk Test Site area in Kazakhstan by double-focusing sector field inductively coupled plasma mass spectrometry (ICP-SFMS) was developed. In order to avoid possible isobaric interferences at m/z 90 for 90Sr determination (e.g. 90Zr+, 40Ar50Cr+, 36Ar54Fe+, 58Ni16O2+, 180Hf2+, etc.), the measurements were performed at medium mass resolution under cold plasma conditions. Pu was separated from uranium by means of extraction chromatography using Eichrom TEVA resin with a recovery of 83%. The limits of detection for 90Sr, 239Pu and 240Pu in water samples were determined as 11, 0.12 and 0.1 fg ml-1, respectively. Concentrations of 90Sr and 239Pu in contaminated groundwater samples ranged from 18 to 32 and from 28 to 856 fg ml-1, respectively. The 240Pu/239Pu isotopic ratio in groundwater samples was measured as 0.17. This isotope ratio indicates that the most probable source of contamination of the investigated groundwater samples was the nuclear weapons tests at the Semipalatinsk Test Site conducted by the USSR in the 1960s.

Zoriy, Miroslav V.; Ostapczuk, Peter; Halicz, Ludwik; Hille, Ralf; Becker, J. Sabine

2005-04-01

265

Industrial contamination of a municipal water-supply lake by induced reversal of ground-water flow, Managua, Nicaragua  

SciTech Connect

Laguna Asososca, a large ground-water-fed volcanic crater, is an important source of municipal water supply for the city of Managua. In 1990, after 65 years of pumping at increasing rates from the crater, the gradient between the Laguna and the highly contaminated Lake Managua had potentially reversed, leading to a scenario where the Laguna was possibly drawing in contaminated ground water from Lake Managua and/or a highly contaminated aquifer below an industrial area located between the Laguna and Lake Managua. A drilling and sampling program undertaken between 1990 and 1992 found: (1) four synthetic organic chemicals in the Laguna (methylene chloride, chloroform, 1,3-dichlorobenzene and 1,4-dichlorobenzene), (2) numerous other synthetic organic chemicals near Laguna Asososca in the ground water below the industrial area, and (3) no evidence of Laguna Asososca drawing water from Lake Managua. It appears that the Laguna Asososca capture zone extended into the industrial area but not as far as Lake Managua. Ground-water flow modeling of the regional ground-water flow system was consistent with the field interpretation. Estimates of the relative mobilities of the synthetic organic chemicals indicated that the chemicals found in the water of Laguna Asososca likely represented the mobile leading edge of a contaminant plume emanating from the industrial area. The simplest and most effective solution to mitigate contamination of Laguna Asososca is to maintain its water level above that of Lake Managua by reducing its pumpage to about 50% of the 1990 rate.

Bethune, D.N.; Farvolden, R.N.; Ryan, M.C.; Guzman, A.L. [Waterloo Centre for Groundwater Research, Ontario (Canada)

1996-07-01

266

Assessment of Arsenic Contamination of Groundwater and Health Problems in Bangladesh  

PubMed Central

Excessive amounts of arsenic (As) in the groundwater in Bangladesh and neighboring states in India are a major public health problem. About 30% of the private wells in Bangladesh exhibit high concentrations of arsenic. Over half the country, 269 out of 464 administrative units, is affected. Similar problems exist in many other parts of the world, including the Unites States. This paper presents an assessment of the health hazards caused by arsenic contamination in the drinking water in Bangladesh. Four competing hypotheses, each addressing the sources, reaction mechanisms, pathways, and sinks of arsenic in groundwater, were analyzed in the context of the geologic history and land-use practices in the Bengal Basin. None of the hypotheses alone can explain the observed variability in arsenic concentration in time and space; each appears to have some validity on a local scale. Thus, it is likely that several bio-geochemical processes are active among the region’s various geologic environments, and that each contributes to the mobilization and release of arsenic. Additional research efforts will be needed to understand the relationships between underlying biogeochemical factors and the mechanisms for arsenic release in various geologic settings.

Khalequzzaman, Md.; Faruque, Fazlay S.; Mitra, Amal K.

2005-01-01

267

Groundwater contamination by nitrates and chlorides washed out from phosphorite ores in the Negev Desert, Israel  

NASA Astrophysics Data System (ADS)

A sharp rise in the nitrate-content (up to 7200 mg L -1) and in the chlorinity (up to 92000 mg L -1) was observed during the 1980's in the water of the Aqrabim spring outflowing in the Negev desert, Israel. The source of pollutants was traced to a resevoir of wastewater derived from the dressing of phosphorite ores mined in the area. These ores and the overlying gravels are characterized by high concentrations of soluble nitrates, chlorides and sulphates. Groundwater flow-paths were delineated by using chemical changes observed in the wastewater reservoir. During the last 6 years, the continuous percolation of wastewater enhanced the flushing of chalk and clay particles from the fractured chert aquifer causing a sharp increase in groundwater flow-rates from the reservoir to the springs from 7.5 m day -1 (in 1980) to 53 m day -1 (in 1986). This change suggests the development of new flow paths. The resulting rapid propagation of the contamination plume may have disastrous consequences on the limited water resources in the northern Arava-Dead Sea area.

Rosenthal, E.; Magaritz, M.; Ronen, D.; Gilead, D.

1988-09-01

268

Laboratory-scale Experiments to Evaluate Tidal Effects on Groundwater Contaminant Discharging to Coastal Waters  

Microsoft Academic Search

The research objective was to investigate the effect of tides on the concentration of groundwater contaminants discharging to a surface water body. This physical-chemical phenomenon was studied using a one-dimensional homogeneous sand column. Results of the experiment were confirmed using a three-dimensional heterogeneous groundwater tank model. A constant water level is imposed upstream, and the downstream water level is regulated

H. Chen; G. Pinder

2009-01-01

269

Removal of Cr(VI) from simulative contaminated groundwater by iron metal  

Microsoft Academic Search

The Cr(VI) removal from simulative contaminated groundwater using zero-valent iron (Fe0) filings, Fe0 powder and nanoscale Fe0 in batch experimental mode was studied. Cr(VI) is a primary pollutant of some soils and groundwater. Zero-valent iron, an important natural reductant, could transform Cr(VI) to Cr(III) which is much less toxic and immobile. The Cr(VI) removal percentage was 87% at a metal

Naman Cissoko; Zhen Zhang; Jinghui Zhang; Xinhua Xu

2009-01-01

270

Effect of salt on aerobic biodegradation of petroleum hydrocarbons in contaminated groundwater  

Microsoft Academic Search

Hydrocarbon-contaminated soil and groundwater at oil and gas production sites may be additionally impacted by salts due to\\u000a release of produced waters. However, little is known about the effect of salt on the in-situ biodegradation of hydrocarbons\\u000a by terrestrial microbes, especially at low temperatures. To study this effect, we prepared a groundwater-soil slurry from\\u000a two sites in Canada: a former

Ania C. Ulrich; Selma E. Guigard; Julia M. Foght; Kathleen M. Semple; Kathryn Pooley; James E. Armstrong; Kevin W. Biggar

2009-01-01

271

Examples of Department of Energy Successes for Remediation of Contaminated Groundwater: Permeable Reactive Barrier and Dynamic Underground Stripping ASTD Projects  

SciTech Connect

Since 1998, the Department of Energy's (DOE) Office of Environmental Management has funded the Accelerated Site Technology Deployment (ASTD) Program to expedite deployment of alternative technologies that can save time and money for the environmental cleanup at DOE sites across the nation. The ASTD program has accelerated more than one hundred deployments of new technologies under 76 projects that focus on a broad spectrum of EM problems. More than 25 environmental restoration projects have been initiated to solve the following types of problems: characterization of the subsurface using chemical, radiological, geophysical, and statistical methods; treatment of groundwater contaminated with DNAPLs, metals, or radionuclides; and other projects such as landfill covers, purge water management systems, and treatment of explosives-contaminated soils. One of the major goals of the ASTD Program is to deploy a new technology or process at multiple DOE sites. ASTD projects are encouraged to identify subsequent deployments at other sites. Some of the projects that have successfully deployed technologies at multiple sites focusing on cleanup of contaminated groundwater include: Permeable Reactive Barriers (Monticello, Rocky Flats, and Kansas City), treating uranium and organics in groundwater; and Dynamic Underground Stripping (Portsmouth, and Savannah River), thermally treating DNAPL source zones. Each year more and more new technologies and approaches are being used at DOE sites due to the ASTD program. DOE sites are sharing their successes and communicating lessons learned so that the new technologies can replace the baseline or standard approaches at DOE sites, thus expediting cleanup and saving money.

Purdy, C.; Gerdes, K.; Aljayoushi, J.; Kaback, D.; Ivory, T.

2002-02-27

272

Gulf of Mexico integrated science - Tampa Bay study, the impact of groundwater and contaminants on Tampa Bay  

USGS Publications Warehouse

Despite the recreational and economic value of coastal bays and estuaries, these ecosystems are often among our most 'troubled' natural environments. Urbanization, agriculture, mining, and shipping are just a few activities that can have a profound and lasting impact on the coastal zone. In order to maintain a healthy coastal ecosystem, it is crucial to develop reasonable management practices around expert scientific information. We still have much to learn about the quantity and quality of groundwater being discharged into Tampa Bay, Florida. We also need to improve our knowledge of a wide range of contaminants entering the bay and must be able to determine where they accumulate in seafloor sediments. Such buried contaminants can potentially be harmful to biota if they are released to the water column. U.S. Geological Survey (USGS) scientists and research partners from the University of South Florida (USF), the University of Florida (UF), and the Florida Marine Research Institute (FMRI) are mapping sources of groundwater, measuring groundwater flow into Tampa Bay, and assessing the impact of contaminants and sediments on bay water quality and ecosystem health.

Swarzenski, Peter W.

2005-01-01

273

Ultrasonic process for remediation of organics-contaminated groundwater/wastewater  

SciTech Connect

A technology is being developed that employs ultrasonic-wave energy for remediation of groundwater/wastewater contaminated with volatile organic compounds such as carbon tetrachloride (CCl{sub 4}) and trichloroethylene (TCE). This paper presents the updated results of a laboratory investigation of ultrasonic groundwater remediation using synthetic groundwaters prepared with laboratory deionized water. Key process parameters investigated included steady-state temperature, contaminant concentration, solution pH, sonication time, and intensity of the applied ultrasonics-wave energy. High destruction efficiencies of the target contaminants were achieved, and the sonication time required for a given degree of destruction decreased with increasing intensity of the applied ultrasonic energy. The sonication time can be further reduced by adding a chemical oxidant such as hydrogen peroxide.

Wu, J.M.; Peters, R.W.

1995-07-01

274

Assessment of groundwater contamination from a hazardous dump site in Ranipet, Tamil Nadu, India  

NASA Astrophysics Data System (ADS)

Tanneries located in an industrial development area of Ranipet (India) manufactured chromate chemicals during 1976-1996. A large quantity of associated hazardous solid wastes has been stacked about 5-m high above ground level, spread over 3.5 ha inside one of the factory premises. The study area receives an average annual rainfall of 1,100 mm. The granitic formation in the northern part of Palar River catchment has high infiltration rates and has resulted in fast migration of the contamination to the water table. Chromium levels in the groundwater were found up to 275 mg/l. The available hydrogeological, geophysical and groundwater quality data bases have been used to construct a groundwater flow and mass transport model for assessing the groundwater contamination and it has been calibrated for the next 30 years. The migration has been found to be very slow, with a groundwater velocity of 10 m/year. This is the first field-scale study of its kind in this industrial area. The findings are of relevance to addressing the groundwater pollution due to indiscriminate disposal practices of hazardous waste in areas located on the phreatic aquifer. Further, it has been reported that the untreated effluent discharge adjacent to the chromium dump site is most influential in the migration of contaminants.

Rao, G. Tamma; Rao, V. V. S. Gurunadha; Ranganathan, K.; Surinaidu, L.; Mahesh, J.; Ramesh, G.

2011-12-01

275

Contamination of groundwater by triazines, metolachlor and alachlor  

NASA Astrophysics Data System (ADS)

The movement of triazines (atrazine, simazine, cyanazine), metolachlor and alachlor were studied in continous irrigated corn in an Evesboro loamy sand soil. Both no-tillage and conventional tillage treatments were used. Atrazine and simazine were detected in the groundwater more frequently than cyanazine and metolachlor. Alachlor, atrazine and simazine moved rapidly to the groundwater if sufficient rainfall occurred shortly after they were applied. Alachlor concentrations ranged from 4.0 to 15.0 ppb and atrazine concentrations ranged from <1.0 to 54 ppb. Metachlor was detected in the groundwater more frequently than cyanazine. Metolachlor concentrations range from < 1.0 to 12.0 ppb and cyanzaine concentrations ranged from < 1.0 to 29.0 ppb. There was no large differences in pesticide movement between conventional tillage and no-tillage.

Ritter, W. F.; Scarborough, R. W.; Chirnside, A. E. M.

1994-01-01

276

The Groundwater Geochemistry of Waste Disposal Facilities  

Microsoft Academic Search

Landfills of solid waste are abundant sources of groundwater pollution. The potential for generatingstrongly contaminated leachate from landfill waste is very substantial. Even for small landfills the timescale can be measured in decades or centuries. This indicates that waste dumps with no measures to control leachate entrance into the groundwater may constitute a source of groundwater contamination long after dumping

P. L. Bjerg; H.-J. Albrechtsen; P. Kjeldsen; T. H. Christensen; I. M. Cozzarelli

2003-01-01

277

Chromium isotope variation along a contaminated groundwater plume: a coupled Cr(VI)- reduction, advective mixing perspective  

NASA Astrophysics Data System (ADS)

Chromium (Cr) is a common contaminant in groundwater, used in electroplating, leather tanning, wood preservation, and as an anti-corrosion agent. Cr occurs in two oxidation states in groundwater: Cr(VI) is highly soluble and mobile, and is a carcinogen; Cr(III) is generally insoluble, immobile and less toxic than Cr(VI). Reduction of Cr(VI) to Cr(III) is thus a central issue in approaches to Cr(VI) contaminant remediation in aquifers. Aqueous Cr(VI) occurs mainly as the chromate (CrO22-) and bichromate (HCrO2-) oxyanions, while Cr(III) is mainly "hexaquo" Cr(H2O)63+. Cr has four naturally-occurring stable isotopes: 50Cr, 52Cr, 53Cr and 54Cr. When Cr(VI) is reduced to Cr(III), the strong Cr-O bond must be broken, resulting in isotopic selection. Ellis et al. (2002) demonstrated that for reduction of Cr(VI) on magnetite and in natural sediment slurries, the change of isotopic composition of the remnant Cr(VI) pool was described by a Rayleigh fractionation model having fractionation factor ?Cr(VI)-Cr(III) = 3.4‰. We attempted to use Cr isotopes as a monitor of Cr(VI) reduction at a field site in Hinkley, California (USA) where groundwater contaminated with Cr(VI) has been under assessment for remediation. Groundwater containing up to 5 ppm Cr(VI) has migrated down-gradient from the contamination source through the fluvial to alluvial sediments to form a well-defined plume. Uncontaminated groundwater in the aquifer immediately adjacent to the plume has naturally-occurring Cr(VI) of 4 ppb or less (CH2M-Hill). In early 2006, colleagues from CH2M-Hill collected 17 samples of groundwater from within and adjacent to the plume. On a plot of ?53Cr vs. log Cr(VI), the data array is strikingly linear and differs markedly from the trend predicted for reduction of Cr(VI) in the contaminated water. There appear to be two groups of data: four samples with ?53Cr >+2‰ and Cr(VI) <4 ppb, and 13 samples with ?53Cr <+2‰ and Cr(VI) >15 ppb. Simple mixing lines between the groundwater samples having <4 ppb Cr(VI), taken to be representative of regional groundwater, and the contaminated water do not pass through the remainder of the data, discounting a simple advective mixing scenario. We hypothesize a more likely scenario that involves both Cr(VI) reduction and advective mixing. As the plume initially expands downgradient, Cr(VI) in water at the leading edge encounters reductant in the aquifer resulting in limited Cr(VI) reduction. As a result of reduction, ?53Cr of Cr(VI) remaining in solution at the leading edge increases along the "reduction" trend from 0 to ~+2‰. Inevitable mixing of this water at the leading edge with regional groundwater results in a suitable mixing end-member to combine with Cr(VI) within the plume in order to explain the bulk of the remaining data. Neither Cr(VI) reduction nor advective mixing of plume and regional groundwaters can explain the data on their own, implying an interplay of at least these two processes during plume evolution. Ellis, A.S., Johnson, T.M. and Bullen, T.D. 2002, Science, 295, 2060-2062.

Bullen, T.; Izbicki, J.

2007-12-01

278

Modeling to Support Groundwater Contaminant Boundaries for the Shoal Underground Nuclear Test  

SciTech Connect

Groundwater flow and radionuclide transport at the Shoal underground nuclear test are characterized using three-dimensional numerical models, based on site-specific hydrologic data. The objective of this modeling is to provide the flow and transport models needed to develop a contaminant boundary defining the extent of radionuclide-contaminated groundwater at the site throughout 1,000 years at a prescribed level of confidence. This boundary will then be used to manage the Project Shoal Area for the protection of the public and the environment.

K. Pohlmann; G. Pohll; J. Chapman; A. Hassan; R. Carroll; C. Shirley

2004-03-01

279

A Framework for Estimating Groundwater Concentrations of VOCs Emanating from a Vadose Zone Source (Invited)  

NASA Astrophysics Data System (ADS)

Soil vapor extraction (SVE) is a prevalent remediation approach for volatile organic compounds (VOCs) in the vadose zone. To support selection of an appropriate endpoint, i.e., the VOC concentration at which the remedy can be terminated for site closure or for transition to another remedy, an evaluation is needed to determine whether vadose zone contamination has been diminished sufficiently to protect groundwater. When vapor-phase diffusive transport is an important component of the overall contaminant fate and transport from a vadose zone source, a numerical analysis has shown that the expected groundwater concentration is controlled by a limited set of parameters, including site-specific dimensions, vadose zone properties, and source characteristics. Based on that approach, a framework was developed for estimating the VOC concentration in groundwater emanating from a vadose zone source. The framework uses results from three-dimensional VOC transport simulations for a matrix of parameter value combinations covering a range of potential site conditions. Interpolation and scaling processes are then applied to estimate contaminant concentrations at compliance (monitoring) wells for specific site conditions of interest. The framework has been incorporated into a user-friendly Microsoft Excel-based spreadsheet tool, which is made available to the public. The spreadsheet methodology provides a less computationally intensive alternative to three-dimensional multiphase modeling, while still allowing for parameter sensitivity and uncertainty analyses. In many cases, the framework spreadsheet may be appropriate to consider the effect of a diminishing vadose zone source over time. In this presentation, the conceptual model and spreadsheet development will be discussed.

Oostrom, M.; Truex, M.; Rice, A. K.; Carroll, K. C.; Simon, M. A.; Becker, D.

2013-12-01

280

A national reconnaissance of pharmaceuticals and other organic wastewater contaminants in the United States--I) groundwater.  

PubMed

As part of the continuing effort to collect baseline information on the environmental occurrence of pharmaceuticals, and other organic wastewater contaminants (OWCs) in the Nation's water resources, water samples were collected from a network of 47 groundwater sites across 18 states in 2000. All samples collected were analyzed for 65 OWCs representing a wide variety of uses and origins. Site selection focused on areas suspected to be susceptible to contamination from either animal or human wastewaters (i.e. down gradient of a landfill, unsewered residential development, or animal feedlot). Thus, sites sampled were not necessarily used as a source of drinking water but provide a variety of geohydrologic environments with potential sources of OWCs. OWCs were detected in 81% of the sites sampled, with 35 of the 65 OWCs being found at least once. The most frequently detected compounds include N,N-diethyltoluamide (35%, insect repellant), bisphenol A (30%, plasticizer), tri(2-chloroethyl) phosphate (30%, fire retardant), sulfamethoxazole (23%, veterinary and human antibiotic), and 4-octylphenol monoethoxylate (19%, detergent metabolite). Although sampling procedures were intended to ensure that all groundwater samples analyzed were indicative of aquifer conditions it is possible that detections of some OWCs could have resulted from leaching of well-construction materials and/or other site-specific conditions related to well construction and materials. Future research will be needed to identify those factors that are most important in determining the occurrence and concentrations of OWCs in groundwater. PMID:18556047

Barnes, Kimberlee K; Kolpin, Dana W; Furlong, Edward T; Zaugg, Steven D; Meyer, Michael T; Barber, Larry B

2008-09-01

281

Contamination on LDEF: Sources, distribution, and history  

NASA Technical Reports Server (NTRS)

An introduction to contamination effects observed on the Long Duration Exposure Facility (LDEF) is presented. The activities reported are part of Boeing's obligation to the LDEF Materials Special Investigation Group. The contamination films and particles had minimal influence on the thermal performance of the LDEF. Some specific areas did have large changes in optical properties. Films also interfered with recession rate determination by reacting with the oxygen or physically shielding underlying material. Generally, contaminant films lessen the measured recession rate relative to 'clean' surfaces. On orbit generation of particles may be an issue for sensitive optics. Deposition on lenses may lead to artifacts on photographic images or cause sensors to respond inappropriately. Particles in the line of sight of sensors can cause stray light to be scattered into sensors. Particles also represent a hazard for mechanisms in that they can physically block and/or increase friction or wear on moving surfaces. LDEF carried a rather complex mixture of samples and support hardware into orbit. The experiments were assembled under a variety of conditions and time constraints and stored for up to five years before launch. The structure itself was so large that it could not be baked after the interior was painted with chemglaze Z-306 polyurethane based black paint. Any analysis of the effects of molecular and particulate contamination must account for a complex array of sources, wide variation in processes over time, and extreme variation in environment from ground to launch to flight. Surface conditions at certain locations on LDEF were established by outgassing of molecular species from particular materials onto adjacent surfaces, followed by alteration of those species due to exposure to atomic oxygen and/or solar radiation.

Pippin, Gary; Crutcher, Russ

1993-01-01

282

Risk assessment for pesticide contamination of groundwater with sparse available data  

NASA Astrophysics Data System (ADS)

The contamination of the water resources by agrochemicals is recognized in industrial countries as a very important environmental problem, nevertheless in most of developing and threshold countries the risks for health and environmental problems are not considered. In these countries agrochemicals, which are forbidden since several years in Europe (e.g. atrazine), are still in use. In some threshold countries monitoring systems are already installed for nutrients (N, P) and also a few for heavy metals, but so far the contamination by pesticides is hardly ever controlled, thus there is no data available about pesticide concentrations in soil and water. The aim of this research is to develop a methodology to show farmers and other water users (water agencies, drinking water supply companies) in basins of developing or threshold countries with sparse available data the risk of contamination of the groundwater resources by pesticides. A few data like pesticide application, precipitation, irrigation, potential evaporation and soil types are available in some regions. If these data is reliable it can be used together with some justified estimated parameters to perform simulations of the fate of pesticides to the groundwater. Therefore in two study cases in Argentina and Chile pesticide models (e.g. PESTAN, IPTM-CS) were used to evaluate the risk of contamination of the groundwater. The results were compared with contamination indicators, like one developed by O. Heredia, for checking their plausibility. Afterwards the results of the models were used as input data for simulations at the catchment scale, for instance for a groundwater simulation model (VISUAL MODFLOW). The results show a great risk for the contamination of the groundwater resources in the selected study areas, especially by atrazine. On this account the findings will be used by local researchers to improve the knowledge and the awareness of farmers and other stakeholders about the contamination of the water resources by pesticides.

Bardowicks, K.; Heredia, O.; Billib, M.; Fernández Cirelli, A.; Boochs, P.

2009-04-01

283

REMEDIATION OF NITRATE-CONTAMINATED GROUNDWATER USING A BIOBARRIER  

Microsoft Academic Search

A biobarrier system has been developed for use in remediating shallow alluvial groundwater. This barrier is made from highly porous materials that are relatively long-lasting, carbon-based (to supply a limiting nutrient in nitrate destruction, in most cases), and extremely inexpensive and easy to emplace. In a series of laboratory studies, we have determined the effectiveness of this barrier at destroying

B. STRIETELMEIR

2000-01-01

284

REMEDIATION OF NITRATE-CONTAMINATED GROUNDWATER USING A BIOBARRIER  

Microsoft Academic Search

A biobarrier system has been developed for use in remediating shallow alluvial groundwater. This barrier is made from highly porous materials that are relatively long-lasting, carbon-based (to supply a limiting nutrient in nitrate destruction, in most cases), extremely inexpensive, and easy to replace. In a series of laboratory studies, we have determined the effectiveness of this barrier at destroying nitrate

B. A. Strietelmeier; M. L. Espinosa

2001-01-01

285

Modeling groundwater contamination transport for the Hanford Environmental Disposal Facility  

SciTech Connect

Preliminary groundwater analyses were performed for the Hanford Environmental Restoration Disposal Facility (ERDF) to demonstrate compliance With dose limit performance objectives in DOE Order 5820.2A. These analyses were designed to determine peak radionuclide concentrations in a theoretical drinking-water well 100 m downstream from the facility. The resulting peak concentrations can be used to determine inventory limits for the facility.

Finfrock, S.H.

1994-10-01

286

CAREER: The Role of Microorganisms in Arsenic Contamination of Groundwater  

Microsoft Academic Search

Arsenic exposure through drinking water affects the health of millions of people world wide. The heath effects of exposure to arsenic through dr inking water range from skin ailments to certain ca ncers (Hopenhayn, 2006). A multidisciplinary approach to studying how arsenic is released into groundwater i s needed to effectively answer many of the questions that exist. A study

Jennifer M. Weldon

287

ELECTROCHEMICAL DEGRADATION OF CHLORINATED CONTAMINANTS IN SEDIMENTS AND GROUNDWATER  

EPA Science Inventory

Chlorinated aliphatic and aromatic compounds account for much of the contamination found at sediments sites. Chlorinated aliphatic hydrocarbons such as trichloroethylene (TCE) occur as serious contaminants at 358 major hazardous waste sites in the USA. TCE is widely used as a sol...

288

Groundwater Monitoring Strategies for Variable Versus Constant Contaminant Loading Functions  

Microsoft Academic Search

Contaminant plumes were derived for constant and variable loading functions at locations within a landfill. Annually, the alternative loading functions injected the same volume of contaminated water. Mass transport modeling was used to evaluate the detection efficiencies of 25 monitoring transects, spaced evenly between the landfill and a downgradient compliance boundary. Respectively, the most efficient transects (requiring the fewest monitoring

Paul F. Hudak

1998-01-01

289

Ground-water and soil contamination near two pesticide-burial sites in Minnesota  

USGS Publications Warehouse

Preliminary investigations of the geology, groundwater hydrology , and soil and groundwater chemistry at sites in Pine and St. Louis Counties, Minnesota, have shown that contamination associated with pesticides buried at the sites is not widespread or highly concentrated. None of the pesticides sampled for in soil and in groundwater at the sites exceeded Minnesota soil and drinking water standards. About 1,500 pounds of lead arsenate were buried at the site in St. Louis County. Nearly 10,000 pounds of lead arsenate, as well as smaller quantities of organic pesticides (such as chlorpropham, DDT, endrin, and aldrin), lime sulfur, and magnesium carbonate were buried at the Pine County site. These chemicals were buried in shallow trenches at the sites during the early 1970's. The first wells drilled at each site were located to establish the direction of horizontal groundwater flow in each area. Groundwater flows to the northeast at the St. Louis County site and to the southeast at the Pine County site. Depths to the water table are about 30 ft at the Pine County site and about 25 ft at the St. Louis County site. In addition, groundwater is perched seasonally at about 5 ft below land surface in the immediate vicinity fo the burial site in Pine County. After the direction of flow was determined, additional wells were drilled down-gradient from the disposal areas at both sites to determine whether contaminations were migrating with groundwater away from the sites. In general, concentrations of lead and arsenic in soil and groundwater were below background concentrations for the areas. Concentrations of organic pesticides generally were below analytical-detection limits. The limited solubility of the chemicals and the tendency of the contaminants to be sorbed on soil particles probably combined to restrict mobilization of the chemicals. (Author 's abstract)

Stark, J. R.; Strudell, J. D.; Bloomgren, P. A.; Eger, P.

1987-01-01

290

Alternative Endpoints and Approaches Selected for the Remediation of Contaminated Groundwater at Complex Sites  

NASA Astrophysics Data System (ADS)

This presentation will focus on findings, statistics, and case studies from a recently-completed report for the Department of Defense's Environmental Security Technology Certification Program (ESTCP) (Project ER-0832) on alternative endpoints and alternative remedial strategies for groundwater remediation under a variety of Federal and state cleanup programs, including technical impracticability (TI) and other Applicable or Relevant and Appropriate Requirement (ARAR) waivers, state and local designations such as groundwater management zones, Alternate Concentration Limits (ACLs), use of monitored natural attenuation (MNA) over long timeframes, and more. The primary objective of the project was to provide environmental managers and regulators with tools, metrics, and information needed to evaluate alternative endpoints for groundwater remediation at complex sites. A statistical analysis of Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) sites receiving TI waivers will be presented as well as case studies of other types of alternative endpoints and alternative remedial strategies to illustrate the variety of approaches used at complex sites and the technical analyses used to predict and document cost, timeframe, and potential remedial effectiveness. Case studies provide examples of the flexible, site-specific, application of alternative endpoints and alternative remedial strategies that have been used in the past to manage and remediate groundwater contamination at complex sites. For example, at least 13 states consider some designation for groundwater containment in their corrective action policies, such as groundwater management zones, containment zones, and groundwater classification exemption areas. These designations typically indicate that groundwater contamination is present above permissible levels. Soil and groundwater within these zones are managed to protect human health and the environment. Lesson learned for the analyses conducted and the case studies evaluated allow for a more careful consideration of alternative, beneficial, and cost-effective cleanup objectives and metrics that can be achieved over the short-term (while eventually meeting long-term cleanup objectives or demonstrating the applicability of alternative endpoints), thus improving the site cleanup process at complex sites where appropriate.

Deeb, R. A.; Hawley, E.

2011-12-01

291

Effects of natural and human factors on groundwater quality of basin-fill aquifers in the southwestern United States-conceptual models for selected contaminants  

USGS Publications Warehouse

As part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program, the Southwest Principal Aquifers (SWPA) study is building a better understanding of the factors that affect water quality in basin-fill aquifers in the Southwestern United States. The SWPA study area includes four principal aquifers of the United States: the Basin and Range basin-fill aquifers in California, Nevada, Utah, and Arizona; the Rio Grande aquifer system in New Mexico and Colorado; and the California Coastal Basin and Central Valley aquifer systems in California. Similarities in the hydrogeology, land- and water-use practices, and water-quality issues for alluvial basins within the study area allow for regional analysis through synthesis of the baseline knowledge of groundwater-quality conditions in basins previously studied by the NAWQA Program. Resulting improvements in the understanding of the sources, movement, and fate of contaminants are assisting in the development of tools used to assess aquifer susceptibility and vulnerability. This report synthesizes previously published information about the groundwater systems and water quality of 15 information-rich basin-fill aquifers (SWPA case-study basins) into conceptual models of the primary natural and human factors commonly affecting groundwater quality with respect to selected contaminants, thereby helping to build a regional understanding of the susceptibility and vulnerability of basin-fill aquifers to those contaminants. Four relatively common contaminants (dissolved solids, nitrate, arsenic, and uranium) and two contaminant classes (volatile organic compounds (VOCs) and pesticide compounds) were investigated for sources and controls affecting their occurrence and distribution above specified levels of concern in groundwater of the case-study basins. Conceptual models of factors that are important to aquifer vulnerability with respect to those contaminants and contaminant classes were subsequently formed. The conceptual models are intended in part to provide a foundation for subsequent development of regional-scale statistical models that relate specific constituent concentrations or occurrence in groundwater to natural and human factors.

Bexfield, Laura M.; Thiros, Susan A.; Anning, David W.; Huntington, Jena M.; McKinney, Tim S.

2011-01-01

292

PERMEABLE REACTIVE BARRIER TREATMENT TECHNOLOGY FOR REMEDIATION OF INORGANIC-CONTAMINATED GROUNDWATER  

Microsoft Academic Search

Permeable reactive treatment wall technology has been studied as a means to remediate inorganic-contaminated groundwater in situ at Los Alamos National Laboratory (LANL), New Mexico, USA. The prevalence of multiple contaminants, including 238, 239, 240Pu, 241Am, 90Sr, 234, 235, 238U, nitrate (NO3 - ) and perchlorate (ClO4 - ), has prompted utilization of novel types of reactive media to immobilize

Tammy P. Taylor; Patrick Longmire; Dale A. Counce; Steve J. Chipera; John P. Kaszuba; James L. Conca

293

Phytoremediation of explosives contaminated groundwater in constructed wetlands: 2. Flow through study. Draft report  

SciTech Connect

This study evaluates the utility of constructed wetlands for remediating explosives contaminated groundwaters using bench scale flow-through type reactors. Specifially the study examines: the degradation of TNT, TNB, RDX, and HMX in contaminated waters in plant lagoons and gravel-based wetlands. The study also provides design recommendations for the wetland demonstration project to be located at the Milan Army Ammunition Plant (MAAP), in Tennessee.

DBehrends, L.L.; Sikora, F.J.; Phillips, W.D.; Baily, E.; McDonald, C.

1996-02-01

294

Groundwater contamination by pesticides and their metabolites: intrinsic properties and hydrodynamic constraints  

NASA Astrophysics Data System (ADS)

The time frame for natural attenuation of crude oil contamination in the subsurface has been studied for the last 30 years at a spill site located near Bemidji, Minnesota, USA. Data from the groundwater contaminant plume show that dissolved benzene concentrations adjacent to the oil decreased by 50% between 1993 and 2007. Concentrations of volatile components in the crude oil source were examined to determine if the benzene decrease was consistent with depletion of the oil source. The changes in volatile content of the oil were studied by analyzing a time series of oil samples collected from five wells. The results show that in 2008 benzene values in the oil ranged from 7% to 61% of the original amount indicating that benzene concentrations are slowly decreasing in the oil. Data from a suite of volatile compounds including alkylbenzenes, naphthalenes, cyclohexanes and C6-C12 n-alkanes show that loss rates of individual compounds are controlled by relative solubility and susceptibility to methanogenic biodegradation. Benzene and ethylbenzene appear to persist under methanogenic conditions at this site, suggesting that dissolution is the primary loss mechanism from the crude oil source. Losses are linearly correlated with pore space oil saturations and consistent with the relative solubilities of these compounds. A microcosm study lasting more than 13 months confirmed persistence of benzene under methanogenic conditions. Compounds for which loss is controlled by methanogenic degradation include the n-alkanes, toluene, and o-xylene. Losses of these compounds correlate better with location in the oil body than with pore space oil saturation, consistent with greater degradation below a topographic depression with focused recharge.

Bekins, B. A.; Baedecker, M. J.; Eganhouse, R. P.; Drennan, D. M.; Herkelrath, W. N.; Warren, E.; Cozzarelli, I.

2011-12-01

295

Health Consultation: Hamilton/Labree Roads Groundwater Contamination Site. Evaluation of United Rentals Indoor Air Sampling Results (July 2002), Chehalis, Lewis County, Washington. EPA Facility ID: WASFN1002174.  

National Technical Information Service (NTIS)

The Washington State Department of Health (DOH) conducted an exposure investigation to evaluate whether employees at a business situated above an area of contaminated groundwater (known as the Hamilton/Labree Roads groundwater contamination site, or site)...

2005-01-01

296

Screening of emerging contaminants and priority substances (2008/105/EC) in reclaimed water for irrigation and groundwater in a volcanic aquifer (Gran Canaria, Canary Islands, Spain).  

PubMed

In semiarid regions, reclaimed water can be an important source of emerging pollutants in groundwater. In Gran Canaria Island, reclaimed water irrigation has been practiced for over thirty years and currently represents 8% of water resources. The aim of this study was to monitor contaminants of emerging concern and priority substances (2008/105/EC) in a volcanic aquifer in the NE of Gran Canaria where the Bandama Golf Course has been sprinkled with reclaimed water since 1976. Reclaimed water and groundwater were monitoring quarterly from July 2009 to May 2010. Only 43% of the 183 pollutants analysed were detected: 42 pharmaceuticals, 20 pesticides, 12 polyaromatic hydrocarbons, 2 volatile organic compounds and 2 flame retardants. The most frequent compounds were caffeine, nicotine, chlorpyrifos ethyl, fluorene, phenanthrene and pyrene. Concentrations were always below 50 ng L(-1), although some pharmaceuticals and one pesticide, cholrpyrifos ethyl, were occasionally detected at higher concentrations. This priority substance for surface water exceeded the maximum threshold (0.1 ?g L(-1)) for pesticide concentration in groundwater (2006/118/EC). Sorption and degradation processes in soil account for more compounds being detected in reclaimed water than in groundwater, and that some contaminants were always detected in reclaimed water, but never in groundwater (flufenamic acid, propyphenazone, terbutryn and diazinon). Furthermore, erythromycin was always detected in reclaimed water (exceeding occasionally 0.1 ?g L(-1)), and was detected only once in groundwater. In contrast, some compounds (phenylephrine, nifuroxazide and miconazole) never detected in reclaimed water, were always detected in groundwater. This fact and the same concentration range detected for the groups, regardless of the water origin, indicated alternative contaminant sources (septic tanks, agricultural practices and sewerage breaks). The widespread detection of high adsorption potential compounds, and the independence of concentration with origin and depths, indicates the existence of preferential flows phenomena as potential contamination route in volcanic fractured materials. PMID:22858460

Estévez, Esmeralda; Cabrera, María del Carmen; Molina-Díaz, Antonio; Robles-Molina, José; Palacios-Díaz, María del Pino

2012-09-01

297

Influence Of Groundwater Discharge On Arsenic Contamination In Sediments  

EPA Science Inventory

A field investigation was conducted to evaluate the impact of a discharging arsenic plume on sediment contaminant characteristics at a site adjacent to a landfill in northeastern Massachusetts. Site characterization included assessment of the hydrologic and chemical samples coll...

298

Laser Fluorescence/Fiber Optic Monitoring of Groundwater Contaminant Biodegradation.  

National Technical Information Service (NTIS)

A one-year research project was conducted to determine the utility of the remote laser-induced fluorescence/fiber optics ground water contaminant detector (RLIF) technique for monitoring biodegradation processes in ground water systems. The project involv...

W. Chudyk

1987-01-01

299

The Use of Bacteria for Remediation of Mercury Contaminated Groundwater  

EPA Science Inventory

Many processes of mercury transformation in the environment are bacteria mediated. Mercury properties cause some difficulties of remediation of mercury contaminated environment. Despite the significance of the problem of mercury pollution, methods of large scale bioremediation ...

300

BIOREMEDIATION OF MIXED VAPOR PHASE CONTAMINANTS FROM SOILS AND GROUNDWATER  

EPA Science Inventory

Soil vapor phase contaminants commonly include combinations of chlorinated ethenes and petroleum hydrocarbons. Many chlorinated ethenes and petroleum hydrocarbons are readily degradable by a range of aerobic soil microorganisms, making the use of biological systems for degrading ...

301

A Combined Hydrological, Geochemical and Geophysical Reconnaissance of Groundwater Contamination In Oilfield Environment (republic of Tatarstan, Russia)  

NASA Astrophysics Data System (ADS)

Numerous brine leakages from production and injection wells and pipelines were ob- served at the site of study situated in Romashkinskoye oilfield. The groundwater flow, which follows the relief, is manifested by five springs. The salinity of these springs significantly increased during 20 years of oil exploitation at the site. The subsurface consists of sandstone, clayey sandstone, siltstone and limestone. Sampling of spring water and soils, as well as geophysical investigations, were carried out to develop the groundwater and contamination flow model of the site. In addition to the traditional bulk soil sampling, the mobile forms of chemical elements were investigated using the diffusion sampling technique (Levitski et al., 1995). The dipole-dipole resistivity and Spontaneous Polarization (SP) maps of the site were obtained. One prospecting bore- hole of 40 m was sunk. Vertical Electrical Sounding (VES) and Time Domain Spec- tral Induced Polarization Sounding (SIP), conducted at several points, were inverted to obtain rock and soil resistivity. The SIP measurements were performed to help geo- logical interpretation of the obtained resistivity cross-sections. The groundwater flow model was developed on the basis of borehole data, debits of the observed springs, and surface geophysical data. The model was calibrated using numerical modelling of SP. The 2D program GWFGEM based on the SillSs approach (1983) was applied. First, the preliminary groundwater flow model was obtained. Based on the coupling flow theory, sources of SP were calculated from water heads. Then, SP was calculated on the basis of SP sources and subsurface resistivity derived from the VES inversion. The above procedure was repeated several times to minimise the discrepancy between the observed and calculated SP. The flow balance for the whole site was obtained. The best indicators of the oil-related contamination at the site were found to be: (1) in groundwater U K, Na and Sr; (2) in bulk soil U Ca, Sr and Ba; and (3) in mobile forms U Mg, Co, Sr. All five springs at the site of study show the presence of oil-related con- tamination in all indicator elements. Comparison of the groundwater flow model and 1 of the geochemical data enables quantification of the contaminant transport rate and volume, as well as the development of a preliminary remediation scheme for the site of study. This work was supported by INTAS, project No 32046. 2

Levitski, A.; Titov, K.; Buès, M.; Ilyin, Yu.; Konosavski, P.; Kharkhordin, I.; Uchaev, V.; Sapozhnikov, B.; Kharkovski, K.

302

Using soil and contaminant properties to assess the potential for groundwater contamination to the lower Great Lakes, USA  

NASA Astrophysics Data System (ADS)

Contaminant risk factors in surface soil were evaluated within the urbanized Rouge River watershed in southeastern Michigan, USA, which includes metropolitan Detroit. An analytical risk factor model and Geographic Information Systems overlays were used to quantify and characterize the potential impacts of five categories of contaminants including DNAPLs (dense nonaqueous phase liquids), LNAPLs (light nonaqueous phase liquids), PAHs (polynuclear aromatic hydrocarbons), PCBs (polychlorinated biphenyls), and lead. The results indicate that DNAPL compounds released into sand, moraine, and sandy and silty clay soil types have the greatest potential to affect groundwater, and impact the Great Lakes ecosystem and the public health.

Kaufman, Martin M.; Rogers, Daniel T.; Murray, Kent S.

2009-01-01

303

A multi-level assessment methodology for determining the potential for groundwater contamination by pesticides  

Microsoft Academic Search

A multi-level pesticide assessment methodology has been developed to permit regulatory personnel to undertake a variety of assessments on the potential for pesticide used in agricultural areas to contaminate the groundwater regime at an increasingly detailed geographical scale of investigation. A multi-level approach accounts for a variety of assessment objectives and detail required in the assessment, the restrictions on the

A. S. Crowe; W. G. Booty

1995-01-01

304

Potential Radiological Doses From Groundwater Contaminated By The Saltstone Disposal Facility  

Microsoft Academic Search

Assessments of radiological dose from usage of groundwater potentially contaminated by the Saltstone Disposal Facility (Z-Area) were made for a hypothetical future resident farmer. These assessments were made using the routine aqueous release model LADTAP XL (C), which is the model used for demonstrating liquid pathway dose compliance at SRS. The dose factors used in LADTAP XL (C) are those

2005-01-01

305

SURFACE-ALTERED ZEOLITES AS PERMEABLE BARRIERS FOR IN SITU TREATMENT OF CONTAMINATED GROUNDWATER  

SciTech Connect

The overall objective of this effort is to develop and test a zeolite-based permeable barrier system for containing and remediating contaminated groundwater. The projected product is an engineered and tested permeable barrier system that can be adopted by the commercial sector.

Robert S. Bowman; Zhaohui Li; Stephen J. Roy; Todd Burt; Timothy L. Johnson; Richard L. Johnson

1999-08-30

306

Remediation of TCE-contaminated groundwater by a permeable reactive barrier filled with plant mulch (Biowall)  

Microsoft Academic Search

A pilot-scale permeable reactive barrier filled with plant mulch was installed at Altus Air Force Base in Oklahoma, USA to treat trichloroethylene (TCE) contamination in groundwater emanating from a landfill. The barrier was constructed in June 2002. It was 139 meters long, 7 meters deep, and 0.5 meters wide. The barrier is also called a Biowall because one of the

Xiaoxia Lu; John T. Wilson; Hai Shen; Bruce M. Henry; Donald H. Kampbell

2007-01-01

307

Grand challenge problems in environmental modeling and remediation: groundwater contaminant transport  

SciTech Connect

This report describes briefly the work of the Center for Subsurface Modeling (CSM) of the University of Texas at Austin (and Rice University prior to September 1995) on the Partnership in Computational Sciences Consortium (PICS) project entitled Grand Challenge Problems in Environmental Modeling and Remediation: Groundwater Contaminant Transport.

Todd Arbogast; Steve Bryant; Clint N. Dawson; Mary F. Wheeler

1998-08-31

308

OASIS: A GEOGRAPHICAL DECISION SUPPORT SYSTEM FOR GROUND-WATER CONTAMINANT MODELING  

EPA Science Inventory

Three new software technologies were applied to develop an efficient and easy to use decision support system for ground-water contaminant modeling. Graphical interfaces create a more intuitive and effective form of communication with the computer compared to text-based interfaces...

309

Contaminant Transport with Groundwater Flow in Unconfined Aquifer (Two-dimensional Numerical Solution)  

Microsoft Academic Search

The nature of physical process of groundwater contamination transport generates complexity in the theoretical formulation. The governing equations, which are 2nd order PDE (partial differential equation), are solved numerically using a finite difference method. To perform the numerical equations, computer code has been written in MATLAB, and a program has been developed. The aquifer is idealized as an unconfined aquifer

HASHIM MOHD KASSIM

310

IN-SITU REDUCTION OF CHROMIUM-CONTAMINATED GROUNDWATER, SOILS, AND SEDIMENTS BY SODIUM DITHIONITE  

EPA Science Inventory

Laboratory studies were conducted to characterize the extent of chromium contamination in the groundwater and underlying soils and sediments of a chrome-plating shop at the USCG Support Center near Elizabeth City, NC. Most of the mobile Cr(VI) is present in the capillary zone ...

311

Study of Inorganic Contaminant Removal from Rocky Mountain Arsenal (RMA) Groundwater.  

National Technical Information Service (NTIS)

Rocky Mountain Arsenal (RMA)has been used as a facility for numerous military and non-military activities which have resulted in the introduction of both organic and inorganic contaminants into the groundwater. Previous treatability studies at RMA have be...

1978-01-01

312

Testing of a benchscale Reverse Osmosis/Coupled Transport system for treating contaminated groundwater  

SciTech Connect

The Reverse Osmosis/Coupled Transport process is a innovative means of removing radionuclides from contaminated groundwater at the Hanford Site. Specifically, groundwater in the 200 West Area of the Hanford Site has been contaminated with uranium, technetium, and nitrate. Investigations are proceeding to determine the most cost effective method to remove these contaminants. The process described in this paper combines three different membrane technologies (reverse osmosis, coupled transport, and nanofiltration to purify the groundwater while extracting and concentrating uranium, technetium, and nitrate into separate solutions. This separation allows for the future use of the radionuclides, if needed, and reduces the amount of waste that will need to be disposed of. This process has the potential to concentrate the contaminants into solutions with volumes in a ratio of 1/10,000 of the feed volume. This compares to traditional volume reductions of 10 to 100 for ion exchange and stand-alone reverse osmosis. The successful demonstration of this technology could result in significant savings in the overall cost of decontaminating the groundwater.

Hodgson, K.M.; Lunsford, T.R.; Panjabi, G.

1994-01-01

313

A national reconnaissance of pharmaceuticals and other organic wastewater contaminants in the United States — I) Groundwater  

Microsoft Academic Search

As part of the continuing effort to collect baseline information on the environmental occurrence of pharmaceuticals, and other organic wastewater contaminants (OWCs) in the Nation's water resources, water samples were collected from a network of 47 groundwater sites across 18 states in 2000. All samples collected were analyzed for 65 OWCs representing a wide variety of uses and origins. Site

Kimberlee K. Barnes; Dana W. Kolpin; Edward T. Furlong; Steven D. Zaugg; Michael T. Meyer; Larry B. Barber

2008-01-01

314

EVALUATION OF SULFATE-REDUCING BACTERIA TO PRECIPITATE MERCURY FROM CONTAMINATED GROUNDWATER  

EPA Science Inventory

Several regions in the Republic of Kazakhstan are contaminated with mercury as a result of releases from industrial plants. Operations at an old chemical plant, "Khimprom", which produced chlorine and alkali in the 1970s - 1990s, resulted in significant pollution of groundwater ...

315

Flux-based method of characteristics for contaminant transport in flowing groundwater  

Microsoft Academic Search

A numerical method for treating advection-dominated contaminant transport in flowing groundwater is described. This method combines advantages of numerical discretizations by finite volume methods (like local mass conservation and the positivity of solutions) and by methods of characteristics (like larger time steps and reduced artificial numerical dispersion). For one-dimensional problems the method can produce equivalent algebraic systems as the finite

Peter Frolkovi?

2002-01-01

316

Reactive barrier treatment of groundwater contaminated by acid mine drainage: sulphur accumulation and sulphide formation  

Microsoft Academic Search

A permeable reactive barrier was installed in August 1995 at the Nickel Rim Mine near Sudbury, Ontario, Canada, for the passive remediation of groundwater contaminated with acid mine drainage. The reactive component of the barrier consists of a mixture of municipal and leaf compost and wood chips; the organic material promotes bacterially-mediated sulphate reduction. Hydrogen sulphide, a product of sulphate

SHAWN G. BENNER; DAVID W. BLOWES

1998-01-01

317

DEVELOPMENT OF BIOREMEDIATION TECHNIQUES FOR MERCURY CONTAMINATED GROUNDWATER IN NORTHERN KAZAKHSTAN"  

EPA Science Inventory

The objective of this research is to establish bacteria to bind or immobilize mobile mercury in groundwater.In the Republic of Kazakhstan and in other areas of the former USSR there are some regions contaminated with mercury as a result of technogenic releases from industrial pla...

318

Contamination of Groundwater by Organic Pollutants Leached from in-Situ Spent Shale.  

National Technical Information Service (NTIS)

The potential for contamination of groundwater by organic pollutants leached from in-situ spent shale was studied in a series of laboratory leaching experiments. Both batch-mode and continuous-flow column experiments were conducted to study the leaching p...

G. L. Amy

1978-01-01

319

Contaminants at Former Manufactured Gas Plants: Sources, Properties, and Processes  

Microsoft Academic Search

In the course of industrialization in the 19th century, manufactured gas plant sites were built in almost every larger town in Europe and the United States. Organic and inorganic contaminations pose a continuing threat to groundwater resources at these locations even though the operations were terminated decades ago. The different coal tars and tar oils present in the subsurface are

Markus Wehrer; Thilo Rennert; Tim Mansfeldt; Kai U. Totsche

2011-01-01

320

Evaluating Ecosystem Services for Reducing Groundwater Nitrate Contamination: Nitrate Attenuation in the Unsaturated and Saturated Zones  

NASA Astrophysics Data System (ADS)

Nitrates are the most common type of groundwater contamination in agricultural regions. Environmental policies targeting nitrates have focused on input control (e.g., restricted fertilizer application), intermediate loads control (e.g., reduce nitrate leached from crop fields), and final loads control (e.g., reduce catchment nitrate loads). Nitrate loads can be affected by hydrological processes in both unsaturated and saturated zones. Although many of these processes have been extensively investigated in literature, they are commonly modeled as exogenous to farm management. A couple of recent studies by scientists from the Lawrence Livermore National Laboratory show that in some situations nitrate attenuation processes in the unsaturated/saturated zone, particularly denitrification, can be intensified by certain management practices to mitigate nitrate loads. Therefore, these nitrate attenuation processes can be regarded as a set of ecosystem services that farmers can take advantage of to reduce their cost of complying with environmental policies. In this paper, a representative California dairy farm is used as a case study to show how such ecosystem attenuation services can be framed within the farm owner's decision-making framework as an option for reducing groundwater nitrate contamination. I develop an integrated dynamic model, where the farmer maximizes discounted net farm profit over multiple periods subject to environmental regulations. The model consists of three submodels: animal-waste-crop, hydrologic, and economic model. In addition to common choice variables such as irrigation, fertilization, and waste disposal options, the farmer can also endogenously choose from three water sources: surface water, deep groundwater (old groundwater in the deep aquifer that is not affected by farm effluent in the short term), and shallow groundwater (drainage water that can be recycled via capture wells at the downstream end of the farm). The capture wells not only recycle wastewater, but can also increase the likelihood of denitrification. Thus the farmer essentially can choose whether, and to which extent, to install capture wells and take advantage of the ecosystem attenuation services. Decision rules from the dynamic optimization model demonstrate best management practices for the farm to improve its economic and environmental performance. I further use an economic valuation technique to value these services. Under the Millennium Ecosystem Assessment framework, nitrate attenuation in the unsaturated and saturated zone provides regulatory ecosystem services to humans, mainly nutrient regulation and waste treatment. With the integrated farm model, the production function approach is adopted to get the economic value of these regulatory services. The results highlight the significant role the environment can play in nitrate pollution control and potential benefits from designing policies that acknowledge this role. The most desirable policies are those that create incentive for farmers to use potential ecosystem services, which significantly reduce environmental compliance costs and increase social welfare.

Wang, J.

2013-12-01

321

[Difference of contaminant composition between landfill leachates and groundwater and its reasons].  

PubMed

In order to investigate the groundwater pollution by landfill leachates, the distribution characteristics of inorganic salt, organic compounds and heavy metals in leachastes from a simple landfill and groundwater and its reason were study using conventional analysis, fluorescence excitation-emission matrix spectra and multivariate statistical analysis. The results showed that the landfill was heterogeneous, and the extracts from the landfill wastes showed a high concentration of NH4(+) -N, but low contents of Cl-, SO4(2-), dissolved organic matter (DOM) and heavy metals. The nitrification process was blocked due to a strong reducing atmosphere in landfill, which caused a low concentration of NO3(-) -N and NO2(-) -N in leachates. Cu was mainly associated with DOM in leachates, while the distribution of the metals Ba, Cd, Cr, Fe, Mn, Ni, Zn and As was primarily related to hydrophobic organic compounds. The contaminate compositions in different groundwater were similar except for the groundwater under the landfill site. In contrast to landfill leachates, the groundwater showed a low concentration of NH4(+) -N, but high concentrations of Cl-, SO4(2-), DOM, NO3(-) -N and NO2(-) -N except for the groundwater under the landfill site. The organic compounds in the groundwater were mainly originated from microbial activity, and the distribution of the metals Ba, Cd, Cu, Fe, Mn and Ni was mainly related to fluorescecent organic matter in DOM. The results showed that the leak point of landfill leachates can be identified through the cluster analysis method on the basis of the contaminant composition in groundwater. PMID:24946594

He, Xiao-Song; Yu, Hong; Xi, Bei-Dou; Cui, Dong-Yu; Pan, Hong-Wei; Li, Dan

2014-04-01

322

Storage and Release of Contaminants in Low Flow Zones in Source and Plumes  

NASA Astrophysics Data System (ADS)

Through a rich body of published research and recent studies at Colorado State University it has been shown that dissolved and sorbed phase contaminants in low flow zones can act as persistent sources of groundwater contamination. This occurs both in source zones and plumes. Examples of low flow zones included silt beds bounded by sand and sand layers bounded by gravel. Primary processes governing storage and release of contaminants in low flow zones include sorption, diffusion, and slow advection. The challenges of stored contaminants are that they can sustain groundwater plumes and adversely affect the timing and magnitude of downgradient water quality improvements associated with remedial actions. The following provides a brief summary of governing processes, implications, and ongoing research. Initially, chlorinated solvents move along the pathways with the greatest transmissivity. This is illustrated in a sand tank study where fluorescein dye in water is pumped through a tank containing interbedded layers of sand and clay. At early time, little if any contamination is present in the low flow layers (clay). With extended time, dissolved phase contaminants are driven into low flow zones by diffusion and/or slow advection. Contaminants in low flow zones are stored in both dissolved and sorbed phases. Removal of the upgradient source reduces contaminant concentrations in transmissive zones and drives releases of contaminants from low flow zones via back diffusion and slow advection. The release process is visually illustrated by the trails of water with fluorescein dye emanating from the clay layers in sand tank studies. Furthermore, analytical data from the tank studies illustrate asymmetrical breakthrough curves with extended tails. Field data from F. E. Warren AFB, WY provides further insights. An iron PRB was installed in 2000. This action reduced TCE concentrations at the barrier by multiple orders of magnitude to values less than 5 ug/L. After five years, TCE concentrations forty and sixty feet down gradient of the barrier dropped by only one order of magnitude. Sustained concentrations of TCE downgradient of the barrier are attributed to desorption and back diffusion from low flow zones. The degree to which stored contaminants can sustain plumes is dependent on site conditions. General conditions that favor sustained release of stored contaminants include: 1) A large degree of geologic heterogeneity, 2) Geologic settings with transmissive zones that are a small fraction of the total volume of the aquifer, 3) Contaminants that have large aqueous solubility, 4) Contaminants that are stable in their physical setting (e.g. chlorinated solvents in oxic environments) 5) Systems with relatively slow groundwater flow rates, 6) Sediments with high fractions of organic carbon, 7) Sites where large amounts of contaminant were released, and 8) Older sites where there has been a large amount of time for contaminants to move into low flow intervals. Primary implications include: 1) Release of stored contaminants can sustain contaminant discharge from source zones, 2) Given near perfect depletion and/or containment of sources, downgradient plumes can persist for extended periods, 3) A large fraction of the total stored contaminant mass can occur outside of source zones, 4) Source zone treatments that solely address transmissive zones may miss substantial contaminant mass in low flow zones and be subject to rebound.

Sale, T. C.; Doner, L. A.; Seger, E. S.

2006-12-01

323

Atacama perchlorate as an agricultural contaminant in groundwater: isotopic and chronologic evidence from Long Island, New York.  

PubMed

Perchlorate (ClO4-) is a common groundwater constituent with both synthetic and natural sources. A potentially important source of ClO4- is past agricultural application of ClO4(-)-bearing natural NO3- fertilizer imported from the Atacama Desert, Chile, but evidence for this has been largely circumstantial. Here we report ClO4- stable isotope data (delta37Cl, delta18O, and delta17O), along with other supporting chemical and isotopic environmental tracer data, to document groundwater ClO4 contamination sources and history in parts of Long Island, New York. Sampled groundwaters were oxic and ClO4- apparently was not affected by biodegradation within the aquifers. Synthetic ClO4- was indicated by the isotopic method in groundwater near a fireworks disposal site at a former missile base. Atacama ClO4- was indicated in agricultural and urbanizing areas in groundwaters with apparent ages > 20 years. In an agricultural area, ClO4- concentrations and ClO4-/NO3- ratios increased with groundwater age, possibly because of decreasing application rates of Atacama NO3- fertilizers and/or decreasing ClO4- concentrations in Atacama NO3- fertilizers in recent years. Because ClO4-/NO3- ratios of Atacama NO3- fertilizers imported in the past (approximately 2 x 10(-3) mol mol(-1)) were much higher than the CO4-/NO3- ratio of recommended drinking-water limits (7 x 10(-5) mol mol(-1) in New York), ClO4- could exceed drinking-water limits even where NO3- does not, and where Atacama NO3- was only a minor source of N. Groundwater ClO4- with distinctive isotopic composition was a sensitive indicator of past Atacama NO3- fertilizer use on Long Island and may be common in other areas that received NO3- fertilizers from the late 19th century through the 20th century. PMID:19731653

Böhlke, John Karl; Hatzinger, Paul B; Sturchio, Neil C; Gu, Baohua; Abbene, Irene; Mroczkowski, Stanley J

2009-08-01

324

[Simulation on remediation of benzene contaminated groundwater by air sparging].  

PubMed

Air sparging (AS) is one of the in situ remedial technologies which are used in groundwater remediation for pollutions with volatile organic compounds (VOCs). At present, the field design of air sparging system was mainly based on experience due to the lack of field data. In order to obtain rational design parameters, the TMVOC module in the Petrasim software package, combined with field test results on a coking plant in Beijing, is used to optimize the design parameters and simulate the remediation process. The pilot test showed that the optimal injection rate was 23.2 m3 x h(-1), while the optimal radius of influence (ROI) was 5 m. The simulation results revealed that the pressure response simulated by the model matched well with the field test results, which indicated a good representation of the simulation. The optimization results indicated that the optimal injection location was at the bottom of the aquifer. Furthermore, simulated at the optimized injection location, the optimal injection rate was 20 m3 x h(-1), which was in accordance with the field test result. Besides, 3 m was the optimal ROI, less than the field test results, and the main reason was that field test reflected the flow behavior at the upper space of groundwater and unsaturated area, in which the width of flow increased rapidly, and became bigger than the actual one. With the above optimized operation parameters, in addition to the hydro-geological parameters measured on site, the model simulation result revealed that 90 days were needed to remediate the benzene from 371 000 microg x L(-1) to 1 microg x L(-1) for the site, and that the opeation model in which the injection wells were progressively turned off once the groundwater around them was "clean" was better than the one in which all the wells were kept operating throughout the remediation process. PMID:23323427

Fan, Yan-Ling; Jiang, Lin; Zhang, Dan; Zhong, Mao-Sheng; Jia, Xiao-Yang

2012-11-01

325

In situ treatment of mixed contaminants in groundwater: Application of zero-valence iron and palladized iron for treatment of groundwater contaminated with trichloroethene and technetium-99  

SciTech Connect

The overall goal of this portion of the project was to package one or more unit processes, as modular components in vertical and/or horizontal recirculation wells, for treatment of volatile organic compounds (VOCs) [e.g., trichloroethene (TCE)] and radionuclides [e.g., technetium (Tc){sup 99}] in groundwater. The project was conceived, in part, because the coexistence of chlorinated hydrocarbons and radionuclides has been identified as the predominant combination of groundwater contamination in the US Department of Energy (DOE) complex. Thus, a major component of the project was the development of modules that provide simultaneous treatment of hydrocarbons and radionuclides. The project objectives included: (1) evaluation of horizontal wells for inducing groundwater recirculation, (2) development of below-ground treatment modules for simultaneous removal of VOCs and radionuclides, and (3) demonstration of a coupled system (treatment module with recirculation well) at a DOE field site where both VOCs and radionuclides are present in the groundwater. This report is limited to the innovative treatment aspects of the program. A report on pilot testing of the horizontal recirculation system was the first report of the series (Muck et al. 1996). A comprehensive report that focuses on the engineering, cost and hydrodynamic aspects of the project has also been prepared (Korte et al. 1997a).

Korte, N.E.; Muck, M.T.; Zutman, J.L.; Schlosser, R.M. [Oak Ridge National Lab., Grand Junction, CO (United States); Liang, L.; Gu, B. [Oak Ridge National Lab., TN (United States). Environmental Sciences Div.; Siegrist, R.L. [Oak Ridge National Lab., TN (United States). Environmental Sciences Div.]|[Colorado School of Mines, Golden, CO (United States); Houk, T.C. [Portsmouth Gaseous Diffusion Plant, Piketon, OH (United States); Fernando, Q. [Univ. of Arizona, Tucson, AZ (United States)

1997-04-01

326

Ground-water contamination from lead shot at Prime Hook National Wildlife Refuge, Sussex County, Delaware  

USGS Publications Warehouse

Prime Hook National Wildlife Refuge is located in southeastern Delaware in coastal lowlands along the margin of Delaware Bay. For 37 years, the Broadkiln Sportsman?s Club adjacent to the refuge operated a trap-shooting range, with the clay-target launchers oriented so that the expended lead shot from the range dropped into forested wetland areas on the refuge property. Investigators have estimated that up to 58,000 shotgun pellets per square foot are present in locations on the refuge where the lead shot fell to the ground. As part of the environmental risk assessment for the site, the U.S. Geological Survey (USGS) investigated the potential for lead contamination in ground water. Results from two sampling rounds in 19 shallow wells indicate that elevated levels of dissolved lead are present in ground water at the site. The lead and associated metals, such as antimony and arsenic (common shotgun pellet alloys), are being transported along shallow ground-water flowpaths toward an open-water slough in the forested wetland adjacent to the downrange target area. Water samples from wells located along the bank of the slough contained dissolved lead concentrations higher than 400 micrograms per liter, and as high as 1 milligram per liter. In contrast, a natural background concentration of lead from ground water in a well upgradient from the site is about 1 microgram per liter. Two water samples collected several months apart from the slough directly downgradient of the shooting range contained 24 and 212 micrograms per liter of lead, respectively. The data indicate that lead from a concentrated deposit of shotgun pellets on the refuge has been mobilized through a combination of acidic water conditions and a very sandy, shallow, unconfined aquifer, and is moving along ground-water flowpaths toward the surface-water drainage. Data from this study will be used to help delineate the lead plume, and determine the fate and transport of lead from the source area.

Soeder, Daniel J.; Miller, Cherie V.

2003-01-01

327

Responding to Industrial Contamination of Groundwater: A Case Study  

Microsoft Academic Search

The case study presented describes the discovery and the investigation of the trichloroethylene and related contamination of a public noncommunity well water supply in Montgomery County, Md. Although the local government's response to this potential public health threat was eventually successful, the government encountered several serious technical, legal, and institutional obstacles. Conclusions are drawn from this experience and recommendations are

Raymond J. Dever

1986-01-01

328

Using Major Elements to Determine Sources of Nitrate in Groundwater, Suffolk County, Long Island, NY  

NASA Astrophysics Data System (ADS)

Suffolk County is the eastern most county on Long Island with an area of 2,500 square kilometers and a population of 1.4 million. Groundwater is the only source of potable water for Suffolk County. Nitrate levels have become a concern as a result of the continued eastward urbanization of Long Island since the mid 1900's. In 2003, 2% of 1000 public supply wells had greater than 10 ppm nitrogen as nitrate, 8% had 6 to 10 ppm nitrogen as nitrate and 62% of the wells were rated as susceptible to increased nitrate contamination based on land use, travel time and prevalence. Nitrogen as nitrate above 10 ppm is harmful to infants and is currently the drinking water standard of the Environmental Protection Agency. The major sources of the nitrate in the urbanized areas are most likely turf grass fertilizer and sewage from septic tank/cesspool systems and sewage treatment plants that provide only secondary treatment. Turf grass occupies about 28% of the land. Two-thirds of the houses have septic tank/cesspool systems and a majority of the sewage treatment plants discharge effluent to the groundwater. Previous investigators of the sources of nitrate in groundwater on Long Island have used 15N values of nitrate-nitrogen to identify nitrate contamination (Bleifuss et al., 2000; Flipse and Bonner, 1985; Flipse et al., 1984; Kreitler et al., 1978). However, due to overlapping source signatures, nitrogen isotopes alone were not sufficient to characterize the sources of nitrate. More recent studies have shown that major elements that accompany nitrate in the groundwater (Bleifuss et al., 2000; Elhatip et al., 2003; Trauth and Xanthopoulos, 1997) may distinguish sources of nitrate with less ambiguity. In this study samples of waste water from septic tank/cesspool systems and sewage treatment plants and samples of soil water collected below turf grass that is not fertilized, fertilized with organic fertilizer and fertilized with chemical fertilizer were analyzed for major elements. Major element data for groundwater from Suffolk County Water Authority municipal wells have been characterized as a function of capture zone land use (Source Water Assessment Project, CDM, 2003). The data for the groundwater and the waste water and the soil water were then compared. The elements Na, Mg, Cl, NO3 and SO4 proved most successful as nitrate tracers on element-element plots. There is a distinct relationship between land use and source of nitrate contamination such that ground waters sourced in: (1) low residential density areas (1 or less dwelling units per acre (DU/acre)) plot in turf grass cultivation fields (2) medium residential areas (2-10 DU/acre) and high residential areas (more than 10 DU/acre) plot as a mixture of turf grass cultivation and wastewater (3) agricultural areas plot in the turf grass cultivation field and (4) vacant or open land use plot close to average rain water compositions.

Munster, J.; Hanson, G.; Bokuniewicz, H.

2004-05-01

329

Evaluation of Using Caged Clams to Monitor Contaminated Groundwater Exposure in the Near-Shore Environment of the Hanford Site 300 Area  

SciTech Connect

The Asiatic clam (Corbicula fluminea) has been identified as an indicator species for locating and monitoring contaminated groundwater in the Columbia River. Pacific Northwest National Laboratory conducted a field study to explore the use of caged Asiatic clams to monitor contaminated groundwater upwelling in the 300 Area near-shore environment and assess seasonal differences in uranium uptake in relation to seasonal flow regimes of the Columbia River. Additional objectives included examining the potential effects of uranium accumulation on growth, survival, and tissue condition of the clams. This report documents the field conditions and procedures, laboratory procedures, and statistical analyses used in collecting samples and processing the data. Detailed results are presented and illustrated, followed by a discussion comparing uranium concentrations in Asiatic clams collected at the 300 Area and describing the relationship between river discharge, groundwater indicators, and uranium in clams. Growth and survival, histology, and other sources of environmental variation also are discussed.

Larson, Kyle B.; Poston, Ted M.; Tiller, Brett L.

2008-01-31

330

Bioaugmented remediation of high concentration BTEX-contaminated groundwater by permeable reactive barrier with immobilized bead.  

PubMed

Ineffective biostimulation requires immediate development of new technologies for remediation of high concentration BTEX-contaminated (benzene, toluene, ethylbenzene and xylene) groundwater. In this study, bioaugmentation with Mycobacterium sp. CHXY119 and Pseudomonas sp. YATO411 immobilized bead was used to remediate BTEX-contaminated groundwater with about 100 mg l(-1) in total concentration. The batch test results showed that the CHXY119 and YATO411 immobilized bead completely biodegraded each BTEX compound, and the maximum biodegradation rates were 0.790 mg l(-1) h(-1) for benzene, 1.113 mg l(-1) h(-1) for toluene, 0.992 mg l(-1) h(-1) for ethylbenzene and 0.231 mg l(-1) h(-1) for p-xylene. The actual mineralization rates were 10.8% for benzene, 10.5% for toluene, 5.8% for ethylbenzene and 11.4% for p-xylene, which indicated that the bioremediation of BTEX by the immobilized bead requires a rather small oxygen supply. Degradation rates achieved by the bioaugmented permeable reactive barrier (Bio-PRB) system of the immobilized bead were 97.8% for benzene, 94.2% for toluene, 84.7% for ethylbenzene and 87.4% for p-xylene; and the toxicity of the groundwater fell by 91.2% after bioremediation by the bioaugmented PRB, which confirmed its great potential for remediating groundwater with high concentrations of contaminants. PMID:23200621

Xin, Bao-Ping; Wu, Chih-Hung; Wu, Cheng-Han; Lin, Chi-Wen

2013-01-15

331

Massive Microbiological Groundwater Contamination Associated with a Waterborne Outbreak in Lake Erie, South Bass Island, Ohio  

PubMed Central

Background A groundwater-associated outbreak affected approximately 1,450 residents and visitors of South Bass Island, Ohio, between July and September 2004. Objectives To examine the microbiological quality of groundwater wells located on South Bass Island, we sampled 16 wells that provide potable water to public water systems 15–21 September 2004. Methods We tested groundwater wells for fecal indicators, enteric viruses and bacteria, and protozoa (Cryptosporidium and Giardia). The hydrodynamics of Lake Erie were examined to explore the possible surface water–groundwater interactions. Results All wells were positive for both total coliform and Escherichia coli. Seven wells tested positive for enterococci and Arcobacter (an emerging bacterial pathogen), and F+-specific coliphage was present in four wells. Three wells were positive for all three bacterial indicators, coliphages, and Arcobacter; adenovirus DNA was recovered from two of these wells. We found a cluster of the most contaminated wells at the southeast side of the island. Conclusions Massive groundwater contamination on the island was likely caused by transport of microbiological contaminants from wastewater treatment facilities and septic tanks to the lake and the subsurface, after extreme precipitation events in May–July 2004. This likely raised the water table, saturated the subsurface, and along with very strong Lake Erie currents on 24 July, forced a surge in water levels and rapid surface water–groundwater interchange throughout the island. Landsat images showed massive influx of organic material and turbidity surrounding the island before the peak of the outbreak. These combinations of factors and information can be used to examine vulnerabilities in other coastal systems. Both wastewater and drinking water issues are now being addressed by the Ohio Environmental Protection Agency and the Ohio Department of Health.

Fong, Theng-Theng; Mansfield, Linda S.; Wilson, David L.; Schwab, David J.; Molloy, Stephanie L.; Rose, Joan B.

2007-01-01

332

Geochemical modeling and multivariate statistical evaluation of trace elements in arsenic contaminated groundwater systems of Viterbo Area, (Central Italy).  

PubMed

Contamination of groundwater by naturally occurring arsenic has recently become a disturbing environmental problem in Viterbo area, Central Italy. Arsenic concentrations in most of the public supply networks exceed the maximum allowable limit of 10 ?g/l (WHO) for drinking water. The primary purpose of this paper is to obtain a better understanding of the factors contributing to the high levels of As in water supply networks. This study focuses on (a) the determination of basic hydrochemical characteristics of groundwater, (b) the identification of the major sources and processes controlling the As contamination in public supply networks, (c) to find out possible relationships among the As and other trace elements through principal component analysis (PCA). Groundwater samples from public water supply wells and springs were collected and analysed for physico-chemical parameters and trace elements. Springs and well water samples are predominantly of the Na-HCO3, Na -Ca-HCO3 and Ca-HCO3 types and the highest arsenic concentrations were observed in Na-HCO3 type water. Eh-pH diagrams reveal that H2AsO4 (-) and HAsO4 (2-), As(V) arsenate, are the dominating As species highlighting slightly to moderately oxidizing conditions. Geochemical modeling indicates that arsenic-bearing phases were undersaturated in the groundwater, however most of the samples were saturated with respect to Fe (i.e. magnetite, hematite and goethite) and Al (diaspore and boehmite) oxide and hydroxide minerals. Concentrations of As, Li, B, Co, Sr, Mo, U and Se are highly correlated (r?>?0.7) with each other, however in some groundwater samples As show also good correlations (r?>?0.5) with Fe and Mn elements reflecting the relationships among the trace elements result from different geochemical processes. Evaluation of the principal component (PCA) analysis and geochemical modeling suggest that the occurrence of As and other trace element concentrations in groundwater are probably derived from (i) weathering and/or dissolution of volcanic source aquifer materials and (ii) adsorption/desorption processes on the Fe and Al oxide and hydroxide minerals. PMID:24926419

Sappa, Giuseppe; Ergul, Sibel; Ferranti, Flavia

2014-01-01

333

Contamination of Groundwater Systems in the US and Canada by Enteric Pathogens, 1990-2013: A Review and Pooled-Analysis  

PubMed Central

Background Up to 150 million North Americans currently use a groundwater system as their principal drinking water source. These systems are a potential source of exposure to enteric pathogens, contributing to the burden of waterborne disease. Waterborne disease outbreaks have been associated with US and Canadian groundwater systems over the past two decades. However, to date, this literature has not been reviewed in a comprehensive manner. Methods and Principal Findings A combined review and pooled-analysis approach was used to investigate groundwater contamination in Canada and the US from 1990 to 2013; fifty-five studies met eligibility criteria. Four study types were identified. It was found that study location affects study design, sample rate and studied pathogen category. Approximately 15% (316/2210) of samples from Canadian and US groundwater sources were positive for enteric pathogens, with no difference observed based on system type. Knowledge gaps exist, particularly in exposure assessment for attributing disease to groundwater supplies. Furthermore, there is a lack of consistency in risk factor reporting (local hydrogeology, well type, well use, etc). The widespread use of fecal indicator organisms in reported studies does not inform the assessment of human health risks associated with groundwater supplies. Conclusions This review illustrates how groundwater study design and location are critical for subsequent data interpretation and use. Knowledge gaps exist related to data on bacterial, viral and protozoan pathogen prevalence in Canadian and US groundwater systems, as well as a need for standardized approaches for reporting study design and results. Fecal indicators are examined as a surrogate for health risk assessments; caution is advised in their widespread use. Study findings may be useful during suspected waterborne outbreaks linked with a groundwater supply to identify the likely etiological agent and potential transport pathway.

Hynds, Paul Dylan; Thomas, M. Kate; Pintar, Katarina Dorothy Milena

2014-01-01

334

Influence of surface water/groundwater interactions on stream and wetland water quality: analytical solutions for coupled contaminant transport equations  

NASA Astrophysics Data System (ADS)

Wetlands are located in transitional zones between uplands and downstream flooded systems and surface water/groundwater interactions are frequently observed especially in riparian wetlands where the water level fluctuates frequently during the rainy season. Moreover, surface water/groundwater interactions also influence the characteristics of contaminant transport in pools and riffles, and in meandering type of streams. Therefore, it is important to investigate and solve these processes accurately to improve the prediction of downstream water quality. Although there are many experimental and numerical studies available in the literature which discuss and model the surface water/ground water interactions in streams and wetlands, very few analytical solutions have been conducted. Analytical solutions are helpful tools for verification of numerical solutions and they provide fast and accurate results for practical problems. Furthermore, they provide an understanding to the influence of each parameter in hydrological and contaminant transport models for streams and wetlands. In order to contribute to the research in understanding the behavior of water quality in streams and wetlands, analytical solutions are developed for the coupled contaminant transport equations of several transient storage and wetland models. Among these models are the wetland model WETland Solute TrANsport Dynamics (WETSAND) developed by Kazezyilmaz-Alhan et al. (2007), the transient storage models developed by Bencala and Walters (1983), and Kazezyilmaz-Alhan and Medina (2006). WETSAND is a general comprehensive wetland model, which has both surface flow and solute transport components. In this wetland model, water quality components are solved by advection-dispersion-reaction equations which incorporate surface water/groundwater interactions by including the incoming/outgoing mass due to the groundwater recharge/discharge. The transient storage model developed by Bencala and Walters (1983) solves the contaminant distribution between main streams and stagnant zones. The transient storage is represented by the mass exchange due to the concentration difference between the stream and the storage zone in this model. The transient storage model developed by Kazezyilmaz-Alhan and Medina (2006) involves several improvements to the transient storage model of Bencala and Walters (1983): advection and dispersion processes are incorporated into the contaminant transport in hyporheic zone and the mass transport between the channel and hyporheic zone is represented by mass flux terms. The solutions of the governing equations are obtained for continuous source type of boundary conditions. Results show that analytical solutions are in good agreement with the numerical solutions.

Melek Kazezyilmaz-Alhan, Cevza

2014-05-01

335

Changes in contaminant mass discharge from DNAPL source mass depletion: evaluation at two field sites.  

PubMed

Changes in contaminant fluxes resulting from aggressive remediation of dense nonaqueous phase liquid (DNAPL) source zone were investigated at two sites, one at Hill Air Force Base (AFB), Utah, and the other at Ft. Lewis Military Reservation, Washington. Passive Flux Meters (PFM) and a variation of the Integral Pumping Test (IPT) were used to measure fluxes in ten wells installed along a transect down-gradient of the trichloroethylene (TCE) source zone, and perpendicular to the mean groundwater flow direction. At both sites, groundwater and contaminant fluxes were measured before and after the source-zone treatment. The measured contaminant fluxes (J; ML(-2)T(-1)) were integrated across the well transect to estimate contaminant mass discharge (M(D); MT(-1)) from the source zone. Estimated M(D) before source treatment, based on both PFM and IPT methods, were approximately 76 g/day for TCE at the Hill AFB site; and approximately 640 g/day for TCE, and approximately 206 g/day for cis-dichloroethylene (DCE) at the Ft. Lewis site. TCE flux measurements made 1 year after source treatment at the Hill AFB site decreased to approximately 5 g/day. On the other hand, increased fluxes of DCE, a degradation byproduct of TCE, in tests subsequent to remediation at the Hill AFB site suggest enhanced microbial degradation after surfactant flooding. At the Ft. Lewis site, TCE mass discharge rates subsequent to remediation decreased to approximately 3 g/day for TCE and approximately 3 g/day for DCE approximately 1.8 years after remediation. At both field sites, PFM and IPT approaches provided comparable results for contaminant mass discharge rates, and show significant reductions (>90%) in TCE mass discharge as a result of DNAPL mass depletion from the source zone. PMID:18632182

Brooks, Michael C; Wood, A Lynn; Annable, Michael D; Hatfield, Kirk; Cho, Jaehyun; Holbert, Charles; Rao, P Suresh C; Enfield, Carl G; Lynch, Kira; Smith, Richard E

2008-11-14

336

Dual wall reverse circulation drilling with multi-level groundwater sampling for groundwater contaminant plume delineation at Paducah Gaseous Diffusion Plant, Paducah, Kentucky  

Microsoft Academic Search

Dual wall reverse circulation (DWRC) drilling was used to drill 48 borings during a groundwater contaminant investigation at the Paducah Gaseous Diffusion Plant, Paducah, Kentucky. This method was selected as an alternative to conventional hollow stem auger drilling for a number of reasons, including the expectation of minimizing waste, increasing the drilling rate, and reducing the potential for cross contamination

D. R. Smuin; E. E. Morti; J. L. Zutman; D. A. Pickering

1995-01-01

337

Mobilization of arsenic and other naturally occurring contaminants in groundwater of the Main Ethiopian Rift aquifers.  

PubMed

This study investigates the mechanisms of arsenic (As) and other naturally occurring contaminants (F(-), U, V, B, and Mo) mobilization from Quaternary sedimentary aquifers of the Main Ethiopian Rift (MER) and their enrichment in the local groundwater. The study is based on systematic measurements of major and trace elements as well as stable oxygen and hydrogen isotopes in groundwater, coupled with geochemical and mineralogical analyses of the aquifer rocks. The Rift Valley aquifer is composed of rhyolitic volcanics and Quaternary lacustrine sediments. X-ray fluorescence (XRF) results revealed that MER rhyolites (ash, tuff, pumice and ignimbrite) and sediments contain on average 72 wt. % and 65 wt. % SiO2, respectively. Petrographic studies of the rhyolites indicate predominance of volcanic glass, sanidine, pyroxene, Fe-oxides and plagioclase. The As content in the lacustrine sediments (mean = 6.6 mg/kg) was higher than that of the rhyolites (mean: 2.5 mg/kg). The lacustrine aquifers of the Ziway-Shala basin in the northern part of MER were identified as high As risk zones, where mean As concentration in groundwater was 22.4 ± 33.5 (range of 0.60-190 ?g/L) and 54% of samples had As above the WHO drinking water guideline value of 10 ?g/L. Field As speciation measurements showed that most of the groundwater samples contain predominantly (~80%) arsenate-As(V) over arsenite-As(III) species. The As speciation together with field data of redox potential (mean Eh = +73 ± 65 mV) and dissolved-O2 (6.6 ± 2.2 mg/L) suggest that the aquifer is predominantly oxidative. Water-rock interactions, including the dissolution of volcanic glass produces groundwater with near-neutral to alkaline pH (range 6.9-8.9), predominance of Na-HCO3 ions, and high concentration of SiO2 (mean: 85.8 ± 11.3 mg/L). The groundwater data show high positive correlation of As with Na, HCO3, U, B, V, and Mo (R(2) > 0.5; p < 0.001). Chemical modeling of the groundwater indicates that Fe-oxides and oxyhydroxides minerals were saturated in the groundwater, suggesting that the As reactivity is controlled by adsorption/desorption processes with these minerals. The data show that As and other oxyanion-forming elements such as U, B, Mo, and V had typically higher concentrations at pH > ~8, reflecting the pH-dependence of their mobilization. Based on the geochemical and stable isotope variations we have established a conceptual model for the occurrence of naturally occurring contaminants in MER groundwater: 1) regional groundwater recharge from the Highland, along the Rift margins, followed by lateral flow and water-rock interactions with the aquifer rocks resulted in a gradual increase of the salinity and naturally occurring contaminants towards the center of the valley; and (2) local ?(18)O-rich lake water recharge into adjacent shallow aquifers, followed by additional mobilization of As and other oxyanion-forming elements from the aquifer rocks. We posit that the combined physical-chemical conditions of the aquifers such as oxidizing state, Na-HCO3 composition, and pH>~8 lead to enhanced mobilization of oxyanion-forming elements from Fe-oxides and consequently contamination of local groundwater. These geochemical conditions characterize groundwater resources along the Eastern African Rift and thus constitute a potential threat to the quality of groundwater in larger areas of Eastern Africa. PMID:23899878

Rango, Tewodros; Vengosh, Avner; Dwyer, Gary; Bianchini, Gianluca

2013-10-01

338

Prediction of groundwater contamination with multivariate regression and probabilistic capture zones.  

PubMed

Probabilistic capture zones are combined with a regression model and used as buffer zones around wells for Tobit regression analysis to predict contaminant concentration of groundwater in an agricultural region. A backward transport equation, which is a mathematical model based on the physical processes of solute transport, is used to delineate probabilistic capture zones. The probabilistic capture zone defines the area where contaminant discharge can have a direct influence, with pertinent probability, on the quality of groundwater pumped from a well. Tobit regression analysis is used to find the relationship between independent regression variables and a dependent variable, which is contaminant concentration in this study. The capture zone and the regression are combined into a model, and its applicability for prediction of nitrate concentration is tested in a small agricultural basin in Chuncheon, Korea, which is occupied mainly by vegetation fields, orchards, and small barns. Three cases of Model 1, Model 2, and Model 3 are compared in which buffer zones are circles, capture zones with probability over 0.1, and capture zones divided into sections with different probabilities, respectively. The resulting regression model describes nitrate concentration in terms of selected independent variables. When the concentrations are calculated with the model, the best fit with the observed concentrations was in Model 3. This result supports the applicability of the method proposed in this study to prediction of contaminant concentration of groundwater. PMID:21043265

Lim, Jeong-Won; Bae, Gwang-Ok; Kaown, Dugin; Lee, Kang-Kun

2010-01-01

339

[Study on the groundwater petroleum contaminant biodegradation by high efficient microorganism].  

PubMed

The groundwater petroleum contaminant biodegradation effect by high efficient hybrid microorganism was. investigated and the groundwater contaminant biodegradation transportation mathematical model was established in this study. The high efficient bacteria was separated and filtrated from the soil contaminated by petroleum hydrocarbon, and it was identified as Pseudomonas, Flavobacterium and Micrococcus. The petroleum degradation rates by these three kinds microorganism were 62%, 56% and 62% respectively in 24 h, and the high petroleum biodegradation rate 85% could be achieved by the hybrid microorganism constituted by these three kinds of microorganism, which was higher than that of any other each single bacteria community. The hybrid microorganism in-flowed into the reactor imitating the aquifer media with the petroleum wastewater, and it could form a steady microorganism zone in the foreside of the reactor. The petroleum biodegradation rate could achieve 60% when the petroleum wastewater flowed through this microorganism zone and the average petroleum biodegradation rate could reach up to 90% in the effluent. The groundwater contaminant biodegradation transportation mathematical model can predict the biodegradation of the wastewater through the microorganism zone effectively, of which the calculating values have good relativity with those of measurement. PMID:16447430

Wang, Zhi-qiang; Wu, Qiang; Ye, Si-yuan; Li, Fu-qin; Xie, Hai-lan; Jin, Xiao-li

2005-11-01

340

Baseline risk assessment for groundwater contamination at the uranium mill tailings site, Gunnison, Colorado  

SciTech Connect

The Gunnison Baseline Risk Assessment for Groundwater Contamination at the Uranium Mill Tailings Site was performed to determine if long-term use of groundwater from domestic wells near the site has a potential for adverse health effects. The risk assessment was based on the results of sampling domestic wells during 1989--1990. A risk assessment evaluates health risks by comparing the amount of a contaminant taken in by a person with the amount of the contaminant that may be toxic. The Gunnison Risk Assessment used high intake values to estimate the maximum levels a person might be exposed to. The results of the risk assessment are divided into cancer (carcinogenic) risks and non-carcinogenic risks. Five key contaminants were evaluated for adverse health risks: uranium, manganese, lead antimony, and cadmium. Due to the potential health risks and the unavoidable uncertainties associated with limited groundwater and toxicity data, it is prudent public health policy to provide a permanent alternate water supply. Additionally, providing a permanent alternate water supply is cost-effective compared to long-term routine monitoring.

Not Available

1990-11-01

341

HISTORICAL CONTAMINATION OF GROUNDWATER RESOURCES IN THE NORTH COAST KARST AQUIFERS OF PUERTO RICO  

PubMed Central

The North Coast Karst Aquifer System of Puerto Rico is the island’s most productive aquifer. The characteristics that make it highly productive also make it vulnerable to contamination. This research, which addresses the historical contamination of groundwater resources in the northern karst region was conducted through integration of spatial hydrogeologic and contaminant concentration data in the La Plata-Arecibo area. The study used GIS technologies and focused on phthalates and chlorinated volatile organic compounds (CVOCs) and phthalates due to their ubiquitous presence in the environment as well as their presence in listed and potential superfund sites in Puerto Rico and U.S. and potential for exposure and health impacts. Results show an extensive historical contamination of the groundwater resources in the northern karst aquifers. Long-term contamination indicates the aquifers’ large capacity for storing and releasing contaminants and reflects a long-term potential for exposure. The degradation of this important water resource has resulted in a subsequent reduction of the extraction capacity and an increase in the cost of use.

Padilla, Ingrid; Irizarry, Celys; Steele, Katherine

2012-01-01

342

A multi-level assessment methodology for determining the potential for groundwater contamination by pesticides.  

PubMed

A multi-level pesticide assessment methodology has been developed to permit regulatory personnel to undertake a variety of assessments on the potential for pesticide used in agricultural areas to contaminate the groundwater regime at an increasingly detailed geographical scale of investigation. A multi-level approach accounts for a variety of assessment objectives and detail required in the assessment, the restrictions on the availability and accuracy of data, the time available to undertake the assessment, and the expertise of the decision maker. The level 1: regional scale is designed to prioritize districts having a potentially high risk for groundwater contamination from the application of a specific pesticide for a particular crop. The level 2: local scale is used to identify critical areas for groundwater contamination, at a soil polygon scale, within a district. A level 3: soil profile scale allows the user to evaluate specific factors influencing pesticide leaching and persistence, and to determine the extent and timing of leaching, through the simulation of the migration of a pesticide within a soil profile. Because of the scale of investigation, limited amount of data required, and qualitative nature of the assessment results, the level 1 and level 2 assessment are designed primarily for quick and broad guidance related to management practices. A level 3 assessment is more complex, requires considerably more data and expertise on the part of the user, and hence is designed to verify the potential for contamination identified during the level 1 or 2 assessment. The system combines environmental modelling, geographical information systems, extensive databases, data management systems, expert systems, and pesticide assessment models, to form an environmental information system for assessing the potential for pesticides to contaminate groundwater. PMID:24202345

Crowe, A S; Booty, W G

1995-05-01

343

Estimation of the time component in the movement of chemicals in contaminated groundwater.  

PubMed Central

For a proper analysis of the potentially causal relationship between exposure to volatile organic chemicals (VOCs) in drinking water and health events, it is essential to know T1, the time when exposure started, and C = f(T), which is the change of the VOC concentration C as a function of time T and the total accumulated exposure (TAE) to VOCs to which an individual was exposed. In the typical situation of incidentally detected pollution of groundwater, no such information is available. This paper describes the development of a method for estimating T1, C = f(T), and TAE as part of an epidemiologic study of the health effects of VOC contamination of an aquifer serving public and private wells. Pooled test results of city wells, tested periodically since 1981, provided the data base for developing a statistical model for estimating C = f(T). This model was then applied to private wells, for which the data of only one water sample were available, to retrospectively estimate their T1. The best-fitting model was a multiple linear regression equation consisting of the natural logarithm of the VOC concentration as the response variable, with the time of sampling, the distance of the wells from the source (expressed as coordinates), the well depth, and the well capacity as determinants. The TAE was calculated by integrating the area under the time-concentration curve.

Freni, S C; Phillips, D L

1987-01-01

344

Delineation of ground-water contamination using soil-gas analyses near Jackson, Tennessee  

USGS Publications Warehouse

An investigation of the ground-water resources near Jackson, West Tennessee, was conducted during 1988-89. The study included determination of the occurrence of contaminants in the shallow aquifer using soil-gas analyses in the unsaturated zone. Between 1980 and 1988, an underground fuel-storage tank leaked about 3,000 gallons of unleaded fuel to the water table about 4 feet below land surface. A survey of soil gas using a gas chromatograph equipped with a photoionization detector showed concentrations of volatile organic compounds greater than IO, 000 parts per million near the leak These compounds were detected in an area about 240 feet long and 110 feet wide extending west from the point source. The chromatograms provided two distinct 'fingerprints' of volatile organic compounds. The first revealed the presence of benzene, toluene, andxylenes, which are constituents of unleaded fuel, in addition to other volatile compounds, in soil gas in the area near the leak The second did not reveal any detectable benzene, toluene, or xylenes in the soil-gas samples, but showed the presence of other unidentified volatile organic compounds in soil gas north of the storage tank. The distribution of total concentrations of volatile organic compounds in the unsaturated zone indicated that a second plume about 200 feet long and 90 feet wide was present about 100 feet north of the storage tank The second plume could have been the result of previous activities at this site during the 1950's or earlier. Activities at the site are believed to have included storage of solvents used at the nearby railyard and flushing of tanks containing tar onto a gravel-covered parking area. The delineation of these plumes has shown that soil-gas analyses can be a useful technique for identifying areas of contamination with volatile organic compounds in shallow water-table aquifers and may have broad applications in similar situations where the water table is relatively close to the surface.

Lee, R. W.

1991-01-01

345

Emerging organic contaminants in surface water and groundwater: a first overview of the situation in Italy.  

PubMed

This paper provides the first review of the occurrence of 161 emerging organic compounds (EOCs) in Italian surface water and groundwater. The reported EOCs belong to the groups of industrials, pharmaceuticals, estrogens and illicit drugs. Occurrence of 137 pesticides was also reported. The reviewed research works have been published between 1997 and 2013. The majority of the studies have been carried out in Northern Italy (n. 30) and to a lower extent in Central Italy (n. 13). Only a limited number of research studies report EOC concentrations in water resources of Southern Italy. The EOCs that have been more frequently studied are in the following descending order, pesticides (16), pharmaceuticals (15), industrials (13), estrogens (7) and illicit drugs (2). Research activities investigating the EOC occurrence in surface water are more numerous than those in groundwater. This is consistent with the higher complexity involved in groundwater sampling and EOC detection. Among the reported EOCs, industrials and pesticides are those occurring in both surface water and groundwater with the highest concentrations (up to 15 × 10(6) and 4.78 × 0(5)ng L(-1), respectively). Concentrations of pharmaceuticals in surface water reach a maximum of 3.59 × 10(3)ng L(-1), whereas only the antimicrobial agent josamycin has been encountered in groundwater with a concentration higher than 100 ng L(-1). Both estrogens and illicit drugs appeared in surface water with concentrations lower than 50 ng L(-1). Groundwater concentrations for estrogens were measured to be below the detection limits, whereas illicit drugs have so far not been studied in groundwater. The present review reveals the serious contamination status of Italian surface water and groundwater especially by pesticides, industrials and to a lower extent by pharmaceuticals and the necessity to foster the research on EOC occurrence in Italian water resources, in particular in Southern Italy where a limited number of investigations currently exist. PMID:24602913

Meffe, Raffaella; de Bustamante, Irene

2014-05-15

346

[Spatial and temporal variability of nitrate contaminant in groundwater in Jinfo Mt. area, Chongqing, China].  

PubMed

The geochemical background of nitrate in groundwater in Jinfo Mt. area was determined, and spatial and temporal variability of nitrate contaminant was analyzed using geochemical, statistical and GIS methods. Twenty-three samples were collected from groundwater discharge points in the study area during 1976-1977, 2004-2006 and 2009, and mass concentration of nitrate in groundwater was tested. The results showed that the geochemical background of nitrate in groundwater in study area was in the range of 0.72-2. 00 mg x L(-1), and the threshold of anomaly was 3.20 mg x L(-1). During 2004-2006 and 2009, the average values of nitrate concentration in groundwater in Jinfo Mt. natural reserve were 2.08, 2.67, 2.59 and 3.92 mg x L(-1); and were 39.08, 25.46, 17.99 and 13.73 mg x L(-1) in the groundwater out of the reserve; the average over-limit rates (standard limit NO3(-) -N < or = 10mg x L(-1)) were 451.64%, 478.61%, 331.85% and 145.67%; the maximum over-limit rates were 1 475.81%, 1 080.39%, 538.20% and 361.78%. Results of interpolation showed that the high value centers of nitrate concentration in groundwater in study area were changing over time, but districts with low nitrate concentration in groundwater in study area were distributed along Jinfo Mt. natural reserve. The application of environmental policy measures and industrial restructuring implemented were reasonable and successful, which had a positive effect to environmental protection. PMID:22295620

Wu, Kun-Yu; Wang, Peng; Shen, Li-Cheng; Xiao, Qiong

2011-11-01

347

Modelling the fate of oxidisable organic contaminants in groundwater  

NASA Astrophysics Data System (ADS)

Subsurface contamination by organic chemicals is a pervasive environmental problem, susceptible to remediation by natural or enhanced attenuation approaches or more highly engineered methods such as pump-and-treat, amongst others. Such remediation approaches, along with risk assessment or the pressing need to address complex scientific questions, have driven the development of integrated modelling tools that incorporate physical, biological and geochemical processes. We provide a comprehensive modelling framework, including geochemical reactions and interphase mass transfer processes such as sorption/desorption, non-aqueous phase liquid dissolution and mineral precipitatation/dissolution, all of which can be in equilibrium or kinetically controlled. This framework is used to simulate microbially mediated transformation/degradation processes and the attendant microbial population growth and decay. Solution algorithms, particularly the split-operator (SO) approach, are described, along with a brief résumé of numerical solution methods. Some of the available numerical models are described, mainly those constructed using available flow, transport and geochemical reaction packages. The general modelling framework is illustrated by pertinent examples, showing the degradation of dissolved organics by microbial activity limited by the availability of nutrients or electron acceptors (i.e., changing redox states), as well as concomitant secondary reactions. Two field-scale modelling examples are discussed, the Vejen landfill (Denmark) and an example where metal contamination is remediated by redox changes wrought by injection of a dissolved organic compound. A summary is provided of current and likely future challenges to modelling of oxidisable organics in the subsurface.

Barry, D. A.; Prommer, H.; Miller, C. T.; Engesgaard, P.; Brun, A.; Zheng, C.

348

Migration of a groundwater contaminant plume by stratabound flow in Waste Area Grouping 1 at Oak Ridge National Laboratory, Oak Ridge, Tennessee. Environmental Restoration Program  

Microsoft Academic Search

The discovery of radiologically contaminated groundwater in core hole CH-8 in the western portion of Waste Area Grouping (WAG) 1 at Oak Ridge National Laboratory (ORNL) prompted a detailed investigation to identify the contaminant plume. Utilizing a working hypothesis of stratabound groundwater flow and contaminant transport, investigators analyzed existing subsurface geologic data to predict the contaminant plume discharge location in

R. H. Ketelle; R. R. Lee

1992-01-01

349

Migration of a groundwater contaminant plume by stratabound flow in Waste Area Grouping 1 at Oak Ridge National Laboratory, Oak Ridge, Tennessee  

Microsoft Academic Search

The discovery of radiologically contaminated groundwater in core hole CH-8 in the western portion of Waste Area Grouping (WAG) 1 at Oak Ridge National Laboratory (ORNL) prompted a detailed investigation to identify the contaminant plume. Utilizing a working hypothesis of stratabound groundwater flow and contaminant transport, investigators analyzed existing subsurface geologic data to predict the contaminant plume discharge location in

R. H. Ketelle; R. R. Lee

1992-01-01

350

Effects of Hydrogeologic Conditions on Groundwater Contamination of CVOCs in the North Coast Karst Aquifer of Puerto Rico  

NASA Astrophysics Data System (ADS)

The karst system of northern Puerto Rico is the most productive aquifer of the island. It serves freshwater to industrial, domestic and agricultural purposes, and contributes to the ecological integrity of the region. The same characteristics that make this a highly productive aquifer, make it vulnerable to contamination of groundwater. Of particular importance is contamination with chlorinated volatile organic compounds (CVOCs), which have been related to preterm birth problems. A great extent of CVOC contamination has been seen in the North Coast of Puerto Rico since the 1970s. The main purposes of this study are (1) to relate the water quality of wells and springs with the hydrogeological conditions in the north coast limestone aquifer of Puerto Rico, and (2) to make a statistical analysis of the historical groundwater contamination in that area. To achieve these objectives, groundwater samples are collected from wells and springs during dry and wet seasons. Results show that trichloroethylene (TCE), tetrachloroethylene (PCE) and chloroform (TCM) are frequently detected in groundwater samples. A greater detection of CVOCs is detected during the wet season than the dry season. This is attributed to a greater capacity to flush stored contaminants during the wet season. Historical analysis of contamination in the north coast of Puerto Rico shows a high capacity of the aquifer to store and release contaminants. Future work will be focused the statistical analysis of the historical groundwater contamination data to understand the behavior of the contaminants in different hydrologic conditions.

Torres Torres, N. I.; Howard, J.; Padilla, I. Y.; Torres, P.; Cotto, I.; Irizarry, C.

2012-12-01

351

Microbial contamination of groundwater at small community water supplies in Finland.  

PubMed

The raw water quality and associations between the factors considered as threats to water safety were studied in 20 groundwater supplies in central Finland in 2002-2004. Faecal contaminations indicated by the appearance of Escherichia coli or intestinal enterococci were present in five small community water supplies, all these managed by local water cooperatives. Elevated concentrations of nutrients in raw water were linked with the presence of faecal bacteria. The presence of on-site technical hazards to water safety, such as inadequate well construction and maintenance enabling surface water to enter into the well and the insufficient depth of protective soil layers above the groundwater table, showed the vulnerability of the quality of groundwater used for drinking purposes. To minimize the risk of waterborne illnesses, the vulnerable water supplies need to be identified and appropriate prevention measures such as disinfection should be applied. PMID:21809781

Pitkänen, Tarja; Karinen, Päivi; Miettinen, Ilkka T; Lettojärvi, Heidi; Heikkilä, Annika; Maunula, Reetta; Aula, Vesa; Kuronen, Henry; Vepsäläinen, Asko; Nousiainen, Liina-Lotta; Pelkonen, Sinikka; Heinonen-Tanski, Helvi

2011-06-01

352

Laboratory-scale Experiments to Evaluate Tidal Effects on Groundwater Contaminant Discharging to Coastal Waters  

NASA Astrophysics Data System (ADS)

The research objective was to investigate the effect of tides on the concentration of groundwater contaminants discharging to a surface water body. This physical-chemical phenomenon was studied using a one-dimensional homogeneous sand column. Results of the experiment were confirmed using a three-dimensional heterogeneous groundwater tank model. A constant water level is imposed upstream, and the downstream water level is regulated by a wave generator that controls the hydraulic head so as to mimic a 12 hour tidal fluctuation. The experimental results demonstrate that the tidal fluctuations in the downstream reservoir result in a decrease in average contaminant concentration at the point of groundwater discharge to the surface-water body. The further upstream the well is located, the smaller the amplitude of the concentration oscillation. In addition, upstream migration of concentration oscillations is observed in spite of a net downstream flow, behavior which is evaluated by comparison to results obtained by mathematical model simulation. Fourier analysis suggests that the dominant frequency of the peaks at different locations along the length of the column is identically two cycles per day. It is shown that the amplitude of the concentration oscillation increases with time at measurement locations at the upstream responding probes, although the contaminant flow is counter to the direction of concentration wave propagation. The classical groundwater flow and transport model cannot fully capture the solute transport under the effect of tidal fluctuation. There appears to be a phenomenon other than classical dispersion affecting the salt transport, a phenomenon that standard groundwater models cannot capture. A multiple-scale model was applied to reproduce the experimental data.

Chen, H.; Pinder, G.

2009-12-01

353

The background state leading to arsenic contamination of Bengal basin groundwater.  

PubMed

The Bengal basin has the world's densest water diversion constructions on the natural courses of rivers. The most damaging water diversion construction is the Farakka Barrage upon the international River Ganges. The diversion of water through this barrage and other constructions upstream of it has reduced the Ganges flow rate by 2.5 times. The resulting downstream effects are the depletion of surface water resources, more withdrawal than recharge of groundwater, sinking groundwater table, spread in depth and extension of the vadose zone, changes in surface features, climatic changes, etc. An investigation was carried out to find the contributions of water diversion to the arsenic contamination of groundwater in the Bengal basin. The reasonable scenario for arsenic contamination is the oxygen deficiency in groundwater and aeration of arsenopyrites buried in the sediment that would remain under water prior to 1975. The mineral forms water-soluble compounds of arsenic when react with atmospheric oxygen. These soluble arsenic compounds infiltrates to the groundwater. This article summarizes the short-time and incomplete study-based quick conclusions reached by investigators that have totally avoided the vital issue of water diversion. It then shows the depleting condition of the water resources under continuing diversions, the generation of favorable condition for arsenic release, the reasons for low sulfur concentration, the reason for first contamination in the Hugly basin, and the hindrance to water's self-purification. The articles advocates that the restoration of the virgin wetland ecosystems in the Bengal basin following the stoppage of the inordinate amount of unilateral upstream water withdrawals can remove the catastrophe. PMID:16459848

Adel, Miah M

2005-12-01

354

The role of retail fertilizer dealers in reducing groundwater contamination: A focus on educational needs  

SciTech Connect

Retail fertilizer dealers are a critical link in the US agricultural production complex. They are positioned to have major impact on annual fertilizer and pesticide use decisions involving over 44 million tons of fertilizer materials and 470 million pounds of active ingredients of pesticides (USDA, 1989). These inputs are key targets in efforts to reduce agrichemical contamination of groundwater. The purpose of this paper is: to focus on the role of the fertilizer/agrichemical dealer in this effort, to discuss educational needs of the dealer in order to operate his own business in compliance with environmental regulations and, to point out the educational and motivational needs of the dealer in order to assist his farmer-customers to use agrichemicals in ways that will eliminate or reduce groundwater contamination from farming operations.

Williams, R.J.; Ransom, J.M.

1989-06-01

355

Upward movement of tritium from contaminated groundwaters: a numerical analysis.  

PubMed

This paper describes a research-oriented modelling exercise that addresses the problem of assessing the movement of tritium from a contaminated perched aquifer to the land surface. Participants were provided with information on water table depth, soil characteristics, hourly meteorological and evapotranspiration data. They were asked to predict the upward migration of tritium through the unsaturated soil into the atmosphere. Eight different numerical models were used to calculate the movement of tritium. The modelling results agree within a factor of two, if very small time and space increments are used. The agreement is not so good when the near-surface soil becomes dry. The modelling of the alternate upward and downward transport of tritium close to the ground surface generally requires rather complex models and detailed input because tritium concentration varies sharply over short distances and is very sensitive to many interactive factors including rainfall amount, evapotranspiration rate, rooting depth and water table position. PMID:15990205

Belot, Y; Watkins, B M; Edlund, O; Galeriu, D; Guinois, G; Golubev, A V; Meurville, C; Raskob, W; Täschner, M; Yamazawa, H

2005-01-01

356

Geophysical characterization, redox zonation, and contaminant distribution at a groundwater/surface water interface  

NASA Astrophysics Data System (ADS)

Three transects along a groundwater/surface water interface were characterized for spatial distributions of chlorinated aliphatic hydrocarbons and geochemical conditions to evaluate the natural bioremediation potential of this environmental system. Partly on the basis of ground penetrating radar measurements, a conductive sediment layer was detected from the shore out to at least 300 m offshore which exhibited gradients in redox pairs and contaminant profiles. The cis-Dichloroethene and 1-chloroethene were predominant in the presence of elevated methane and ferrous iron concentrations and depressed sulfate and aquifer solids-bound iron concentrations. The shallow monitoring points were generally hypoxic to aerobic and exhibited values of specific conductance reflective of near-shore lake water, indicating reoxygenation of the contaminant plume due to wave infiltration. The barge transect yielded trace contaminant concentrations and showed evidence of sulfate reduction. These analyses contributed to the understanding of processes affecting contaminant fate and transport at near-shore mixing zones.

Lendvay, J. M.; Sauck, W. A.; McCormick, M. L.; Barcelona, M. J.; Kampbell, D. H.; Wilson, J. T.; Adriaens, P.

1998-12-01

357

Nonpoint source contamination of the Mississippi river and its tributaries by herbicides  

USGS Publications Warehouse

A study of the Mississippi River and its tributaries during July-August 1991, October-November 1991, and April-May 1992 has indicated that the entire navigable reach of the river is contaminated with a complex mixture of agrochemicals and their transformation products derived from nonpoint sources. Twenty-three compounds were identified, including triazine, chloroacetanilide, thiocarbamate, phenylurea, pyridazine, and organophosphorus pesticides. The upper and middle Mississippi River Basin farm lands are major sources of herbicides applied to corn, soybeans, and sorghum. Farm lands in the lower Mississippi River Basin are a major source of rice and cotton herbicides. Inputs of the five major herbicides atrazine, cyanazine, metolachlor, alachlor, and simazine to the Mississippi River are mainly from the Minnesota, Des Moines, Missouri, and Ohio Rivers. Ratios of desethylatrazine/atrazine potentially are useful indicators of groundwater and surface water interactions in the Mississippi River. These ratios suggested that during baseflow conditions, there is a significant groundwater contribution to the river. The Mississippi River thus serves as a drainage channel for pesticide-contaminated surface and groundwater from the midwestern United States. Conservative estimates of annual mass transport indicated that about 160 t of atrazine, 71 t of cyanazine, 56 t of metolachlor, and 18 t of alachlor were discharged into the Gulf of Mexico in 1991.

Pereira, W. E.; Hostettler, F. D.

1993-01-01

358

Source and Processes of Dissolved Organic Matter in a Bangladesh Groundwater  

Microsoft Academic Search

Arsenic contamination of groundwater is a global health crisis, especially in Bangladesh where an estimated 40 million people are at risk. The release of geogenic arsenic bound to sediments into groundwater is thought to be influenced by dissolved organic matter (DOM) through several biogeochemical processes. Abiotically, DOM can promote the release of sediment bound As through the formation of DOM-As

D. M. McKnight; B. E. Simone; N. Mladenov; Y. Zheng; T. M. Legg; D. Nemergut

2010-01-01

359

Assessment of rural ground-water contamination by agricultural chemicals in sensitive areas of Michigan  

SciTech Connect

The vulnerability of drinking-water supplies to agricultural contamination in three Michigan counties is discussed. The results of nitrate and atrazine analysis of drinking water from 38 wells in those 3 counties is described. Widespread nitrate contamination was demonstrated in agricultural areas with vulnerable aquifers. In addition, atrazine, a widely used herbicide was found in 11 of the 38 wells samples, with concentrations and patterns not conforming to findings in other mid-western states. The need for a comprehensive inventory of the ground-water quality in rural areas of Michigan is emphasized in the report, which describes results from the first year of a 2-year study.

Ervin, J.L.; Kittleson, K.M.

1988-04-01

360

A procedure to design a Permeable Adsorptive Barrier (PAB) for contaminated groundwater remediation.  

PubMed

A procedure to optimize the design of a Permeable Adsorptive Barrier (PAB) for the remediation of a contaminated aquifer is presented in this paper. A computer code, including different routines that describe the groundwater contaminant transport and the pollutant capture by adsorption in unsteady conditions over the barrier solid surface, has been developed. The complete characterization of the chemical-physical interactions between adsorbing solids and the contaminated water, required by the computer code, has been obtained by experimental measurements. A case study in which the procedure developed has been applied to a tetrachloroethylene (PCE)-contaminated aquifer near a solid waste landfill, in the district of Napoli (Italy), is also presented and the main dimensions of the barrier (length and width) have been evaluated. Model results show that PAB is effective for the remediation of a PCE-contaminated aquifer, since the concentration of PCE flowing out of the barrier is everywhere always lower than the concentration limit provided for in the Italian regulations on groundwater quality. PMID:20846781

Erto, A; Lancia, A; Bortone, I; Di Nardo, A; Di Natale, M; Musmarra, D

2011-01-01

361

Remediation of Perchloroethylene Contaminated Groundwater by Permeable Reactive Barrier Using Iron, Granular Activated Carbon, and Soil  

Microsoft Academic Search

The objective of this study is to evaluate the effects of zero-valent iron (ZVI), granular activated carbon (GAC) and soil as materials to build permeable reactive barrier (PRB). Flow-through Column experiments were conducted to evaluate the reactivity and adsorptive capacity of various materials for Perchloroethylene(PCE) contaminated groundwater. Columns were packed with various materials such as ZVI, GAC, and Soil. A

L. Jeon; D. Lee; H. Chang

2005-01-01

362

Permeable reactive barriers: A sustainable technology for cleaning contaminated groundwater in developing countries  

Microsoft Academic Search

Permeable reactive barriers (PRBs) are a proven technology for remediating contaminated groundwater, particularly on industrial and mining sites. PRBs are a sustainable technology that can operate over a long time scale with low maintenance. Over the past 10–15 years, there have been great strides in refining site characterisation techniques (i.e. geophysical techniques), developing\\/discovering reactive materials\\/sorbents (i.e. Fe0 filings), and the

D. H. Phillips

2009-01-01

363

Modelling the remediation of contaminated groundwater using zero-valent iron barrier  

Microsoft Academic Search

This paper presents results of modelling studies on remediation of groundwater contaminated with uranium using a zero-valent iron permeable reactive barrier (ZVI PRB) at the U.S. Oak Ridge Y-12 site that are used to establish modelling techniques that are of value to other sites such as in the UK. A systematic modelling methodology has been developed to study the problem

S. Kwong; J. Small; B. Tahar

2007-01-01

364

Treatment of Perchlorate-Contaminated Groundwater Using Highly Selective, Regenerable Ion-Exchange Technologies  

Microsoft Academic Search

Treatment of perchlorate-contaminated water using highly selective, regenerable ion-exchange and perchlorate-destruction technologies was demonstrated at a field site in California. Four treatment and four regeneration cycles were carried out, and no significant deterioration of resin performance was noted in two years. The bifunctional resin (Purolite A-530E) treated about 37,000 empty bed volumes (BVs) of groundwater before a significant breakthrough of

Baohua Gu; Gilbert M. Brown; Chen-Chou Chiang

2007-01-01

365

Transuranic Contamination in Sediment and Groundwater at the U.S. DOE Hanford Site  

Microsoft Academic Search

A review of transuranic radionuclide contamination in sediments and groundwater at the DOEs Hanford Site was conducted. The review focused primarily on plutonium-239\\/240 and americium-241; however, other transuranic nuclides were discussed as well, including neptunium-237, plutonium-238, and plutonium-241. The scope of the review included liquid process wastes intentionally disposed to constructed waste disposal facilities such as trenches and cribs, burial

KJ Cantrell; Kirk J

2009-01-01

366

Ecosystem Perspective of Groundwater Arsenic Contamination in India and Relevance in Policy  

Microsoft Academic Search

Millions of people living in India are at risk by consuming arsenic contaminated groundwater. Several technological solutions\\u000a have failed to address the problem due to segmental approaches, resulting in human suffering for a period of three decades.\\u000a The article is based on an analysis of arsenic-related health problems from an ecosystem perspective through a primary survey\\u000a conducted in five arsenic

Atanu Sarkar

2010-01-01

367

Agriculture and groundwater nitrate contamination in the Seine basin. The STICS-MODCOU modelling chain.  

PubMed

A software package is presented here to predict the fate of nitrogen fertilizers and the transport of nitrate from the rooting zone of agricultural areas to surface water and groundwater in the Seine basin, taking into account the long residence times of water and nitrate in the unsaturated and aquifer systems. Information on pedological characteristics, land use and farming practices is used to determine the spatial units to be considered. These data are converted into input data for the crop model STICS which simulates the water and nitrogen balances in the soil-plant system with a daily time-step. A spatial application of STICS has been derived at the catchment scale which computes the water and nitrate fluxes at the bottom of the rooting zone. These fluxes are integrated into a surface and groundwater coupled model MODCOU which calculates the daily water balance in the hydrological system, the flow in the rivers and the piezometric variations in the aquifers, using standard climatic data (rainfall, PET). The transport of nitrate and the evolution of nitrate contamination in groundwater and to rivers is computed by the model NEWSAM. This modelling chain is a valuable tool to predict the evolution of crop productivity and nitrate contamination according to various scenarios modifying farming practices and/or climatic changes. Data for the period 1970-2000 are used to simulate the past evolution of nitrogen contamination. The method has been validated using available data bases of nitrate concentrations in the three main aquifers of the Paris basin (Oligocene, Eocene and chalk). The approach has then been used to predict the future evolution of nitrogen contamination up to 2015. A statistical approach allowed estimating the probability of transgression of different concentration thresholds in various areas in the basin. The model is also used to evaluate the cost of the damage resulting of the treatment of drinking water at the scale of a groundwater management unit in the Seine river basin. PMID:17275068

Ledoux, E; Gomez, E; Monget, J M; Viavattene, C; Viennot, P; Ducharne, A; Benoit, M; Mignolet, C; Schott, C; Mary, B

2007-04-01

368

Arsenic and Other Metal Contamination of Groundwaters in the Industrial Area of Thessaloniki, Northern Greece  

Microsoft Academic Search

In groundwater, used for drinking water supply in the greater industrial area of Thessaloniki, in Northern Greece, concentrations of total arsenic exceeded the WHO provisional guideline value and the EU maximum contaminant level (MCL) of 10 ?g\\/L. The concentration of total arsenic was in the range between 4–130 ?g\\/L, whereas the median value was 36 ?g\\/L and the average concentration

Ioannis A. Katsoyiannis; Athanasios A. Katsoyiannis

2006-01-01

369

Simulation of contaminated groundwater migration in fractured rock by a laminar pipe-flow model  

Microsoft Academic Search

In this paper, the ability of a laminar pipe-flow model to reproduce the hydrodynamic transport of contaminated groundwater in fractured rock is investigated. It is assumed that the cross-section areas are circular and that the flow is laminar. The molecular diffusion is neglected as well as the impact of variations in velocity over the cross-section area. It is assumed that

Peter Dahlblom

1992-01-01

370

Assessment of groundwater contamination by landfill leachate: A case in México  

Microsoft Academic Search

In México, uncontrolled landfills or open-dumps are regularly used as “sanitary landfills”. Interactions between landfills\\/open-dumps and shallow unconfined aquifers have been widely documented. Therefore, evidence showing the occurrence of aquifer contamination may encourage Mexican decision makers to enforce environmental regulations.Traditional methods such as chemical analysis of groundwater, hydrological descriptions, and geophysical studies including vertical electrical sounding (VES) and ground penetrating

Jaime A. Reyes-López; Jorge Ramírez-Hernández; Octavio Lázaro-Mancilla; Concepción Carreón-Diazconti; Miguel Martín-Loeches Garrido

2008-01-01

371

Assessing the vulnerability of a karst groundwater system to contamination by pharmaceuticals  

NASA Astrophysics Data System (ADS)

Contamination of drinking water supplies is a serious problem and a potential threat to public health. Organic micropollutants such as pharmaceuticals and personal care products are identified as an environmental risk and concern has been raised about their environmental presence and fate. These compounds are present in effluents of wastewater treatment plants (WWTPs) in concentrations of up to several µg/L, and they have frequently been detected in surface waters and groundwater systems. A popular method for wastewater disposal in karst areas is the injection of wastewater into open sinkholes. Subsequently, the wastewater infiltrates rapidly along conduits and through the fractured karst aquifer. This is a major contributing factor to the contamination of karst aquifers. To address the vulnerability of such systems against relatively mobile organic micropollutants, we investigated the occurrence of two pharmaceuticals (diclofenac, ibuprofen) in combination with the groundwater heterogeneity and flow pathways in the aquifer. Groundwater samples and effluents of three WWTPs were repeatedly collected during a field campaign in the Franconian Alb karst system which is located in southern Germany. These results were coupled with hydrogeological investigations such as tracer tests, application of environmental isotopes (3H), and modeling. The results of this study demonstrated that (i) both pharmaceuticals are mobile in the karst aquifer and thus represent a risk for contamination of karst water, (ii) the transport of pharmaceuticals in the fractured system with mean transit times of some years affects the karst groundwater contamination, and (iii) long-term wastewater injection containing organic micropollutants into karst ecosystems may contribute to water quality deterioration over years.

Einsiedl, Florian; Radke, Michael

2010-05-01

372

Influence of topsoil of pyroclastic origin on microbial contamination of groundwater in fractured carbonate aquifers  

Microsoft Academic Search

The aim of the research was to analyse the influence of a topsoil of pyroclastic origin on microbial contamination of groundwater\\u000a in a carbonate aquifer and verify the reliability of thermotolerant coliforms and fecal enterococci as bacterial indicators.\\u000a The research was carried out through hydrogeological and microbiological monitoring at an experimental field site in Italy\\u000a during two hydrologic years and

Gino Naclerio; Emma Petrella; Valentina Nerone; Vincenzo Allocca; Pantaleone De Vita; Fulvio Celico

2008-01-01

373

Removal of petroleum hydrocarbons from contaminated groundwater using an electrocoagulation process: Batch and continuous experiments  

Microsoft Academic Search

The efficacy of an electrocoagulation process (ECP) was evaluated for the treatment of petroleum-contaminated groundwater and quantified as the total petroleum hydrocarbon (TPH) removed. Various operating variables were examined for their effects on TPH removal; these variables included electrode materials (aluminum, iron, and steel), water pH (4 to 11), current density (2 to 18mA\\/cm2), reaction time (2 to 60min), aeration,

Gholamreza Moussavi; Rasoul Khosravi; Mahdi Farzadkia

2011-01-01

374

Tracing the Sources and History of Subsurface Contamination at the Hanford Site in Washington Using High-Precision Uranium Isotopic Measurements  

Microsoft Academic Search

Groundwater contamination at the Hanford Site, Washington, resulted from decades of nuclear fuel production and processing. Understanding the fate and transport of contaminants has been complicated by the presence of multiple potential sources within relatively small areas. The contrasts in isotopic composition between natural and anthropogenic uranium promotes the measurement of uranium isotopic composition as a fingerprint and tracer of

J. N. Christensen; P. E. Dresel; M. E. Conrad; K. Maher; D. J. Depaolo

2003-01-01

375

Probabilistic assessment of ground-water contamination. 2: Results of case study  

SciTech Connect

The first paper in this series presented a geostatistical framework for obtaining a probabilistic assessment of ground-water contamination. This paper presents the results of a case study that applies this framework to define the spatial extent and severity of nitrate and Dacthal (dimethyl tetrachloroterephthalate or DCPA, a herbicide) contamination in the unsaturated and saturated zones for a 150 km{sup 2} site near Ontario, Oregon. Sediment samples collected from 35 boreholes were used to compute vertical accumulations of nitrate and DCPA in the unsaturated zone. Measured nitrate and DCPA concentrations in ground-water samples collected from 42 wells were used to compute vertical accumulations of nitrate and DCPA in the saturated zone. Sample variograms were fit with nugget and spherical models to describe the pattern of spatial continuity of nitrate and DCPA concentrations and accumulations. Conditional, sequential Gaussian simulation was used to generate 100 simulations for each variable on a 0.5 x 0.5 km grid. Probabilistic summaries of these simulations were used to develop (a) maps showing the probability of contamination exceeding specified threshold values, (b) probability distributions for contaminant accumulation and concentration at unsampled locations, (c) probabilistic descriptions for the location of contaminant-plume boundaries, and (d) probability distributions for the total contaminated area and total contaminant mass. The results demonstrate that interpretations of site characterization data to determine the extent and magnitude of contamination at a site will vary depending upon the level of uncertainty that will be tolerated by the decision maker. This case study also illustrates the potential applicability and utility of the probabilistic approach for the interpretation of site characterization data and the design of future data collection activities.

Istok, J.D. [Oregon State Univ., Corvallis, OR (United States). Dept. of Civil Engineering; Rautman, C.A. [Sandia National Labs., Albuquerque, NM (United States). Geohydrology Dept.

1996-11-01

376

PILOT STUDIES OF IN-SITU BIO-TRANSFORMATION OF MERCURY-CONTAMINATED GROUNDWATER IN KAZAKHSTAN UTILIZING NATIVE BACTERIA  

EPA Science Inventory

Several regions in the Republic of Kazakhstan and throughout the former USSR are contaminated with mercury resulting from industrial releases. Our studies directed towards determining the feasibility of developing a biological filter, which when placed into the path the groundwat...

377

THE USE OF CONSTRUCTED WETLANDS TO PHYTOREMEDIATE EXPLOSIVES-CONTAMINATED GROUNDWATER AT THE MILAN ARMY AMMUNITION PLANT, MILAN, TENNESSEE  

EPA Science Inventory

The groundwaters beneath many Army ammunition plants in the United States are contaminated with explosives. To help address this problem, the USAEC and TVA initiated a field demonstration program to evaluate the technical feasibility of using constructed wetlands for remediating ...

378

Assessing the impact of VOC-contaminated groundwater on surface water at the city scale.  

PubMed

This study is believed to be one of the first to assess the impact of urban VOC-(volatile organic compound) contaminated groundwater on river-water quality at the city scale. A network of riverbed piezometers was used to study the 7.4-km urbanised reach of the River Tame that flows across the groundwater-effluent unconfined Triassic sandstone aquifer underlying the city of Birmingham (UK). Aquifer groundwater contained significant chlorinated VOC contamination due to the city's industrial heritage. Chlorinated VOC-contaminated baseflow was widespread along the reach with trichloroethene (TCE) dominant. VOC concentrations in riverbed piezometers were in the range 0.1-100 microg/l with typical regulatory limits occasionally exceeded by an order of magnitude. Although anaerobic biodegradation products such as cis-dichloroethene were widespread, they were unlikely to have formed in the generally aerobic riverbed. The lack of anaerobic conditions was ascribed to insufficient accumulation of low-permeability, organic-carbon rich riverbed sediments in this medium-high energy river. Assumptions a priori that natural attenuation of chlorinated VOCs will occur via reductive dechlorination in urban riverbeds are likely in error, particularly where deposits of medium-high permeability exist transmitting much of the baseflow. Surface-water quality impacts were nevertheless still low with in-river TCE increasing by just 2 microg/l over the 7.4-km reach. Agreement of baseflow contaminant flux estimates based on five flow-concentration product methods was achieved to within an order of magnitude with 22-200 kg/yr of TCE estimated to discharge to the 7.4-km reach (equivalent to 0.8-7.5 mg/d/m2 of riverbed). Such uncertainty was not regarded as unreasonable when the large measurement scale and geological and chemical heterogeneities are considered. Improved flux estimation methods and greater monitoring densities are nevertheless warranted. Considering Birmingham's long industrial history and known incidence of VOC-contaminated groundwater, the city-scale impact of VOC-contaminated groundwater upon surface-water quality was judged to be relatively modest. PMID:17182150

Ellis, Paul A; Rivett, Michael O

2007-04-01

379

Coal is a potential source of naphthenic acids in groundwater.  

PubMed

Naphthenic acids, with the general formula C(n)H(2n+Z)O(2), are found in conventional petroleums and oil sands ores. These acids are toxic to aquatic life, so their discharge from petroleum processing into receiving waters must be avoided. In a previous study, naphthenic acids were putatively identified in groundwaters from two domestic wells that were distant from petroleum sources. However, coal deposits were near these wells. In this study, waters from the two wells were extracted and analyzed by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry to unequivocally confirm the presence of naphthenic acids and other organic acids. In addition, distilled water was percolated through three crushed coal samples and the leachates were shown to contain a variety of organic acids, including naphthenic acids. These results clearly demonstrate that coal is a source of naphthenic acids and that the naphthenic acids can leach into groundwaters. Thus, the presence of naphthenic acids in waters cannot be solely attributed to petroleum or petroleum industry activities. PMID:19185332

Scott, Angela C; Whittal, Randy M; Fedorak, Phillip M

2009-03-15

380

Nitrate contamination in groundwater at farmlands in Nsawam, Ghana: The role of fractures from azimuthal resistivity surveys  

Microsoft Academic Search

Nitrate contamination of groundwater at farmlands in Nsawam, Ghana, has become a growing concern in recent times. Water samples were obtained from water groundwater wells in the study area and concentrations of nitrates, lead, arsenic, cadmium, copper, zinc and chromium were measured and analyzed. Three of the wells showed nitrate concentrations levels that reached 3-5 times the permissible limits for

F. K. Boadu

2006-01-01

381

Delineation of fluoride contaminated groundwater around a hot spring in Nayagarh, Orissa, India using geochemical and resistivity studies  

Microsoft Academic Search

Geochemical and geoelectrical investigations were carried out around a hot spring near village Singhpur, Nayagarh District of Orissa to delineate the extent of fluoride contamination in groundwater. Fluoride concentration is observed to be very high in both hot spring and groundwater of Singhpur village compared with surrounding ones. Vertical electrical sounding (VES) studies in the area reveal the presence of

N. Kundu; M. Panigrahi; S. Sharma; S. Tripathy

2002-01-01

382

Biodegradation of creosote and pentachlorophenol in contaminated groundwater: Chemical and biological assessment  

SciTech Connect

Shake flask studies examined the rate and extent of biodegradation of pentachlorophenol (PCP) and 42 components of coal-tar creosote present in contaminated groundwater recovered from the American Creosote Works Superfund site, Pensacola, FL. The ability of indigenous soil microorganisms to remove these contaminants from aqueous solutions was determined by gas chromatographic analysis of organic extracts of biotreated groundwater. Changes in potential environmental and human health hazards associated with the biodegradation of this material were determined at intervals by Microtox assays and fish toxicity and teratogenicity tests. After 14 days of incubation at 30C, indigenous microorganisms effectively removed 100, 99, 94, 88, and 87% of measured phenolic and lower-molecular-weight polycyclic aromatic hydrocarbons (PAHS) and S-heterocyclic, N-heterocyclic, and O-heterocyclic constituents of creosote, respectively. However, only 53% of the higher-molecular-weight PAHS were degraded; PCP was not removed. Despite the removal of a majority of the organic contaminants through biotreatment, only a slight decrease in the toxicity and teratogenicity of biotreated groundwater was observed. Data suggest that toxicity and teratogenicity are associated with compounds difficult to treat biologically and that one may not necessarily rely on indigenous microorganisms to effectively remove these compounds in a reasonable time span.

Mueller, J.G.; Lantz, S.E. (Southern Bio Products, Inc., Gulf Breeze, FL (USA)); Middaugh, D.P.; Chapman, P.J. (US Environmental Protection Agency, Gulf Breeze, FL (USA))

1991-05-01

383

Biodegradation of creosote and pentachlorophenol in contaminated groundwater: chemical and biological assessment.  

PubMed Central

Shake flask studies examined the rate and extent of biodegradation of pentachlorophenol (PCP) and 42 components of coal-tar creosote present in contaminated groundwater recovered from the American Creosote Works Superfund site, Pensacola, Fla. The ability of indigenous soil microorganisms to remove these contaminants from aqueous solutions was determined by gas chromatographic analysis of organic extracts of biotreated groundwater. Changes in potential environmental and human health hazards associated with the biodegradation of this material were determined at intervals by Microtox assays and fish toxicity and teratogenicity tests. After 14 days of incubation at 30 degrees C, indigenous microorganisms effectively removed 100, 99, 94, 88, and 87% of measured phenolic and lower-molecular-weight polycyclic aromatic hydrocarbons (PAHs) and S-heterocyclic, N-heterocyclic, and O-heterocyclic constituents of creosote, respectively. However, only 53% of the higher-molecular-weight PAHs were degraded; PCP was not removed. Despite the removal of a majority of the organic contaminants through biotreatment, only a slight decrease in the toxicity and teratogenicity of biotreated groundwater was observed. Data suggest that toxicity and teratogenicity are associated with compounds difficult to treat biologically and that one may not necessarily rely on indigenous microorganisms to effectively remove these compounds in a reasonable time span; to this end, alternative or supplemental approaches may be necessary. Similar measures of the toxicity and teratogenicity of treated material may offer a simple, yet important, guide to bioremediation effectiveness. Images

Mueller, J G; Middaugh, D P; Lantz, S E; Chapman, P J

1991-01-01

384

3-D Seismic Tomography Survey at a Groundwater Contamination Site  

NASA Astrophysics Data System (ADS)

As part of an ongoing environmental characterization project at Hill Air Force Base near Ogden, Utah, a 3-D seismic survey led by a team from Rice University was performed over a contaminated aquifer in 2000. This site contains significant amounts of dense non-aqueous phase liquids (DNAPLs) in a shallow aquifer less than ~15 m deep. The aquifer is bounded below by a clay aquiclude, in which a paleochannel acts as a trap for the contaminants. The overburden consists of Quaternary sands, gravels and clays. Imaging the structure of the paleochannel at depths up to 15 m is the main target of the survey. The four week experiment included 3-D reflection, 3-D refraction, checkshot surveys and vertical seismic profiles using wells up to 15m deep. Here we present traveltime tomography results from the 3-D refraction survey which consisted of 596 RefTek Texan recorders deployed uniformly in a stationary rectangular grid over an area of 95m by 36m. A shot from a .223 caliber rifle was fired 30cm from each receiver station, yielding a dataset with about 360,000 traces. The arrival times of the refracted waves were used in a 3-D tomographic inversion to image the seismic velocity structure of the study area. The iterative, nonlinear tomographic approach employs regularization to smooth the model perturbations with respect to a simple 1-D starting/reference model. The resulting velocity model shows that the near-surface velocity increases by roughly a factor of 5 in the upper 15m, from about 300m/s to 1500m/s. Cross-sections through the model show a north-south trending low-velocity feature interpreted to be the channel structure. The low-velocity feature is best viewed via depth slices which define an anomaly that roughly outlines the geometry of the buried paleo-channel based on well data. A comparison between the 3-D velocity model and time slices through a brute stack of the 3-D reflection data also show close agreement (see Dana et al. this session). Checkerboard tests applied to the velocity model establishes a 7.5m lateral resolution throughout most of the depth range of interest. While the long wavelength features of the model reveal the paleo-channel, the velocity model is likely a broad and smooth characterization of the true velocity structure.

Azaria, A.; Zelt, C.; Levander, A.

2002-12-01

385

Quantitative assessment of intrinsic groundwater vulnerability to contamination using numerical simulations.  

PubMed

Intrinsic vulnerability assessment to groundwater contamination is part of groundwater management in many areas of the world. However, popular assessment methods estimate vulnerability only qualitatively. To enhance vulnerability assessment, an approach for quantitative vulnerability assessment using numerical simulation of water flow and solute transport with transient boundary conditions and new vulnerability indicators are presented in this work. Based on a conceptual model of the unsaturated underground with distinct hydrogeological layers and site specific hydrological characteristics the numerical simulations of water flow and solute transport are applied on each hydrogeological layer with standardized conditions separately. Analysis of the simulation results reveals functional relationships between layer thickness, groundwater recharge and transit time. Based on the first, second and third quartiles of solute mass breakthrough at the lower boundary of the unsaturated zone, and the solute dilution, four vulnerability indicators are extracted. The indicator transit time t(50) is the time were 50% of solute mass breakthrough passes the groundwater table. Dilution is referred as maximum solute concentration C(max) in the percolation water when entering the groundwater table in relation to the injected mass or solute concentration C(0) at the ground surface. Duration of solute breakthrough is defined as the time period between 25% and 75% (t(25%)-t(75%)) of total solute mass breakthrough at the groundwater table. The temporal shape of the breakthrough curve is expressed with the quotient (t(25%)-t(50%))/(t(25%)-t(75%)). Results from an application of this new quantitative vulnerability assessment approach, its advantages and disadvantages, and potential benefits for future groundwater management strategies are discussed. PMID:19853887

Neukum, Christoph; Azzam, Rafig

2009-12-20

386

High Resolution Analysis of Contaminated Aquifer Sediments and Groundwater—What Can be Learned in Terms of Natural Attenuation?  

Microsoft Academic Search

High-resolution depth-resolved monitoring was applied to groundwater and sediments samples in a tar oil contaminated aquifer. Today, it is not fully clear, whether groundwater-based lines of evidence are always sufficient to adequately assess natural attenuation (NA) potentials and processes going on in situ. Our data unveiled small-scale heterogeneities, steep physical-chemical and microbial gradients, as well as hot spots of contaminants

Bettina Anneser; Giovanni Pilloni; Anne Bayer; Tillmann Lueders; Christian Griebler; Florian Einsiedl; Lars Richters

2010-01-01

387

Design of optimal, reliable plume capture schemes: Application to the Gloucester landfill ground-water contamination problem  

Microsoft Academic Search

A ground-water quality management model is applied to the Gloucester Landfill site, located near Ottawa, Canada, to examine the effectiveness of various single-well pumping schemes for the capture of dissolved contaminants. Deterministic and stochastic design analyses are conducted through ground-water solute transport modeling of the site. The purpose of the modeling analysis is to develop contaminant capture designs that both

R. M. Gailey; S. M. Gorelick

2009-01-01

388

High Energy Electron Injection (E-Beam) Technology for the 'Ex-Situ' Treatment of MtBE-Contaminated Groundwater  

NASA Astrophysics Data System (ADS)

This Innovative Technology Evaluation Report documents the results of a demonstration of the high-energy electron injection (E-Beam) technology in application to groundwater contaminated with methyl t-butyl ether (MtBE) and with benzene, toluene, ethylbenzene, and xylenes (BTEX). The E-beam technology destroys organic contaminants in groundwater through irradiation with a beam of high-energy electrons. The demonstration was conducted at the Naval Base Ventura County (NBVC) in Port Hueneme, California.

Venosa, A. D.

2002-09-01

389

Simulations of groundwater flow, transport, and age in Albuquerque, New Mexico, for a study of transport of anthropogenic and natural contaminants (TANC) to public-supply wells  

USGS Publications Warehouse

Vulnerability to contamination from manmade and natural sources can be characterized by the groundwater-age distribution measured in a supply well and the associated implications for the source depths of the withdrawn water. Coupled groundwater flow and transport models were developed to simulate the transport of the geochemical age-tracers carbon-14, tritium, and three chlorofluorocarbon species to public-supply wells in Albuquerque, New Mexico. A separate, regional-scale simulation of transport of carbon-14 that used the flow-field computed by a previously documented regional groundwater flow model was calibrated and used to specify the initial concentrations of carbon-14 in the local-scale transport model. Observations of the concentrations of each of the five chemical species, in addition to water-level observations and measurements of intra-borehole flow within a public-supply well, were used to calibrate parameters of the local-scale groundwater flow and transport models. The calibrated