These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
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.

Matthew Babcock

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

Identification of multiple sources of groundwater contamination by dual isotopes.  

PubMed

Chlorinated solvents are one of the most commonly detected groundwater contaminants in industrial areas. Identification of polluters and allocation of contaminant sources are important concerns in the evaluation of complex subsurface contamination with multiple sources. In recent years, compound-specific isotope analyses (CSIA) have been employed to discriminate among different contaminant sources and to better understand the fate of contaminants in field-site studies. In this study, the usefulness of dual isotopes (carbon and chlorine) was shown in assessments of groundwater contamination at an industrial complex in Wonju, Korea, where groundwater contamination with chlorinated solvents such as trichloroethene (TCE) and carbon tetrachloride (CT) was observed. In November 2009, the detected TCE concentrations at the study site ranged between nondetected and 10,066?µg/L, and the CT concentrations ranged between nondetected and 985?µg/L. In the upgradient area, TCE and CT metabolites were detected, whereas only TCE metabolites were detected in the downgradient area. The study revealed the presence of separate small but concentrated TCE pockets in the downgradient area, suggesting the possibility of multiple contaminant sources that created multiple comingling plumes. Furthermore, the variation of the isotopic (?(13) C and ?(37) Cl) TCE values between the upgradient and downgradient areas lends support to the idea of multiple contamination sources even in the presence of detectable biodegradation. This case study found it useful to apply a spatial distribution of contaminants coupled with their dual isotopic values for evaluation of the contaminated sites and identification of the presence of multiple sources in the study area. PMID:24164437

Kaown, Dugin; Shouakar-Stash, Orfan; Yang, Jaeha; Hyun, Yunjung; Lee, Kang-Kun

2014-01-01

4

Sources of Nitrate Contamination in Groundwater Under Developing Asian Megacities  

NASA Astrophysics Data System (ADS)

The status of nitrate, nitrite and ammonium 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 d15N and d18O) 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. The exponential increase in nitrate d15N along with the nitrate reduction and clear d18O/d15N slopes of nitrate (~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 nitrate contamination via active denitrification and reduced nitrification. Our results showed that nitrate and ammonium 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.

Umezawa, Y.; Hosono, T.; Onodera, S.; Siringan, F.; Buapeng, S.; Delinom, R. M.; Yoshimizu, C.; Tayasu, I.; Nagata, T.; Taniguchi, M.

2008-12-01

5

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

6

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

7

Sources of arsenic and fluoride in highly contaminated soils causing groundwater contamination in Punjab, Pakistan  

SciTech Connect

Highly contaminated groundwater, with arsenic (As) and fluoride (F{sup -}) concentrations of up to 2.4 and 22.8 mg/L, respectively, has been traced to anthropogenic inputs to the soil. In the present study, samples collected from the soil surface and sediments from the most heavily polluted area of Punjab were analyzed to determine the F{sup -} and As distribution in the soil. The surface soils mainly comprise permeable aeolian sediment on a Pleistocene terrace and layers of sand and silt on an alluvial flood plain. Although the alluvial sediments contain low levels of F, the terrace soils contain high concentrations of soluble F{sup -} (maximum, 16 mg/kg; mean, 4 mg/kg; pH > 8.0). Three anthropogenic sources were identified as fertilizers, combusted coal, and industrial waste, with phosphate fertilizer being the most significance source of F{sup -} accumulated in the soil. The mean concentration of As in the surface soil samples was 10.2 mg/kg, with the highest concentration being 35 mg/kg. The presence of high levels of As in the surface soil implies the contribution of air pollutants derived from coal combustion and the use of fertilizers. Intensive mineral weathering under oxidizing conditions produces highly alkaline water that dissolves the F{sup -} and As adsorbed on the soil, thus releasing it into the local groundwater.

Farooqi, A.; Masuda, H.; Siddiqui, R.; Naseem, M. [Fatima Jinnah Women University, Rawalpindi (Pakistan). Dept. of Environmental Science

2009-05-15

8

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

9

Arsenic Contamination of Groundwater: A Review of Sources, Prevalence, Health Risks, and Strategies for Mitigation  

PubMed Central

Arsenic contamination of groundwater in different parts of the world is an outcome of natural and/or anthropogenic sources, leading to adverse effects on human health and ecosystem. Millions of people from different countries are heavily dependent on groundwater containing elevated level of As for drinking purposes. As contamination of groundwater, poses a serious risk to human health. Excessive and prolonged exposure of inorganic As with drinking water is causing arsenicosis, a deteriorating and disabling disease characterized by skin lesions and pigmentation of the skin, patches on palm of the hands and soles of the feet. Arsenic poisoning culminates into potentially fatal diseases like skin and internal cancers. This paper reviews sources, speciation, and mobility of As and global overview of groundwater As contamination. The paper also critically reviews the As led human health risks, its uptake, metabolism, and toxicity mechanisms. The paper provides an overview of the state-of-the-art knowledge on the alternative As free drinking water and various technologies (oxidation, coagulation flocculation, adsorption, and microbial) for mitigation of the problem of As contamination of groundwater. PMID:25374935

Shikha

2014-01-01

10

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

PubMed

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 regime. In addition, the sheer extension of the contamination at megasites as well as the existence of large densely populated areas and land of high-reuse value prevent a simple risk management strategy of use restriction for the whole area. Since a complete clean-up of the groundwater on a megasite is neither economically feasible nor technically possible within a reasonable time-frame, a multi-approach remediation strategy is needed, taking into account the immediate risks for human health, ecosystem and so-called "protectable goods". Moreover, the contaminants at megasites typically represent a dangerous cocktail of multiple harmful substances stemming from a variety of sources, which may interact with each other and complicate the search for an appropriate remediation strategy. At the SAFIRA-project site in Bitterfeld approaches for in situ remediation of multiple contaminants in groundwater are being tested. Alternatives in local implementation strategies as well as consequences of long-term restrictions for megasites like Bitterfeld need an independent evaluation of the situation using a risk-based approach. For this reason, a GIS-based 3D model of the area including geology, contaminants, hydrogeology, land-use and protected areas has been built. The regional groundwater pollution is characterized by contamination profiles of all monitored substances. In the area of investigation, e.g. threefold and fourfold threshold levels of chlorinated methane, ethane and ethene as well as HCH-isomers, mono-, di- and tetrachlorobenzene, DDT-isomers and benzene are frequently detected in groundwater, that means in at least 60% of the wells that were sampled. High median values of more than 10 microg/l were calculated for cis/trans-1,2-dichloroethene, 1,2-dichloroethane, chloroethene and monochlorobenzene. In general, the regional distribution of contaminants reflect the different sources and pathways, and give first results from a regional point of view, depending on a land-use classification of specific areas. PMID:12676483

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

2003-04-11

11

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

12

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

13

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

14

Groundwater nitrate contamination and use of Cl/Br ratio for source appointment.  

PubMed

Source appointment for groundwater nitrate contamination is critical in prioritizing effective strategy for its mitigation. Here, we assessed the use of Cl/Br ratio and statistical correlation of hydro-chemical parameters to identify the nitrate source to the groundwater. A total of 228 samples from 19 domestic wells distributed throughout the study area were collected during June 2011-May 2012 and analyzed for various physicochemical parameters. Study area was divided into three spatial zones based on demographic features, viz., northern, southern, and central part. Nitrate concentration in 57 % of samples exceeded the prescribed safe limit for drinking stipulated by the World Health Organization (WHO) and Bureau of Indian standards (BIS). The central part of the study area showed elevated nitrate concentration ranging from below detection limit (BDL) to 263.5 mg/l as NO3 (-) and demonstrated high attenuation within the immediate vicinity thereby restricting diffusion of the nitrate to the adjacent parts. Resolution of correlation matrix as statistical indicator for nitrate contamination was poor. Seventy-seven percent of samples with high nitrate concentration (>45 mg/l as NO3 (-)) showed strong association with high Cl/Br mass ratio (350-900), indicating mixing of sewage and septic tank effluents with groundwater as a primary source for the nitrate in the studied area. Nitrate level during monsoon (BDL, 229.9 mg/l as NO3 (-)), post-monsoon (BDL, 263.5 mg/l as NO3 (-)), and pre-monsoon (0.5-223.1 mg/l as NO3 (-)) indicated additional contribution of surface leaching to groundwater. PMID:25638054

Samantara, M K; Padhi, R K; Satpathy, K K; Sowmya, M; Kumaran, P

2015-02-01

15

Groundwater contamination field methods  

NASA Astrophysics Data System (ADS)

Half of the drinking water in the United States comes from groundwater; 75% of the nation's cities obtain all or part of their supplies from groundwater; and the rural areas are 95% dependent upon groundwater. Therefore it is imperative that every possible precaution be taken to protect the purity of the groundwater.Because of the increasing interest in prevention of groundwater contamination and the need for nationally recognized methods for investigation of contamination, a symposium entitled “Field Methods for Groundwater Contamination Studies and Their Standardization” was held February 2-7, 1986, in Cocoa Beach, Fla. The symposium was sponsored and organized by the American Society for Testing and Materials (ASTM) Committee D18 on Soil and Rock and Committee D19 on Water. Gene Collins of the National Institute for Petroleum and Energy Research (Bartlesville, Okla.) was symposium chair, and Ivan Johnson (A. Ivan Johnson, Inc., Consulting, Arvada, Colo.) was vice chair.

Johnson, Ivan

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

Bioremediation of contaminated groundwater  

SciTech Connect

The present invention relates to a method for in situ bioremediation of contaminated soil and groundwater. In particular, the invention relates to remediation of contaminated soil and groundwater by the injection of nutrients to stimulate growth of pollutant-degrading microorganisms. The United States Government has rights in this invention pursuant to Contract No. DE-AC09-89SR18035 between the US Department of Energy and Westinghouse Savannah River Company.

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

1992-12-31

19

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

20

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.

2010-12-01

21

Groundwater Contamination Potential from Stormwater  

E-print Network

1 Groundwater Contamination Potential from Stormwater Infiltration Robert Pitt, University (CSOs). Introduction (cont.) · Scattered information is available addressing groundwater impacts cities · EPA 1983 NURP work on groundwater beneath Fresno and Long Island infiltration basins · NRC 1994

Clark, Shirley E.

22

Bioremediation of contaminated groundwater  

DOEpatents

An apparatus and method 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 periodicially 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.

Hazen, Terry C. (Augusta, GA); Fliermans, Carl B. (Augusta, GA)

1995-01-01

23

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

24

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

25

Groundwater source contamination mechanisms: Physicochemical profile clustering, risk factor analysis and multivariate modelling  

NASA Astrophysics Data System (ADS)

An integrated domestic well sampling and "susceptibility assessment" programme was undertaken in the Republic of Ireland from April 2008 to November 2010. Overall, 211 domestic wells were sampled, assessed and collated with local climate data. Based upon groundwater physicochemical profile, three clusters have been identified and characterised by source type (borehole or hand-dug well) and local geological setting. Statistical analysis indicates that cluster membership is significantly associated with the prevalence of bacteria (p = 0.001), with mean Escherichia coli presence within clusters ranging from 15.4% (Cluster-1) to 47.6% (Cluster-3). Bivariate risk factor analysis shows that on-site septic tank presence was the only risk factor significantly associated (p < 0.05) with bacterial presence within all clusters. Point agriculture adjacency was significantly associated with both borehole-related clusters. Well design criteria were associated with hand-dug wells and boreholes in areas characterised by high permeability subsoils, while local geological setting was significant for hand-dug wells and boreholes in areas dominated by low/moderate permeability subsoils. Multivariate susceptibility models were developed for all clusters, with predictive accuracies of 84% (Cluster-1) to 91% (Cluster-2) achieved. Septic tank setback was a common variable within all multivariate models, while agricultural sources were also significant, albeit to a lesser degree. Furthermore, well liner clearance was a significant factor in all models, indicating that direct surface ingress is a significant well contamination mechanism. Identification and elucidation of cluster-specific contamination mechanisms may be used to develop improved overall risk management and wellhead protection strategies, while also informing future remediation and maintenance efforts.

Hynds, Paul; Misstear, Bruce D.; Gill, Laurence W.; Murphy, Heather M.

2014-04-01

26

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

27

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

28

Identification of sources and behavior of agricultural contaminants in groundwater using nitorgen and sulfur isootope in Haean basin, Korea  

NASA Astrophysics Data System (ADS)

The Haean basin shows a bowl-shaped topographic feature and the drainage system shows a dendritic pattern. The study area is consisted of forests (58.0%), vegetable fields (27.6%), rice paddy fields (11.4%) and fruit fields (0.5%). Most of residents in the study area practice agriculture and paddy rice and vegetables (Chinese radish) are the typical crops grown. The concentration of nitrate in groundwater showed 0.8 ~ 67.3 mg/L in June, 2012 and 2.0 ~ 65.7 mg/L in September, 2012. Hydrogeochemical values and stable isotope ratios of dissolved nitrate and sulfate in groundwater were used to identify contamination sources and transformation processes in shallow groundwater. The ?15N-NO3- values in the study area ranged between +5.2 and +16.9‰ in June and between +4.4 and +13.0‰ in September. The sulfate concentration in groundwater samples obtained from the study area varied from 0.8 to 16.5 mg/L in June and 0 to 19.7 mg/L in September. ?34S-SO42- values ranged from +2.9 to +11.7‰ in June and +1.6 to +8.2‰ in September. The values of ?15N-NO3- and ?34S-SO42- in September were slightly decreased than those of values in June. The chemical composition of groundwater in vegetable and fruit fields showed slightly lower values of ?34S-SO42- and ?15N-NO3- indicated that a mixture of synthetic and organic fertilizers is responsible for groundwater contamination with agro-chemicals. Most groundwater from forests and paddy fields showed slightly higher values of ?15N-NO3- suggested that organic fertilizer is introduced into subsurface.

Kaown, Dugin; Kim, Heejung; Mayer, Bernard; Hyun, Yunjung; Lee, Jin-Yong; Lee, Kang-Kun

2013-04-01

29

Costs of groundwater contamination  

SciTech Connect

Two factors determine the cost of groundwater contamination: (1) the ways in which water was being used or was expected to be used in the future and (2) the physical characteristics of the setting that constrain the responses available to regain lost uses or to prevent related damages to human health and the environment. Most contamination incidents can be managed at a low enough cost that uses will not be foreclosed. It is important to take into account the following when considering costs: (1) natural cleansing through recharge and dilution can take many years; (2) it is difficult and costly to identify the exact area and expected path of a contamination plume; and (3) treatment or replacement of contaminated water often may represent the cost-effective strategy for managing the event. The costs of contamination include adverse health effects, containment and remediation, treatment and replacement costs. In comparing the costs and benefits of prevention programs with those of remediation, replacement or treatment, it is essential to adjust the cost/benefit numbers by the probability of their actual occurrence. Better forecasts of water demand are needed to predict more accurately the scarcity of new supply and the associated cost of replacement. This research should include estimates of the price elasticity of water demand and the possible effect on demand of more rational cost-based pricing structures. Research and development of techniques for in situ remediation should be encouraged.

O'Neil, W.B.; Raucher, R.S. (Environmental Protection Agency, Washington, DC (United States))

1990-01-01

30

Solutions Remediate Contaminated Groundwater  

NASA Technical Reports Server (NTRS)

During the Apollo Program, NASA workers used chlorinated solvents to clean rocket engine components at launch sites. These solvents, known as dense non-aqueous phase liquids, had contaminated launch facilities to the point of near-irreparability. Dr. Jacqueline Quinn and Dr. Kathleen Brooks Loftin of Kennedy Space Center partnered with researchers from the University of Central Florida's chemistry and engineering programs to develop technology capable of remediating the area without great cost or further environmental damage. They called the new invention Emulsified Zero-Valent Iron (EZVI). The groundwater remediation compound is cleaning up polluted areas all around the world and is, to date, NASA's most licensed technology.

2010-01-01

31

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

NASA Astrophysics Data System (ADS)

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 and weekly from February October 2005 at Blue Hole Spring, which drains outlying farm lands and the town of Versailles in the Inner Bluegrass Region of Kentucky. Physicochemical parameters (discharge, temperature, specific conductance, and pH) were measured continuously during the entire period. The AC/TC ratio, which had been employed only in surface water-quality studies, was used with FC counts, precipitation and discharge data to determine sources of fecal loading to ground water as result of land-use practices. An AC/TC ratio < 10 demonstrates fresh input of fecal matter, while a larger ratio can represent a variety of occurrences, including aged fecal material input and/or lack of nutrient input into the system. AC/TC ratio data in the 2002 04 dataset behaved similarly to surface waters, with ratios > 10 during dry periods and < 10 during wet periods, while the 2005 data demonstrated a very irregular pattern. The difference in these two data sets indicated a compositional change within the groundwater basin between the two sampling periods, perhaps as a result of construction at a sewage treatment plant adjoining the spring. Solute (rhodamine WT fluorescent dye and bromide) and particle (1-?m diameter fluorescent latex microspheres) tracer tests were conducted during summer 2006 to examine contaminant mobility within the system under base-flow and storm-flow conditions. Rainfall was limited prior to the base-flow trace, totaling 0.025 cm within 2 weeks prior to the slug injection. Base-flow discharge averaged 400 m3/s and solute breakthrough began ~ 7.5 hours post injection and cleared the system after 77 hours. For the storm-flow trace, rainfall totaled 3.12 cm prior to injection, with another 9.35 cm of rainfall occurring over the two week monitoring period. Spring discharge during the storm-flow trace averaged 0.443 m3/s, with a maximum of 0.503 m3/s. Under storm-flow conditions solute breakthrough began ~ 2.33 hours post injection, with particle breakthrough beginning ~ 2.5 hours post injection. Bromide concentrations at the spring were < 0.1 ppm (the detection limit, or DL) 5.5 hours after injection, while rhodamine WT concentrations were < DL (0.1 ppb) 14 hours post injection. Microspheres were detected at the spring until 164 hours after injection. These traces demonstrate that storms in this karst basin can accelerate solute movement, and particles can remain mobile for as long as 1 week after introduction.

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

2006-12-01

32

Using groundwater age to understand sources and dynamics of nutrient contamination through the catchment into Lake Rotorua, New Zealand  

NASA Astrophysics Data System (ADS)

The water quality of Lake Rotorua has declined continuously over the past 50 yr despite mitigation efforts over recent decades. Delayed response of the groundwater discharges to historic land-use intensification 50 yr ago was the reason suggested by early tritium measurements, which indicated large transit times through the groundwater system. We use the isotopic and chemistry signature of the groundwater for detailed understanding of the origin, fate, flow pathways, lag times, and future loads of contaminants. A unique set of high-quality tritium data over more than four decades, encompassing the time when the tritium spike from nuclear weapons testing moved through the groundwater system, allows us to determine detailed age distribution parameters of the water discharging into Lake Rotorua. The Rotorua volcanic groundwater system is complicated due to the highly complex geology that has evolved through volcanic activity. Vertical and steeply-inclined geological contacts preclude a simple flow model. The extent of the Lake Rotorua groundwater catchment is difficult to establish due to the deep water table in large areas, combined with inhomogeneous groundwater flow patterns. Hierarchical cluster analysis of the water chemistry parameters provided evidence of the recharge source of the large springs near the lake shore, with discharge from the Mamaku ignimbrite through lake sediment layers. Groundwater chemistry and age data show clearly the source of nutrients that cause lake eutrophication, nitrate from agricultural activities and phosphate from geologic sources. With a naturally high phosphate load reaching the lake continuously via all streams, the only effective way to limit algae blooms and improve lake water quality in such environments is by limiting the nitrate load. The groundwater in the Rotorua catchment, once it has passed through the soil zone, shows no further decrease in dissolved oxygen, indicating absence of electron donors in the aquifer that could facilitate microbial denitrification reactions. Nitrate from land-use activities that leaches out of the root zone of agricultural land into the deeper part of the groundwater system must be expected to travel with the groundwater to the lake. The old age and the highly mixed nature of the water discharges imply a very slow and lagged response of the streams and the lake to anthropogenic contaminants in the catchment, such as nitrate. Using the age distribution as deduced from tritium time series data measured in the stream discharges into the lake allows prediction of future nutrient loads from historic land-use activities 50 yr ago. For Hamurana Stream, the largest stream to Lake Rotorua, it takes more than a hundred years for the groundwater-dominated stream discharge to adjust to changes in land-use activities. These time scales apply to activities that cause contamination, but also to remediation action.

Morgenstern, U.; Daughney, C. J.; Leonard, G.; Gordon, D.; Donath, F. M.; Reeves, R.

2014-08-01

33

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

34

Groundwater Ages and Stable Isotope Fingerprints of Contaminated Water to Examine Potential Solute Sources at a Uranium Processing Mill  

NASA Astrophysics Data System (ADS)

To evaluate sources of high solute concentrations in groundwater near a uranium processing facility, groundwater recharge dates are correlated to specific solute concentrations and depth in the water column. Stable isotopes are also used as potential fingerprints of water sourced from mill tailing cells. Passive diffusion samplers, to be analyzed for 3He/4He ratio, were deployed in 15 different wells with samplers at two depths in the saturated interval. Low-flow purging and sampling was then conducted to isolate sampling points at different depths in the wells, with sampling at multiple depths being completed in 4 of the 15 wells sampled. Laboratory analyses were conducted for CFC recharge age, as well as T/3He recharge age. Contract laboratories analyzed for: deuterium and oxygen-18 isotopes of water; sulfur-34 and oxygen-18 isotopes of sulfate; trace metals uranium, manganese, and selenium; and nitrate and sulfate. Analysis for 235U/238U isotope ratios will be conducted to further identify fingerprint signals of source water. Groundwater recharge ages determined using CFC analysis show some vertical stratification in ages across the water column. Upon initial data processing and analysis, measured CFC ages ranged from 30 to 40 years within the water column of one well to only several years difference in another well. Additional results for trace metal concentrations, stable isotope ratios, and T/3He recharge ages will be reported when results are received. Further post-processing of CFC laboratory analysis and noble gas analyses will provide greater clarity as to groundwater ages within the aquifer and, combined with field pumping data, will allow for a comprehensive groundwater model to be constructed. This study provides great insight to potential mine tailings leakage problems and using isotopes and groundwater age dating techniques as a means of tracing contaminated groundwater to the leakage source. Utilizing stable isotopes of water and sulfate, combined with isotope ratios of uranium, create a powerful tool for fingerprinting mine tailings waters and tracing contaminated waters back to a potential leakage point.

Hurst, T. G.; Solomon, D. K.

2007-12-01

35

Contaminant source and release history identification in groundwater: A multi-step approach  

NASA Astrophysics Data System (ADS)

The paper presents a new multi-step approach aiming at source identification and release history estimation. The new approach consists of three steps: performing integral pumping tests, identifying sources, and recovering the release history by means of a geostatistical approach. The present paper shows the results obtained from the application of the approach within a complex case study in Poland in which several areal sources were identified. The investigated site is situated in the vicinity of a former chemical plant in southern Poland in the city of Jaworzno in the valley of the W?wolnica River; the plant has been in operation since the First World War producing various chemicals. From an environmental point of view the most relevant activity was the production of pesticides, especially lindane. The application of the multi-step approach enabled a significant increase in the knowledge of contamination at the site. Some suspected contamination sources have been proven to have minor effect on the overall contamination. Other suspected sources have been proven to have key significance. Some areas not taken into consideration previously have now been identified as key sources. The method also enabled estimation of the magnitude of the sources and, a list of the priority reclamation actions will be drawn as a result. The multi-step approach has proven to be effective and may be applied to other complicated contamination cases. Moreover, the paper shows the capability of the geostatistical approach to manage a complex real case study.

Gzyl, G.; Zanini, A.; Fr?czek, R.; Kura, K.

2014-02-01

36

Evaluation for Early Life Stage Fall Chinook Salmon Exposed to Hexavalent Chromium from a Contaminated Groundwater Source  

SciTech Connect

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 ?g/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 µg/L chromium appear adequate to protect fall Chinook salmon populations.

Patton, Gregory W.; Dauble, Dennis D.; McKinstry, Craig A.

2007-09-01

37

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

38

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

39

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

40

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. PMID:8354172

Piver, W T

1993-01-01

41

Groundwater recharge and agricultural contamination  

USGS Publications Warehouse

Agriculture has had direct and indirect effects on the rates and compositions of groundwater recharge and aquifer biogeochemistry. Direct effects include dissolution and transport of excess quantities of fertilizers and associated materials and hydrologic alterations related to irrigation and drainage. Some indirect effects include changes in water-rock reactions in soils and aquifers caused by increased concentrations of dissolved oxidants, protons, and major ions. Agrilcultural activities have directly or indirectly affected the concentrations of a large number of inorganic chemicals in groundwater, for example NO3-, N2, Cl, SO42-, H+, P, C, K, Mg, Ca, Sr, Ba, Ra, and As, as well a wide variety of pesticides and other organic compounds. For reactive contaminants like NO3-, a combination of chemical, isotopic, and environmental-tracer analytical approaches might be required to resolve changing inputs from subsequent alterations as causes of concentration gradients in groundwater. Groundwater records derived from multi-component hydrostratigraphic data can be used to quantify recharge rates and residence times of water and dissolved contaminants, document past variations in recharging contaminant loads, and identify natural contaminant-remediation processes. These data indicate that many of the world's surficial aquifers contain transient records of changing agricultural contamination from the last half of the 20th century. The transient agricultural groundwater signal has important implications for long-term trends and spatial heterogeneity in discharge.

Böhlke, J.K.

2002-01-01

42

Remediation of groundwater contaminated with radioactive compounds  

Technology Transfer Automated Retrieval System (TEKTRAN)

Both naturally radioactive isotopes and isotopes from man-made sources may appear in groundwater. Depending on the physical and chemical characteristics of the contaminant, different types of treatment methods must be applied to reduce the concentration. The following chapter discusses treatment opt...

43

Groundwater.  

ERIC Educational Resources Information Center

Presents a literature review of groundwater quality covering publications of 1977. This review includes: (1) sources of groundwater contamination; and (2) management of groundwater. A list of 59 references is also presented. (HM)

Braids, Olin C.; Gillies, Nola P.

1978-01-01

44

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

45

Arsenic Contamination of Groundwater at Zimapán, Mexiko  

Microsoft Academic Search

Arsenic contamination of groundwater has been detected in the Zimapán Valley, Mexico. Concentrations as much as 1.097 mg\\/L were observed in water pumped from one of the most productive wells. Three sources of arsenic are known. The natural source is produced by the oxidation of arsenic-bearing minerals; polluted water pumped from the deepest wells is derived from this source and

M. A. Armienta; R. Rodriguez; A. Aguayo; N. Ceniceros; G. Villaseñor; O. Cruz

1997-01-01

46

Source Differentiation for Benzene and Chlorobenzene Groundwater Contamination: A Field Application of Stable Carbon and Hydrogen Isotope Analyses  

Microsoft Academic Search

This article investigates the combined use of compound-specific isotope analyses, hydrogeologic data, contaminant concentrations, and site history to investigate sources of benzene and chlorobenzene contamination in a shallow and deep aquifer. For benzene, ?C and ?H values suggested two source areas in the northeastern and southeastern portion of the shallow aquifer and possible contaminant migration from the shallow to the

Silvia A. Mancini; Georges Lacrampe-Couloume; Barbara Sherwood Lollar

2008-01-01

47

Identification of an Assemblage of Indicator Organisms to Assess Timing and Source of Bacterial Contamination in Groundwater  

Microsoft Academic Search

Bacterial contamination of drinking water wells is a commonproblem in many rural areas. Some of this contamination may berelated to manure spreading or housing of livestock; another source is on-site septic systems. Current indicator organisms are able to detect the presence of fecal contamination, but where there may be more than one potential source of fecal material, the current indicators

M. J. Conboy; M. J. Goss

2001-01-01

48

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

49

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

50

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

51

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

52

Recent advances in the bioremediation of arsenic-contaminated groundwaters  

Microsoft Academic Search

The biological treatment of groundwaters is used primarily to remove electron donors from water sources, providing (biologically) stable drinking water, which preclude bacterial regrowth during subsequent water distribution. To the electron donors belong also the dissolved metal cations of ferrous iron and manganese, which are common contaminants found in most (anaerobic) groundwaters. The removal of iron and manganese is usually

Anastasios I. Zouboulis; Ioannis A. Katsoyiannis

2005-01-01

53

Groundwater dynamics and arsenic contamination in Bangladesh  

Microsoft Academic Search

Although arsenic contaminated groundwater in Bangladesh is a serious health issue, little is known about the complex transient patterns of groundwater flow that flush solutes from aquifers and carry solutes into the subsurface. Hydrologic modeling results for our field site in the Munshiganj district indicate that groundwater flow is vigorous, flushing the aquifer over time-scales of decades to a century,

Charles F. Harvey; Khandaker N. Ashfaque; Winston Yu; A. B. M. Badruzzaman; M. Ashraf Ali; Peter M. Oates; Holly A. Michael; Rebecca B. Neumann; Roger Beckie; Shafiqul Islam; M. Feroze Ahmed

2006-01-01

54

Extent and Severity of Groundwater Arsenic Contamination in Bangladesh  

Microsoft Academic Search

In Bangladesh, the majority of the irrigation and drinking water is supplied from underground sources due to the limitation of surface water. In recent years, arsenic contamination has emerged as a fresh blow to the country. This paper gives an overview of the extent and severity of groundwater arsenic contamination in Bangladesh, as well as a review of the latest

Toshihiko Kawachi; Eiji Ichion

2001-01-01

55

Aerobic biodegradation of trichloroethylene and phenol co-contaminants in groundwater by a bacterial community using hydrogen peroxide as the sole oxygen source.  

PubMed

Trichloroethylene (TCE) and phenol were often found together as co-contaminants in the groundwater of industrial contaminated sites. An effective method to remove TCE was aerobic biodegradation by co-metabolism using phenol as growth substrates. However, the aerobic biodegradation process was easily limited by low concentration of dissolved oxygen (DO) in groundwater, and DO was improved by air blast technique with difficulty. This study enriched a bacterial community using hydrogen peroxide (H2O2) as the sole oxygen source to aerobically degrade TCE by co-metabolism with phenol in groundwater. The enriched cultures were acclimatized to 2-8?mM H2O2 which induced catalase, superoxide dismutase and peroxidase to decompose H2O2 to release O2 and reduce the toxicity. The bacterial community could degrade 120?mg/L TCE within 12 days by using 8?mM H2O2 as the optimum concentration, and the TCE degradation efficiency reached up to 80.6%. 16S rRNA gene cloning and sequencing showed that Bordetella, Stenotrophomonas sp., Sinorhizobium sp., Variovorax sp. and Sphingobium sp. were the dominant species in the enrichments, which were clustered in three phyla: Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria. Polymerase chain reaction detection proved that phenol hydroxylase (Lph) gene was involved in the co-metabolic degradation of phenol and TCE, which indicated that hydroxylase might catalyse the epoxidation of TCE to form the unstable molecule TCE-epoxide. The findings are significant for understanding the mechanism of biodegradation of TCE and phenol co-contamination and helpful for the potential applications of an aerobic bioremediation in situ the contaminated sites. PMID:25220534

Li, Hui; Zhang, Shi-Yang; Wang, Xiao-Li; Yang, Jie; Gu, Ji-Dong; Zhu, Rui-Li; Wang, Ping; Lin, Kuang-Fei; Liu, Yong-di

2015-03-01

56

Implications of uncertainty in exposure assessment for groundwater contamination  

USGS Publications Warehouse

Decision-making on regulation, mitigation, and treatment of drinking water contamination depends, in part, on estimates of human exposure. Assessment of past, present and potential future exposure levels requires quantitative characterization of the contaminant sources, the transport of contaminants and the level of actual human exposure to the contaminated water. Failure to consider the uncertainties in these three components of exposure assessment can lead to poor decisions such as implementing an inappropriate mitigation strategy or failing to regulate an important contaminant. Three examples from US Geological Survey hydrogeologic studies in southern California are presented to illustrate some of the unique uncertainties associated with exposure assessment for groundwater contamination.

Reichard, Eric G.; Izbicki, John A.; Martin, Peter

1995-01-01

57

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

58

Using cassava distiller's dried grains as carbon and microbe sources to enhance denitrification of nitrate-contaminated groundwater.  

PubMed

Nitrate removal from synthetic and real groundwater was investigated by using cassava distiller's dried grains (CDDG), which served as sole carbon source as well as the only microbe seed. It was found that remarkably higher total nitrogen removal efficiency (96.8±0.6 %) could be reached; the accumulation of nitrite and the releases of organic compounds, meanwhile, were insignificant in the denitrification process. Scanning electron microscope (SEM) analysis showed that CDDG were degraded during the denitrification process. Further investigation showed that CDDG were anaerobically hydrolyzed and acidified to butyric acid, acetic acid, and carbohydrate, which could be utilized directly as the reducing equivalent providers for denitrification by the microorganisms separated from CDDG. Microbial community analysis revealed that the fungi and bacteria present in the original CDDG functioned as the denitrifiers, which mainly consisted of Aspergillus (69.8 %) and Rhizomucor (15.9 %) in the fungi community and Burkholderia (20.6 %) and Rhizobium (15.9 %) in the bacteria community, respectively. Finally, the use of CDDG as both carbon and microbial sources for real groundwater denitrification was testified to be feasible and safe with a total nitrogen removal efficiency of around 100 %. PMID:25343978

Wan, Rui; Zheng, Xiong; Chen, Yinguang; Wang, Huaichen

2014-10-26

59

Effect of land use and urbanization on hydrochemistry and contamination of groundwater from Taejon area, Korea  

Microsoft Academic Search

Taejon Metropolitan City located in the central part of South Korea has grown and urbanized rapidly. The city depends heavily on groundwater as a water resource. Because of ubiquitous pollution sources, the quality and contamination have become important issues for the urban groundwater supply. This study has investigated the chemical characteristics and the contamination of groundwater in relation to land

Chan Ho Jeong

2001-01-01

60

REMOVAL OF ORGANIC CONTAMINANTS FROM GROUNDWATER.  

EPA Science Inventory

More are than lOO million Americans depend on groundwater as a source of drinking water. hree quarters of U.S. cities get their water supplies totally or in part from groundwater and one-third of the largest cities rely on groundwater for at least part of their potable water supp...

61

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

E-print Network

Enhanced detection of groundwater contamination from a leaking waste disposal site by microbial in disposal sites cited as a significant source of groundwater contamination in both the United States into the subsurface from leaking landfills. Detecting leachate contamination using statistical techniques

Vermont, University of

62

Groundwater Nitrate Contamination Risk Assessment in Canicattì area (Sicily)  

NASA Astrophysics Data System (ADS)

Groundwaters play a dominant role in the Sicily, because as most part of Mediterranean countries this island is interested by the phenomenon of desertification and the quality of the groundwater reservoir is one of the most important aim for the management policy strategies. During last decade most of the Italian regions the nitrate levels in river and groundwaters have increased gradually over mainly as a consequence of large-scale agricultural application of manure and fertilizers, thereby threatening drinking water quality. The excessive use of chemicals and fertilizers increases the risk to pollution of surface and groundwater from diffuse source, an important reflex to human health and the environment. The studied area is located in Canicattì (central Sicily, Italy), the current land use (grape, olive grove and almond) is the main source of groundwater pollution. In order to investigate the effect of the over farming on the groundwater quality we report the study on the potential risk of contamination from nitrate of agricultural origin through the join of the application of two parametric methods: the IPNOA method (the intrinsic nitrate contamination risk from Agricultural sources) applied to define the Nitrate Vulnerable Zones and the SINTACS method applied to determine the aquifer vulnerability to contamination.

Pisciotta, Antonino; Cusimano, Gioacchino; Favara, Rocco

2010-05-01

63

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

64

RAPID REMOVAL OF A GROUNDWATER CONTAMINANT PLUME.  

USGS Publications Warehouse

A groundwater management model is used to design an aquifer restoration system that removes a contaminant plume from a hypothetical aquifer in four years. The design model utilizes groundwater flow simulation and mathematical optimization. Optimal pumping and injection strategies achieve rapid restoration for a minimum total pumping cost. Rapid restoration is accomplished by maintaining specified groundwater velocities around the plume perimeter towards a group of pumping wells located near the plume center. The model does not account for hydrodynamic dispersion. Results show that pumping costs are particularly sensitive to injection capacity. An 8 percent decrease in the maximum allowable injection rate may lead to a 29 percent increase in total pumping costs.

Lefkoff, L. Jeff; Gorelick, Steven M.

1985-01-01

65

Hydraulic gradient control for groundwater contaminant removal  

USGS Publications Warehouse

The Rocky Mountain Arsenal near Denver, Colarado, U.S.A., is used as a realistic setting for a hypothetical test of a procedure that plans the hydraulic stabilization and removal of a groundwater contaminant plume. A two-stage planning procedure successfully selects the best wells and their optimal pumping/recharge schedules to contain the plume while a well or system of wells within the plume removes the contaminated water. In stage I, a combined groundwater flow and solute transport model is used to simulate contaminant removal under an assumed velocity field. The result is the approximated plume boundary location as a function of time. In stage II, a linear program, which includes a groundwater flow model as part of the set of constraints, determines the optimal well selection and their optimal pumping/recharge schedules by minimizing total pumping and recharge. The simulation-management model eliminates wells far from the plume perimeter and activates wells near the perimeter as the plume decreases in size. This successfully stablizes the hydraulic gradient during aquifer cleanup.The Rocky Mountain Arsenal near Denver, Colorado, USA, is used as a realistic setting for a hypothetical test of a procedure that plans the hydraulic stabilization and removal of a groundwater contaminant plume. A two-stage planning procedure successfully selects the best wells and their optimal pumping/recharge schedules to contain the plume while a well or system of wells within the plume removes the contaminated water. In stage I, a combined groundwater flow and solute transport model is used to simulate contaminant removal under an assumed velocity field. The result is the approximated plume boundary location as a function of time. In stage II, a linear program, which includes a groundwater flow model as part of the set of constraints, determines the optimal well selection and their optimal pumping/recharge schedules by minimizing total pumping and recharge. Refs.

Fisher, Atwood D.; Gorelick, S.M.

1985-01-01

66

Complexity of Groundwater Contaminants at DOE Sites  

SciTech Connect

The U.S. Department of Energy (DOE) is responsible for the remediation and long-term stewardship of one of the world's largest groundwater contamination portfolios, with a significant number of plumes containing various contaminants, and considerable total mass and activity. As of 1999, the DOE's Office of Environmental Management was responsible for remediation, waste management, or nuclear materials and facility stabilization at 144 sites in 31 states and one U.S. territory, out of which 109 sites were expected to require long-term stewardship. Currently, 19 DOE sites are on the National Priority List. The total number of contaminated plumes on DOE lands is estimated to be 10,000. However, a significant number of DOE sites have not yet been fully characterized. The most prevalent contaminated media are groundwater and soil, although contaminated sediment, sludge, and surface water also are present. Groundwater, soil, and sediment contamination are present at 72% of all DOE sites. A proper characterization of the contaminant inventory at DOE sites is critical for accomplishing one of the primary DOE missions -- planning basic research to understand the complex physical, chemical, and biological properties of contaminated sites. Note that the definitions of the terms 'site' and 'facility' may differ from one publication to another. In this report, the terms 'site,' 'facility' or 'installation' are used to identify a contiguous land area within the borders of a property, which may contain more than one plume. The term 'plume' is used here to indicate an individual area of contamination, which can be small or large. Even though several publications and databases contain information on groundwater contamination and remediation technologies, no statistical analyses of the contaminant inventory at DOE sites has been prepared since the 1992 report by Riley and Zachara. The DOE Groundwater Data Base (GWD) presents data as of 2003 for 221 groundwater plumes at 60 DOE sites and facilities. Note that Riley and Zachara analyzed the data from only 18 sites/facilities including 91 plumes. In this paper, we present the results of statistical analyses of the data in the GWD as guidance for planning future basic and applied research of groundwater contaminants within the DOE complex. Our analyses include the evaluation of a frequency and ranking of specific contaminants and contaminant groups, contaminant concentrations/activities and total contaminant masses and activities. We also compared the results from analyses of the GWD with those from the 1992 report by Riley and Zachara. The difference between our results and those summarized in the 1992 report by Riley and Zachara could be caused by not only additional releases, but also by the use of modern site characterization methods, which more accurately reveal the extent of groundwater contamination. Contaminated sites within the DOE complex are located in all major geographic regions of the United States, with highly variable geologic, hydrogeologic, soil, and climatic conditions. We assume that the information from the 60 DOE sites included in the GWD are representative for the whole DOE complex. These 60 sites include the major DOE sites and facilities, such as Rocky Flats Environmental Technology Site, Colorado; Idaho National Laboratory, Idaho; Savannah River Site, South Carolina; Oak Ridge Reservation, Tennessee; and Hanford Reservation, Washington. These five sites alone ccount for 71% of the value of the remediation work.

Hazen, T.C.; Faybishenko, B.; Jordan, P.

2010-12-03

67

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

68

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.

69

Arsenic contamination in groundwater: some analytical considerations  

Microsoft Academic Search

For countries such as Bangladesh with a significant groundwater arsenic problem, there is an urgent need for the arsenic-contaminated wells to be identified as soon as possible and for appropriate action to be taken. This will involve the testing of a large number of wells, potentially up to 11 million in Bangladesh alone. Field-test kits offer the only practical way

David G. Kinniburgh; Walter Kosmus

2002-01-01

70

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.

71

Activated Peroxygens for Remediation of Contaminated Soil and Groundwater  

E-print Network

i Activated Peroxygens for Remediation of Contaminated Soil and Groundwater Ph.D. thesis Submitted May 2011 #12;ii Activated Peroxygens for Remediation of Contaminated Soil and Groundwater Ph.D. thesis peroxygens for remediation of contaminated soil and groundwater" along with 5 papers describing part

Hansen, René Rydhof

72

Preventing pesticide contamination of groundwater while maximizing irrigated crop yield  

NASA Astrophysics Data System (ADS)

A simulation/optimization model is developed for maximizing irrigated crop yield while avoiding unacceptable pesticide leaching. The optimization model is designed to help managers prevent non-point source contamination of shallow groundwater aquifers. It computes optimal irrigation amounts for given soil, crop, chemical, and weather data and irrigation frequencies. It directly computes the minimum irrigated crop yield reduction needed to prevent groundwater contamination. Constraint equations used in the model maintain a layered soil moisture volume balance; describe percolation, downward unsaturated zone solute transport and pesticide degradation; and limit the amount of pesticide reaching groundwater. Constraints are linear, piecewise linear, nonlinear, and exponential. The problem is solved using nonlinear programming optimization. The model is tested for different scenarios of irrigating corn. The modeling approach is promising as a tool to aid in the development of environmentally sound agricultural production practices. It allows direct estimation of trade-offs between crop production and groundwater protection for different management approaches. More frequent irrigation tends to give better crop yield and reduce solute movement. Trade-offs decrease with increasing irrigation frequency. More frequent irrigation reduces yield loss due to moisture stress and requires less water to fill the root zone to field capacity. This prevents the solute from moving to deeper soil layers. Yield-environmental quality trade-offs are smaller for deeper groundwater tables because deeper groundwater allows more time for chemical degradation.

Peralta, R. C.; Hegazy, M. A.; Musharrafieh, G. R.

1994-11-01

73

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...

74

Lead Groundwater Contamination of Groundwater in the Northeast of Buenos Aires Province, Argentina.  

E-print Network

Lead Groundwater Contamination of Groundwater in the Northeast of Buenos Aires Province, Argentina in the Northeast of the Province of Buenos Aires, Argentina has produced an intense development of the groundwater and evaluating the environmental impact from the transport of contaminants in groundwater. Key words lead

Santos, Juan

75

Dilution and volatilization of groundwater contaminant discharges in streams.  

PubMed

An analytical solution to describe dilution and volatilization of a continuous groundwater contaminant plume into streams is developed for risk assessment. The location of groundwater plume discharge into the stream (discharge through the side versus bottom of the stream) and different distributions of the contaminant plume concentration (Gaussian, homogeneous or heterogeneous distribution) are considered. The model considering the plume discharged through the bank of the river, with a uniform concentration distribution was the most appropriate for risk assessment due to its simplicity and limited data requirements. The dilution and volatilization model is able to predict the entire concentration field, and thus the mixing zone, maximum concentration and fully mixed concentration in the stream. It can also be used to identify groundwater discharge zones from in-stream concentration measurement. The solution was successfully applied to published field data obtained in a large and a small Danish stream and provided valuable information on the risk posed by the groundwater contaminant plumes. The results provided by the dilution and volatilization model are very different to those obtained with existing point source models, with a distributed source leading to a larger mixing length and different concentration field. The dilution model can also provide recommendations for sampling locations and the size of impact zones in streams. This is of interest for regulators, for example when developing guidelines for the implementation of the European Water Framework Directive. PMID:25496819

Aisopou, Angeliki; Bjerg, Poul L; Sonne, Anne T; Balbarini, Nicola; Rosenberg, Louise; Binning, Philip J

2015-01-01

76

Dilution and volatilization of groundwater contaminant discharges in streams  

NASA Astrophysics Data System (ADS)

An analytical solution to describe dilution and volatilization of a continuous groundwater contaminant plume into streams is developed for risk assessment. The location of groundwater plume discharge into the stream (discharge through the side versus bottom of the stream) and different distributions of the contaminant plume concentration (Gaussian, homogeneous or heterogeneous distribution) are considered. The model considering the plume discharged through the bank of the river, with a uniform concentration distribution was the most appropriate for risk assessment due to its simplicity and limited data requirements. The dilution and volatilization model is able to predict the entire concentration field, and thus the mixing zone, maximum concentration and fully mixed concentration in the stream. It can also be used to identify groundwater discharge zones from in-stream concentration measurement. The solution was successfully applied to published field data obtained in a large and a small Danish stream and provided valuable information on the risk posed by the groundwater contaminant plumes. The results provided by the dilution and volatilization model are very different to those obtained with existing point source models, with a distributed source leading to a larger mixing length and different concentration field. The dilution model can also provide recommendations for sampling locations and the size of impact zones in streams. This is of interest for regulators, for example when developing guidelines for the implementation of the European Water Framework Directive.

Aisopou, Angeliki; Bjerg, Poul L.; Sonne, Anne T.; Balbarini, Nicola; Rosenberg, Louise; Binning, Philip J.

2015-01-01

77

Estimating exposure to groundwater contaminants in karst areas  

NASA Astrophysics Data System (ADS)

Large multidisciplinary projects investigate health effects and environmental impacts of contamination. Such multidisciplinary projects challenge groundwater hydrologist because they demand estimations of human or environmental exposure to groundwater contaminants. But especially in karst regions, groundwater quality is subject to rapid changes resulting from highly dynamic flow systems with rapid groundwater recharge and contaminant transport in karst conduits. There is a strong need for tools that allow the quantification of the risk of contaminant exposure via the karst groundwater and its temporal variation depending on rainfall events and overall hydrological conditions. A fact that makes the assessment of contaminant exposure even more difficult is that many contaminants behave differently in the subsurface than the groundwater, because they do not dissolve and exist as a separate phase. Important examples are particulate contaminants, such as bacteria, and non-aqueous phase liquids (NAPLs), such as many organic compounds. Both are ubiquitous in the environment and have large potential for health impacts. It is known from bacterial contamination of karst springs that such contamination is strongly related to flow conditions. Bacteria, which are present at the land surface, in the soil, rock matrix or the conduit system, are immobile during base flow conditions. During storm events however, they become mobilized and are rapidly transported through the conduit flow system from sources to areas of potential exposure. As a result, bacteria concentrations that most times are low at a spring can show a high peak during storm flow. Conceptual models exist that suggest that the transport of NAPLs in karst aquifers is, just like bacterial contamination, related to flow conditions. Light NAPLs that reach the saturated zone float and accumulate on the water table; and dense NAPLs sink downward in the aquifer until they are trapped in pores, fractures and conduits where they remain stationary under base flow conditions. During storm flows, however, they can be dragged downstream or flushed as suspensions and emulsions. As a result, storm flow can send previously immobilized NAPLs to exposure zones in toxic pulses. An approach is presented to estimate the risk of contaminant exposure by bacteria and NAPLs via the groundwater under variable hydrological conditions (Butscher et al. 2011). The approach uses an indicator that is expressed as the Dynamic Vulnerability Index (DVI). This index is defined as the ratio of conduit to matrix flow contributions to spring discharge, and is calculated based on a numerical model simulating karst groundwater flow. The approach is illustrated at a test site in Switzerland, where calculated DVI was compared to the occurrence of fecal indicators during five storm flow events. Key words: karst hydrogeology; groundwater contamination; fecal indicators; NAPLs; numerical modeling References: Butscher, C. Auckenthaler, A., Scheidler, S., Huggenberger, P. (2011). Validation of a Numerical Indicator of Microbial Contamination for Karst Springs. Ground Water 49 (1), 66-76.

Butscher, C.

2012-12-01

78

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

USGS Publications Warehouse

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.

Rubin, H.; Buddemeier, R.W.

2002-01-01

79

Restoring contaminated groundwater. An achievable goal  

Microsoft Academic Search

According to a new National Research Council (NRC) study published this month, groundwater restoration may be possible for sites with relatively simple contamination scenarios, but for the most complex sites, which includes the majority of Superfund sites, existing technologies may be unable to restore significant areas to health-based standards. In addition to analyzing conventional pump-and-treat systems, the committee evaluated innovative

Jacqueline A. MacDonald; Michael C. Kavanaugh

1994-01-01

80

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

81

The Development of the Contaminant Exceedance Rating System (CERS) for Comparing Groundwater Contaminant Data.  

E-print Network

?? The typical approach to mapping groundwater contaminant plumes involves drawing plume contours out to each contaminant’s site-specific cleanup criterion. Cleanup criteria differ between contaminants,… (more)

Mierzwiak, Sara M.

2012-01-01

82

Understanding shallow groundwater contamination in Bwaise slum, Kampala, Uganda  

NASA Astrophysics Data System (ADS)

Groundwater in unsewered urban areas is heavily contaminated by onsite sanitation activities and is believed to be an important source of nutrients ex-filtrating into streams and thus contributing to eutrophication of Lakes in urban areas. Currently the fate of nutrients and especially phosphorus leached into groundwater in such areas is not well known. In this study, we undertook an extensive investigation of groundwater in Bwaise slum, Kampala Uganda to understand the distribution and fate of sanitation-related nutrients N and P that are leached into groundwater. Transects of monitoring wells were installed in Bwaise slum and downstream of the slum. From these wells, water levels were measured and water quality analyses done to understand the distribution and composition of the nutrients, how they evolve downstream and the possible subsurface processes affecting their fate during transport. These findings are necessary to evaluate the risk of eutrophication posed by unsewered areas in urban cities and to design/implement sanitation systems that will effectively reduce the enrichment of these nutrients in groundwater. Key words: fate, groundwater, nutrients, processes, slums

Nyenje, P. M.; Havik, J.; Foppen, J. W.; Uhlenbrook, S.

2012-04-01

83

Waveform tomography at a groundwater contamination site: Surface reflection data  

E-print Network

Waveform tomography at a groundwater contamination site: Surface reflection data Fuchun Gao1 , Alan at a groundwater-contamination site at Hill Air Force Base in Utah. The paleochannel, which is incised. ByAu- gust 2005, 1265 contamination sites across the United States were on the National Priority List

Pratt, R. Gerhard

84

Remediation of Groundwater Contaminated by Nuclear Waste  

NASA Astrophysics Data System (ADS)

A Workshop on Accelerating Development of Practical Field-Scale Bioremediation Models; An Online Meeting, 23 January to 20 February 2008; A Web-based workshop sponsored by the U.S. Department of Energy Environmental Remediation Sciences Program (DOE/ERSP) was organized in early 2008 to assess the state of the science and knowledge gaps associated with the use of computer models to facilitate remediation of groundwater contaminated by wastes from Cold War era nuclear weapons development and production. Microbially mediated biological reactions offer a potentially efficient means to treat these sites, but considerable uncertainty exists in the coupled biological, chemical, and physical processes and their mathematical representation.

Parker, Jack; Palumbo, Anthony

2008-07-01

85

groundwater nitrogen source identification and remediation  

E-print Network

groundwater nitrogen source identification and remediation The Seymour Aquifer is a shallow aquifer, the Seymour Aquifer has the highest groundwater pollution potential of all the major aqui- fers in Texas drinking water standards. Potential sources of nitrate in groundwater include atmospheric deposi- tion

86

Contaminant Transport in Groundwater for Environmental Performance Assessment  

E-print Network

L E Y Contaminant Transport in Groundwater for Environmentalcontaminant transport models. The increasing complexity of environmentalenvironmental Reviews of the organization of this report provides a review of the regulatory perspective on contaminant

Rubin, Yoram N

1997-01-01

87

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

88

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

89

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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 cont...

90

Wellhead treatment costs for groundwater contaminated with pesticides: A preliminary analysis for pineapple in Hawaii  

Microsoft Academic Search

In Hawaii, trace concentrations of pesticides used in the production of pineapple were found in the groundwater supplies of Mililani Town in the Pearl Harbor Basin on the island of Oahu. Groundwater serves as the major source of drinking water and residents pay for wellhead treatment of the contaminated water, via their monthly water bill. The agricultural chemical users within

Ephraim D. Leon-Guerrero; Keith Loague; Richard E. Green

1994-01-01

91

Groundwater Arsenic Contamination, Its Health Impact and Mitigation Program in Nepal  

Microsoft Academic Search

About 47% of Nepal's total population is living in Terai region and 90% of them are relying on groundwater as their major source of drinking water. About 200,000 shallow tubewells have been installed by different agencies in 20 Terai districts, serving 11 million people. Recently, arsenic contamination of groundwater has been recognized as a public health problem in Nepal. This has

Roshan R. Shrestha; Mathura P. Shrestha; Narayan P. Upadhyay; Riddhi Pradhan; Rosha Khadka; Arinita Maskey; Makhan Maharjan; Sabita Tuladhar; Binod M. Dahal; Kabita Shrestha

2003-01-01

92

Arsenic Contaminated Groundwater and Its Treatment Options in Bangladesh  

PubMed Central

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

2012-01-01

93

Enhanced In Situ Bioremediation of BTEX-Contaminated Groundwater by  

E-print Network

Enhanced In Situ Bioremediation of BTEX-Contaminated Groundwater by Combined Injection of Nitrate. Introduction Remediation by natural attenuation (RNA) is the preferred method (1) for addressing groundwater, at siteswherethenaturalgroundwaterflowisveryslow,intrinsic biodegradation processes can be limited by the rate at which the groundwater supplies

California at Berkeley, University of

94

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

95

Phytoremediation of Arsenic-Contaminated Groundwater by the Arsenic Hyperaccumulating Fern Pteris vittata L  

Microsoft Academic Search

Arsenic concentrations in a much larger fraction of U.S. groundwater sources will exceed the maximum contaminant limit when the new 10 ?g L EPA standard for drinking water takes effect in 2006. Thus, it is important to develop remediation technologies that can meet this new standard. Phytoremediation of arsenic-contaminated groundwater is a relatively new idea. In this research, an arsenic-hyperaccumulating

S. Tu; Lena Q. Ma; Abioye O. Fayiga; Edward J. Zillioux

2004-01-01

96

Delineation of a wellhead protection zone and determination of flowpaths from potential groundwater contaminant source areas at Camp Ripley, Little Falls, Minnesota.  

SciTech Connect

Groundwater at Camp Ripley, Minnesota, is recharged both on post and off site and discharged to rivers, wetlands, and pumping wells. The subsurface geologic materials have a wide range of permeabilities and are arranged in a complex fashion as a result of the region's multiple glacial advances. Correlation of individual glacial geologic units is difficult, even between nearby boreholes, because of the heterogeneities in the subsurface. This report documents the creation of a numerical model of groundwater flow for Camp Ripley and hydrologically related areas to the west and southwest. The model relies on a hydrogeological conceptual model built on the findings of a University of Minnesota-Duluth drilling and sampling program conducted in 2001. Because of the site's stratigraphic complexity, a geostatistical approach was taken to handle the uncertainty of the subsurface correlation. The U.S. Geological Survey's MODFLOW code was used to create the steady-state model, which includes input data from a variety of sources and is calibrated to water levels in monitoring wells across much of the site. This model was used for several applications. Wellhead protection zones were delineated for on-site production wells H, L, and N. The zones were determined on the basis of a probabilistic assessment of the groundwater captured by these wells; the assessment, in turn, had been based on multiple realizations of the study area's stratigraphy and groundwater flowfield. An additional application of the model was for estimating flowpaths and times of travel for groundwater at Camp Ripley's range areas and waste management facilities.

Quinn, J. J.; Environmental Science Division

2006-12-22

97

Using Pre-Modeled Scenarios to Estimate Groundwater VOC Concentrations Resulting from Vadose Zone Sources  

SciTech Connect

Soil vapor extraction (SVE) is a prevalent remediation approach for volatile contaminants in the vadose zone. To support selection of an appropriate endpoint for the SVE remedy, an evaluation is needed to determine whether vadose zone contamination has been diminished sufficiently to protect groundwater. When vapor-phase transport is an important component of the overall contaminant fate and transport from a vadose zone source, the contaminant concentration expected in groundwater is controlled by a limited set of parameters, including specific site dimensions, vadose zone properties, and source characteristics. An approach was developed for estimating the contaminant concentration in groundwater resulting from a contaminant source in the vadose zone based on pre-modeling contaminant transport for a matrix of parameter value combinations covering a range of potential site conditions. An interpolation and scaling process are then applied to estimate groundwater impact for site-specific conditions.

Oostrom, Martinus; Truex, Michael J.; Rice, Amy K.; Johnson, Christian D.; Carroll, Kenneth C.; Becker, Dave; Simon, Michelle A.

2014-04-28

98

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

99

Soda ash treatment of a strontium-90-contaminated groundwater seep  

SciTech Connect

A /sup 90/Sr-contaminated groundwater seep on the perimeter of a low-level radioactive solid waste disposal area at the Oak Ridge National Laboratory (ORNL) was treated by burying 315 kg of soda ash in the groundwater flow path leading to the seep, and placing 45 kg of soda ash on the surface of the seep. The concentration of /sup 90/Sr in the seep water fell from an average of 7000 Bq L/sup -1/ to 900 Bq L/sup -1/ for the 90 d after burial, followed by a period of gradual rise back to pretreatment levels over the next 100 d. The electrical conductivity and pH of the seep water increased following soda ash burial, while water hardness fell. Hardness was highly correlated (r = 0.84) with /sup 90/Sr concentrations over the entire 2-year observation period, indicating the similar behavior of /sup 90/Sr and soluble Ca and Mg. This in situ softening of, and /sup 90/Sr precipitation from, the seep water was achieved by coprecipitation of /sup 90/Sr with Ca(Mg)CO/sub 3/ until the buried soda ash was depleted by dissolution in the groundwater. The soda ash treatment of groundwater seeps appears to be most practical as an interim technique for those situations requiring an immediate, but temporary, corrective action. During this limited but effective period, more permanent corrective actions could be planned at the source of contamination. The electrical conductivity, pH, and hardness of the larger surface stream, into which this seep discharges, were not affected by the soda ash burial, most likely due to the approximately 2000-fold dilution effected by this stream.

Spalding, B.P.; Munro, I.I.

1983-01-01

100

Optimization of remedial pumping schemes for a ground-water site with multiple contaminants  

SciTech Connect

This paper presents an optimization analysis of the remedial pumping design for a contaminated aquifer located in Elmira, Ontario, Canada. The remediation task presented in the paper is to remove two ground-water contaminant species, NDMA (N-nitrosodimethylamine) and chlorobenzene, to such extent that the specified ground-water quality standards are met. The contaminants, NDMA and chlorobenzene, have different initial plume configurations and retardation characteristics. The required quality standard for NDMA is five orders of magnitude smaller than the initial peak concentration. The objective is to minimize total pumping, and the constraints incorporate ground-water quality requirements on the maximum and the spatially averaged residual concentrations, with contaminant source control being considered. On the combination of simulation and optimization, the results of this study indicate that the performance of an optimization algorithm based on gradient search is controlled by the specified cleanup levels, and that contaminant concentrations can be nonconvex and nonsmooth for some pumping schemes.

Xiang, Y.; Sykes, J.F.; Thomson, N.R. [Univ. of Waterloo, Ontario (Canada). Dept. of Civil Engineering

1996-01-01

101

Risk Assessment of Groundwater Contamination: A Multilevel Fuzzy Comprehensive Evaluation Approach Based on DRASTIC Model  

PubMed Central

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, Yan; Zhong, Ming

2013-01-01

102

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

103

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

E-print Network

Biotreatment of groundwater contaminated with MTBE: interaction of common environmental co of groundwater with the gasoline additive methyl tert-butyl ether (MTBE) is often accompanied by many aromatic, a laboratory-scale biotrickling filter for groundwater treatment inoculated with a microbial consortium

104

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...

105

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...

106

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 ...

107

Different Strategies for Biological Remediation of Perchlorate Contaminated Groundwater  

E-print Network

occupied the pore space and plugged the reactor, even more,space to vent out, and contaminated groundwater was fed into the reactorspace per day. A ZVI-PRB system can be described as a plug flow reactor

Wang, Yue

2012-01-01

108

IMPLICATIONS OF ALTERNATIVE POLICIES ON NITRATE CONTAMINATION OF GROUNDWATER  

Microsoft Academic Search

This study estimates the cost effectiveness of alternative environmental policies for controlling nitrate contamination of groundwater in the Seymour aquifer region of Texas. Results from biophysical simulation model are integrated with a farm-level optimization model. The study also compares the cost of bottled water, used as the lower-bound estimate of benefits of groundwater protection, with the least costly environmental policy.

Manzoor E. Chowdhury; Ronald D. Lacewell

1996-01-01

109

Predicting groundwater arsenic contamination in Southeast Asia from surface parameters  

Microsoft Academic Search

Arsenic contamination of groundwater resources threatens the health of millions of people worldwide, particularly in the densely populated river deltas of Southeast Asia. Although many arsenic-affected areas have been identified in recent years, a systematic evaluation of vulnerable areas remains to be carried out. Here we present maps pinpointing areas at risk of groundwater arsenic concentrations exceeding 10mugl-1. These maps

Lenny Winkel; Michael Berg; Manouchehr Amini; Stephan J. Hug; C. Annette Johnson

2008-01-01

110

Groundwater contaminants in the deep benthic zone of urban streams in Canada (Invited)  

NASA Astrophysics Data System (ADS)

There is little information available on the potential threat that groundwater containing land-based contaminants poses to aquatic ecosystems in urban environments. In this study, a rapid screening approach was applied at the stream reach-scale for eight urban streams (reaches from 100 to < 1000 m). The objective was to determine what types of groundwater contaminants could be detected in the deeper benthic zone of these streams, if any, to start to address questions of whether such contaminants are a concern and which types are the most problematic. The benthic community may be especially at risk since it may experience higher contaminant concentrations than the stream itself due to fewer losses from sorption, degradation and volatilization processes. For each stream, groundwater samples from below the stream bed (typically 25-75 cm) were collected using a drive-point mini-profiler at intervals of 10-15 m along the stream and were subsequently analysed for general chemistry and a wide range of common and emerging urban contaminants. For a few test streams with known contamination, the area of contamination was identified with this technique. In addition, previously unknown contaminants or areas of contamination were identified at all nine streams. Identified contaminants included benzene and other petroleum hydrocarbons, fuel oxygenates (e.g. MTBE), perchlorate, pesticides, artificial sweeteners, and various chlorinated solvent compounds. In addition, elevated levels of nitrate, phosphate, some heavy metals, including cadmium and arsenic, and elevated chloride (likely indicating road salt) were detected. Most streams had many different types of contaminants, often overlapping over small stretches, and together often covering substantial portions of the monitored reach. The findings provide support for this screening approach for delineating areas of potential ecological concern and identifying possible sources of groundwater contamination, for urban settings. They also suggest that the presence of multiple groundwater contaminants may be a more common threat to the benthic community of urban streams than currently perceived.

Roy, J. W.; Bickerton, G.

2010-12-01

111

Assessing soil and groundwater contamination in a metropolitan redevelopment project.  

PubMed

The purpose of this study was to assess contaminated soil and groundwater for the urban redevelopment of a rapid transit railway and a new mega-shopping area. Contaminated soil and groundwater may interfere with the progress of this project, and residents and shoppers may be exposed to human health risks. The study area has been remediated after application of first remediation technologies. Of the entire area, several sites were still contaminated by waste materials and petroleum. For zinc (Zn) contamination, high Zn concentrations were detected because waste materials were disposed in the entire area. For petroleum contamination, high total petroleum hydrocarbon (TPH) and hydrocarbon degrading microbe concentrations were observed at the depth of 7 m because the underground petroleum storage tank had previously been located at this site. Correlation results suggest that TPH (soil) concentration is still related with TPH (groundwater) concentration. The relationship is taken into account in the Spearman coefficient (?). PMID:23307052

Yun, Junki; Lee, Ju Young; Khim, Jeehyeong; Ji, Won Hyun

2013-08-01

112

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

Peter Riemersma

113

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

114

Wellhead treatment costs for groundwater contaminated with pesticides: A preliminary analysis for pineapple in Hawaii  

Microsoft Academic Search

In Hawaii, trace concentrations of pesticides used in the production of pineapple were found in the groundwater supplies of\\u000a Mililani Town in the Pearl Harbor Basin on the island of Oahu. Groundwater serves as the major source of drinking water and\\u000a residents pay for wellhead treatment of the contaminated water, via their monthly water bill. The agricultural chemical users\\u000a within

Ephraim D. Leon-Guerrero; Keith Loague; Richard E. Green

1994-01-01

115

Impacts of arsenic contamination in groundwater: case study of some villages in Bangladesh  

Microsoft Academic Search

The contamination of groundwater in Bangladesh by arsenic is a widespread and serious environmental problem, affecting mainly\\u000a the rural population who rely extensively on groundwater for drinking and cooking. The study conducted survey work in a few\\u000a affected villages of the Northwest region in Bangladesh. The household survey gathered information on the respondents (affected\\u000a by arsenic) water usage and sources,

Nurun Nahar

2009-01-01

116

Nonpoint source pollution management models for regional groundwater quality control  

SciTech Connect

Several steady-state groundwater quality management models useful for investigating regional groundwater wasteload allocation from nonpoint sources are presented. These management models are constructed as linear programming optimization models. Equations from a finite difference, steady-state, two-dimensional horizontal, unconfined, advective contaminant transport model are used as part of each optimization problem constraint set. The management models were applied over the Sole Source aquifer of Barnstable County, Massachusetts. Barnstable County is incurring widespread nitrate contamination from distributed septic systems which serve 88 percent of the population. The modeling approach requires general data normally available through state geological surveys, regional planning commissions, and the census bureau. The optimal regional nonpoint source groundwater wasteload allocations are generated from this data as are resultant contaminant distributions, boundaries of critical recharge areas, and the associated water quality tradeoffs for changes in existing and proposed land use (or source) management schemes. The optimal wasteload allocations were translated into estimates of distributed source densities and land use development patterns.

Hatfield, K.

1988-01-01

117

Petroleum contaminated ground-water: Remediation using activated carbon  

Microsoft Academic Search

Ground-water contamination resulting from the leakage of crude oil and refined petroleum products during extraction and processing operations is a serious and a growing environmental problem in Nigeria. Consequently, a study of the use of activated carbon (AC) in the clean up was undertaken with the aim of reducing the water contamination to a more acceptable level. In the experiments

M. J. Ayotamuno; R. B. Kogbara; S. O. T. Ogaji; S. D. Probert

2006-01-01

118

Effect of land use and urbanization on hydrochemistry and contamination of groundwater from Taejon area, Korea  

NASA Astrophysics Data System (ADS)

Taejon Metropolitan City located in the central part of South Korea has grown and urbanized rapidly. The city depends heavily on groundwater as a water resource. Because of ubiquitous pollution sources, the quality and contamination have become important issues for the urban groundwater supply. This study has investigated the chemical characteristics and the contamination of groundwater in relation to land use. An attempt was made to distinguish anthrophogenic inputs from the influence of natural chemical weathering on the chemical composition of groundwater at Taejon. Groundwater samples collected at 170 locations in the Taejon area show very variable chemical composition of groundwater, e.g. electrical conductance ranges from 65 to 1,290 ?S/cm. Most groundwater is weakly acidic and the groundwater chemistry is more influenced by land use and urbanization than by aquifer rock type. Most groundwater from green areas and new town residential districts has low electrical conductance, and is of Ca-HCO 3 type, whereas the chemical composition of groundwater from the old downtown and industrial district is shifted towards a Ca-Cl (NO 3+SO 4) type with high electrical conductance. A number of groundwater samples in the urbanized area are contaminated by high nitrate and chlorine, and exhibit high hardness. The EpCO 2, that is the CO 2 content of a water sample relative to pure water, was computed to obtain more insight into the origin of CO 2 and bicarbonate in the groundwater. The CO 2 concentration of groundwater in the urbanized area shows a rough positive relationship with the concentration of major inorganic components. The sources of nitrate, chlorine and excess CO 2 in the groundwater are likely to be municipal wastes of unlined landfill sites, leaky latrines and sewage lines. Chemical data of commercial mineral water from other Jurassic granite areas were compared to the chemical composition of the groundwater in the Taejon area. Factor analysis of the chemical data shows that the HCO 3- and NO 3- concentrations have the highest factor loadings on factor 1 and factor 2, respectively. Factors 1 and 2 represent major contributions from natural processes and human activities, respectively. The results of the factor analysis indicate that the levels of Ca 2+, Mg 2+, Na +, Cl - and SO 42- derive from both pollution sources and natural weathering reactions.

Jeong, Chan Ho

2001-11-01

119

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

120

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

121

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

122

Groundwater contamination downstream of a contaminant penetration site. II. Horizontal penetration of the contaminant plume.  

PubMed

Part I of this study (Rubin, H.; Buddemeier, R.W. Groundwater Contamination Downstream of a Contaminant Penetration Site Part 1: Extension-Expansion of the Contaminant Plume. J. of Environmental Science and Health Part A (in press).) addressed cases, in which a comparatively thin contaminated region represented by boundary layers (BLs) developed within the freshwater aquifer close to contaminant penetration site. However, at some distance downstream from the penetration site, the top of the contaminant plume reaches the top or bottom of the aquifer. This is the location of the "attachment point," which comprises the entrance cross section of the domain evaluated by the present part of the study. It is shown that downstream from the entrance cross section, a set of two BLs develop in the aquifer, termed inner and outer BLs. It is assumed that the evaluated domain, in which the contaminant distribution gradually becomes uniform, can be divided into two sections, designated: (a) the restructuring section, and (b) the establishment section. In the restructuring section, the vertical concentration gradient leads to expansion of the inner BL at the expense of the outer BL, and there is almost no transfer of contaminant mass between the two layers. In the establishment section, each of the BLs occupies half of the aquifer thickness, and the vertical concentration gradient leads to transfer of contaminant mass from the inner to the outer BL. By use of BL approximations, changes of salinity distribution in the aquifer are calculated and evaluated. The establishment section ends at the uniformity point, downstream from which the contaminant concentration profile is practically uniform. The length of the restructuring section, as well as that of the establishment section, is approximately proportional to the aquifer thickness squared, and is inversely proportional to the transverse dispersivity. The study provides a convenient set of definitions and terminology that are helpful in visualizing the gradual development of uniform contaminant concentration distribution in an aquifer subject to contaminant plume penetration. The method developed in this study can be applied to a variety of problems associated with groundwater quality, such as initial evaluation of field data, design of field data collection, the identification of appropriate boundary conditions for numerical models, selection of appropriate numerical modeling approaches, interpretation and evaluation of field monitoring results, etc. PMID:12413211

Rubin, Hillel; Buddemeier, Robert W

2002-11-01

123

Groundwater contamination downstream of a contaminant penetration site. II. Horizontal penetration of the contaminant plume  

USGS Publications Warehouse

Part I of this study (Rubin, H.; Buddemeier, R.W. Groundwater Contamination Downstream of a Contaminant Penetration Site Part 1: Extension-Expansion of the Contaminant Plume. J. of Environmental Science and Health Part A (in press).) addressed cases, in which a comparatively thin contaminated region represented by boundary layers (BLs) developed within the freshwater aquifer close to contaminant penetration site. However, at some distance downstream from the penetration site, the top of the contaminant plume reaches the top or bottom of the aquifer. This is the location of the "attachment point," which comprises the entrance cross section of the domain evaluated by the present part of the study. It is shown that downstream from the entrance cross section, a set of two BLs develop in the aquifer, termed inner and outer BLs. It is assumed that the evaluated domain, in which the contaminant distribution gradually becomes uniform, can be divided into two sections, designated: (a) the restructuring section, and (b) the establishment section. In the restructuring section, the vertical concentration gradient leads to expansion of the inner BL at the expense of the outer BL, and there is almost no transfer of contaminant mass between the two layers. In the establishment section, each of the BLs occupies half of the aquifer thickness, and the vertical concentration gradient leads to transfer of contaminant mass from the inner to the outer BL. By use of BL approximations, changes of salinity distribution in the aquifer are calculated and evaluated. The establishment section ends at the uniformity point, downstream from which the contaminant concentration profile is practically uniform. The length of the restructuring section, as well as that of the establishment section, is approximately proportional to the aquifer thickness squared, and is inversely proportional to the transverse dispersivity. The study provides a convenient set of definitions and terminology that are helpful in visualizing the gradual development of uniform contaminant concentration distribution in an aquifer subject to contaminant plume penetration. The method developed in this study can be applied to a variety of problems associated with groundwater quality, such as initial evaluation of field data, design of field data collection, the identification of appropriate boundary conditions for numerical models, selection of appropriate numerical modeling approaches, interpretation and evaluation of field monitoring results, etc.

Rubin, H.; Buddemeier, R.W.

2002-01-01

124

Statistical evidence on the effectiveness of sewering to protect groundwater from VOC contamination  

NASA Astrophysics Data System (ADS)

Volatile organic compounds (VOCs) are an important source of contamination of groundwater supplies in Massachusetts and many parts of the United States. One local response is to require sewering in wellhead protection areas as an easily enforceable policy designed to reduce the probability of VOC contamination of groundwater. Data were collected for 238 wellhead protection areas in Massachusetts on VOC contamination levels and the sewered and unsewered land uses in those aquifer recharge areas. Logistic regression procedures were used to see whether sewering had any statistical effect on likelihood of contamination of well water. The results provided limited, but not overpowering, support for the idea that requiring commercial and industrial land uses to use sewers would reduce the chance of VOC contamination.

Willis, Cleve E.; Sacheti, Sandeep

1996-03-01

125

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

126

Arsenic Contamination in Groundwater of North Eastern India  

Microsoft Academic Search

Groundwater arsenic contamination and sufferings of people have been reported in 20 countries in different parts of the world. The magnitude is considered highest in five Asian countries and the severity is in order of Bangladesh>India>Mangolia>China>Taiwan. In all these countries, more and more groundwater withdrawal is taking place because of increase in agricultural irrigation. In India after West Bengal and

A. K. Singh

127

Relation of Nickel Concentrations in Tree Rings to Groundwater Contamination  

NASA Astrophysics Data System (ADS)

Increment cores were collected from trees growing at two sites where groundwater is contaminated by nickel. Proton-induced X ray emission spectroscopy was used to determine the nickel concentrations in selected individual rings and in parts of individual rings. Ring nickel concentrations were interpreted on the basis of recent concentrations of nickel in aquifers, historical information about site use activities, and model simulations of groundwater flow. Nickel concentrations in rings increased during years of site use but not in trees outside the contaminated aquifers. Consequently, it was concluded that trees may preserve in their rings an annual record of nickel contamination in groundwater. Tulip trees and oaks contained higher concentrations of nickel than did sassafras, sweet gum, or black cherry. No evidence was found that nickel accumulates consistently within parts of individual rings or that nickel is translocated across ring boundaries.

Yanosky, Thomas M.; Vroblesky, Don A.

1992-08-01

128

Ethanol-based in situ bioremediation of acidified, nitrate-contaminated groundwater.  

PubMed

A novel approach for the in situ bioremediation of acidified, nitrate-contaminated groundwater was developed. Ethanol was introduced into the groundwater to enhance the activity of intrinsic denitrifying micro-organisms. Infiltration of the carbon source was made via an infiltration gallery constructed in the unsaturated zone to avoid clogging problems and to allow wider distribution of ethanol in the groundwater. The changes in the groundwater geochemistry and soil gas composition were monitored at the site to evaluate the efficiencies of the infiltration system and nitrate removal. Moreover, the impact of pH and ethanol addition on the denitrification rate was studied in laboratory. A reduction of 95% was achieved in the groundwater nitrate concentrations during the study. Neither clogging problems nor inefficient introduction of ethanol into the saturated zone were observed. Most crucial to the denitrifying communities was pH, values above 6 were required for efficient denitrification. PMID:25019597

Salminen, Jani M; Petäjäjärvi, Sanna J; Tuominen, Sirkku M; Nystén, Taina H

2014-10-15

129

The Groundwater Foundation  

NSDL National Science Digital Library

The Groundwater Foundation is a non-profit organization dedicated to educating and motivating people to care for and about groundwater. The section Groundwater Basics contains numerous information on groundwater issues, including the following subjects: what is groundwater; how much do we depend on groundwater; groundwater protection, hydrologic cycle, contamination and concerns, sources of groundwater contamination, wells and how they work, ten ways to help conserve and protect groundwater, groundwater ABCs - a glossary of groundwater-related terminology, and source water assessment and protection guide and training materials. Also of interest are kids and youth sections with activities and games, as well as a listing of the foundation's publications and events.

130

Identification and Tracing Groundwater Contamination by Livestock Burial Sites  

NASA Astrophysics Data System (ADS)

Foot-and-mouth disease (FMD) or hoof-and-mouth disease is a severe plague for animal farming that affects cloven-hoofed animals such as cattle, pigs, sheep, and goats. Since it is highly infectious and can be easily proliferated by infected animals, contaminated equipments, vehicles, clothing, people, and predators. It is widely known that the virus responsible for FMD is a picornavirus, the prototypic member of the genus Aphthovirus. A serious outbreak of foot-and-mouth disease, leading to the stamping out of 3.53 millions of pigs and cattle and the construction of 4,538 burial sites until 15th March, 2011. The build-up of carcass burial should inevitably produce leachate by the decomposition of buried livestock affecting the surround environment such as air, soil, groundwater, and surface water. The most important issues which are currently raised by scientists are groundwater contamination by leachate from the livestock burial sites. This study examined the current status of FMD outbreak occurred in 2010-2011 and the issues of groundwater contamination by leachate from livestock burial sites. The hydrogeochemical, geophysical, and hydrogeological studies were executed to identify and trace groundwater contamination by leachate from livestock burial sites. Generally livestock mortality leachate contains high concentrations of NH3-N, HCO3-, Cl-, SO42-, K+, Na+, P along with relative lesser amounts of iron, calcium, and magnesium. The groundwater chemical data around four burial sites showed high NH3-N, HCO3-, and K+ suggesting the leachate leakage from burial sites. This is also proved by resistivity monitoring survey and tracer tests. The simulation results of leachate dispersion showed the persistent detrimental impacts for groundwater environment for a long time (~50 years). It is need to remove the leachate of burial sites to prevent the dispersion of leachate from livestock burial to groundwater and to monitor the groundwater quality. The most important forthcoming issues for livestock burial are the treatment of leachate, protection of groundwater contamination by leachate, prevention of land slide, and prevention of rainfall percolation into burial site. It is also needed to develop the remediation, prospecting, and management technologies of groundwater contamination by carcass burial.

Ko, K.; Ha, K.; Park, S.; Kim, Y.; Lee, K.

2011-12-01

131

Assessment of ground-water contamination in the alluvial aquifer near West Point, Kentucky  

USGS Publications Warehouse

Well inventories, water level measurements, groundwater quality samples, surface geophysical techniques (specifically, electromagnetic techniques), and test drilling were used to investigate the extent and sources of groundwater contamination in the alluvial aquifer near West Point, Kentucky. This aquifer serves as the principal source of drinking water for over 50,000 people. Groundwater flow in the alluvial aquifer is generally unconfined and moves in a northerly direction toward the Ohio River. Two large public supply well fields and numerous domestic wells are located in this natural flow path. High concentrations of chloride in groundwater have resulted in the abandonment of several public supply wells in the West Point areas. Chloride concentrations in water samples collected for this study were as high as 11,000 mg/L. Electromagnetic techniques indicated and test drilling later confirmed that the source of chloride in well waters was probably improperly plugged or unplugged, abandoned oil and gas exploration wells. The potential for chloride contamination of wells exists in the study area and is related to proximity to improperly abandoned oil and gas exploration wells and to gradients established by drawdowns associated with pumped wells. Periodic use of surface geophysical methods, in combination with added observation wells , could be used to monitor significant changes in groundwater quality related to chloride contamination. (USGS)

Lyverse, M.A.; Unthank, M.D.

1988-01-01

132

Optimal dynamic management of groundwater pollutant sources.  

USGS Publications Warehouse

The linear programing-superposition method is presented for managing multiple sources of groundwater pollution over time. The method uses any linear solute transport simulation model to generate a unit source-concentration response matrix that is incorporated into a management model. -from Authors

Gorelick, S.M.; Remson, I.

1982-01-01

133

Diffusion in random velocity fields with applications to contaminant transport in groundwater  

E-print Network

Diffusion in random velocity fields with applications to contaminant transport in groundwater is the mathematical object underlying cur- rently used stochastic models of transport in groundwater. The essential: Groundwater, Transport processes, Ergodicity, Random fields, Random walk, PDF methods 1. Introduction

Suciu, Nicolae

134

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

135

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

136

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

137

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

138

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....

139

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

140

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

141

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

142

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

143

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...

144

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

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

Linking bacterial diversity and geochemistry of uranium-contaminated groundwater  

Microsoft Academic Search

To understand the link between bacterial diversity and geochemistry in uranium-contaminated groundwater, microbial communities were assessed based on clone libraries of 16S rDNA genes from the USDOE Oak Ridge Field Research Centre (FRC) site. Four groundwater wells (GW835, GW836, FW113-47 and FW215-49) with a wide range of pH (3 to 7), nitrate (44 to 23,400 mg L), uranium (0.73 to 60.36 mg L) and

Kelly Cho; Alma Zholi; Dylan Frabutt; Matthew Flood; Dalton Floyd; Sonia M. Tiquia

2012-01-01

147

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

148

Nebraska's groundwater legacy: Nitrate contamination beneath irrigated cropland  

PubMed Central

A 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?20 years of management. Average annual concentrations in 10 MAs are increasing (p?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

2014-01-01

149

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

150

Natural Gas as the Source of Benzene in Groundwater  

Microsoft Academic Search

An investigation to evaluate the source of benzene in groundwater samples at a rural landfill in southwestern Louisiana was performed using isotopic and geochemical parameters as tracers of the fluids potentially transporting the benzene to groundwater. Leachate water had 2,649 tritium units while background groundwater and samples with benzene detections were both below 1. C in groundwater methane was 2.3%

Henry B. Kerfoot; Warren D. Brady; William H. Schramm; Mark A. Allendorf

2009-01-01

151

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.; Böhlke, J.K.; Dody, A.

2004-01-01

152

Evaluation of sustained release polylactate electron donors for removal of hexavalent chromium from contaminated groundwater  

E-print Network

www.regenesis.com/contaminated-site-remediation-products/chlorinated solvent contaminated sites, (Koenigsberg, 2001)contaminated groundwater by in-situ cometabolic reduction. Sixth Annual In-Situ and On-Site

Brodie, E.L.

2012-01-01

153

Superfund record of decision (EPA Region 7): Hastings Groundwater Contamination Site, Hastings, NE, June 1993  

SciTech Connect

The decision document presents the selected interim remedial actions for the Well Number 3 ground water operable units. The Well Number 3 Subsite is a subsite of the Hastings Ground Water Contamination Site, Hastings, Nebraska. The interim action ROD addresses two separate areas of groundwater contamination. Plume 1 is characterized by carbon tetrachloride (CCl4) and chloroform (CHCl3) contamination. Plume 2 is characterized primarily by trichloroethene (TCE), 1,1,1-trichloroethane (TCA), tetrachloroethene (PCE) and dichloroethene (DEC) contamination. These interim ground water remedies were developed to protect public health, welfare and the environment by controlling the migration and reducing the volume and mass of contaminants present in the ground water beneath and downgradient from each source area of the Well Number 3 Subsite.

Not Available

1993-06-30

154

Black Swans and the Effectiveness of Remediating Groundwater Contamination  

NASA Astrophysics Data System (ADS)

Black swans, outliers, dominate science far more than do predictable outcomes. Predictable success constitutes the Black Swan in groundwater remediation. Even the National Research Council concluded that remediating groundwater to drinking water standards has failed in typically complex hydrogeologic settings where heterogeneities and preferential flow paths deflect flow paths obliquely to hydraulic gradients. Natural systems, be they biological or physical, build upon a combination of large-scale regularity coupled to chaos at smaller scales. We show through a review of over 25 case studies that groundwater remediation efforts are best served by coupling parsimonious site characterization to natural and induced geochemical tracer tests to at least know where contamination advects with groundwater in the subsurface. In the majority of our case studies, actual flow paths diverge tens of degrees from anticipated flow paths because of unrecognized heterogeneities in the horizontal direction of transport, let alone the vertical direction. Consequently, regulatory agencies would better serve both the public and the environment by recognizing that long-term groundwater cleanup probably is futile in most hydrogeologic settings except to relaxed standards similar to brownfielding. A Black Swan

Siegel, D. I.; Otz, M. H.; Otz, I.

2013-12-01

155

ATTENUATION OF GROUND-WATER CONTAMINANT PULSES  

EPA Science Inventory

Analytical solutions to the one-dimensional advection-dispersion equation are presented for several cases where the source concentration is either input continuously at a periodically fluctuating level or input as a single pulse of finite duration. The solute of interest can unde...

156

Y-12 Groundwater Protection Program Extent Of The Primary Groundwater Contaminants At The Y-12 National Security Complex  

SciTech Connect

This report presents data summary tables and maps used to define and illustrate the approximate lateral extent of groundwater contamination at the U.S. Department of Energy (DOE) Y-12 National Security Complex (Y-12) in Oak Ridge, Tennessee. The data tables and maps address the primary (i.e., most widespread and mobile) organic, inorganic, and radiological contaminants in the groundwater. The sampling locations, calculated contaminant concentrations, plume boundary values, and paired map format used to define, quantify, delineate, and illustrate the approximate extent of the primary organic, inorganic, and radiological contaminants in groundwater at Y-12 are described.

none,

2013-12-01

157

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

158

Fitting a groundwater contaminant transport model by L1 and L2 parameter estimators  

NASA Astrophysics Data System (ADS)

This paper presents a study on the use of linear and nonlinear L1-norm parameter estimators to fit an analytical groundwater contaminant transport model with nonuniform contaminant source distributions. The model solution is obtained as a superposition of an analytical solution developed by Cleary (Cleary, R.W., Analytical Models for Groundwater Pollution and Hydrology, 208 Long Island Groundwater Pollution Study, draft report, vol. 3, Princeton University, NJ, 1978). Comparisons with the commonly used linear and nonlinear L2-norm estimators are conducted. The posterior statistical inference theory by Nyquist (Nyquist, H., Commun. Statist.-Theor. Meth., 1983, 12, 2511-24) and Gonin and Money (Gonin, G. & Money, A.H., Commun. Statist.-Theor. Meth., 1985, 14, 827-40) is used to provide the posterior covariance matrix and the probability distribution for the unknown parameter vector. As the conclusion, it is suggested that in view of the nature of groundwater contaminant transport modeling, L1-norm estimators may be preferred as robust alternatives to L2-norm estimators in solving parameter estimation problems.

Xiang, Yanyong; Thomson, N. R.; Sykes, J. F.

159

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

PubMed

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. PMID:23948235

Mair, Alan; El-Kadi, Aly I

2013-10-01

160

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

161

Spatial control of groundwater contamination, using principal component analysis  

NASA Astrophysics Data System (ADS)

A study on the geochemistry of groundwater was carried out in a river basin of Andhra Pradesh to probe into the spatial controlling processes of groundwater contamination, using principal component analysis (PCA). The PCA transforms the chemical variables, pH, EC, Ca2+, Mg2+, Na+, K+, HCO, Cl-, SO, NO and F-, into two orthogonal principal components (PC1 and PC2), accounting for 75% of the total variance of the data matrix. PC1 has high positive loadings of EC, Na+, Cl-, SO, Mg2+ and Ca2+, representing a salinity controlled process of geogenic (mineral dissolution, ion exchange, and evaporation), anthropogenic (agricultural activities and domestic wastewaters), and marine (marine clay) origin. The PC2 loadings are highly positive for HCO , F-, pH and NO, attributing to the alkalinity and pollution controlled processes of geogenic and anthropogenic origins. The PC scores reflect the change of groundwater quality of geogenic origin from upstream to downstream area with an increase in concentration of chemical variables, which is due to anthropogenic and marine origins with varying topography, soil type, depth of water levels, and water usage. Thus, the groundwater quality shows a variation of chemical facies from Na+ > Ca2+ > Mg2+ > K+: HCO > Cl- > SO NO > F-at high topography to Na+ > Mg2+ > Ca2+ > K+: Cl- > HCO > SO NO > F- at low topography. With PCA, an effective tool for the spatial controlling processes of groundwater contamination, a subset of explored wells is indexed for continuous monitoring to optimize the expensive effort.

Rao, N. Subba

2014-06-01

162

Assessment of groundwater pathways and contaminant transport in Florida and Georgia using multiple chemical and microbiological indicators  

USGS Publications Warehouse

The hydrogeology of Florida, especially in the northern part of the state, and southwestern Georgia is characterized by a predominance of limestone aquifers overlain by varying amounts of sands, silts, and clays. This karstic system of aquifers and their associated springs is particularly vulnerable to contamination from various anthropogenic activities at the land surface. Numerous sinkholes, disappearing streams, and conduit systems or dissolution pathways, often associated with large spring systems, allow rapid movement of contaminants from the land surface to the groundwater system with little or no attenuation or degradation. The fate of contaminants in the groundwater system is not fully understood, but traveltimes from sources are greatly reduced when conduits are intercepted by pumping wells and springs. Contaminant introduction to groundwater systems in Florida and Georgia is not limited to seepage from land surface, but can be associated with passive (drainage wells) and forced subsurface injection (aquifer storage and recovery, waste-water disposal).

Mahon, Gary L.

2011-01-01

163

Robust decision analysis for environmental management of groundwater contamination sites  

E-print Network

In contrast to many other engineering fields, the uncertainties in subsurface processes (e.g., fluid flow and contaminant transport in aquifers) and their parameters are notoriously difficult to observe, measure, and characterize. This causes severe uncertainties that need to be addressed in any decision analysis related to optimal management and remediation of groundwater contamination sites. Furthermore, decision analyses typically rely heavily on complex data analyses and/or model predictions, which are often poorly constrained as well. Recently, we have developed a model-driven decision-support framework (called MADS; http://mads.lanl.gov) for the management and remediation of subsurface contamination sites in which severe uncertainties and complex physics-based models are coupled to perform scientifically defensible decision analyses. The decision analyses are based on Information Gap Decision Theory (IGDT). We demonstrate the MADS capabilities by solving a decision problem related to optimal monitoring ...

Vesselinov, Velimir V; Katzman, Danny

2013-01-01

164

Perchlorate contamination of groundwater from fireworks manufacturing area in South India.  

PubMed

Perchlorate contamination was investigated in groundwater and surface water from Sivakasi and Madurai in the Tamil Nadu State of South India. Sensitive determination of perchlorate (LOQ?=?0.005 ?g/L) was achieved by large-volume (500 ?L) injection ion chromatography coupled with tandem mass spectrometry. Concentrations of perchlorate were <0.005-7,690 ?g/L in groundwater (n?=?60), <0.005-30.2 ?g/L in surface water (n?=?11), and 0.063-0.393 ?g/L in tap water (n?=?3). Levels in groundwater were significantly higher in the fireworks factory area than in the other locations, indicating that the fireworks and safety match industries are principal sources of perchlorate pollution. This is the first study that reports the contamination status of perchlorate in this area and reveals firework manufacture to be the pollution source. Since perchlorate levels in 17 out of 57 groundwater samples from Sivakasi, and none from Madurai, exceeded the drinking water guideline level proposed by USEPA (15 ?g/L), further investigation on human health is warranted. PMID:23108714

Isobe, Tomohiko; Ogawa, Shohei P; Sugimoto, Rina; Ramu, Karri; Sudaryanto, Agus; Malarvannan, Govindan; Devanathan, Gnanasekaran; Ramaswamy, Babu Rajendran; Munuswamy, Natesan; Ganesh, Deavaraj Sankar; Sivakumar, Jeyaraj; Sethuraman, A; Parthasarathy, V; Subramanian, Annamalai; Field, Jennifer; Tanabe, Shinsuke

2013-07-01

165

Associations of free-living bacteria and dissolved organic compounds in a plume of contaminated groundwater  

USGS Publications Warehouse

Associations of free-living bacteria (FLB) and dissolved organic contaminants in a 4-km-long plume of sewage-contaminated groundwater were investigated. Abundance of FLB in the core of the plume (as delineated by maximum specific conductance) steadily decreased in the direction of flow from a point 0.25 km downgradient from the source to the toe of the plume. At 0.25 km downgradient, FLB comprised up to 31% of the total bacterial population, but constituted < 7% of the population at 2 km downgradient. Abundance of FLB correlated strongly (r = 0.80 n = 23) with total dissolved organic carbon (DOC) in contaminated groundwater between 0.64 and 2.1 km downgradient, although distributions of individual contaminants such as di-, tri- and tetrachloroethene were highly variable, and their association with FLB less clear. Numbers of FLB in the downgradient portion of the plume which is contaminated with branched-chain alkylbenzenesulfonate (ABS) surfactants were low (< 5??108/L) in spite of relatively high levels of DOC (up to 4 mg/L). However, abundance of FLB correlated strongly with non-surfactant DOC along vertical transects through the plume. The ratio of FLB to DOC and the ratio of FLB to attached bacteria generally decreased in the direction of flow and, consequently, with the age of the organic contaminants.

Harvey, R.W.; Barber, L.B., II

1992-01-01

166

Remediation of Petroleum-Contaminated Groundwater Using High Carbon Content Fly Ash  

E-print Network

1 Remediation of Petroleum-Contaminated Groundwater Using High Carbon Content Fly Ash M. Melih for retardation of petroleum contaminants in barrier applications. Sorbed amounts measured in batch scale tests on remediation efficiency. INTRODUCTION Remediation of groundwater contaminated with petroleum-based products has

Aydilek, Ahmet

167

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

168

Unclassified Source Term and Radionuclide Data for the Groundwater Flow and Contaminant Transport Model of Corrective Action Units 101 and 102: Central and Western Pahute Mesa, Nye County, Nevada, Revision 0  

SciTech Connect

This report documents the evaluation of the information and data available on the unclassified source term and radionuclide contamination for Central and Western Pahute Mesa: Corrective Action Units (CAUs) 101 and 102.

McCord, John

2004-08-01

169

Chlorobenzene degradation by bacteria isolated from contaminated groundwater  

SciTech Connect

Bacterial isolates were obtained from groundwater and soils contaminated with chlorobenzene (CB). The isolates were tested to determine whether the natural community could remove the groundwater contaminants. These isolates were identified and characterized as to their ability to grow on CB and related aromatic compounds. The complete consortium could mineralize approximately 54% of the CB within 7 days, with no accumulation of 3-chlorocatechol. Metabolic pathways were evaluated for several isolates. One phenotype was characterized by the ability to degrade CB by the modified ortho pathway. One strain also degraded p-dichlorobenzene by using the same pathway. Isolates exhibiting a second phenotype degraded p-cresol, benzene, and phenol by the classical ortho pathway and accumulated 3-chlorocatechol when grown in the presence of CB. Strains of the third phenotype grew on complex media in the presence of CB but did not transform any of the aromatic compounds tested. The results suggest that the indigenous microbial community at the contaminated site would be able to degrade CB if provided with the appropriate conditions.

Nishino, S.F.; Spain, J.C. (Tyndall Air Force Base, FL (United States)); Belcher, L.A. (E.I. du Pont de Nemours and Co., Inc., Newark, DE (United States)); Litchfield, C.D. (DuPont Environmental Remediation Services, Aston, PA (United States))

1992-05-01

170

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

171

Using discriminant analysis to determine sources of salinity in shallow groundwater prior to hydraulic fracturing.  

PubMed

High-volume hydraulic fracturing (HVHF) gas-drilling operations in the Marcellus Play have raised environmental concerns, including the risk of groundwater contamination. Fingerprinting water impacted by gas-drilling operations is not trivial given other potential sources of contamination. We present a multivariate statistical modeling framework for developing a quantitative, geochemical fingerprinting tool to distinguish sources of high salinity in shallow groundwater. The model was developed using new geochemical data for 204 wells in New York State (NYS), which has a HVHF moratorium and published data for additional wells in NYS and several salinity sources (Appalachian Basin brines, road salt, septic effluent, and animal waste). The model incorporates a stochastic simulation to predict the geochemistry of high salinity (>20 mg/L Cl) groundwater impacted by different salinity sources and then employs linear discriminant analysis to classify samples from different populations. Model results indicate Appalachian Basin brines are the primary source of salinity in 35% of sampled NYS groundwater wells with >20 mg/L Cl. The model provides an effective means for differentiating groundwater impacted by basin brines versus other contaminants. Using this framework, similar discriminatory tools can be derived for other regions from background water quality data. PMID:25062431

Lautz, Laura K; Hoke, Gregory D; Lu, Zunli; Siegel, Donald I; Christian, Kayla; Kessler, John Daniel; Teale, Natalie G

2014-08-19

172

Sources of uncertainty in climate change impacts on groundwater recharge  

Microsoft Academic Search

This paper assesses the significance of the many sources of uncertainty in future groundwater recharge estimation, based on lessons learnt from an integrated approach to assessing the regional impacts of climate and socio-economic change on groundwater recharge in East Anglia, UK. Many factors affect simulations of future groundwater recharge including changed precipitation and temperature regimes, coastal flooding, urbanization, woodland establishment,

I. P. Holman

2007-01-01

173

Vulnerability of recently recharged groundwater in principal aquifers of the United States to nitrate contamination  

USGS Publications Warehouse

Recently recharged water (defined here as <60 years old) is generally the most vulnerable part of a groundwater resource to nonpoint-source nitrate contamination. Understanding at the appropriate scale the interactions of natural and anthropogenic controlling factors that influence nitrate occurrence in recently recharged groundwater is critical to support best management and policy decisions that are often made at the aquifer to subaquifer scale. New logistic regression models were developed using data from the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) program and National Water Information System for 17 principal aquifers of the U.S. to identify important source, transport, and attenuation factors that control nonpoint source nitrate concentrations greater than relative background levels in recently recharged groundwater and were used to predict the probability of detecting elevated nitrate in areas beyond the sampling network. Results indicate that dissolved oxygen, crops and irrigated cropland, fertilizer application, seasonally high water table, and soil properties that affect infiltration and denitrification are among the most important factors in predicting elevated nitrate concentrations. Important differences in controlling factors and spatial predictions were identified in the principal aquifer and national-scale models and support the conclusion that similar spatial scales are needed between informed groundwater management and model development.

Gurdak, Jason J.; Qi, Sharon L.

2012-01-01

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

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

176

Analysis of Model Uncertainties to Support Risk-Based Decisions Regarding Groundwater Contamination  

NASA Astrophysics Data System (ADS)

Model simulations are widely used in environmental management decision processes. However, there are various sources of uncertainty that commonly impact the model results. Consequently, it is crucial to account for all the possible model uncertainties that impact the model results so that they are adequately considered in the management decision process. Here we discuss an uncertainty analysis of model simulations related to a contamination site located within Los Alamos National Laboratory, NM. We describe how uncertainties are quantified and propagated through a series of coupled groundwater models and then used in a risk-based decision analysis to identify and rank alternative actions to protect the environment and water users from potential impacts of groundwater contamination from former liquid-effluent discharges. Uncertainties in the contaminant source, infiltration distribution, and transport through the unsaturated and saturated zones are analyzed using a series of alternative conceptual models and stochastic model parameters. Alternative conceptual models and uncertain model parameters are defined to encompass a large range of possible uncertainties associated with potential groundwater flow and transport based on existing data and expert knowledge about the system. In all, eight alternative conceptual models using 38 uncertain parameters were analyzed. For each conceptual model and related stochastic parameter realization, we simulate contaminant transport from the contaminant outfall to water-supply wells over the next 1000 years. Based on the simulated contaminant concentrations in the groundwater pumped by water-supply wells, we evaluate health risk for the receptors. Based on the model results, sensitivity analysis is applied to identify the parameters and conceptual model elements causing high concentrations at the water-supply wells. Decision analysis is applied to define the optimal course(s) of action, which may include clean-up, stabilization, additional characterization, and monitoring. If additional characterization is identified as an action that can reduce risk, the sensitivity analysis yields information not only about which parameters should be better characterized (and which should not), but also to what degree the uncertainty or variability in a specific parameter should be reduced. If the uncertainty is reduced to within the defined limits through characterization, then an updated risk assessment would calculate reduced risk. The results of our analysis demonstrate that due to dilution of the contaminants in the regional aquifer and within the water-supply wells, all of the alternative conceptual models yield low, calculated risk for the receptors. The uncertainty in model predictions is affected principally by the uncertainty in conceptualization. Currently, field exploration and study at the site continues, and these new data will allow us to test whether the uncertainties included in the risk assessment are broad enough so that the obtained conclusions will not change.

Birdsell, K. H.; Vesselinov, V. V.; Davis, P.; Hollis, D.; Newman, B. D.; Echohawk, J. C.

2005-12-01

177

Suitability of artificial sweeteners as indicators of raw wastewater contamination in surface water and groundwater.  

PubMed

There is no quantitative data on the occurrence of artificial sweeteners in the aquatic environment in Southeast Asian countries, particularly no information on their suitability as indicators of raw wastewater contamination on surface water and groundwater. This study provided the first quantitative information on the occurrence of artificial sweeteners in raw wastewater, surface water and groundwater in the urban catchment area in Singapore. Acesulfame, cyclamate, saccharin, and sucralose were ubiquitous in raw wastewater samples at concentrations in the range of ng/L-?g/L, while other sweeteners were not found or found only in a few of the raw wastewater samples. Residential and commercial effluents were demonstrated to be the two main sources of artificial sweeteners entering the municipal sewer systems. Relatively higher concentrations of the detected sweeteners were frequently found in surface waters at the sampling sites located in the residential/commercial areas. No significant difference in the concentrations of the detected sweeteners in surface water or groundwater was noted between wet and dry weather conditions (unpaired T-test, p> 0.05). Relatively higher concentrations and detection frequencies of acesulfame, cyclamate and saccharin in surface water samples were observed at the potentially impacted sampling sites, while these sweeteners were absent in most of the background surface water samples. Similarly, acesulfame, cyclamate, and saccharin were found in most groundwater samples at the monitoring well (GW6), which is located close to known leaking sewer segment; whereas these were absent in the background monitoring well, which is located in the catchment with no known wastewater sources. Taken together, the results suggest that acesulfame, cyclamate, and saccharin can be used as potential indicators of raw wastewater contamination in surface water and groundwater. PMID:24156949

Tran, Ngoc Han; Hu, Jiangyong; Li, Jinhua; Ong, Say Leong

2014-01-01

178

Contamination by Arsenate in Oxidizing Groundwater, Southern Gulf Coast Aquifer System, Texas  

NASA Astrophysics Data System (ADS)

Groundwater arsenic concentrations exceed the U.S. EPA maximum contaminant level for drinking water (10 ?g/L) in about one-third of wells in the southern Gulf Coast Aquifer System (GCAS) in Texas, representing a potential public health hazard and an environmental compliance challenge to numerous small public water supply systems. The aim of this study is to better understand the hydrogeochemical mechanisms underpinning the widespread distribution of elevated groundwater arsenic concentrations in the region. Here we focus upon arsenic contamination in unconfined portions of the aquifer system. The investigation is based upon chemical analyses of a field transect of 27 groundwater samples collected from across three units of the GCAS; stratified water quality sampling from one additional well; and relevant water chemistry data from the Texas Water Development Board groundwater database (more than 500 samples). Chemical results from the field study showed that carbonate weathering and active recharge in the unconfined zone result in circum-neutral pH and oxidizing redox conditions, which are typically amenable to arsenic immobilization by adsorption of As(V) onto mineral oxides and clays. However, arsenic concentrations were found up to 129 ?g/L (median 12 ?g/L), and As(V) represented nearly 100% of total arsenic. Concentrations generally decreased with increasing distance from the Catahoula Formation (which contains abundant volcanic ash presumed to be the original arsenic source), through the overlying Jasper, Evangeline and Chicot Aquifers. Statistically significant pairwise correlations with arsenic were found for vanadium, silica and potassium, all of which were released during weathering of volcanic sediments and their degradation products. Silica that was co-released with arsenic may compete for sorption sites and reduce the capacity for arsenic adsorption. An important role for variable arsenic source availability was suggested by regional spatial distributions and vertical stratification of arsenic concentrations. Further investigations will address whether observed groundwater arsenic distributions may be relatable to patterns of paleofluvial transport of arsenic-bearing sediments.

Gates, J. B.; Nicot, J.; Reedy, R. C.; Scanlon, B. R.

2009-12-01

179

Hydrogeochemical characterization of contaminated groundwater in Patancheru industrial area, southern India.  

PubMed

The groundwater is one of the most contaminated natural resources in Patancheru industrial area due to unplanned and haphazard industrial growth and urbanization without following basic pollution control norms. The rapid industrialization initiated in early 1970 has started showing up its after effects few years later in the form of physiochemical contamination of the both surface and groundwater bodies of the area. It has resulted in local people being deprived of safe drinking water, plant and aquatic life has severely affected, and situation is deteriorating over the years in the area in spite of some preventive and remedial measures being initiated. The focus of the present study is to understand the chemical characteristics of groundwater and geochemical processes the contaminant water is undergoing which are normally imprinted in its ionic assemblages. The water samples collected in pre- and post-monsoon seasons from forty two groundwater and four surface water sources were analyzed for major constituents such as Ca(2+), Mg(2+), Na(+), K(+), CO (3) (-) , HCO (3) (-) , Cl(-), SO (4) (2-) , NO (3) (-) , and F(-), and selected samples were tested for ten important trace metals like Fe, Pb, Bi, Mn, Cr, Co, Ni, Cu, Zn, and Cd. Na(+) among cations and Cl(-) among anions dominate the water in both the seasons where as Ca(2+), HCO (3) (-) , and Cl(-) show significant reduction in their ionic strength in post-monsoon. The groundwater in general is of mixed type, but most of it belong to Na(+)-Cl(-), Na(+)-HCO (3) (-) , Ca(2+)-Mg(2+)-HCO (3) (-) , and Ca(2+)-Mg(2+)-Cl(-) facies. The Na(+) and Ca(2+) are in the transitional state with Na(+) replacing Ca(2+) and HCO (3) (-) -Cl(-) due to physiochemical changes in the aquifer system. The evaluation of hydrochemistry through various ionic indices, ratios, and plots suggest that silicate-carbonate weathering, ion exchange, dissolution, and evaporation processes are responsible for origin of the present chemical status of the groundwater which is also controlled by the contamination from extraneous sources that could have accelerated the dissolution processes. Gibbs plots authenticate that the evolution of water chemistry is influenced by interaction of percolating water with aquifer matrix apart from anthropogenic enrichment of elements which get over concentrated due to evaporation. PMID:21773865

Reddy, A G S; Saibaba, Boraa; Sudarshan, Ganji

2012-06-01

180

Pathogens in Dairy Farming: Source Characterization and Groundwater Impacts  

NASA Astrophysics Data System (ADS)

Intense animal husbandry is of growing concern as a potential contamination source of enteric pathogens as well as antibiotics. To assess the public health risk from pathogens and their hydrologic pathways, we hypothesize that the animal farm is not a homogeneous diffuse source, but that pathogen loading to the soil and, therefore, to groundwater varies significantly between the various management units of a farm. A dairy farm, for example, may include an area with calf hutches, corrals for heifers of various ages, freestalls and exercise yards for milking cows, separate freestalls for dry cows, a hospital barn, a yard for collection of solid manure, a liquid manure storage lagoon, and fields receiving various amounts of liquid and solid manure. Pathogen shedding and, hence, therapeutic and preventive pharmaceutical treatments vary between these management units. We are implementing a field reconnaissance program to determine the occurrence of three different pathogens ( E. coli, Salmonella, Campylobacter) and one indicator organism ( Enterococcus) at the ground-surface and in shallow groundwater of seven different management units on each of two farms, and in each of four seasons (spring/dry season, summer/irrigation season, fall/dry season, winter/rainy season). Initial results indicate that significant differences exist in the occurrence of these pathogens between management units and between organisms. These differences are weakly reflected in their occurrence in groundwater, despite the similarity of the shallow geologic environment across these sites. Our results indicate the importance of differentiating sources within a dairy farm and the importance of understanding subsurface transport processes for these pathogens.

Atwill, E. R.; Watanabe, N.; Li, X.; Hou, L.; Harter, T.; Bergamaschi, B.

2007-12-01

181

REMEDIATION OF NITRATE-CONTAMINATED GROUNDWATER USING A BIOBARRIER  

SciTech Connect

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 nitrate and perchlorate in groundwater from Mortandad Canyon at Los Alamos National Laboratory (LANL). This groundwater was obtained from a monitoring well, MCO-5, which is located in the flowpath of the discharge waters from the LANL Radioactive Liquid Waste Treatment Facility (RLWTF). Water with elevated nitrate levels has been discharged from this plant for many years, until recently when the nitrate levels have been brought under the discharge limits. However, the historical discharge has resulted in a nitrate plume in the alluvial groundwater in this canyon. The LANL Multi-Barrier project was initiated this past year to develop a system of barriers that would prevent the transport of radionuclides, metals, colloids and other contaminants, including nitrate and perchlorate, further down the canyon in order to protect populations down-gradient. The biobarrier. will be part of this Multi-Barrier system. We have demonstrated the destruction of nitrate at levels up to 6.5-9.7 mhl nitrate (400-600 mg/L), and that of perchlorate at levels of about 4.3 {micro}M perchlorate (350 ppb). We have quantified the populations of microorganisms present in the biofilm that develops on the biobarrier. The results of this research will be discussed along with other potential applications of this system.

B. STRIETELMEIR; ET AL

2000-12-01

182

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

USGS Publications Warehouse

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.

Barnes, K.K.; Kolpin, D.W.; Furlong, E.T.; Zaugg, S.D.; Meyer, M.T.; Barber, L.B.

2008-01-01

183

Arsenic Groundwater Contamination in Middle Ganga Plain, Bihar, India: A Future Danger?  

Microsoft Academic Search

The pandemic of arsenic poisoning due to contaminated groundwater in West Bengal, India, and all of Bangladesh has been thought to be limited to the Ganges Delta (the Lower Ganga Plain), despite early survey reports of arsenic contamination in groundwater in the Union Territory of Chandigarh and its surroundings in the northwestern Upper Ganga Plain and recent findings in the

Dipankar Chakraborti; Subhash C. Mukherjee; Shyamapada Pati; Mrinal K. Sengupta; Mohammad M. Rahman; Uttam K. Chowdhury; Dilip Lodh; Chitta R. Chanda; Anil K. Chakraborti; Gautam K. Basu

2003-01-01

184

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

185

Evaluation of the ground-water contaminant plume extending from the 183-H Solar Evaporation Basins  

SciTech Connect

The 183-H Solar Evaporation Basins, located on the Hanford Site in southeastern Washington State, were used for solar concentration and storage of process wastes that consisted of nitric, sulfuric, and hydrofluoric acids, contaminated by heavy metals and radionuclides, and neutralized by sodium hydroxide. By 1977, it was apparent that leakage from the basins had reached the unconfined aquifer, causing elevated ground-water concentrations of nitrate, chromium, technetium-99, and uranium. The resulting plume is superimposed on a larger, pre-existing plume from upgradient sources that is characterized by the same contaminants, but with different relative concentrations. The plumes discharge into the Columbia River, 210 m from the basins. This study examines the relative concentration ratios of the contaminants, determines which wells in the monitoring network surrounding the basins have been affected by basin leakage, assigns reasonable plume boundaries, and shows the separate contribution of each plume to ground-water contamination downgradient from the basins. 10 refs., 8 figs., 4 tabs.

Hall, S.H.

1989-10-01

186

Groundwater and Surface Water: Understanding the Interaction  

NSDL National Science Digital Library

This site provides an introduction to groundwater-surface water interactions and how groundwater can be affected by land use. The page describes threats to groundwater, common contaminants, sources of contamination, and groundwater management approaches and tools. A short glossary and a groundwater quiz are also included.

Nancy Phillips

187

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

188

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.

189

Wellhead treatment costs for groundwater contaminated with pesticides: A preliminary analysis for pineapple in Hawaii  

NASA Astrophysics Data System (ADS)

In Hawaii, trace concentrations of pesticides used in the production of pineapple were found in the groundwater supplies of Mililani Town in the Pearl Harbor Basin on the island of Oahu. Groundwater serves as the major source of drinking water and residents pay for wellhead treatment of the contaminated water, via their monthly water bill. The agricultural chemical users within the Pearl Harbor Basin do not include these wellhead treatment costs in their production costs. The agricultural industry benefits from using pesticides but does not pay the entire societal cost of using these chemicals. In this study we evaluate the specific financial cost of wellhead treatment, and not the economic value of groundwater. While wellhead treatment costs could conceivably be shared by several parties, this study focuses on the financial impact of the pineapple industry alone. This study factors annual wellhead treatment costs into annual pineapple production costs to measure the effect on annual financial return from pineapple production. Wellhead treatment costs are calculated from the existing granulated activated carbon (GAC) water treatment facility for Millilani Wells I and II. Pineapple production costs are estimated from previous cost of production studies. The inclusion of wellhead treatment costs produces different production-cost results, depending on the scale of analysis. At the local scale, the Mililani wellhead treatment costs can be factored into the production costs of the pineapple fields, which were probably responsible for contamination of the Mililani Wells, without causing a deficit in economic return. At the larger regional scale, however, the return from all of the pineapple grown in the Pearl Harbor Basin can not sustain the cost of wellhead treatmentfor the entire water supply of the basin. Recommendations point to the prevention of groundwater contamination as more cost-effective measure than wellhead treatment.

Leon-Guerrero, Ephraim D.; Loague, Keith; Green, Richard E.

1994-01-01

190

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

191

Ground-water contamination in East Bay Township, Michigan  

USGS Publications Warehouse

Glacial deposits, as much as 360 feet thick, underlie the study area. The upper 29 to 118 feet, a sand and gravel unit, is the aquifer tapped by all wells in the area. This unit is underlain by impermeable clay that is at least 100 feet thick. Ground-water flow is northeastward at an estimated rate of 2 to 5 feet per day. Hydraulic conductivities in the aquifer range from 85 to 250 feet per day; 120 feet per day provided the best match of field data in a ground-water flow model. The depth to water ranged from 1 to 20 feet. Chemical analyses indicate that ground water is contaminated with organic chemicals from near the Hangar/Administration building at the U.S. Coast Guard Air Station at East Bay, about 4,300 feet northeast. The plume, which follows ground-water flow lines, ranges from 180 to 400 feet wide. In the upper reach of the plume, hydrocarbons less dense than water occur at the surface of the water table; they move downward in the aquifer as they move toward east Bay. Maximum concentrations of the major organic compounds include: benzene, 3,390 ug/L; toluene, 55,500 ug/L; xylene, 3,900 ug/L, tetrachloroethylene, 3,410 ug/L; amd bis (2-ethyl hexyl) phthalate, 2,100 ug/L. Soils are generally free of these hydrocarbons; however, in the vicinity of past drum storage, aircraft maintenance operations, and fuel storage and dispensing , as much as 1,100 ug/kg of tetrachloroethylene and 1,500 ug/kg of bis (-ethyl hexyl) phthalate were detected. At a few locations higher molecular weight hydrocarbons, characteristic of petroleum distillates were found. (USGS)

Twenter, F.R.; Cummings, T.R.; Grannemann, N.G.

1985-01-01

192

Sources of Weld Metal Oxygen Contamination During  

E-print Network

) Sources of Weld Metal Oxygen Contamination During Submerged Arc Welding The oxygen level of submerged arc weld metal is controlled by Si02 decomposition in most acidic fluxes whereas the oxygen level of weld metal oxygen contamination and pro- vide guidelines for design and selec- tion of welding

Eagar, Thomas W.

193

RAFT: A simulator for ReActive Flow and Transport of groundwater contaminants  

SciTech Connect

This report documents the use of the simulator RAFT for the ReActive flow and Transport of groundwater contaminants. RAFT can be used as a predictive tool in the design and analysis of laboratory and field experiments or it can be used for the estimation of model/process parameters from experiments. RAFT simulates the reactive transport of groundwater contaminants in one, two-, or three-dimensions and it can model user specified source/link configurations and arbitrary injection strategies. A suite of solvers for transport, reactions and regression are employed so that a combination of numerical methods best suited for a problem can be chosen. User specified coupled equilibrium and kinetic reaction systems can be incorporated into RAFT. RAFT is integrated with a symbolic computational language MAPLE, to automate code generation for arbitrary reaction systems. RAFT is expected to be used as a simulator for engineering design for field experiments in groundwater remediation including bioremediation, reactive barriers and redox manipulation. As an integrated tool with both the predictive ability and the ability to analyze experimental data, RAFT can help in the development of remediation technologies, from laboratory to field.

Chilakapati, A.

1995-07-01

194

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

195

Baseline risk assessment of groundwater contamination at the Uranium Mill Tailings Site near Gunnison, Colorado  

SciTech Connect

This Baseline Risk Assessment of Groundwater Contamination at the Uranium Mill Tailings Site Near Gunnison, Colorado evaluates potential impacts to public health or the environment resulting from groundwater contamination at the former uranium mill processing site. The tailings and other contaminated material at this site are being placed in an off-site disposal cell by the US Department of Energy`s (DOE) Uranium Mill Tailings Remedial Action (UMTRA) Project. Currently, the UMTRA Project is evaluating groundwater contamination. This is the second risk assessment of groundwater contamination at this site. The first risk assessment was performed primarily to evaluate existing domestic wells. This risk assessment evaluates the most contaminated monitor wells at the processing site. It will be used to assist in determining what remedial action is needed for contaminated groundwater at the site after the tailings are relocated. This risk assessment follows an approach outlined by the US Environmental Protection Agency (EPA). The first step is to evaluate groundwater data collected from monitor wells at the site. Evaluation of these data showed that the main contaminants in the groundwater are cadmium, cobalt, iron, manganese, sulfate, uranium, and some of the products of radioactive decay of uranium.

Not Available

1993-12-01

196

Non-agricultural sources of groundwater nitrate: a review and case study.  

PubMed

Nitrate is often seen as an agricultural pollutant of groundwater and so is expected to be at higher concentrations in the groundwaters surrounding a city than in those beneath it. However the difference between rural and urban nitrate concentrations is often small, due to the non-agricultural sources of nitrogen that are concentrated in cities. This paper illustrates the source and significance of non-agricultural nitrogen for groundwater and presents a case study of nitrate loading in the city of Nottingham. Major sources of nitrogen in urban aquifers are related to wastewater disposal (on-site systems and leaky sewers), solid waste disposal (landfills and waste tips). The major sources of nitrogen in the Nottingham area are mains leakage and contaminated land with approximately 38% each of a total load of 21 kg N ha(-1) year(-1). PMID:15607159

Wakida, Fernando T; Lerner, David N

2005-01-01

197

Characterization of Persistent Volatile Contaminant Sources in the Vadose Zone  

NASA Astrophysics Data System (ADS)

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 changes in source zone architecture 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, K. C.; Truex, M. J.; Brusseau, M. L.; Parker, K. R.; Mackley, R. D.; Rohay, V. J.

2012-12-01

198

Statistical analysis of ground-water contamination at the alert apron and northern landfill areas of Wurtsmith AFB, Michigan. Final report  

Microsoft Academic Search

Two plumes of contamination are analyzed to determine their extent, composition, and movement. The large number of ground-water monitoring wells sampled over the past eight years at Wurtsmith AFB allow this analysis to be performed directly from empirical data, with minimal assumptions about solute transport mechanisms. Conclusions are drawn about the likely sources of contamination in the two plumes, the

P. Hunter; S. Naber; J. Verducci

1988-01-01

199

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

NASA Astrophysics Data System (ADS)

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 NH4+; and in situ natural gradient 15NH4+ 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 NH4+. 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 NH4+-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.

BöHlke, J. K.; Smith, Richard L.; Miller, Daniel N.

2006-05-01

200

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.

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

2006-01-01

201

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.

202

Risk-based prioritization methodology for the classification of groundwater pollution sources.  

PubMed

Water management is one of the EU environmental priorities and it is one of the most serious challenges that today's major cities are facing. The main European regulation for the protection of water resources is represented by the Water Framework Directive (WFD) and the Groundwater Directive (2006/118/EC) which require the identification, risk-based ranking and management of sources of pollution and the identification of those contamination sources that threaten the achievement of groundwater's good quality status. The aim of this paper is to present a new risk-based prioritization methodology to support the determination of a management strategy for the achievement of the good quality status of groundwater. The proposed methodology encompasses the following steps: 1) hazard analysis, 2) pathway analysis, 3) receptor vulnerability analysis and 4) relative risk estimation. Moreover, by integrating GIS functionalities and Multi Criteria Decision Analysis (MCDA) techniques, it allows to: i) deal with several sources and multiple impacted receptors within the area of concern; ii) identify different receptors' vulnerability levels according to specific groundwater uses; iii) assess the risks posed by all contamination sources in the area; and iv) provide a risk-based ranking of the contamination sources that can threaten the achievement of the groundwater good quality status. The application of the proposed framework to a well-known industrialized area located in the surroundings of Milan (Italy) is illustrated in order to demonstrate the effectiveness of the proposed framework in supporting the identification of intervention priorities. Among the 32 sources analyzed in the case study, three sources received the highest relevance score, due to the medium-high relative risks estimated for Chromium (VI) and Perchloroethylene. The case study application showed that the developed methodology is flexible and easy to adapt to different contexts, thanks to the possibility to introduce specific relevant parameters identified according to expert judgment and data availability. PMID:25437767

Pizzol, Lisa; Zabeo, Alex; Critto, Andrea; Giubilato, Elisa; Marcomini, Antonio

2015-02-15

203

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

204

Estimating the Impact of Vadose Zone Sources on Groundwater to Support Performance Assessment of Soil Vapor Extraction  

SciTech Connect

A generalized conceptual model approach was developed that can be used to estimate the impact of volatile contaminant sources in the vadose zone on groundwater for sites where soil vapor extraction (SVE) operations have diminished source strength. The model has the potential to be broadly applicable for sites where vapor-phase transport dominates. The primary target for this conceptual model and related numerical modeling estimate of groundwater impact is for sites where contaminants have been removed from readily accessible portions of the subsurface, but where contaminants may persist in localized portions of the vadose zone. This paper describes the conceptual model, uses numerical simulations to evaluate the parameters controlling impact to groundwater, and presents estimated results for a range of input conditions. Over the implied ranges, the compliance well concentrations showed (inverse) proportionality with source concentration, Henry’s Law constant, and well screen length. An increase in site recharge caused a linear response in well concentration, with slopes dependent on the groundwater velocity. All other tested parameters resulted in nonlinear responses. The functional relationship between dimensional and transport parameters and resulting groundwater concentrations provide a basis for establishing a structured approach to evaluating the potential risk to groundwater posed by a vadose zone source. This type of evaluation is particularly important to sites where SVE has been applied and reduced contaminant concentrations, but has reached a condition of diminishing returns such that a site must consider whether continuation of SVE, remedy modifications, or closure is warranted.

Oostrom, Martinus; Truex, Michael J.; Rice, Amy K.; Johnson, Christian D.; Carroll, Kenneth C.; Becker, Dave; Simon, Michelle A.

2014-03-13

205

Nonpoint Source Contamination EPA official identifies roadblocks  

E-print Network

Region 7 in Kansas City, Kan. Production agriculture, construc- tion sites and urban runoff are sources and urban runoff. "But the key issue is production agriculture," Hutton said. Hutton commented on the statusNonpoint Source Contamination EPA official identifies roadblocks to successful NPS management "NPS

Nebraska-Lincoln, University of

206

Aerated treatment pond technology with biofilm promoting mats for the bioremediation of benzene, MTBE and ammonium contaminated groundwater  

Microsoft Academic Search

A novel aerated treatment pond for enhanced biodegradation of groundwater contaminants was tested under field conditions. Coconut fibre and polypropylene textiles were used to encourage the development of contaminant-degrading biofilms. Groundwater contaminants targeted for removal were benzene, methyl tert-butyl ether (MTBE) and ammonium. Here, we present data from the first 14 months of operation and compare contaminant removal rates, volatilization

Sven Jechalke; Carsten Vogt; Nils Reiche; Alessandro G. Franchini; Helko Borsdorf; Thomas R. Neu; Hans H. Richnow

2010-01-01

207

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

208

Groundwater contamination and risk assessment of industrial complex in Busan Metropolitan City, Korea  

NASA Astrophysics Data System (ADS)

In Korea, the potential of groundwater contamination in urban areas is increasing by industrial and domestic waste waters, leakage from oil storage tanks and sewage drains, leachate from municipal landfill sites and so on. Nowadays, chlorinated organic compounds such as trichloroethylene (TCE) and tetrachloroethylene (PCE), which are driving residential area as well as industrial area, are recognized as major hazardous contaminants. As well known, TCE is wisely used industrial activities such as degreasing, metal stripping, chemical manufacturing, pesticide production, coal gasification plants, creosote operation, and also used in automobile service centers, photo shops and laundries as cleaning solvent. Thus, groundwater protection in urban areas is important issue in Korea This study is to understand groundwater quality and contamination characteristics and to estimate risk assessment in Sasang industrial complex, Busan Metropolitan City. Busan Metropolitan City is located on southeastern coast of the Korean peninsula and is the second largest city in South Korea with a population of 3.8 millions. The geology of the study area is composed of andesite, andesitic tuff, biotite granite and alluvium (Kim et al., 1998). However, geology cannot be identified on the surface due to pavement and buildings. According to drill logs in the study area, the geologic section consists in landfill, fine sand, clay, gravelly clay, and biotite granite from the surface. Biotite granite appears 5.5- 6 m depth. Groundwater samples were collected at twenty sites in Sasang industrial complex. The groundwater samples are plotted on Piper's trilinear diagram, which indicates Ca-Cl2 type. The groundwater may be influenced by salt water because Sasang industrial complex is located near the mouse of Nakdong river that flows to the South Sea. The Ca-Cl2 water type may be partly influenced by anthropogenic contamination in the study area, since water type in granite area generally belongs Ca-HCO3 or Na-HCO3 types. TDS (107-14,500 /L), EC (225-25,500 ?S/cm), salinity (100-15,500 /kg), Na+ (13.39-2,866 /L) and Cl- (15.3-7,066 /L) concentrations are also higher than those of general groundwater. This fact indicates that groundwater in study area was polluted by saline water and/or anthropogenic sources. TCE, PCE, 1.1.1-trichloroethane (TCA) were analyzed by Busan Metropolitan City Institute of Health &Environment. PCE and TCA are not detected most of sites, while TCE is detected most of the sites and exceeds drinking water standard of Korea 0.03 /L. It is considered that TCE was derived from variety contamination sources such as car-washing centers, transportation companies, iron molding factories and waste treating companies. Risk assessment to human health and environmental resources by groundwater contamination was conducted. The RBCA Tool Kit for Chemical Releases can be used for the risk assessment at Tier 1 and Tier 2. The risk assessment determines risk-based concentration of constituents of concerns (COCs) that moves through groundwater, soil and air. It also evaluates carcinogenic risk and toxic effect when receptor exposures to the COCs. Tier 1 analysis determines risk-based screening levels (RBSLs) for one-site exposure. Tier 2 analysis evaluates RBSL and/or site-specific target levels (SSTLs) for both on-site and off-site receptor. RBSLs were calculated as 2.2E-2 /L for TCE and as 4.7E-3 /L for PCE at Tier 1 risk assessment. Average concentrations of TCE and PCE from measuring the groundwater samples were 0.15 mg/L and 0.016 mg/L, respectively. The actual measured values are higher than the RBSLs. Carcinogenic risk of TCE to animals was identified as B2 (inadequate or no human evidence but sufficient animal evidence). From this result, we will conduct the further detail risk assessment at Tier 2 level before conducting groundwater remediation. ACKNOWLEDGEMENT The authors wish to acknowledge the financial support of the Korea Science &Engineering Foundation (KOSEF) under the Basic Research Program (grant no: R02-2001-00249).

Hamm, S.-Y.; Ryu, S. M.; Cheong, J.-Y.; Woo, Y.-J.

2003-04-01

209

Groundwater Pollution Source Identification Using Trained ANN Model  

NASA Astrophysics Data System (ADS)

Remediation of groundwater contamination is one of the foremost challenges for the present generation. Exact knowledge of the location of the pollution source is essential to tackle this problem. Pollution sources have several important characteristics - location, strength and release period - that can be employed to single out a specific source. Breakthrough curves, which are the temporal distribution of concentration data at a given location, can be utilized to identify the location of an unknown pollution source. However, there is a lag between the time when the readings are taken at the observation well and the time when the source becomes active. In real field situations there is little or no information about this lag. We develop a methodology to identify the location of a pollution source, without using the lag time or the source strength as known parameters, by using an Artificial Neural Network (ANN) based technique. Breakthrough curves are primarily dependent on four variables, namely, source location, strength, release period and lag time. To develop an ANN model, the impact because of strength and lag time has been eliminated in a step-wise fashion. First, the breakthrough curve is normalized, between 0 and 1, by dividing concentration data by the maximum concentration value observed. Then, only the portion of the breakthrough curve near the peak is used as an input to train the ANN model. It has been shown that the breakthrough curve under these conditions is only dependent on the source location and release period, and is unique for a given combination of source strength and release period. An ANN model with one hidden layer is trained using the Levenberg-Marquardt algorithm. The modified breakthrough curve is used as an input to the ANN model while the source strength and release period constitute the output. The number of neurons in the hidden layer has been selected by minimizing the mean squared error for different number of hidden neurons. Performance of the model has been evaluated for a one dimensional case with error-free data. Results obtained indicate that the proposed ANN model is capable of solving the pollution source identification problem without requiring the lag time or source strength to be pre-specified.

Ayaz, M.; Srivastava, R.

2012-04-01

210

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.

2014-12-01

211

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

212

IN SITU CHEMICAL OXIDATION OF RDX-CONTAMINATED GROUNDWATER WITH PERMANGANATE AT THE NEBRASKA ORDNANCE PLANT.  

E-print Network

??Groundwater beneath the former Nebraska Ordnance Plant (NOP) is contaminated with the explosive hexahydro-1 ,3,5-trinitro-1 ,3,5-triazine (RDX). Laboratory and pilot-scale experiments were performed to quantify… (more)

Albano, Jeffrey. A.

2009-01-01

213

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...

214

Risk assessment of groundwater contamination from hydraulic fracturing fluid spills in Pennsylvania  

E-print Network

Fast-paced growth in natural gas production in the Marcellus Shale has fueled intense debate over the risk of groundwater contamination from hydraulic fracturing and the shale gas extraction process at large. While several ...

Fletcher, Sarah Marie

2012-01-01

215

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...

216

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...

217

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...

218

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...

219

Impacts on groundwater recharge areas of megacity pumping: analysis of potential contamination of Kolkata, India, water supply  

USGS Publications Warehouse

Water supply to the world's megacities is a problem of quantity and quality that will be a priority in the coming decades. Heavy pumping of groundwater beneath these urban centres, particularly in regions with low natural topographic gradients, such as deltas and floodplains, can fundamentally alter the hydrological system. These changes affect recharge area locations, which may shift closer to the city centre than before development, thereby increasing the potential for contamination. Hydrogeological simulation analysis allows evaluation of the impact on past, present and future pumping for the region of Kolkata, India, on recharge area locations in an aquifer that supplies water to over 13 million people. Relocated recharge areas are compared with known surface contamination sources, with a focus on sustainable management of this urban groundwater resource. The study highlights the impacts of pumping on water sources for long-term development of stressed city aquifers and for future water supply in deltaic and floodplain regions of the world.

Sahu, Paulami; Michael, Holly A.; Voss, Clifford I.; Sikdar, Pradip K.

2013-01-01

220

Bioremediation Of Groundwater Contaminated Wtih Gasoline Hydrocarbons And Oxygenates Using A Membrane-Based Reactor  

EPA Science Inventory

The objective of this study was to operate a novel, field-scale, aerobic bioreactor and assess its performance in the ex situ treatment of groundwater contaminated with gasoline from a leaking underground storage tank in Pascoag, RI. The groundwater contained elevated concentrat...

221

Source and Processes of Dissolved Organic Matter in a Bangladesh Groundwater  

NASA Astrophysics Data System (ADS)

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 complexes and competitive interactions between As and DOM for sorption sites on the sediment. Additionally, the labile portion of groundwater DOM can serve as an electron donor to support microbial growth and the more recalcitrant humic DOM may serve as an electron shuttle, facilitating the eventual reduction of ferric iron present as iron oxides in sediments and consequently the mobilization of sorbed As and organic material. The goal of this study is to understand the source of DOM in representative Bangladesh groundwaters and the DOM sorption processes that occur at depth. We report chemical characteristics of representative DOM from a surface water, a shallow low-As groundwater, mid-depth high-As groundwater from the Araihazar region of Bangladesh. The humic DOM from groundwater displayed a more terrestrial chemical signature, indicative of being derived from plant and soil precursor materials, while the surface water humic DOM had a more microbial signature, suggesting an anthropogenic influence. In terms of biogeochemical processes occurring in the groundwater system, there is evidence from a diverse set of chemical characteristics, ranging from 13C-NMR spectroscopy to the analysis of lignin phenols, for preferential sorption onto iron oxides influencing the chemistry and reactivity of humic DOM in high As groundwater in Bangladesh. Taken together, these results provide chemical evidence for anthropogenic influence and the importance of sorption reactions at depth controlling the water quality of high As groundwater in Bangladesh.

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

2010-12-01

222

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

223

Natural attenuation processes for remediation of arsenic contaminated soils and groundwater  

Microsoft Academic Search

Arsenic (As) contamination presents a hazard in many countries. Natural attenuation (NA) of As-contaminated soils and groundwater may be a cost-effective in situ remedial option. It relies on the site intrinsic assimilative capacity and allows in-place cleanup. Sorption to solid phases is the principal mechanism immobilizing As in soils and removing it from groundwater. Hydroxides of iron, aluminum and manganese,

Suiling Wang; Catherine N. Mulligan

2006-01-01

224

GROUNDWATER QUALITY PROTECTION PRACTICES  

E-print Network

#12;GROUNDWATER QUALITY PROTECTION PRACTICES Submitted to: Environment Canada 224 West Esplanade.............................................................................................1 2.0 GROUNDWATER RESOURCES WITHIN THE FRASER BASIN.................3 2.1 Lower Fraser Region..............................................................................5 3.0 COMMON SOURCES OF GROUNDWATER CONTAMINATION ...............6 3.1 Category 1 - Sources Designed

225

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

226

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...

227

Hydrogeologic controls on ground-water and contaminant discharge to the Columbia River near the Hanford Townsite  

SciTech Connect

The purpose of this study is to quantify ground-water and contaminant discharge to the Columbia River in the Hanford Townsite vicinity. The primary objectives of the work are to: describe the hydrogeologic setting and controls on ground-water movement and contaminant discharge to the Columbia River; understand the river/aquifer relationship and its effects on contaminant discharge to the Columbia River; quantify the ground-water and contaminant mass discharge to the Columbia River; and provide data that may be useful for a three-dimensional model of ground-water flow and contaminant transport in the Hanford Townsite study area. The majority of ground-water contamination occurs within the unconfined aquifer; therefore, ground-water and contaminant discharge from the unconfined aquifer is the emphasis of this study. The period of study is primarily from June 1990 through March 1992.

Luttrell, S.P.; Newcomer, D.R.; Teel, S.S.; Vermeul, V.R.

1992-11-01

228

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

229

INDEPENDENT TECHNICAL EVALUATION AND RECOMMENDATIONS FOR CONTAMINATED GROUNDWATER AT THE DEPARTMENT OF ENERGY OFFICE OF LEGACY MANAGEMENT RIVERTON PROCESSING SITE  

SciTech Connect

The U.S. Department of Energy Office of Legacy Management (DOE-LM) manages the legacy contamination at the Riverton, WY, Processing Site – a former uranium milling site that operated from 1958 to 1963. The tailings and associated materials were removed in 1988-1989 and contaminants are currently flushing from the groundwater. DOE-LM commissioned an independent technical team to assess the status of the contaminant flushing, identify any issues or opportunities for DOE-LM, and provide key recommendations. The team applied a range of technical frameworks – spatial, temporal, hydrological and geochemical – in performing the evaluation. In each topic area, an in depth evaluation was performed using DOE-LM site data (e.g., chemical measurements in groundwater, surface water and soil, water levels, and historical records) along with information collected during the December 2013 site visit (e.g., plant type survey, geomorphology, and minerals that were observed, collected and evaluated). A few of the key findings include: ? Physical removal of the tailings and associated materials reduced contaminant discharges to groundwater and reduced contaminant concentrations in the near-field plume. ? In the mid-field and far-field areas, residual contaminants are present in the vadose zone as a result of a variety of factors (e.g., evaporation/evapotranspiration from the capillary fringe and water table, higher water levels during tailings disposal, and geochemical processes). ? Vadose zone contaminants are widely distributed above the plume and are expected to be present as solid phase minerals that can serve as “secondary sources” to the underlying groundwater. The mineral sample collected at the site is consistent with thermodynamic predictions. ? Water table fluctuations, irrigation, infiltration and flooding will episodically solubilize some of the vadose zone secondary source materials and release contaminants to the groundwater for continued down gradient migration – extending the overall timeframe for flushing. ? Vertical contaminant stratification in the vadose zone and surficial aquifer will vary from location to location. Soil and water sampling strategies and monitoring well construction details will influence characterization and monitoring data. ? Water flows from the Wind River, beneath the Riverton Processing Site and through the plume toward the Little Wind River. This base flow pattern is influenced by seasonal irrigation and other anthropogenic activities, and by natural perturbations (e.g., flooding). ? Erosion and reworking of the sediments adjacent to the Little Wind River results in high heterogeneity and complex flow and geochemistry. Water flowing into oxbow lakes (or through areas where oxbow lakes were present in the past) will be exposed to localized geochemical conditions that favor chemical reduction (i.e., “naturally reduced zones”) and other attenuation processes. This attenuation is not sufficient to fully stabilize the plume or to reduce contaminant concentrations in the groundwater to target levels. Consistent with these observations, the team recommended increased emphasis on collecting data in the zones where secondary source minerals are projected to accumulate (e.g., just above the water table) using low cost methods such as x-ray fluorescence. The team also suggested several low cost nontraditional sources of data that have the potential to provide supplemental data (e.g., multispectral satellite imagery) to inform and improve legacy management decisions. There are a range of strategies for management of the legacy contamination in the groundwater and vadose zone near the Riverton Processing Site. These range from the current strategy, natural flushing, to intrusive remedies such as plume scale excavation of the vadose zone and pump & treat. Each option relates to the site specific conditions, issues and opportunities in a unique way. Further, each option has advantages and disadvantages that need to be weighed. Scoping evaluation was performed for three major classes

Looney, B.; Denham, M.; Eddy-Dilek, C.

2014-05-06

230

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

231

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

232

Size-Selective Predation on Groundwater Bacteria by Nanoflagellates in an Organic-Contaminated Aquifer  

Microsoft Academic Search

Time series incubations were conducted to provide estimates for the size selectivities and rates of protistan grazing that may be occurring in a sandy, contaminated aquifer. The experiments involved four size classes of fluorescently labeled groundwater bacteria (FLB) and 2- to 3-mm-long nanoflagellates, primarily Spumella guttula (Ehrenberg) Kent, that were isolated from contaminated aquifer sediments (Cape Cod, Mass.). The greatest

N. E. KINNER; R. W. HARVEY; K. BLAKESLEE; G. NOVARINO; L. D. MEEKER

1998-01-01

233

Using models to simulate the movement of contaminants through groundwater flow systems  

Microsoft Academic Search

Prediction of the movement of contaminants in groundwater systems through the use of models has been given increased emphasis in recent years because of the growing trend toward subsurface disposal of wastes. Prediction is especially critical when nuclear wastes are involved. Contaminant transport models which include the effects of dispersion have been applied to several field situations. However, factors that

Mary P. Anderson; John A. Cherry

1979-01-01

234

Surface altered zeolites as permeable barriers for in situ treatment of contaminated groundwater  

SciTech Connect

The authors characterized surfactant-modified zeolite (SMZ) for its ability to sorb organic and inorganic contaminants from water. The ultimate objective is to use SMZ as a permeable barrier to prevent migration of contaminants in groundwater. This report summarizes results under Phase 1 of a three-phase project leading to a full-scale field demonstration of SMZ permeable- barrier technology.

NONE

1996-11-01

235

Organic contaminants in groundwater mar an underground coal gasification site in northeastern Wyoming  

Microsoft Academic Search

Three groundwater samples collected near two underground coal gasification (UCG) sites 15 months after the end of gasification were analysed for dissolved organic contaminants. The contaminants consisted of phenols, aromatic carboxylic acids, aromatic hydrocarbons, ketones, aldehydes, pyridines, quinolines, isoquinolines, and aromatic amines. Concentrations ranged up to about 50 ppm with large variations both in the relative concentrations of acidic, neutral,

Daniel H. Stuermer; Douglas J. Ng; Clarence J. Morris

1982-01-01

236

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...

237

PHYTOREMEDIATION: USING PLANTS TO CLEAN UP CONTAMINATED SOIL, GROUNDWATER, AND WASTEWATER  

EPA Science Inventory

Phytoremediation is an emerging cleanup technology for contaminated soils, groundwater, and wastewater that is both low-tech and low-cost. The cleanup technology is defined as the use of green plants to remove, contain, or render harmless such environmental contaminants as heavy ...

238

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...

239

RESEARCH ON GROUND-WATER CONTAMINATED BY DEPOSITS OF SOLID WASTE  

Microsoft Academic Search

SUMMARY Field investigations at large waste sites of industrial and municipal origin allow to determine the rules of behaviour of contaminants in the ground more completely than laboratory experiments and small scale field investigations. The difference of the chemical and bacteriological quality of groundwater before and after passing the waste site gives the amount of the contamination. The changes of

Arthur GOLWER; Georg MATTHESS

240

Behavioral response to contamination risk information in a spatially explicit groundwater environment: Experimental evidence  

NASA Astrophysics Data System (ADS)

paper assesses the effectiveness of aquifer monitoring information in achieving more sustainable use of a groundwater resource in the absence of management policy. Groundwater user behavior in the face of an irreversible contamination threat is studied by applying methods of experimental economics to scenarios that combine a physics-based, spatially explicit, numerical groundwater model with different representations of information about an aquifer and its risk of contamination. The results suggest that the threat of catastrophic contamination affects pumping decisions: pumping is significantly reduced in experiments where contamination is possible compared to those where pumping cost is the only factor discouraging groundwater use. The level of information about the state of the aquifer also affects extraction behavior. Pumping rates differ when information that synthesizes data on aquifer conditions (a "risk gauge") is provided, despite invariant underlying economic incentives, and this result does not depend on whether the risk information is location-specific or from a whole aquifer perspective. Interestingly, users increase pumping when the risk gauge signals good aquifer status compared to a no-gauge treatment. When the gauge suggests impending contamination, however, pumping declines significantly, resulting in a lower probability of contamination. The study suggests that providing relatively simple aquifer condition guidance derived from monitoring data can lead to more sustainable use of groundwater resources.

Li, Jingyuan; Michael, Holly A.; Duke, Joshua M.; Messer, Kent D.; Suter, Jordan F.

2014-08-01

241

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

242

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 29.6 mg/L (mean of 11.2 mg/L) in surface water, and from 0.1 to 19.4 mg/L (mean of 2.8 mg/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

243

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

244

California GAMA Program: Sources and Transport of Nitrate in Groundwater in the Livermore Valley Basin, California  

SciTech Connect

A critical component of the State Water Resource Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) Program is to assess the major threats to groundwater resources that supply drinking water to Californians (Belitz et al., 2004). Nitrate concentrations approaching and greater than the maximum contaminant level (MCL) are impairing the viability of many groundwater basins as drinking water sources Source attribution and nitrate fate and transport are therefore the focus of special studies under the GAMA program. This report presents results of a study of nitrate contamination in the aquifer beneath the City of Livermore, where high nitrate levels affect both public supply and private domestic wells. Nitrate isotope data are effective in determining contaminant sources, especially when combined with other isotopic tracers such as stable isotopes of water and tritium-helium ages to give insight into the routes and timing of nitrate inputs to the flow system. This combination of techniques is demonstrated in Livermore, where it is determined that low nitrate reclaimed wastewater predominates in the northwest, while two flowpaths with distinct nitrate sources originate in the southeast. Along the eastern flowpath, {delta}{sup 15}N values greater than 10{per_thousand} indicate that animal waste is the primary source. Diminishing concentrations over time suggest that contamination results from historical land use practices. The other flowpath begins in an area where rapid recharge, primarily of low nitrate imported water (identified by stable isotopes of water and a tritium-helium residence time of less than 1 year), mobilizes a significant local nitrate source, bringing groundwater concentrations above the MCL of 45 mg NO{sub 3} L{sup -1}. In this area, artificial recharge of imported water via local arroyos induces flux of the contaminant to the regional aquifer. The low {delta}{sup 15}N value (3.1{per_thousand}) in this location implicates synthetic fertilizer. Geochemical modeling supports the hypothesis of separate sources, one including organic carbon, as from animal waste, and one not. In addition to these anthropogenic sources, natural nitrate background levels between 15 and 20 mg NO{sub 3} L{sup -1} are found in deep wells with residence times greater than 50 years.

Beller, H; Eaton, G F; Ekwurzel, B E; Esser, B K; Hu, Q; Hudson, G B; Leif, R; McNab, W; Moody-Bartel, C; Moore, K; Moran, J E

2005-11-18

245

Use of iron-based technologies in contaminated land and groundwater remediation: a review.  

PubMed

Reactions involving iron play a major role in the environmental cycling of a wide range of important organic, inorganic and radioactive contaminants. Consequently, a range of environmental clean-up technologies have been proposed or developed which utilise iron chemistry to remediate contaminated land and surface and subsurface waters, e.g. the use of injected zero zero-valent iron nanoparticles to remediate organic contaminant plumes; the generation of iron oxyhydroxide-based substrates for arsenic removal from contaminated waters; etc. This paper reviews some of the latest iron-based technologies in contaminated land and groundwater remediation, their current state of development, and their potential applications and limitations. PMID:18692221

Cundy, Andrew B; Hopkinson, Laurence; Whitby, Raymond L D

2008-08-01

246

EFFECTS OF IN-SITU BIOSPARGING ON PENTACHLOROPHENOL (PCP) DEGRADATION AND BACTERIAL COMMUNITIES IN PCP CONTAMINATED GROUNDWATER.  

E-print Network

?? This study examined the effect of in-situ biosparging on pentachlorophenol (PCP) degradation and bacterial communities in PCP contaminated groundwater. Bacteria were identified by sequencing… (more)

Stokes, Carrlet Elizabeth

2011-01-01

247

Comparison of indigenous and bio-augmented pentachlorophenol (PCP) degrading bacteria for remediation of PCP in contaminated groundwater.  

E-print Network

?? The objective was to compare pentachlorophenol (PCP) degradation in contaminated groundwater by indigenous and bio-augmented (Sphingobium chlorophenolicum and Burkholderia cepacia) PCP degrading bacteria. Indigenous… (more)

Joshi, Vaibhav Venkatesh

2013-01-01

248

Estimation of Contaminant Subslab Concentration in Vapor Intrusion Including Lateral Source–Building Separation  

PubMed Central

Most current vapor-intrusion screening models employ the assumption of a subsurface homogenous source distribution, and groundwater data obtained from nearby monitoring wells are usually taken to reflect the source concentration for several nearby buildings. This practice makes it necessary to consider the possible influence of lateral source–building separation. In this study, a new way to estimate subslab (nonbiodegradable) contaminant concentration is introduced that includes the influence of source offset with the help of a conformal transform technique. Results from this method are compared with those from a three-dimensional numerical model. Based on this newly developed method, a possible explanation is provided here for the great variation in the attenuation factors of the soil vapor concentrations of groundwater-to-subslab contaminants found in the EPA vapor-intrusion database. PMID:24795543

Yao, Yijun; Shen, Rui; Pennell, Kelly G.; Suuberg, Eric M.

2014-01-01

249

In-situ photocatalytic remediation of organic contaminants in groundwater  

E-print Network

This research is about the development of a photocatalytic reactor design, Honeycomb, for in-situ groundwater remediation. Photocatalysis, typically a pseudo first order advanced oxidation process, is initiated via the illumination of UVA light...

Lim, Leonard Lik Pueh

2010-07-06

250

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

251

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

252

[Simulation on contamination forecast and control of groundwater in a certain hazardous waste landfill].  

PubMed

On the basis of site investigation and data collection of a certain hazardous waste landfill, the groundwater flow and solute transport coupled models were established by applying Visual Modflow software, which was used to conduct a numerical simulation that forecast the transport process of Cr6+ in groundwater and the effects of three control measures (ground-harden, leakage-proof barriers and drainage ditches) of contaminants transport after leachate leakage happened in impermeable layer of the landfill. The results show that the contamination plume of Cr6+ transports with groundwater flow direction, the contamination rang would reach the pool's boundary in 10 years, and the distance of contamination transport is 1 450 m. But the diffusion range of contamination plume would not be obviously expanded between 10 and 20 years. While the ground is hardened, the contamination plume would not reach the pool's boundary in 20 years. When the leakage-proof barrier is set in the bottom of water table aquifer, the concentration of Cr6+ is higher than that the leakage-proof barrier is unset, but the result is just opposite when setting the leakage-proof barrier in the bottom of underlying aquifer. The range of contamination plume is effectively controlled by setting drainage ditches that water discharge is 2 642 m3 x d(-1), which makes the monitoring wells would not be contaminated in 20 years. Moreover, combining the ground-harden with drainage ditches can get the best effect in controlling contaminants diffusion, and meanwhile, the drainage ditches' daily discharge is reduced to 1 878 m3 x d(-1). Therefore, it is suggested that the control measure combining the ground-harden with drainage ditches should apply to prevent contamination diffusion in groundwater when leachate leakage have happened in impermeable layer of the landfill. PMID:22452190

Ma, Zhi-Fei; An, Da; Jiang, Yong-Hai; Xi, Bei-Dou; Li, Ding-Long; Zhang, Jin-Bao; Yang, Yu

2012-01-01

253

Statistical analysis of ground-water contamination at the alert apron and northern landfill areas of Wurtsmith AFB, Michigan. Final report  

SciTech Connect

Two plumes of contamination are analyzed to determine their extent, composition, and movement. The large number of ground-water monitoring wells sampled over the past eight years at Wurtsmith AFB allow this analysis to be performed directly from empirical data, with minimal assumptions about solute transport mechanisms. Conclusions are drawn about the likely sources of contamination in the two plumes, the adequacy of the data for making risk assessments, and the likely consequences of alternative programs of remediation.

Hunter, P.; Naber, S.; Verducci, J.

1988-07-01

254

Paleosols in central Illinois as potential sources of ammonium in groundwater  

USGS Publications Warehouse

Glacially buried paleosols of pre-Holocene age were evaluated as potential sources for anomalously large concentrations of ammonium in groundwater in East Central Illinois. Ammonium has been detected at concentrations that are problematic to water treatment facilities (greater than 2.0 mg/L) in this region. Paleosols characterized for this study were of Quaternary age, specifically Robein Silt samples. Paleosol samples displayed significant capacity to both store and release ammonium through experiments measuring processes of sorption, ion exchange, and weathering. Bacteria and fungi within paleosols may significantly facilitate the leaching of ammonium into groundwater by the processes of assimilation and mineralization. Bacterial genetic material (DNA) was successfully extracted from the Robein Silt, purified, and amplified by polymerase chain reaction to produce 16S rRNA terminal restriction fragment length polymorphism (TRFLP) community analyses. The Robein Silt was found to have established diverse and viable bacterial communities. 16S rRNA TRFLP comparisons to well-known bacterial species yielded possible matches with facultative chemolithotrophs, cellulose consumers, nitrate reducers, and actinomycetes. It was concluded that the Robein Silt is both a source and reservoir for groundwater ammonium. Therefore, the occurrence of relatively large concentrations of ammonium in groundwater monitoring data may not necessarily be an indication of only anthropogenic contamination. The results of this study, however, need to be placed in a hydrological context to better understand whether paleosols can be a significant source of ammonium to drinking water supplies. ?? 2009 National Ground Water Association.

Glessner, J.J.G.; Roy, W.R.

2009-01-01

255

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

256

Groundwater pollution on the Zambian Copperbelt: deciphering the source and the risk.  

PubMed

The protection of groundwater resources is of great importance in many semi-arid and sub-tropical environments. The Copperbelt of Zambia is one such environment and due to the high proportion of tailings impoundments, residue heaps, high-density informal settlements and extensive sulfidic ore deposits in the region, its groundwater resources are under threat of anthropogenic or geogenic pollution. One such pollutant plume is investigated in this study, to determine its origin, rate of progression and the environmental and health risk it poses. Geological and geochemical investigation strongly suggests an upslope tailings impoundment as the source of contaminants, with the edge of the pollution plume lying 500-700 m downstream of the impoundment. Although cobalt, nickel and zinc concentrations were elevated within the polluted groundwater, the concentrations are low as a result of sulfide precipitation and adsorption within the aquifer, and meets guidelines for drinking water quality. Attenuation of heavy metals is linked to tailings dam and aquifer pH, with the high buffering capacity of each implying that these processes of attenuation are likely to continue removing harmful metals from the aquifer. Thus, it appears unlikely that the contaminated groundwater will present a major environmental risk at this site. However, tailings impoundments are widespread throughout the Copperbelt: sites with low tailings dam buffer capacity and in catchments on crystalline bedrock geology, groundwater pollution through tailings dam leachate may liberate high concentrations of heavy metals into the shallow groundwater, potentially posing a serious human health risk to the communities using the water resources and an environmental risk to the downstream ecosystems. PMID:15172568

von der Heyden, C J; New, M G

2004-07-01

257

Pollution potential of oil-contaminated soil on groundwater resources in Kuwait.  

PubMed

The only natural freshwater resource of Kuwait occurs as lenses floating on the saline groundwater in the northern part of the country, near to the oil fields. Rainwater is the only means of recharge of this limited groundwater resource. This groundwater is used as bottled drinking water and the fresh groundwater aquifer is considered as a strategic drinking water reserve for Kuwait. As a result of the 1991 Gulf War, the upper soil layer has been widely contaminated with crude oil and crude oil combustion products, which are potential pollutants likely affecting the groundwater resources. Significant efforts have been made to assess this pollution. These included: (a) a soil survey for assessing the soil contamination, and (b) leaching experiments to characterise the mobilization of the soil-associated pollutants. Fluorescence measurement techniques were used during field surveys as well as for laboratory testing. In addition, determination of the total extractable matter (TEM), total petroleum hydrocarbons (TPH), and GC/MS measurement of polyaromatic hydrocarbons (PAHs) were performed for the assessments. The laser induced fluorescence (LIF) measurement, having good correlation with the other laboratory measurements, was proved to provide necessary information for the assessment of the oil-contamination level in the desert soil. The subsequent leaching test with water demonstrated the mobilization of the fluorescing compounds (e.g. PAHs), and the alteration in the leaching characteristics of the contamination during the long-term environmental weathering of the oil. PMID:12793688

Literathy, P; Quinn, M; Al-Rashed, M

2003-01-01

258

Exploiting Laguerre Functions to Regularize Contaminant Source History Recovery Problems  

NASA Astrophysics Data System (ADS)

The problem of recovering contaminant source histories in the subsurface represents a highly multidimensional (in reality, infinite-dimensional) inverse problem, even if the location of the source and all groundwater parameters are known precisely. Essentially, one attempts to determine a time series of concentrations at the source location based on concentrations measured down gradient. The inverse problem defined by the advection dispersion equation is known to be unstable, and cannot be solved for real data without some sort of regularizing constraint, usually enforcing temporal smoothness. A number of techniques for this task have been previously discussed in the literature, including Bayesian techniques and classical regularization techniques, such as Tikhonov regularization. Recently the authors have presented a new technique exploiting the convolution and orthogonality properties of Laguerre functions to model contaminant transport between a source and a receptor as an input-output system, using only linear algebra. This technique generalizes well to inverse modelling, an approach that will be presented for the first time. The new inverse technique works by expanding both an analytic forward model and observed monitoring well data in the same Laguerre function basis, and then computing, by linear algebra alone, the inverse solution. The inversion of the low-order terms of the Laguerre series can be shown to be numerically stable, and also to enforce smoothness on the recovered solution (implicitly containing a sort of regularizing constraint). This approach has a number of advantages over existing techniques. It allows direct estimation of the source history, obviating the need for running multiple forward models (as in MCMC Bayesian approaches), and avoids the need for selecting an arbitrary penalty functional (as in Tikhonov regularization). Simulation results comparing the performance of this approach to existing approaches will be presented.

Hansen, S. K.; Kueper, B. H.

2012-12-01

259

Heavy metal contamination from geothermal sources.  

PubMed Central

Liquid-dominated hydrothermal reservoirs, which contain saline fluids at high temperatures and pressures, have a significant potential for contamination of the environment by heavy metals. The design of the power conversion cycle in a liquid-dominated geothermal plant is a key factor in determining the impact of the installation. Reinjection of the fluid into the reservoir minimizes heavy metal effluents but is routinely practiced at few installations. Binary power cycles with reinjection would provide even cleaner systems but are not yet ready for commercial application. Vapor-dominated systems, which contain superheated steam, have less potential for contamination but are relatively uncommon. Field data on heavy metal effluents from geothermal plants are sparse and confounded by contributions from "natural" sources such as geysers and hot springs which often exist nearby. Insofar as geothermal power supplies are destined to multiply, much work is required on their environmental effects including those caused by heavy metals. PMID:1227849

Sabadell, J E; Axtmann, R C

1975-01-01

260

Multivariate statistical assessment of heavy metal pollution sources of groundwater around a lead and zinc plant  

PubMed Central

The contamination of groundwater by heavy metal ions around a lead and zinc plant has been studied. As a case study groundwater contamination in Bonab Industrial Estate (Zanjan-Iran) for iron, cobalt, nickel, copper, zinc, cadmium and lead content was investigated using differential pulse polarography (DPP). Although, cobalt, copper and zinc were found correspondingly in 47.8%, 100.0%, and 100.0% of the samples, they did not contain these metals above their maximum contaminant levels (MCLs). Cadmium was detected in 65.2% of the samples and 17.4% of them were polluted by this metal. All samples contained detectable levels of lead and iron with 8.7% and 13.0% of the samples higher than their MCLs. Nickel was also found in 78.3% of the samples, out of which 8.7% were polluted. In general, the results revealed the contamination of groundwater sources in the studied zone. The higher health risks are related to lead, nickel, and cadmium ions. Multivariate statistical techniques were applied for interpreting the experimental data and giving a description for the sources. The data analysis showed correlations and similarities between investigated heavy metals and helps to classify these ion groups. Cluster analysis identified five clusters among the studied heavy metals. Cluster 1 consisted of Pb, Cu, and cluster 3 included Cd, Fe; also each of the elements Zn, Co and Ni was located in groups with single member. The same results were obtained by factor analysis. Statistical investigations revealed that anthropogenic factors and notably lead and zinc plant and pedo-geochemical pollution sources are influencing water quality in the studied area. PMID:23369182

2012-01-01

261

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

262

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

263

Treatment of TNT contaminated soil and groundwater using plant-based enzyme systems  

SciTech Connect

Trinitrotoluene (TNT) is considered toxic and a mutagen. For over 100 years, TNT has been widely used in explosives for both military and commercial applications. Soil and groundwater contamination by TNT is prevalent at military bases, manufacturing facilities and at commercial (such as mining) sites were TNT was used or stored. TNT is a difficult compound to treat. It is resistant to complete microbial degradation. Although incineration is feasible, it can be costly. One promising technology is degradation using plant enzyme systems, which has become known as phytoremediation. This paper will highlight bench and field studies of phytoremediation of TNT contaminated soil and groundwater. Parameters for developing a model will be discussed.

Medina, V.F.; Wolfe, L.; McCutcheon, S.C. [Environmental Protection Agency, Athens, GA (United States)

1995-12-31

264

In-situ remediation system and method for contaminated groundwater  

DOEpatents

A system for removing volatile contaminants from a subsurface plume of contamination comprising two sets of wells, a well for injecting a fluid into a saturated zone on one side of the plume and an extracting well for collecting the fluid together with volatilized contaminants from the plume on the other side of the plume. The fluid enables the volatile contaminants to be volatilized and carried therewith through the ground to the extracting well. Injecting and extracting wells are preferably horizontal wells positioned below the plume in the saturated zone and above the plume in the vadose zone, respectively. The fluid may be air or other gas or a gas and liquid mixture depending on the type of contaminant to be removed and may be preheated to facilitate volatilization. Treatment of the volatilized contamination may be by filtration, incineration, atmospheric dispersion or the like.

Corey, John C. (Aiken, SC); Looney, Brian B. (Aiken, SC); Kaback, Dawn S. (Aiken, SC)

1989-01-01

265

In-situ remediation system and method for contaminated groundwater  

DOEpatents

A system for removing volatile contaminants from a subsurface plume of contamination comprising two sets of wells, a well for injecting a fluid into a saturated zone on one side of the plume and an extracting well for collecting the fluid together with volatilized contaminants from the plume on the other side of the plume. The fluid enables the volatile contaminants to be volatilized and carried therewith through the ground to the extracting well. Injecting and extracting wells are preferably horizontal wells positioned below the plume in the saturated zone and above the plume in the vadose zone, respectively. The fluid may be air or other gas or a gas and liquid mixture depending on the type of contaminant to be removed and may be preheated to facilitate volatilization. Treatment of the volatilized contamination may be by filtration, incineration, atmospheric dispersion or the like. 3 figs.

Corey, J.C.; Looney, B.B.; Kaback, D.S.

1989-05-23

266

Groundwater arsenic contamination on the Ganges Delta: biogeochemistry, hydrology, human perturbations, and human suffering on a large scale  

Microsoft Academic Search

Over the last several decades, much of population of Bangladesh and West Bengal switched their water supply from surface water to groundwater. Tragically, much of the region's groundwater is dangerously contaminated by arsenic, and consumption of this water has already created severe health effects. Here we consider how groundwater flow may affect arsenic biogeochemistry and we compare the vertical patterns

Charles F. Harvey; Christopher H. Swartz; Abu Bohran M. Badruzzaman; Nicole Keon-Blute; Winston Yu; M. Ashraf Ali; Jenny Jay; Roger Beckie; Volker Niedan; Daniel Brabander; Peter M. Oates; Khandaker N. Ashfaque; Shafiqul Islam; Harold F. Hemond; M. Feroze Ahmed

2005-01-01

267

Treatability study on the Bear Creek Valley characterization area at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. Phase II work plan for S-3 site contaminated groundwater interception--in-field media evaluation and groundwater capture methods  

SciTech Connect

A treatability study is being conducted to support implementation:of early actions at the S-3 Site in the Bear Creek Valley (BCV) Characterization Area (CA). The objectives of the early actions Will be (1) to reduce concentrations of uranium and nitrate in Bear Creek and (2) to reduce contaminants of concern in North Tributary (NT)-1 and NT-2. The BCV CA is located within the US DOE`s Oak Ridge Reservation in Tennessee. Hazardous and radioactive materials from the Y-12 Plant operations were, disposed of at various sites within BCV. Groundwater and surface water in the BCV CA have been contaminated. The remedial investigation (RI) for the BCV CA identified that the greatest mass flux of contaminants from the various sources migrates via groundwater at the source and discharges to surface water in Bear Creek and its tributaries. In the RI, the combined discharge from the S-3 Site and the Boneyard/Burnyard (BYBY) was identified as accounting for 75% of the cancer risk and more than 80% of the chemical toxicity to Potential downgradient human receptors. In addition, the S-3 Site has caused degradation of surface water quality in upper Bear Creek and two of its tributaries. The BCV CA treatability study focuses on capture and treatment of shallow groundwater before it discharges to tributary waters. The objectives Of treatment of this groundwater are (1) to reduce the concentrations of uranium and nitrate in NT-1 and Bear Creek such that the concentrations of these chemicals in surface water and groundwater are reduced to acceptable levels, (2) to reduce the concentrations of nitrate and metals, and reduce the overall concentration of total dissolved solids; and (3) to hydraulically contain the plume of contaminated, groundwater that is moving in bedrock in the Nolichucky Shale such that the rate of contaminant discharge will be reduced in the long term. The objective of Phase II is to produce conceptual designs for treatment system configurations.

NONE

1996-12-01

268

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

269

REMOVAL OF ORGANIC CONTAMINANTS FROM GROUNDWATER: STATUS OF EPA (ENVIRONMENTAL PROTECTION AGENCY) DRINKING WATER RESEARCH PROGRAM  

EPA Science Inventory

Groundwater is a natural resource of enormous value. Three-quarters of U.S. cities get their water supplies totally or in part from groundwater and more than half of all Americans rely on it for drinking water. Ninety percent of rural households have no source other than groundwa...

270

Groundwater flow dynamics and arsenic source characterization in an aquifer system of West Bengal, India  

NASA Astrophysics Data System (ADS)

groundwater flow modeling, reverse particle tracking, and environmental tracers are used to locate the source of geogenic As affecting an aquifer in West Bengal. The aquifer is hosted by point-bar sands deposited in a meandering fluvial environment. Wells tapping the aquifer exhibit As concentrations up to 531 ?g/L. High-As groundwaters are recharged in ponds marking an abandoned river channel. The source of As is traced to the underlying fine-grained channel-fill sediments. Arsenic release within these sediments is accompanied by a concomitant release of Br and DOC indicating that these species may be decay products of natural organobromines codeposited along with As. Mass transfer of As to the dissolved phase and its flushing from source sediments are described using a simplified reactive solute transport model. Based on this model, a characteristic reaction time for mass transfer is estimated at 6.7 years. Average groundwater residence times in the source are estimated to have declined from 16.6 to 6.6 years with the advent of intensive irrigation pumping. The ratio of residence and reaction times, a Damköhler number, has declined correspondingly from 2.49 to 0.99, indicating a shift from transport to reaction rate limited As mobilization. Greater insight into the As problem in SE Asia may be achieved by shifting the focus of field investigations from aquifers to potential contamination sources in aquitards.

Desbarats, A. J.; Koenig, C. E. M.; Pal, T.; Mukherjee, P. K.; Beckie, R. D.

2014-06-01

271

Fate of gasoline oxygenates in conventional and multilevel wells of a contaminated groundwater table in Düsseldorf, Germany.  

PubMed

In a gasoline-contaminated site in Düsseldorf, Germany a two-year monitoring program was carried out to determine the presence, behavior, and fate of 12 gasoline additives in a total of 96 samples from 14 groundwater wells. The origin of contamination was suspected to be a gasoline spill at a gas station. Target compounds were methyl-tert-butyl ether (MTBE), its main degradation products, tert-butyl alcohol (TBA) and tert-butyl formate (TBF); other gasoline additives, oxygenate dialkyl ethers: Ethyl-tert-butyl ether (ETBE), tert-amyl methyl ether (TAME) and diisopropyl ether (DIPE); aromatics: Benzene, toluene, ethylbenzene and xylenes (BTEX), and other compounds causing odor problems: Dicyclopentadiene and trichloroethylene. Purge and trap coupled with gas chromatography-mass spectrometry permitted detection of ng/L concentrations. Ninety of the 96 samples analyzed contained MTBE at levels varying between 0.01 to 645 microg/L. Five contaminated hot spots were identified with levels up to U.S. Environmental Protection Agency (U.S. EPA) drinking water advisory values (20-40 microg/L) and one of them doubling Danish suggested toxicity level of 350 microg/L at a depth of 11 m. No significant natural attenuation was found in MTBE degradation, although samples with high levels of MTBE contained 0.1 to 440 microg/L of TBA. These levels were attributed to its presence in the contamination source more than MTBE degradation. tert-Butyl alcohol was found to be recalcitrant in groundwater. In all cases, BTEX were at low concentrations or not detected, showing less persistence than MTBE. The monitoring of the contamination plume showed that the distribution of the MTBE and TBA in the aquifer formed a similar vertical concentration profile that was influenced by the groundwater flow direction. PMID:16398114

Rosell, Monica; Lacorte, Sílvia; Forner, Claudia; Rohns, Hans-Peter; Irmscher, Rudolf; Barceló, Damià

2005-11-01

272

Fluidized-bed adsorption bioreactor for the treatment of groundwater contaminated with solvents at low concentration  

SciTech Connect

Volatile organic compounds (VOCs) are a major source of water contamination in the US. They pose a threat to the environment and are a potential hazard to human health. Trichloroethylene (TCE) is the most common of these pollutants. TCE is usually remediated through pumping and treating it, using either air stripping or granular activated carbon. Bioremediation is an alternative treatment that uses microbes to convert hazardous substances into nonhazardous compounds. A fluidized bed adsorption bioreactor is examined here for the treatment of groundwater contaminated at low concentrations. This pilot study showed that the packed adsorbent bed could be loaded in approximately 36 hours at a flow rate of 120 mL/min. The remediation phase of the process took approximately 13 days. The reduction in the TCE concentration in the sorbent during each round indicated that it was being remediated by the microbiological process. Areas that need to be improved are the rate of remediation and the loading capacity of the adsorption beds. Currently, each complete cycle of loading and remediating requires 2 weeks while only mineralizing 58 mg of TCE per column.

Miyares, P.H.; Teeter, C.V.; Martel, C.J.

1999-01-01

273

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

274

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

275

Inorganic contaminants from diffuse pollution in shallow groundwater of the Campanian Plain (Southern Italy). Implications for geochemical survey.  

PubMed

The Campanian Plain (CP) shallow aquifer (Southern Italy) represents a natural laboratory to validate geochemical methods for differentiating diffuse anthropogenic pollution from natural water-rock interaction processes. The CP is an appropriate study area because of numerous potential anthropogenic pollution vectors including agriculture, animal husbandry, septic/drainage sewage systems, and industry. In order to evaluate the potential for geochemical methods to differentiate various contamination vectors, 538 groundwater wells from the shallow aquifer in Campanian Plain (CP) were sampled. The dataset includes both major and trace elements. Natural water-rock interactions, which primarily depend on local lithology, control the majority of geochemical parameters, including most of the major and trace elements. Using prospective statistical methods in combination with the traditional geochemical techniques, we determined the chemical variables that are enriched by anthropogenic contamination (i.e. NO3, SO4 and U) by using NO3 as the diagnostic variable for detecting polluted groundwater. Synthetic agricultural fertilizers are responsible for the majority of SO4 and U pollution throughout the CP area. Both SO4 and U are present in the groundmass of synthetic fertilizers; the uranium concentration is specifically applicable as a tracer for non-point source agricultural fertilizer contamination. The recognition of non-geological (anthropogenic) inputs of these elements has to be considered in the geochemical investigations of contaminated aquifers. PMID:25638062

Cuoco, E; Darrah, T H; Buono, G; Verrengia, G; De Francesco, S; Eymold, W K; Tedesco, D

2015-02-01

276

Remediation of arsenic-contaminated soils and groundwaters  

DOEpatents

An in situ method is described for extraction of arsenic contaminants from a soil medium and remediation of the medium including contacting the medium with an extractant solution, directing the solution within and through the medium, and collecting the solution and contaminants. The method can also be used for arsenate and/or arsenite removal. 8 figs.

Peters, R.W.; Frank, J.R.; Feng, X.

1998-06-23

277

Remediation of arsenic-contaminated soils and groundwaters  

DOEpatents

An in situ method for extraction of arsenic contaminants from a soil medium and remediation of the medium including contacting the medium with an extractant solution, directing the solution within and through the medium, and collecting the solution and contaminants. The method can also be used for arsenate and/or arsenite removal.

Peters, Robert W. (Naperville, IL); Frank, James R. (Glen Ellyn, IL); Feng, Xiandong (West Richland, WA)

1998-01-01

278

STATISTICAL ESTIMATION AND VISUALIZATION OF GROUND-WATER CONTAMINATION DATA  

EPA Science Inventory

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 estimates are nonparametric re...

279

TYPES AND EFFECTS OF MICROBIAL CONTAMINATION OF GROUNDWATER  

EPA Science Inventory

Waterborne illness can be contracted by ingestion of contaminated water or ice; during bathing, swimming, or wading; from inhalation of aerosols, gases, or vapors from contaminated water or waste water. he general unavailability of water for bathing and washing also contributes a...

280

Land-use change and costs to rural households: a case study in groundwater nitrate contamination  

NASA Astrophysics Data System (ADS)

Loss of grassland from conversion to agriculture threatens water quality and other valuable ecosystem services. Here we estimate how land-use change affects the probability of groundwater contamination by nitrate in private drinking water wells. We find that conversion of grassland to agriculture from 2007 to 2012 in Southeastern Minnesota is expected to increase the future number of wells exceeding 10 ppm nitrate-nitrogen by 45% (from 888 to 1292 wells). We link outputs of the groundwater well contamination model to cost estimates for well remediation, well replacement, and avoidance behaviors to estimate the potential economic value lost due to nitrate contamination from observed land-use change. We estimate 0.7-12 million in costs (present values over a 20 year horizon) to address the increased risk of nitrate contamination of private wells. Our study demonstrates how biophysical models and economic valuation can be integrated to estimate the welfare consequences of land-use change.

Keeler, Bonnie L.; Polasky, Stephen

2014-07-01

281

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

282

Assessment of groundwater contamination at Wurtsmith Air Force Base, Michigan, 1982-85  

Microsoft Academic Search

The Arrow Street purge system, installed in 1982 to remove contaminants from the Building 43 plume, has lowered concentrations of trichloroethylene (TCE) in groundwater in the central part of the most contaminated area from a range of 1,000 to 2,000 microg\\/L to about 200 microg\\/L. TCE is not escaping off-Base from this area. In the southern part of the Base

T. R. Cummings; F. R. Twenter

1986-01-01

283

Bioremediation of benzene-, MTBE- and ammonia-contaminated groundwater with pilot-scale constructed wetlands  

Microsoft Academic Search

In this pilot-scale constructed wetland (CW) study for treating groundwater contaminated with benzene, MTBE, and ammonia-N, the performance of two types of CWs (a wetland with gravel matrix and a plant root mat) was investigated. Hypothesized stimulative effects of filter material additives (charcoal, iron(III)) on pollutant removal were also tested. Increased contaminant loss was found during summer; the best treatment

Eva M. Seeger; Peter Kuschk; Helga Fazekas; Peter Grathwohl; Matthias Kaestner

2011-01-01

284

IN SITU PRECIPITATION FOR REMEDIATION OF HEAVY METAL CONTAMINATED GROUNDWATER AT A NON FERROUS INDUSTRIAL SITE  

Microsoft Academic Search

An extensive pilot program is performed in order to design an in-situ remediation system for historic groundwater contamination with heavy metals near a non ferrous metals producing plant in Belgium. A profound site characterization has been performed, in order to obtain a detailed cross-section of the subsoil and a detailed understanding of the contaminated aquifer(s) present in the water bearing

Karolien Vanbroekhoven; Francis Van den Broeck; Karel Feyaerts; Eric Van den Broeck

2007-01-01

285

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

286

Discriminating between point and non-point sources of atrazine contamination of a sandy aquifer.  

PubMed

This study analyses the sources of atrazine contamination in the Brusselian sandy aquifer of central Belgium. Atrazine has in the past been used for both agricultural and non-agricultural applications, but it is difficult to distinguish the contamination originating from these two sources. The spatial and temporal covariance of atrazine concentrations was studied by fitting semi-variogram models to monitoring data. Correlation ranges were found to be 600 m and 600-700 days, respectively. The results were used to apply a declustering algorithm before examining the distribution of atrazine concentrations measured in groundwater. Monitoring data appeared to follow a pseudo-lognormal distribution, as a lognormality test was negative. An inflexion point on the cumulative density function was thought to indicate the two different pollution processes, i.e., agricultural and non-agricultural contamination sources. A non-parametric one-way analysis of variance suggested that the vast majority of atrazine in groundwater was from non-agricultural, point sources. This was supported by the strong relationship between mean concentrations and land use, whilst other environmental variables, such as soil organic matter or groundwater depth, produced less meaningful results. PMID:16055171

Leterme, Bertrand; Vanclooster, Marnik; Rounsevell, Mark D A; Bogaert, Patrick

2006-06-01

287

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 ...

288

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...

289

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...

290

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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...

291

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

292

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

293

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

294

Neuropathy in Arsenic Toxicity from Groundwater Arsenic Contamination in West Bengal, India  

Microsoft Academic Search

Large number of people from 9 out of 18 districts of West Bengal, India are endemically exposed to arsenic contaminated groundwater due to drinking of tubewell water containing arsenic level above World Health Organization's maximum permissible limit of 50 µg\\/L. From our ongoing studies on neurological involvement in patients of arsenicosis from different districts of West Bengal, we report our findings

Subhash Chandra Mukherjee; Mohammad Mahmudur Rahman; Uttam Kumar Chowdhury; Mrinal Kumar Sengupta; Dilip Lodh; Chitta Ranjan Chanda; Kshitish Chandra Saha; Dipankar Chakraborti

2003-01-01

295

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 ...

296

Groundwater Contamination by Road Salt: Steady-State Concentrations in East Central Massachusetts  

Microsoft Academic Search

The average steady-state contamination of groundwater by road salt in the suburban area around Boston, on the assumption that current rates of application of salt will continue, is about 160 milligrams of sodium chloride per liter of water (100 milligrams of chloride per liter). This value is compared with values of 50 to 100 milligrams of chloride per liter found

Edwin E. Huling; Thomas C. Hollocher

1972-01-01

297

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 ...

298

Delta Chromium-53/52 isotopic composition of native and contaminated groundwater, Mojave Desert, USA  

USGS Publications Warehouse

Chromium(VI) concentrations in groundwater sampled from three contaminant plumes in aquifers in the Mojave Desert near Hinkley, Topock and El Mirage, California, USA, were as high as 2600, 5800 and 330 ?g/L, respectively. ?53/52Cr compositions from more than 50 samples collected within these plumes ranged from near 0‰ to almost 4‰ near the plume margins. Assuming only reductive fractionation of Cr(VI) to Cr(III) within the plume, apparent fractionation factors for ?53/52Cr isotopes ranged from ?app = 0.3 to 0.4 within the Hinkley and Topock plumes, respectively, and only the El Mirage plume had a fractionation factor similar to the laboratory derived value of ? = 3.5. One possible explanation for the difference between field and laboratory fractionation factors at the Hinkley and Topock sites is localized reductive fractionation of Cr(VI) to Cr(III), with subsequent advective mixing of native and contaminated water near the plume margin. Chromium(VI) concentrations and ?53/52Cr isotopic compositions did not uniquely define the source of Cr near the plume margin, or the extent of reductive fractionation within the plume. However, Cr(VI) and ?53/52Cr data contribute to understanding of the interaction between reductive and mixing processes that occur within and near the margins of Cr contamination plumes. Reductive fractionation of Cr(VI) predominates in plumes having higher ?app, these plumes may be suitable for monitored natural attenuation. In contrast, advective mixing predominates in plumes having lower ?app, the highly dispersed margins of these plumes may be difficult to define and manage.

Izbicki, John A.; Bullen, Thomas D.; Martin, Peter; Schroth, Brian

2012-01-01

299

Tracing the phosphorus contamination sources and reducing the phosphorus contamination in HPGe crystal growth  

NASA Astrophysics Data System (ADS)

The net impurity concentration and the dislocation density for the grown crystals must be controlled within a narrow range of values to produce crystals acceptable for large-volume coaxial germanium detector fabrication. Phosphorus is the main shallow level donor in high purity germanium crystal. The phosphorus contamination is a disaster for growing p-type high-purity germanium crystal. The phosphorus contamination mainly comes from crucible, insulation, ambient gas or crystal growth chamber. Regrowth method was used to trace the phosphorus contamination sources. The contamination level from sources was discussed in detail in this paper. For different contamination source, targeted approaches were used to reduce the contamination.

Wang, Guojian; Guan, Yutong; Yang, Gang; Govani, Jayesh; Khizar, Muhammad; Mei, Hao; Mei, Dongming

2013-03-01

300

A top specified boundary layer (TSBL) approximation approach for the simulation of groundwater contamination processes  

USGS Publications Warehouse

This paper presents improvements in the 'classical boundary layer' (CBL) approximation method to obtain simple but robust initial characterization of aquifer contamination processes. Contaminants are considered to penetrate into the groundwater through the free surface of the aquifer. The improved method developed in this study is termed the 'top specified boundary layer' (TSBL) approach. It involves the specification of the contaminant concentration at the top of the contaminated 'region of interest' (ROI), which is simulated as a boundary layer. the TSBL modification significantly improves the ability of the boundary layer method to predict the development of concentration profiles over both space and time. The TSBL method can be useful for the simulation of cases in which the contaminant concentration is prescribed at the aquifer's free surface as well as for cases in which the contaminant mass flux is prescribed at the surface.

Rubin, H.; Buddemeier, R.W.

1996-01-01

301

Mobilization Of Polonium-210 In Naturally-Contaminated Groundwater, Churchill County, Nevada  

NASA Astrophysics Data System (ADS)

Polonium-210 activities in groundwater rarely exceed about 40 mBq/L because it strongly binds to sediments. The recent discovery of natural 210Po at levels ranging from below 1 to 6,300±280 mBq/L in 62 drinking-water wells in Lahontan Valley, Churchill County, Nevada, led to a geochemical investigation of the processes responsible for its mobilization from the aquifer sediments. The source of the 210Po is radioactive decay of uranium in sediments transported into the valley by erosion of granitic rocks in the Sierra Nevada during the Pleistocene. There is little spatial or depth variability in 210Pb activity in study-area sediments (average 35 Bq/kg) and detailed analysis at a contaminated well indicates mobilization of <0.5 percent of the 210Po in the sediments would account for all of the 210Po in the well water. Elevated 210Po activities (>200 mBq/L) are associated with anoxic water (DO <0.1 mg/L) with high pH (commonly >9.0). Investigations in the 1980s by William Burnett and colleagues of naturally-contaminated wells in Florida showed that 210Po was mobilized by sulfate-reducing bacteria and remained in solution as long as sulfides did not accumulate above certain levels. Similarly, ?34SSO4 values in Lahontan Valley indicate that significant sulfate reduction has occurred in wells containing >200 mBq/L of 210Po, but sulfide is not accumulating and its concentrations are low (<0.03 mg/L) in 25 of 28 of those wells. In our working hypothesis, mobilization of 210Po in Lahontan Valley is linked to reduction of Mn oxides by sulfide in an anaerobic sulfur cycle (Figure 1). Such a sulfur cycle is consistent with the high pH, less than predicted ?18OSO4 values, low sulfide concentrations, and presence of elemental sulfur in the water. Results from the Nevada and Florida investigations suggest that 210Po contamination may be more widespread than previously recognized, occurring in groundwater near uranium-mine operations and other uranium containing sediments when sulfate-reducing conditions develop in the subsurface. Possible linkage of anaerobic S cycle, Mn reduction, and Po mobilization

Seiler, R. L.; Stillings, L. L.; Cutler, N.

2009-12-01

302

Baseline risk assessment of groundwater contamination at the Uranium Mill Tailings Site near Gunnison, Colorado. Revision 1  

SciTech Connect

This report evaluates potential impacts to public health or the environment resulting from groundwater contamination at the former uranium mill processing site. The tailings and other contaminated material at this site are being placed in an off-site disposal cell by the US Department of Energy`s (DOE) Uranium Mill Tailings Remedial Action (UMTRA) Project. Currently, the UMTRA Project is evaluating groundwater contamination. This is the second risk assessment of groundwater contamination at this site. The first risk assessment was performed primarily to evaluate existing domestic wells to determine the potential for immediate human health and environmental impacts. This risk assessment evaluates the most contaminated groundwater that flows beneath the processing site towards the Gunnison River. The monitor wells that have consistently shown the highest concentration of most contaminants are used in this risk assessment. This risk assessment will be used in conjunction with additional activities and documents to assist in determining what remedial action is needed for contaminated groundwater at the site after the tailings are relocated. This risk assessment follows an approach outlined by the US Environmental Protection Agency (EPA). The first step is to evaluate groundwater data collected from monitor wells at the site. Evaluation of these data showed that the main contaminants in the groundwater are cadmium, cobalt, iron, manganese, sulfate, uranium, and some of the products of radioactive decay of uranium.

Not Available

1994-04-01

303

Development of a screening tool to assess the temporal risk of pesticides leaching to groundwater using the source, target, vector approach. An Irish case study for shallow groundwater.  

PubMed

During this study, a groundwater screening tool was developed to assess the temporal risk of groundwater contamination from the use of pesticides. It is based on a source, vector, target approach. The method utilised in this study uses a semi-quantitative probabilistic risk assessment where the input parameters were classified and assigned a relative score from 1 to 5 (i.e. 1?=?no risk and 5?=?high risk). The model was parameterised by using national data and calibrated with 2 years of national pesticide groundwater monitoring data. After calibration, two specific sites were selected for model validation. Based on the presence of the source, vector and target, the evaluation indicated that the temporal risk is site specific (i.e. May to December for the country model, June to September for the Oak Park site and September for the Castledockrell site). A sensitivity analysis performed on the national scale revealed that the groundwater vulnerability category (gv), the clay content (cc%), the persistence of pesticides in soil (DT50) and the rainfall represented by wet day (wd) were the most important parameters that affected model predictions (correlation coefficients of 0.54, -0.39, 0.35 and 0.31, respectively), highlighting the importance of soil hydrogeological conditions, soil type and rainfall in influencing water model predictions. The model developed can help to identify the temporal risk from pesticides to groundwater and guide regulators in highlighting at-risk periods, therefore allowing more focused monitoring programmes. PMID:25663403

Labite, Herve E; Cummins, Enda

2015-03-01

304

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

SciTech Connect

Perchlorate (ClO{sub 4}{sup -}) is a common groundwater constituent with both synthetic and natural sources. A potentially important source of ClO{sub 4}{sup -} is past agricultural application of ClO{sub 4}{sup -}-bearing natural NO{sub 3}{sup -} fertilizer imported from the Atacama Desert, Chile, but evidence for this has been largely circumstantial. Here we report ClO{sub 4}{sup -} stable isotope data ({delta}{sup 37}Cl, {delta}{sup 18}O, and {Delta}{sup 17}O), along with other supporting chemical and isotopic environmental tracer data, to document groundwater ClO{sub 4}{sup -} contamination sources and history in parts of Long Island, New York. Sampled groundwaters were oxic and ClO{sub 4}{sup -} apparently was not affected by biodegradation within the aquifers. Synthetic ClO{sub 4}{sup -} was indicated by the isotopic method in groundwater near a fireworks disposal site at a former missile base. Atacama ClO{sub 4}{sup -} was indicated in agricultural and urbanizing areas in groundwaters with apparent ages >20 years. In an agricultural area, ClO{sub 4}{sup -} concentrations and ClO{sub 4}{sup -}/NO{sub 3}{sup -} ratios increased with groundwater age, possibly because of decreasing application rates of Atacama NO{sub 3}{sup -} fertilizers and/or decreasing ClO{sub 4}{sup -} concentrations in Atacama NO{sub 3}{sup -} fertilizers in recent years. Because ClO{sub 4}{sup -}/NO{sub 3}{sup -} ratios of Atacama NO{sub 3}{sup -} fertilizers imported in the past (2 x 10{sup -3} mol mol{sup -1}) were much higher than the ClO{sub 4}{sup -}/NO{sub 3}{sup -} ratio of recommended drinking-water limits (7 x 10{sup -5} mol mol{sup -1} in New York), ClO{sub 4}{sup -} could exceed drinking-water limits even where NO{sub 3}{sup -} does not, and where Atacama NO{sub 3}{sup -} was only a minor source of N. Groundwater ClO{sub 4}{sup -} with distinctive isotopic composition was a sensitive indicator of past Atacama NO{sub 3}{sup -} fertilizer use on Long Island and may be common in other areas that received NO{sub 3}{sup -} fertilizers from the late 19th century through the 20th century.

Bohlke, J. K. [U.S. Geological Survey, Reston, VA; Hatzinger, Paul B. [Shaw Environmental, Inc., Lawrenceville, NJ; Sturchio, N. C. [University of Illinois, Chicago; Gu, Baohua [ORNL; Abbene, I. [U.S. Geological Survey; Mroczkowki, S. J. [U.S. Geological Survey

2009-01-01

305

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

306

Development of one-dimensional computational fluid dynamics code 'GFLOW' for groundwater flow and contaminant transport analysis  

SciTech Connect

Prediction of groundwater movement and contaminant transport in soil is an important problem in many branches of science and engineering. This includes groundwater hydrology, environmental engineering, soil science, agricultural engineering and also nuclear engineering. Specifically, in nuclear engineering it is applicable in the design of spent fuel storage pools and waste management sites in the nuclear power plants. Ground water modeling involves the simulation of flow and contaminant transport by groundwater flow. In the context of contaminated soil and groundwater system, numerical simulations are typically used to demonstrate compliance with regulatory standard. A one-dimensional Computational Fluid Dynamics code GFLOW had been developed based on the Finite Difference Method for simulating groundwater flow and contaminant transport through saturated and unsaturated soil. The code is validated with the analytical model and the benchmarking cases available in the literature. (authors)

Rahatgaonkar, P. S.; Datta, D.; Malhotra, P. K.; Ghadge, S. G. [Nuclear Power Corporation of India Ltd., R-2, Ent. Block, Nabhikiya Urja Bhavan, Anushakti Nagar, Mumbai - 400 094 (India)

2012-07-01

307

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

308

Methods Used to Assess the Susceptibility to Contamination of Transient, Non-Community Public Ground-Water Supplies in Indiana  

USGS Publications Warehouse

The Safe Water Drinking Act of 1974 as amended in 1996 gave each State the responsibility of developing a Source-Water Assessment Plan (SWAP) that is designed to protect public-water supplies from contamination. Each SWAP must include three elements: (1) a delineation of the source-water protection area, (2) an inventory of potential sources of contaminants within the area, and (3) a determination of the susceptibility of the public-water supply to contamination from the inventoried sources. The Indiana Department of Environmental Management (IDEM) was responsible for preparing a SWAP for all public-water supplies in Indiana, including about 2,400 small public ground-water supplies that are designated transient, non-community (TNC) supplies. In cooperation with IDEM, the U.S. Geological Survey compiled information on conditions near the TNC supplies and helped IDEM complete source-water assessments for each TNC supply. The delineation of a source-water protection area (called the assessment area) for each TNC ground-water supply was defined by IDEM as a circular area enclosed by a 300-foot radius centered at the TNC supply well. Contaminants of concern (COCs) were defined by IDEM as any of the 90 contaminants for which the U.S. Environmental Protection Agency has established primary drinking-water standards. Two of these, nitrate as nitrogen and total coliform bacteria, are Indiana State-regulated contaminants for TNC water supplies. IDEM representatives identified potential point and nonpoint sources of COCs within the assessment area, and computer database retrievals were used to identify potential point sources of COCs in the area outside the assessment area. Two types of methods-subjective and subjective hybrid-were used in the SWAP to determine susceptibility to contamination. Subjective methods involve decisions based upon professional judgment, prior experience, and (or) the application of a fundamental understanding of processes without the collection and analysis of data for a specific condition. Subjective hybrid methods combine subjective methods with quantitative hydrologic analyses. The subjective methods included an inventory of potential sources and associated contaminants, and a qualitative description of the inherent susceptibility of the area around the TNC supply. The description relies on a classification of the hydrogeologic and geomorphic characteristics of the general area around the TNC supply in terms of its surficial geology, regional aquifer system, the occurrence of fine- and coarse-grained geologic materials above the screen of the TNC well, and the potential for infiltration of contaminants. The subjective hybrid method combined the results of a logistic regression analysis with a subjective analysis of susceptibility and a subjective set of definitions that classify the thickness of fine-grained geologic materials above the screen of a TNC well in terms of impedance to vertical flow. The logistic regression determined the probability of elevated concentrations of nitrate as nitrogen (greater than or equal to 3 milligrams per liter) in ground water associated with specific thicknesses of fine-grained geologic materials above the screen of a TNC well. In this report, fine-grained geologic materials are referred to as a geologic barrier that generally impedes vertical flow through an aquifer. A geologic barrier was defined to be thin for fine-grained materials between 0 and 45 feet thick, moderate for materials between 45 and 75 feet thick, and thick if the fine-grained materials were greater than 75 feet thick. A flow chart was used to determine the susceptibility rating for each TNC supply. The flow chart indicated a susceptibility rating using (1) concentrations of nitrate as nitrogen and total coliform bacteria reported from routine compliance monitoring of the TNC supply, (2) the presence or absence of potential sources of regulated contaminants (nitrate as nitrogen and coliform bac

Arihood, Leslie D.; Cohen, David A.

2006-01-01

309

Phytoremediation of Nitrate-Contaminated Groundwater by Desert Phreatophytes  

Microsoft Academic Search

Two native halophytic shrubs were evaluated for phytoremediation of a nitrate- contaminated aquifer at a former uranium mill site. The shrubs, Sarcobatus vermiculatus and Atriplex canescens, obligate and facultative phreatophytes, respectively, dominate the desert plant community. Stable isotope signatures suggested that both species are rooted into the nitrate plume, a depth averaging more than 10 meters. Aerial photography and ground

Casey McKeon; Edward P. Glenn; David Moore; W. Jody Waugh

310

Assessment of seawater intrusion and nitrate contamination on the groundwater quality in the Korba coastal plain of Cap-Bon (North-east of Tunisia)  

NASA Astrophysics Data System (ADS)

In recent years, seawater intrusion and nitrate contamination of groundwater have become a growing concern for people in rural areas in Tunisia where groundwater is always used as drinking water. The coastal plain of Korba (north-east of Tunisia) is a typical area where the contamination of the aquifer in the form of saltwater intrusion and high nitrate concentrations is very developed and represents the major consequence of human activities. The objective of this study is to evaluate groundwater resource level, to determine groundwater quality and to assess the risk of NO3- pollution in groundwater using hydrogeochemical tools. Groundwater were sampled and analyzed for physic-chemical parameters: Ca2+, Mg2+, Na+, K+, Cl-, SO42-, HCO3-, NO3-, Total Dissolved Solid and of the physical parameters (pH, electrical conductivity and the temperature). The interpretation of the analytical results is shown numerically and graphically through the ionic deviations, Piper Diagram, seawater fractions and binary diagrams. Moreover, electrical conductivity investigations have been used to identify the location of the major intrusion plumes in this coastal area and to obtain new information on the spatial scales and dynamics of the fresh water-seawater interface. Those processes can be used as indicators of seawater intrusion progression. First, the hydrogeochemical investigation of this aquifer reveals the major sources of contamination, represented by seawater intrusion. Thus, the intensive extraction of groundwater from aquifer reduces freshwater outflow to the sea, creates several drawdown cones and lowering of the water table to as much as 12 m below mean sea level in the center part of the study area especially between Diarr El Hojjej and Tafelloun villages, causing seawater migration inland and rising toward the wells. Moreover, the results of this study revealed the presence of direct cation exchange linked to seawater intrusion and dissolution processes associated with cations exchange. Second, a common contaminant identified in groundwater is dissolved nitrogen in the form of nitrate. The average nitrate concentration of the aquifer is about 30.44 mg/l, but contents as great as about 50 mg/l occur in the central region where seawater has been identified. Nitrate survey reveals that nitrate concentration above the drinking water standard (50 mg/l) covered an area of 122.64 km2, which accounts for 28% of the whole area. Irrigation with the nitrogen fertilizers, domestic sewage, industrial wastewater and movement of contaminants in areas of high hydraulic gradients within the drawdown cones probably are responsible for localized peaks of the nitrate concentration. It is suggested that risk assessment of nitrate pollution is useful for a better management of groundwater resources, preventing soil salinisation and minimizing nitrate pollution in groundwater.

Zghibi, Adel; Tarhouni, Jamila; Zouhri, Lahcen

2013-11-01

311

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. PMID:17589591

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

2007-01-01

312

Baseline risk assessment of groundwater contamination at the uranium mill tailings site near Shiprock, New Mexico. Draft  

SciTech Connect

This report evaluates potential impact to public health or the environment resulting from groundwater contamination at the former uranium mill processing site. The tailings and other contaminated material at this site were placed in a disposal cell on the site in 1986 by the US Department of Energy`s (DOE) Uranium Mill Tailings Remedial Action (UMTRA) Project. Currently, the UMTRA Project is evaluating groundwater contamination. This risk assessment is the first document specific to this site for the Groundwater Project. This risk assessment follows the approach outlined by the US Environmental Protection Agency (EPA). The first step is to evaluate groundwater data collected from monitor wells at the site. Evaluation of these data showed that the main contaminants in the floodplain groundwater are arsenic, magnesium, manganese, nitrate, sodium, sulfate, and uranium. The complete list of contaminants associated with the terrace groundwater could not be determined due to the lack of the background groundwater quality data. However, uranium, nitrate, and sulfate are evaluated since these chemicals are clearly associated with uranium processing and are highly elevated compared to regional waters. It also could not be determined if the groundwater occurring in the terrace is a usable water resource, since it appears to have originated largely from past milling operations. The next step in the risk assessment is to estimate how much of these contaminants people would be exposed to if a drinking well were installed in the contaminated groundwater or if there were exposure to surface expressions of contaminated water. Potential exposures to surface water include incidental contact with contaminated water or sediments by children playing on the floodplain and consumption of meat and milk from domestic animals grazed and watered on the floodplain.

Not Available

1993-09-01

313

Using trees to remediate groundwaters contaminated with chlorinated hydrocarbons. 1998 annual progress report  

SciTech Connect

'Industrial practices in the past have resulted in contamination of groundwater with chlorinated hydrocarbons (CHCs) at many DOE sites, such as Hanford and Savannah River. Such contamination is a major problem because existing groundwater remediation technologies are expensive and difficult. An inexpensive method for groundwater remediation is greatly needed. Trees could be used to remediate CHC polluted groundwater at minimal cost (phytoremediation). Before phytoremediation can be extensively applied, the authors must determine the range of compounds that are attacked, the effects of metabolic products on the plants and the environment, and the effect of transpiration and concentration of CHC on uptake and metabolism. They will test the ability of hybrid poplar to take up and transform the chlorinated methanes, ethanes and ethylenes. The rate of uptake and transformation by poplar of TCE as a function of concentration in the soil, transpiration rate and illumination level will be determined. Methods will be developed to permit rapid testing of plants from contaminated sites for species able to oxidize and sequester chlorinated compounds. They will identify the nature of the bound residues of TCE metabolism in poplar. They will identify the mechanisms involved in CHC oxidation in poplar and use genetic manipulations to enhance that activity. They will introduce the genes for mammalian cytochrome P-450-IIE1, known to oxidize light CHCs such as TCE to attempt to increase the CHC metabolism capacity of poplar. The results of this research will place phytoremediation of CHCs on a firm scientific footing, allowing a rational assessment of its application to groundwater contamination. This report summarizes the results of the first 1.5 years of work on a three-year project.'

Strand, S.E.; Gordon, M.P.

1998-06-01

314

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. PMID:24806545

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

2014-01-01

315

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

316

COMBINATION OF A SOURCE REMOVAL REMEDY AND BIOREMEDIATION FOR THE TREATMENT OF A TCE CONTAMINATED AQUIFER  

EPA Science Inventory

Historical disposal practices of chlorinated solvents have resulted in the widespread contamination of ground-water resources. These ground-water contaminants exist in the subsurface as free products, residual and vapor phases, and in solution. The remediation of these contamin...

317

The fluxes and transport mechanisms of groundwater and surface water contaminants (Cd, Zn, Pb, As, and Cr) into a fluvial system: Palmerton, PA  

NASA Astrophysics Data System (ADS)

Surface water is frequently the only pathway considered when evaluating fluxes of contaminants into fluvial systems. This practice likely underestimates elemental fluxes leaving contaminated properties through groundwater and impacting the health of nearby ecosystems as well as possibly threatening drinking water sources. These two contaminant pathways are also likely to exhibit two different transport mechanisms, with surface water contaminants likely sorbed to suspended particles and groundwater contaminants transported in the dissolved phase. Well characterized sites, such as the historic Zinc Smelter site located in Palmerton PA, provide an ideal opportunity to characterize the relative contributions of groundwater and surface water to larger river systems. At this site, airfall and runoff contamination of the groundwater and surface waters occurred for more than 80 years. While the plant closed in 1980, the local groundwater and surface water are likely still carrying the legacy of site contamination. Results from water samples taken from the Lehigh River 7 km north and 6 km south of the West Plant of the Zinc Smelter show that zinc flux increases through the reach along the river, especially during high flow periods. The maximum rise in dissolved zinc, which occurred during a high flow period, was 1000 g/min and the minimum, at base flow, was 80 g/min. Using sequential filtration, particulate transport of zinc can be evaluated. The maximum rise in particulate zinc was 4300 g/min and the minimum was 10 g/min at high flow and base flow respectively. Two tributaries, entering the river along the reach, account for a portion of the overall increase, with groundwater and other surface water sources accounting for the remainder. Cadmium, lead, and chromium show behavior similar to zinc, but at lower concentrations. Very little arsenic was found in any of the samples. Groundwater zinc concentrations in a shallow aquifer below the West Plant range from 130 ?g/L to 340 ?g/L, nearly all in the dissolved phase. The transport of dissolved zinc to the stream channel must then be coupled to reactions that sorb the zinc to particulate materials in the fluvial system.

Blake, J.; Peters, S. C.

2009-12-01

318

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

319

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

320

[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

321

[Review of dual stable isotope technique for nitrate source identification in surface- and groundwater in China].  

PubMed

Water nitrate (NO3-) contamination is a world-wide environmental problem under the effects of intensive human activities. Sources identification of NO3- contamination in water is important for better management of water quality. Dual stable isotope data of nitrate nitrogen (delta15N) and nitrate oxygen (delta18O) combined with other stable isotopes and chemical analysis data have been frequently used to identify NO3- sources, differentiate percentage of the different NO3- sources and assess the nitrification/denitrification processes of surface water, groundwater and precipitation, respectively. This review summarized the analysis technique of nitrate delta15N and delta18O in domestic and abroad, assessed typical values of delta15N, delta18O from different NO3- sources and evaluated the progress in application of dual stable isotope of delta15N and delta18O technique to trace NO3- sources in surface- and ground-water. Both ion exchange-AgNO3 and bacteria denitrifying methods have been successfully used in tracing water nitrate sources nationwide. The comprehensive metadata analysis of nitrate sources showed that the delta15N values of sewage and manure, soil, precipitation, fertilizer ranged from 3 per thousand to 17 per thousand, 3 per thousand to 8 per thousand, - 9 per thousand to 9 per thousand, -2 per thousand to 4 per thousand, respectively. And the delta15N values of ammonium fertilizer ranged from - 4 per thousand to 2 per thousand. According to the stable isotope technique, sewage and manure were identified as the major nitrate sources of surface- and ground-water in China. This indicated that municipal sewage and aquaculture exerted serious influence on the nitrate pollution of surface water. In the future, long-term monitoring, dual stable isotope fingerprinting and hydro-chemical analysis should be applied together to quantitatively differentiate contribution of nitrate sources, and to assess seasonal dynamic of nitrate sources. It will provide useful scientific basis for water environmental management of China. PMID:25338404

Xu, Zhi-Wei; Zhang, Xin-Yu; Yu, Gui-Rui; Sun, Xiao-Min; Wen, Xue-Fa

2014-08-01

322

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

323

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 ...

324

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...

325

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

326

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

327

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

328

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

329

Groundwater arsenic contamination in Brahmaputra river basin: a water quality assessment in Golaghat (Assam), India  

Microsoft Academic Search

Distribution of arsenic (As) and its compound and related toxicology are serious concerns nowadays. Millions of individuals\\u000a worldwide are suffering from arsenic toxic effect due to drinking of As-contaminated groundwater. The Bengal delta plain,\\u000a which is formed by the Ganga–Padma–Meghna–Brahmaputra river basin, covering several districts of West Bengal, India, and Bangladesh\\u000a is considered as the worst As-affected alluvial basin. The

Mridul Chetia; Soumya Chatterjee; Saumen Banerjee; Manash J. Nath; Lokendra Singh; Ravi B. Srivastava; Hari P. Sarma

2011-01-01

330

A Geochemical Reaction Model for Titration of Contaminated Soil and Groundwater at the Oak Ridge Reservation  

NASA Astrophysics Data System (ADS)

This study investigates geochemical reactions during titration of contaminated soil and groundwater at the Oak Ridge Reservation in eastern Tennessee. The soils and groundwater exhibits low pH and high concentrations of aluminum, calcium, magnesium, manganese, various trace metals such as nickel and cobalt, and radionuclides such as uranium and technetium. The mobility of many of the contaminant species diminishes with increasing pH. However, base additions to increase pH are strongly buffered by various precipitation/dissolution and adsorption/desorption reactions. The ability to predict acid-base behavior and associated geochemical effects is thus critical to evaluate remediation performance of pH manipulation strategies. This study was undertaken to develop a practical but generally applicable geochemical model to predict aqueous and solid-phase speciation during soil and groundwater titration. To model titration in the presence of aquifer solids, an approach proposed by Spalding and Spalding (2001) was utilized, which treats aquifer solids as a polyprotic acid. Previous studies have shown that Fe and Al-oxyhydroxides strongly sorb dissolved Ni, U and Tc species. In this study, since the total Fe concentration is much smaller than that of Al, only ion exchange reactions associated with Al hydroxides are considered. An equilibrium reaction model that includes aqueous complexation, precipitation, ion exchange, and soil buffering reactions was developed and implemented in the code HydroGeoChem 5.0 (HGC5). Comparison of model results with experimental titration curves for contaminated groundwater alone and for soil- water systems indicated close agreement. This study is expected to facilitate field-scale modeling of geochemical processes under conditions with highly variable pH to develop practical methods to control contaminant mobility at geochemically complex sites.

Zhang, F.; Parker, J. C.; Gu, B.; Luo, W.; Brooks, S. C.; Spalding, B. P.; Jardine, P. M.; Watson, D. B.

2007-12-01

331

Identification of Groundwater Contamination Causes Around Subway Tunnels at a Coastal Area in Korea, Using Hydrogeological and Geostatistical Analyses  

NASA Astrophysics Data System (ADS)

The cause for the deterioration of groundwater quality was identified by hydrogeological investigations and geostatisitical analyses at a coastal area in Busan, Korea. The city has many tunnels for three subway lines, for communication cables and for electrical cables under the ground. The groundwater levels of 135 wells were measured during the dry and wet seasons. The average groundwater level was 7.81 m above the mean sea level in dry season, and 9.11 m in wet season. Groundwater was sampled at 135 wells developed in shallow and deep aquifers. The average water temperature in wet season was 5.5 degrees C higher than that in dry season. The average of pH was 0.4 higher, and the average of DO was 0.6 mg/L lower in wet season. The average of EC was 136 ?S/cm higher in wet season. The total quantity of discharged groundwater from subway tunnels was 2,282,000 m3/year at the study area. It was 2.4 times the sustainable development yield of groundwater. So the groundwater level was seriously decreased at the study area. The maximum groundwater level around the subway was located at 30 ~ 32 m below the mean sea level. The deep drawdown of groundwater level brought about the inflow of sea water and river water. The groundwater around the subway lines was contaminated by sea water and the salinized water of the Suyeong River. The quality of groundwater was not reached to the standard of potable, domestic, agricultural and industrial uses. The distribution maps of groundwater level and quality were produced using a geostatistical method, kriging. The maps were very useful to find out the causes of groundwater contamination at the study area. The maps identified that sea water and river water infiltrated the inland groundwater and contaminated the groundwater around the subway lines, because the groundwater level was seriously drawdowned by the groundwater discharge from the subway tunnels. The groundwater was also contaminated by seawater intrusion at the coastal area.

Kim, D.; Kim, T.; Chung, S.; Yang, S.

2009-12-01

332

A study of methods to reduce groundwater contamination around the Kimpo landfill in Korea.  

PubMed

Four different methods were studied to reduce the groundwater contamination around the Kimpo landfill in Korea by leakage of a leachate. The hydraulic parameters were measured for this study and then the groundwater flow and contaminant transport systems around the Kimpo landfill were simulated with MODFLOW and MT3D models. Both the method of establishing 5 sets of Radial Collector Well Laterals (RCWLs) within the landfill and a method utilizing the wells for dewatering condensed water brought about a 70% leachate elimination efficiency. Their construction costs were cheap, and the maximum concentrations of chloride and phenol in the leachate effluent were high. Meanwhile, a method establishing an interception wall to the 2nd layer at the cirumference of the landfill and 22 sets of RCWLs within it brought about a 92% leachate elimination efficiency. Its construction cost was expensive, and the maximum concentrations of chloride and phenol in the leachate effluent were low. A method of establishing an interception wall to the 3rd layer and 40 sets of RCWLs brought about a 97% leachate elimination efficiency. Its construction cost was the most expensive, and the maximum concentrations of chloride and phenol were low. Conclusively, a method of establishing 22 sets of RCWLs was evaluated as the most stable and economical option to reduce groundwater contamination concentration below drinking water standard. PMID:12088379

Kim, G; Shon, J; Won, H; Hyun, J; Oh, W

2002-05-01

333

Biodegradation of creosote and pentachlorophenol in contaminated ground-water: 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, 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 the material were determined at intervals by Microtox assays and fish toxicity and teratogenicity tests. After 14 days of incubation at 30 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. (Copyright (c) 1991, American Society for Microbiology.)

Mueller, J.G.; Middaugh, D.P.; Lantz, S.E.; Chapman, P.J.

1991-01-01

334

Zero valent iron reduces toxicity and concentrations of organophosphate pesticides in contaminated groundwater.  

PubMed

The potential of zero valent iron (ZVI) for remediation of contaminated groundwater from an abandoned chemical disposal site was examined through batch and column experiments. The key contaminants were organophosphate pesticides but the chemical analysis also comprised additional 22 compounds including synthesis intermediates and degradation products of organophosphates. The ZVI treatment showed that all the contaminants were degraded with the exception of two diesters (phosphorothioates). The most rapid reduction was found for methyl parathion, ethyl parathion and malathion, which had first-order degradation rate constants on the order of 10(-3) min(-1). In the study, acute toxicity towards freshwater crustaceans (Daphnia magna) was included to evaluate the overall efficiency of ZVI treatment of the complex mixture. The acute toxicity tests with D. magna showed that the untreated groundwater was highly toxic. Thus, 50% of the daphnids were unable to swim upon 24h exposure to groundwater diluted 770 times. ZVI facilitated degradation resulted in a complete toxicity removal for the first four pore volumes, where after a three times dilution caused 50% inhibition of the mobility of the daphnids. The rapid degradation of the highly toxic organophosphates combined with the significant decrease in the ecotoxicological potential shows a promising potential for site remediation of organophosphates with ZVI technologies. PMID:23021613

Fjordbøge, Annika S; Baun, Anders; Vastrup, Troels; Kjeldsen, Peter

2013-01-01

335

Air Force ground-water contamination cleanup: an evaluation of the pump-and-treat method. Master's thesis  

Microsoft Academic Search

This thesis is an attempt to determine the effectiveness of the Air Force's use of pump-and-treat technology to remediate groundwater contamination. The study is divided into four major sections: (1) literature survey of ground-water contamination problems and remediation technology; (2) identification of bases where pump-and-treat technology has been employed; (3) collection of quantitative data from bases for analysis; (4) analysis

Ammons

1988-01-01

336

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

337

Biogeochemical control on groundwater arsenic contamination - a laboratory batch reactor approach  

NASA Astrophysics Data System (ADS)

Microbial metabolism plays an important role in groundwater arsenic contamination, but how microbial metabolisms impact arsenic levels and mobility in groundwater is not well understood. This study takes the bedrock aquifer of the Willamette Basin, Oregon as an example and examines potential microbial metabolisms and their impact on groundwater arsenic chemistry using sediment slurry experiments. The slurries were prepared using aquifer sediments and artificial groundwater and included 1) a sterile control, 2) slurries with in situ aquifer conditions, 3) slurries amended with ethanol as an electron donor, and 4) slurries with the addition of ethanol and sulfate. The slurries were incubated at in situ temperature for two months. Aqueous and gas samples were collected to monitor chemical compositions of the slurries; sediments were sampled for enumerating microbial functional groups using the most probable number method and for analyzing solid-phase iron, sulfide, and arsenic. The results suggest the presence of a complex biogeochemical reaction network in the aquifer; this network consists of microbial iron reduction, arsenate reduction, sulfate reduction, and methanogenesis. These metabolisms can occur simultaneously in the aquifer, controlling groundwater arsenic speciation and concentrations. The results also offer new insights into the thermodynamic favorability of microbial reduction of iron and arsenate as well as the potential of arsenic detoxification in aquifers.

Maguffin, S. C.; Jin, Q.

2011-12-01

338

California GAMA Program: Sources and transport of nitrate in shallow groundwater in the Llagas Basin of Santa Clara County, California  

SciTech Connect

A critical component of the State Water Resource Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) Program is to assess the major threats to groundwater resources that supply drinking water to Californians (Belitz et al., 2004). Nitrate is the most pervasive and intractable contaminant in California groundwater and is the focus of special studies under the GAMA program. This report presents results of a study of nitrate contamination in the aquifer beneath the cities of Morgan Hill and Gilroy, CA, in the Llagas Subbasin of Santa Clara County, where high nitrate levels affect several hundred private domestic wells. The main objectives of the study are: (1) to identify the main source(s) of nitrate that issue a flux to the shallow regional aquifer (2) to determine whether denitrification plays a role in the fate of nitrate in the subbasin and (3) to assess the impact that a nitrate management plan implemented by the local water agency has had on the flux of nitrate to the regional aquifer. Analyses of 56 well water samples for major anions and cations, nitrogen and oxygen isotopes of nitrate, dissolved excess nitrogen, tritium and groundwater age, and trace organic compounds, show that synthetic fertilizer is the most likely source of nitrate in highly contaminated wells, and that denitrification is not a significant process in the fate of nitrate in the subbasin except in the area of recycled water application. In addition to identifying contaminant sources, these methods offer a deeper understanding of how the severity and extent of contamination are affected by hydrogeology and groundwater management practices. In the Llagas subbasin, the nitrate problem is amplified in the shallow aquifer because it is highly vulnerable with high vertical recharge rates and rapid lateral transport, but the deeper aquifers are relatively more protected by laterally extensive aquitards. Artificial recharge delivers low-nitrate water and provides a means of long-term remediation. Examination of nitrate concentration in relation to groundwater age indicates that the nitrate management plan has not yet resulted in a decrease in the flux of nitrate to the shallow aquifer in the areas tested.

Moran, J E; McNab, W; Esser, B; Hudson, G; Carle, S; Beller, H; Kane, S; Tompson, A B; Letain, T; Moore, K; Eaton, G; Leif, R; Moody-Bartel, C; Singleton, M

2005-06-29

339

Identification of groundwater nitrate sources in pre-alpine catchments: a multi-tracer approach  

NASA Astrophysics Data System (ADS)

Porous aquifers in pre-alpine areas are often used as drinking water resources due to their good water quality status and water yield. Maintaining these resources requires knowledge about possible sources of pollutants and a sustainable management practice in groundwater catchment areas. Of particular interest in agricultural areas, like in pre-alpine regions, is limiting nitrate input as main groundwater pollutant. Therefore, the objective of the presented study is i) to identify main nitrate sources in a pre-alpine groundwater catchment with current low nitrate concentration using stable isotopes of nitrate (d18O and d15N) and ii) to investigate seasonal dynamics of nitrogen compounds. The groundwater catchment areas of four porous aquifers are located in Southern Germany. Most of the land use is organic grassland farming as well as forestry and residential area. Thus, potential sources of nitrate mainly are mineral fertilizer, manure/slurry, leaking sewage system and atmospheric deposition of nitrogen compounds. Monthly freshwater samples (precipitation, river water and groundwater) are analysed for stable isotope of water (d2H, d18O), the concentration of major anions and cations, electrical conductivity, water temperature, pH and oxygen. In addition, isotopic analysis of d18O-NO3- and d15N-NO3- for selected samples is carried out using the denitrifier method. In general, all groundwater samples were oxic (10.0±2.6mg/L) and nitrate concentrations were low (0.2 - 14.6mg/L). The observed nitrate isotope values in the observation area compared to values from local precipitation, sewage, manure and mineral fertilizer as well as to data from literature shows that the nitrate in freshwater samples is of microbial origin. Nitrate derived from ammonium in fertilizers and precipitation as well as from soil nitrogen. It is suggested that a major potential threat to the groundwater quality is ammonia and ammonium at a constant level mainly from agriculture activities as well as continuously release of nitrogen stored in agricultural soils due to mineralization processes. In all groundwater and river water samples a seasonal variation of nitrate sources and concentration is absent but nitrate in precipitation shows a clear seasonal variation with peaks in spring and fall according to agricultural activity. This points to dilution effects of high nitrate inputs due to the large groundwater volume and mean residence time and highlights the function of soil as initial sink for nitrogen compounds delivered by fertilizer. Even though nitrate contamination was low in the study area, the results emphasize the importance of reducing additional nitrate sources in pre-alpine oxic aquifers. This will maintain the good water quality status of the aquifers and enable its use for drinking water supply.

Stoewer, Myriam; Stumpp, Christine

2014-05-01

340

Preliminary evaluation of ground-water contamination by coal-tar derivatives, St. Louis Park area, Minnesota  

USGS Publications Warehouse

Operation of a coal-tar distillation and wood preserving plant for 1918-72 in St. Louis Park, Minnesota, resulted in ground-water contamination. This report presents the results of the first year (1979) of an ongoing study. By 1932, water in the Prairie du Chien-Jordan aquifer, the region 's major source of ground water, was contaminated 3,500 feet from the plant. The hydraulic characteristics of the Prairie du Chien-Jordan aquifer , its long contamination history, and fluctuating pumpage combine to creat a complex distribution of coal-tar derivatives observed in the aquifer. The Prairie du Chien-Jordan aquifer underlies the area at depths of 250 to 500 feet and is overlain by two bedrock aquifers (Platteville and St. Peter), two confining beds (Glenwood and basal part of St. Peter), and 70 to 100 feet of glacial drift. Multiaquifer wells in the area have permitted contaminated water from near-surface aquifers to flow downward into the Prairie du Chien-Jordan aquifer. Flow rates of 20 to 150 gallons per minute from the shallower aquifers into the Prairie du Chien-Jordan aquifer were observed in five wells. In the drift, a hydrocarbon fluid phase is moving vertically downward relative to the aqueous phase. Dissolved constituents in the drift and Platteville aquifer, the uppermost bedrock unit over most of the area, have moved at least 4,000 feet. Low-molecular-weight compounds are moving preferentially through the drift and Platteville aquifer system. (USGS)

Hult, Marc F.; Schoenberg, Michael

1981-01-01

341

Groundwater Contamination by Nitrates in the Yucatan Peninsula, Mexico  

Microsoft Academic Search

Limestone is the main rock type that underlies the northern Yucatan Peninsula, and the region is therefore characterized by karstic features and high permeability and porosity. Rainfall infiltrates rapidly through fissures until it reaches the water table. No surface waters exist in the area, except in sinkholes and at the coastal margin, and the aquifer is the only source of

1997-01-01

342

Review of arsenic removal technologies for contaminated groundwaters.  

SciTech Connect

This review was compiled to summarize the technologies currently being investigated to remove arsenic from drinking waters, with a special focus on developing and third-world countries where the problem is exacerbated by flooding and depressed economic conditions. The reason for compiling this report is to provide background material and a description of competing technologies currently described in the literature for arsenic removal. Based on the sophistication and applicability of current technologies, Argonne National Laboratory may develop an improved method based on magnetic particle technology. Magnetic particle sorbents may afford improved reaction rates, facilitate particle-water separation, and offer reusability. Developing countries like Vietnam and Bangladesh cannot afford expensive, large-scale treatments to remove arsenic from drinking waters to acceptable limits (from 50 ppb to 10 ppb, depending on the country). Low-cost, effective technologies that can be readily available at the household or community level are needed to solve the present crisis. Appropriate technologies should meet certain criteria, including the following: The treatment must be applicable over a wide range of arsenic concentrations; It should be easy to use without running water or electricity; and The materials for the treatment should be cheap and readily available, and/or suitable for reuse. Our review of arsenic removal technologies and procedures indicates that iron filings, ferric salts, granular ferric hydroxide, alumina manganese oxide, Aqua-bind., and Kimberlite tailings are potentially low-cost sorbents that can remove arsenic after simple mixing in a relatively short time. However, all these technologies suffer from significant shortcomings. Ferric salts are cheap and very effective at removing arsenic but the reaction rates are slow. Fixed-bed columns make use of activated alumina and iron-coated sands but do not work well with groundwater having high concentrations of iron because iron precipitates in the presence of air, which could clog and foul the column. Synthetic sorbents are highly selective and effective and do not pose a significant waste disposal concern because they are generally non-hazardous. Aqua-bind. is perhaps the most effective synthetic sorbent available for removing arsenic, but it must be mass-produced to realize low cost. Naturally occurring solids are cheap and remove arsenic well; however, the removal rate is often very slow and the solids can harbor bacteria. This report reviews competing technologies for removal of water-borne arsenic to establish a baseline for technology improvements. Specifically, the information in this report will serve as a basis for developing a low-cost separation technology using functionalized magnetic particles to adsorb arsenic and permanent magnets to separate the arsenic-loaded magnetic particles from the cleaned water.

Vu, K. B.; Kaminski, M. D.; Nunez, L.

2003-05-02

343

In-situ bioremediation of TCE-contaminated groundwater  

SciTech Connect

This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). A barrier to wider use of in situ bioremediation technology is that results are often variable and difficult to predict. In situ bioremediation has shown some very notable and well publicized successes, but implementation of the technology is complex. An incomplete understanding of the effects of variable site characteristics and the lack of adequate tools to predict and measure success have made the design, control and validation of bioremediation more empirical than desired. The long-term objective of this project is to improve computational tools used to assess and optimize the expected performance of bioremediation at a site. An important component of the approach is the explicit inclusion of uncertainties and their effect on the end result. The authors have extended their biokinetics model to include microbial competition and predation processes. Predator species can feed on the microbial species that degrade contaminants, and the simulation studies show that species interactions must be considered when designing in situ bioremediation systems. In particular, the results for TCE indicate that protozoan grazing could reduce the amount of biodegradation by about 20%. These studies also indicate that the behavior of barrier systems can become complex due to predator grazing.

Travis, B.J. [Los Alamos National Lab., NM (United States); Rosenberg, N.D. [Lawrence Livermore National Lab., CA (United States)

1998-12-31

344

Submarine groundwater discharge (SGD) has received increased attention as a potential source for the oceanic bud-  

E-print Network

16 Submarine groundwater discharge (SGD) has received increased attention as a potential source; Burnett et al. 2001, 2002). The term "submarine groundwater discharge" has been used in the literature for the time-series measurement of submarine groundwater discharge Edward Sholkovitz, Craig Herbold

345

Assessment of natural attenuation of ground-water contamination at sites FT03, LF13, and WP14/LF15, Dover Air Force Base, Delaware  

USGS Publications Warehouse

Water-quality, aquifer-sediment, and hydro-logic data were used to assess the effectiveness of natural attenuation of ground-water contamination at Fire Training Area Three, the Rubble Area Landfill, the Liquid Waste Disposal Landfill, and the Receiver Station Landfill in the East Management Unit of Dover Air Force Base, Delaware. These sites, which are contaminated with chlorinated solvents and fuel hydrocarbons, are under-going long-term monitoring to determine if natural attenuation continues to sufficiently reduce contaminant concentrations to meet regulatory requirements. This report is the first assessment of the effectiveness of natural attenuation at these sites since long-term monitoring began in 1999, and follows a preliminary investigation done in 1995?96. This assessment was done by the U.S. Geological Survey in cooperation with the U.S. Air Force.Since 1995?96, additional information has been collected and used in the current assessment. The conclusions in this report are based primarily on ground-water samples collected from January through March 2000. Previous analytical results from selected wells, available geologic and geo-physical well logs, and newly acquired information such as sediment organic-carbon measurements, hydraulic-conductivity measurements determined from slug tests on wells in the natural attenuation study area, and water-level measurements from surficial-aquifer wells also were used in this assessment. This information was used to: (1) calculate retardation factors and estimate contaminant migration velocities, (2) improve estimates of ground-water flow directions and inferred contaminant migration pathways, (3) better define the areal extent of contamination and the proximity of contaminants to discharge areas and the Base boundary, (4) develop a better under-standing of the vertical variability of contaminant concentrations and redox conditions, (5) evaluate the effects of temporal changes on concentrations in the plumes and source areas, and (6) determine whether intrinsic biodegradation is occurring at these sites.The water-quality data indicate that intrinsic biodegradation is occurring at all three sites. The strongest indication of intrinsic biodegradation is the detection of tetrachloroethene and trichloroethene breakdown products within and down-gradient of the source areas. The patterns of electron acceptors and metabolic by-products indicate that contaminant biodegradation has changed the prevailing geochemistry of the surficial aquifer, creating the strongly reducing conditions necessary for chlorinated solvent bio-degradation. Geochemical changes include depleted dissolved oxygen and elevated ferrous iron and methane levels relative to concentrations in uncontaminated zones of the surficial aquifer. At Fire Training Area Three and the Rubble Area Landfill sites, natural attenuation appears to be adequate for controlling the migration of the contaminant plumes. At the third site, the Liquid Waste Disposal and Receiver Station Landfills, the plume is larger and the uncertainty about the effectiveness of natural attenuation in reducing contaminant concentrations and controlling plume migration is greater. Ground-water data indicate, however, that U.S. Environmental Protection Agency maximum contaminant levels were not exceeded in any point-of-compliance wells located along the Base boundary.The information presented in this report led to the development of improved conceptual models for these sites, and to the recognition of four issues that are currently unclear and may need further study. These issues include delineating the areal and vertical extent of the contaminant plumes in greater detail, determining the extent of intrinsic biodegradation downgradient of the Liquid Waste Disposal and Receiver Station Landfills, deter-mining the fate of contaminants in the ground-water discharge areas, and determining the effect of temporal variability in source concentrations and ground-water

Barbaro, Jeffrey R.

2002-01-01

346

Sources of sulfate supporting anaerobic metabolism in a contaminated aquifer  

USGS Publications Warehouse

Field and laboratory techniques were used to identify the biogeochemical factors affecting sulfate reduction in a shallow, unconsolidated alluvial aquifer contaminated with landfill leachate. Depth profiles of 35S-sulfate reduction rates in aquifer sediments were positively correlated with the concentration of dissolved sulfate. Manipulation of the sulfate concentration in samples revealed a Michaelis-Menten-like relationship with an apparent Km and Vmax of approximately 80 and 0.83 ??M SO4-2??day-1, respectively. The concentration of sulfate in the core of the leachate plume was well below 20 ??M and coincided with very low reduction rates. Thus, the concentration and availability of this anion could limit in situ sulfate-reducing activity. Three sulfate sources were identified, including iron sulfide oxidation, barite dissolution, and advective flux of sulfate. The relative importance of these sources varied with depth in the alluvium. The relatively high concentration of dissolved sulfate at the water table is attributed to the microbial oxidation of iron sulfides in response to fluctuations of the water table. At intermediate depths, barite dissolves in undersaturated pore water containing relatively high concentrations of dissolved barium (???100 ??M) and low concentrations of sulfate. Dissolution is consistent with the surface texture of detrital barite grains in contact with leachate. Laboratory incubations of unamended and barite-amended aquifer slurries supported the field observation of increasing concentrations of barium in solution when sulfate reached low levels. At a deeper highly permeable interval just above the confining bottom layer of the aquifer, sulfate reduction rates were markedly higher than rates at intermediate depths. Sulfate is supplied to this deeper zone by advection of uncontaminated groundwater beneath the landfill. The measured rates of sulfate reduction in the aquifer also correlated with the abundance of accumulated iron sulfide in this zone. This suggests that the current and past distributions of sulfate-reducing activity are similar and that the supply of sulfate has been sustained at these sites.

Ulrich, G.A.; Breit, G.N.; Cozzarelli, I.M.; Suflita, J.M.

2003-01-01

347

Long-term natural attenuation of carbon and nitrogen within a groundwater plume after removal of the treated wastewater source  

USGS Publications Warehouse

Disposal of treated wastewater for more than 60 years onto infiltration beds on Cape Cod, Massachusetts produced a groundwater contaminant plume greater than 6 km long in a surficial sand and gravel aquifer. In December 1995 the wastewater disposal ceased. A long-term, continuous study was conducted to characterize the post-cessation attenuation of the plume from the source to 0.6 km downgradient. Concentrations and total pools of mobile constituents, such as boron and nitrate, steadily decreased within 1-4 years along the transect. Dissolved organic carbon loads also decreased, but to a lesser extent, particularly downgradient of the infiltration beds. After 4 years, concentrations and pools of carbon and nitrogen in groundwater were relatively constant with time and distance, but substantially elevated above background. The contaminant plume core remained anoxic for the entire 10-year study period; temporal patterns of integrated oxygen deficit decreased slowly at all sites. In 2004, substantial amounts of total dissolved carbon (7 mol C m-2) and fixed (dissolved plus sorbed) inorganic nitrogen (0.5 mol N m-2) were still present in a 28-m vertical interval at the disposal site. Sorbed constituents have contributed substantially to the dissolved carbon and nitrogen pools and are responsible for the long-term persistence of the contaminant plume. Natural aquifer restoration at the discharge location will take at least several decades, even though groundwater flow rates and the potential for contaminant flushing are relatively high.

Repert, D.A.; Barber, L.B.; Hess, K.M.; Keefe, S.H.; Kent, D.B.; LeBlanc, D.R.; Smith, R.L.

2006-01-01

348

Size-Selective Predation on Groundwater Bacteria by Nanoflagellates in an Organic-Contaminated Aquifer  

PubMed Central

Time series incubations were conducted to provide estimates for the size selectivities and rates of protistan grazing that may be occurring in a sandy, contaminated aquifer. The experiments involved four size classes of fluorescently labeled groundwater bacteria (FLB) and 2- to 3-?m-long nanoflagellates, primarily Spumella guttula (Ehrenberg) Kent, that were isolated from contaminated aquifer sediments (Cape Cod, Mass.). The greatest uptake and clearance rates (0.77 bacteria · flagellate?1 · h?1 and 1.4 nl · flagellate?1 · h?1, respectively) were observed for 0.8- to 1.5-?m-long FLB (0.21-?m3 average cell volume), which represent the fastest growing bacteria within the pore fluids of the contaminated aquifer sediments. The 19:1 to 67:1 volume ratios of nanoflagellate predators to preferred bacterial prey were in the lower end of the range commonly reported for other aquatic habitats. The grazing data suggest that the aquifer nanoflagellates can consume as much as 12 to 74% of the unattached bacterial community in 1 day and are likely to have a substantive effect upon bacterial degradation of organic groundwater contaminants. PMID:9464400

Kinner, N. E.; Harvey, R. W.; Blakeslee, K.; Novarino, G.; Meeker, L. D.

1998-01-01

349

Size-selective predation on groundwater bacteria by nanoflagellates in an organic-contaminated aquifer  

USGS Publications Warehouse

Time series incubations were conducted to provide estimates for the size selectivities and rates of protistan grazing that may be occurring in a sandy, contaminated aquifer. The experiments involved four size classes of fluorescently labeled groundwater bacteria (FLB) and 2- to 3-??m-long nanoflagellates, primarily Spumella guttula (Ehrenberg) Kent, that were isolated from contaminated aquifer sediments (Cape Cod, Mass.). The greatest uptake and clearance rates (0.77 bacteria flagellate-1 ?? h-1 and 1.4 nl. flagellate-1 ?? h-1, respectively) were observed for 0.8- to 1.5-??m- long FLB (0.21-??m3 average cell volume), which represent the fastest growing bacteria within the pore fluids of the contaminated aquifer sediments. The 19:1 to 67:1 volume ratios of nanoflagellate predators to preferred bacterial prey were in the lower end of the range commonly reported for other aquatic habitats. The grazing data suggest that the aquifer nanoflagellates can consume as much as 12 to 74% of the unattached bacterial community in 1 day and are likely to have a substantive effect upon bacterial degradation of organic groundwater contaminants.

Kinner, N.E.; Harvey, R.W.; Blakeslee, K.; Novarino, G.; Meeker, L.D.

1998-01-01

350

Simulated impacts of artificial groundwater recharge and discharge of the source area and source volume of an Atlantic Coastal Plain Stream, Delaware, USA  

USGS Publications Warehouse

A numerical groundwater-flow model was used to characterize the source area and volume of Phillips Branch, a baseflow-dominated stream incising a highly permeable unconfined aquifer on the low relief Delmarva Peninsula, USA. Particle-tracking analyses indicate that the source area (5.51 km2) is ~20% smaller than the topographically defined watershed (6.85 km2), and recharge entering ~37% of the surface watershed does not discharge to Phillips Branch. Groundwater residence time within the source volume ranges from a few days to almost 100 years, with 95% of the volume "flushing" within 50 years. Artificial discharge from groundwater pumping alters the shape of the source area and reduces baseflow due to the interception of stream flow paths, but has limited impacts on the residence time of groundwater discharged as baseflow. In contrast, artificial recharge from land-based wastewater disposal substantially reduces the source area, lowers the range in residence time due to the elimination of older flow paths to the stream, and leads to increased discharge to adjacent surface-water bodies. This research suggests that, in this and similar hydrogeologic settings, the "watershed" approach to water-resource management may be limited, particularly where anthropogenic stresses alter the transport of soluble contaminants through highly permeable unconfined aquifers.

Kasper, Joshua W.; Denver, Judish M.; McKenna, Thomas E.; Ullman, William J.

2010-01-01

351

An application of supported liquid membranes for removal of inorganic contaminants from groundwater  

SciTech Connect

This review paper summarizes the results of an investigation on teh use of supported liquid membranes for the removal of uranium (VI) and some anionic contaminants (technetium(VII), chromium(VI) and nitrates) from the Hanford site groundwater. As a membrane carrier for U(VI), bis(2,4,4-trimethylpentyl)phosphinic acid was selected because of its high selectivity over calcium and magnesium. The water soluble complexing agent 1-hydroxyethane-1,1-diphosphonic acid was used as stripping agent. For the anionic contaminants the long-chain aliphatic amines Primene JM-T (primary)., Amberlite LA-1 (secondary) and trilaurylamine (tertiary) were investigated as membrane carriers. Among these amines, Amberlite LA-2 proved to be the most effective carrier for the simultaneous removal of the investigated anion contaminants. A good long-term stability (at least one month) of the liquid membranes was obtained, especially in the uranium(VI) removal. 8 refs., 4 figs., 4 tabs.

Chiarizia, R. [Argonne National Lab., IL (United States); [Westinghouse Hanford Co., Richland, WA (United States); Horwitz, E.P. [Argonne National Lab., IL (United States); Hodgson, K.M. [Westinghouse Hanford Co., Richland, WA (United States)

1991-12-31

352

An application of supported liquid membranes for removal of inorganic contaminants from groundwater  

SciTech Connect

This review paper summarizes the results of an investigation on teh use of supported liquid membranes for the removal of uranium (VI) and some anionic contaminants (technetium(VII), chromium(VI) and nitrates) from the Hanford site groundwater. As a membrane carrier for U(VI), bis(2,4,4-trimethylpentyl)phosphinic acid was selected because of its high selectivity over calcium and magnesium. The water soluble complexing agent 1-hydroxyethane-1,1-diphosphonic acid was used as stripping agent. For the anionic contaminants the long-chain aliphatic amines Primene JM-T (primary)., Amberlite LA-1 (secondary) and trilaurylamine (tertiary) were investigated as membrane carriers. Among these amines, Amberlite LA-2 proved to be the most effective carrier for the simultaneous removal of the investigated anion contaminants. A good long-term stability (at least one month) of the liquid membranes was obtained, especially in the uranium(VI) removal. 8 refs., 4 figs., 4 tabs.

Chiarizia, R. (Argonne National Lab., IL (United States) Westinghouse Hanford Co., Richland, WA (United States)); Horwitz, E.P. (Argonne National Lab., IL (United States)); Hodgson, K.M. (Westinghouse Hanford Co., Richland, WA (United States))

1991-01-01

353

Fluoride ion contamination in the groundwater of Mithi sub-district, the Thar Desert, Pakistan  

NASA Astrophysics Data System (ADS)

Groundwater samples were collected from various localities of Mithi sub-district of the Thar Desert of Pakistan and analysed for fluoride ion along with other chemical parameters. The area is mainly covered by sand dunes and kaolin/granite at variable depths. Results showed that collected water samples were severely contaminated by the presence of fluoride ion and most of the samples have higher concentration than prescribed WHO standards (1.5 mg/l) for drinking water. Fluoride ion concentrations ranged between 0.09 and 11.63 mg/l with mean and median values of 3.64 and 3.44 mg/l, respectively, in this area whereas, distribution pattern showed high concentrations in the vicinity of Islamkot and Mithi towns. The content of F- has also been correlated with other major ions found in the groundwater of the study area. The positive correlation of F- with Na+ and HCO3 - showed that the water with high Na+ and HCO3 - stabilizes F- ions in the groundwater of the Thar Desert. The pH versus F- plots signifies high fluoride concentration at higher pH values, implying that alkaline environment favours the replacement of exchangeable OH- with F- in the groundwater of Mithi area. The saturation indices (SI) of fluorite (CaF2) and calcite (CaCO3) in the groundwater samples showed that most of the samples are oversaturated with respect to calcite whereas majority of samples have been found under saturated with respect to fluorite. The log TDS and Na/Na+Ca ratio reflected supremacy of weathering of rocks, which promotes the availability of fluoride ions in the groundwater. Piper diagram has been used to classify the hydrofacies. In the cation triangle, all samples are Na-type, while the anion triangle reflects major dominance of Cl-type with a minor influence of HCO3 - and SO4 -.

Rafique, Tahir; Naseem, Shahid; Bhanger, Muhammad I.; Usmani, Tanzil H.

2008-11-01

354

Remediation of contaminated land and groundwater: experience in England and Wales.  

PubMed

Remediation of contaminated land and groundwater is of common international concern. The context and approach taken to the problem are, however, country-specific. A survey of remedial activity occurring within England and Wales over the period 1996-1999 was commissioned by the Environment Agency (for England and Wales) to establish a baseline against which future trends in remedial activity could be judged. This paper: explains the context of contaminated land and groundwater remediation in England and Wales (Britain); provides an overview of the 1996-1999 survey of remedial activity, discussing its findings within its legislative and institutional context; and, discusses the survey results of significance to the management of contaminated land and groundwater internationally. The survey obtained specific data from 367 remediated sites supplemented by general data from a further 1189 contaminated (not necessarily remediated) sites. The survey aimed to be, and was indicative of remediation practice, and did not seek to identify every remediation scheme operating. Previous anecdotal evidences were generally confirmed. Civil engineering-based techniques dominated and were used at 94% of sites with in situ techniques (predominantly vapour extraction-based) on 16% and ex situ on just 5%. Although disposal to landfill was dominant and occurred at over 80% of sites, integrated use of multiple techniques was common. Remediation was predominantly of soil (rather than water), development-based, designed to protect human health and reflected national development-led and 'suitable for use' policies. Lessons of international relevance from the survey and general British experience are drawn concerning remediation technique selection, regulatory and financial support of innovative remediation techniques and demonstration sites, competent use of risk-based approaches to allow pragmatic remediation and effective use of quality guidelines, need for effective guidance to highlight water quality issues, the necessity of post remediation monitoring to prove remediation effectiveness and the keeping of remediation databases. PMID:12357658

Rivett, M O; Petts, J; Butler, B; Martin, I

2002-07-01

355

Fate of sulfamethoxazole, 4-nonylphenol, and 17??-estradiol in groundwater contaminated by wastewater treatment plant effluent  

USGS Publications Warehouse

Organic wastewater contaminants (OWCs) were measured in samples collected from monitoring wells located along a 4.5-km transect of a plume of groundwater contaminated by 60 years of continuous rapid infiltration disposal of wastewater treatment plant effluent. Fifteen percent of the 212 OWCs analyzed were detected, including the antibiotic sulfamethoxazole (SX), the nonionic surfactant degradation product 4-nonylphenol (NP), the solvent tetrachloroethene (PCE), and the disinfectant 1,4-dichlorobenzene (DCB). Comparison of the 2005 sampling results to data collected from the same wells in 1985 indicates that PCE and DCB are transported more rapidly in the aquifer than NP, consistent with predictions based on compound hydrophobicity. Natural gradient in situ tracer experiments were conducted to evaluate the subsurface behavior of SX, NP, and the female sex hormone 17??-estradiol (E2) in two oxic zones in the aquifer: (1) a downgradient transition zone at the interface between the contamination plume and the overlying uncontaminated groundwater and (2) a contaminated zone located beneath the infiltration beds, which have not been loaded for 10 years. In both zones, breakthrough curves for the conservative tracer bromide (Br -) and SX were nearly coincident, whereas NP and E2 were retarded relative to Br- and showed mass loss. Retardation was greater in the contaminated zone than in the transition zone. Attenuation of NP and E2 in the aquifer was attributed to biotransformation, and oxic laboratory microcosm experiments using sediments from the transition and contaminated zones show that uniform-ring-labeled 14C 4-normal-NP was biodegraded more rapidly (30-60% recovered as 14CO2 in 13 days) than 4- 14C E2 (20-90% recovered as 14CO2 in 54 days). There was little difference in mineralization potential between sites. ?? 2009 American Chemical Society.

Barber, L.B.; Keefe, S.H.; LeBlanc, D.R.; Bradley, P.M.; Chapelle, F.H.; Meyer, M.T.; Loftin, K.A.; Kolpin, D.W.; Rubio, F.

2009-01-01

356

BACTERIA USED TO PRECIPITATE MERCURY IN CONTAMINATED GROUNDWATER OF PAVLODAR, KAZAKHSTAN  

EPA Science Inventory

Abstract for poster presentation: A number of regions in Kazakhstan are contaminated with soluble mercury originating from industrial sources. A chlor-alkali plant that operated from 1970-1990 caused contamination of ground water near a northern suburb of Pavlodar city. The plume...

357

Field-based detection and monitoring of uranium in contaminated groundwater using two immunosensors  

SciTech Connect

Field-based monitoring of environmental contaminants has long been a need for environmental scientists. Described herein are two kinetic exclusion-based immunosensors, a field portable sensor (FPS) and an inline senor, that were deployed at the Integrated Field Research Challenge Site of the U.S. Department of Energy in Rifle, CO. Both sensors utilized a monoclonal antibody that binds to a U(VI)-dicarboxyphenanthroline complex (DCP) in a kinetic exclusion immunoassay format. These sensors were able to monitor changes of uranium in groundwater samples from {approx} 1 {micro}M to below the regulated drinking water limit of 126 nM (30 ppb). The FPS is a battery-operated sensor platform that can determine the uranium level in a single sample in 5-10 min, if the instrument has been previously calibrated with standards. The average minimum detection level (MDL) in this assay was 0.33 nM (79 ppt), and the MDL in the sample (based on a 1:200?1:400 dilution) was 66?132 nM (15.7?31.4 ppb). The inline sensor, while requiring a grounded power source, has the ability to autonomously analyze multiple samples in a single experiment. The average MDL in this assay was 0.12 nM (29 ppt), and the MDL in the samples (based on 1:200 or 1:400 dilutions) was 24?48 nM (5.7?11.4 ppb). Both sensor platforms showed an acceptable level of agreement (r{sup 2} = 0.94 and 0.76, for the inline and FPS, respectively) with conventional methods for uranium quantification.

Melton, S.J.; Yu, H.; Williams, K.H.; Morris, S.A.; Long, P.E.; Blake, D.A.

2009-05-01

358

Inspection and monitoring plan, contaminated groundwater seeps 317/319/ENE Area, Argonne National Laboratory  

SciTech Connect

During the course of completing the Resource Conservation and Recovery Act (RCRA) Facility Investigation (RFI) in the 317/319/East-Northeast (ENE) Area of Argonne National Laboratory-East (ANL-E), groundwater was discovered moving to the surface through a series of groundwater seeps. The seeps are located in a ravine approximately 600 ft south of the ANL-E fence line in Waterfall Glen Forest Preserve. Samples of the seep water were collected and analyzed for selected parameters. Two of the five seeps sampled were found to contain detectable levels of organic contaminants. Three chemical species were identified: chloroform (14--25 {micro}g/L), carbon tetrachloride (56--340 {micro}g/L), and tetrachloroethylene (3--6 {micro}g/L). The other seeps did not contain detectable levels of volatile organics. The nature of the contaminants in the seeps will also be monitored on a regular basis. Samples of surface water flowing through the bottom of the ravine and groundwater emanating from the seeps will be collected and analyzed for chemical and radioactive constituents. The results of the routine sampling will be compared with the concentrations used in the risk assessment. If the concentrations exceed those used in the risk assessment, the risk calculations will be revised by using the higher numbers. This revised analysis will determine if additional actions are warranted.

NONE

1996-10-11

359

Development and applications of two finite element groundwater flow and contaminant transport models: FEWA and FEMA  

SciTech Connect

This paper presents the construction, verification, and application of two groundwater flow and contaminant transport models: A Finite Element Model of Water Flow through Aquifers (FEWA) and A Finite Element Model of Material Transport through Aquifers (FEMA). The construction is based on the finite element approximation of partial differential equations of groundwater flow (FEWA) and of solute movement (FEMA). The particular features of FEWA and FEMA are their versatility and flexibility for dealing with nearly all vertically integrated two-dimensional problems. The models were verified against both analytical solutions and widely used US Geological Survey finite difference approximations. They were then applied for calibration and validation, using data obtained in experiments at the Engineering Test Facility at Oak Ridge National Laboratory. Results indicated that the models are valid for this specific site. To demonstrate the versatility anf flexibility of the models, they were applied to two hypothetical, but realistic, complex problems and three field sites across the United States. In these applications the models yielded good agreement with the field data for all three sites. Finally, the predictive capabilities of the models were demonstrated using data obtained at the Hialeah Preston site in Florida. This case illustrates the capability of FEWA and FEMA as predictive tools and their usefulness in the management of groundwater flow and contaminant transport. 25 refs.

Yeh, G.T.; Wong, K.V.; Craig, P.M.; Davis, E.C.

1985-01-01

360

Water Science:What on Earth is groundwater?Where does it come from? How can it get contaminated?  

E-print Network

Water Science:What on Earth is groundwater?Where does it come from? How can it get contaminated: For the aquifer - clear plastic bottle (2 litre) with flat sides, some white gravel, a bucket or dishpan, water, and a little masking tape For the well ­ a wide drinking straw, and a spray bottle pump For the contaminant

Pedersen, Tom

361

Arsenic contamination of groundwater and prevalence of arsenical dermatosis in the Hetao plain area, Inner Mongolia, China  

Microsoft Academic Search

An investigation was carried out on arsenic contamination of groundwater and prevalence of arsenical dermatosis in the Hetao plain of Inner Mongolia Autonomous Region, China. Based on the screening of water samples from 96 randomly selected wells in this Region, two areas (Wuyuan and Alashan) were chosen as highly contaminated areas because arsenic in the water samples was higher than

Xiaojuan Guo; Yoshihisa Fujino; Satoshi Kaneko; Kegong Wu; Yajuan Xia; Takesumi Yoshimura

2001-01-01

362

Subchronic exposure to a mixture of groundwater-contaminating metals through drinking water induces oxidative stress in male rats  

Microsoft Academic Search

The current study examines the oxidative stress-inducing potential of a mixture of metals, representative of groundwater contamination in different areas of India. Male albino rats were exposed to the mixture through drinking water for 90 days at 0, 1, 10 and 100 times the mode concentrations of the metals in contaminated waters and at concentrations equal to their WHO maximum

Sachin Hanmantrao Jadhav; Souvendra Nath Sarkar; Meena Kataria; Harish Chandra Tripathi

2007-01-01

363

Potential effect of natural gas wells on alluvial groundwater contamination at the Kansas City Plant  

SciTech Connect

This report is the result of a request for further information about several abandoned natural gas wells at the US Department of Energy`s Kansas City Plant (KCP). The request was prompted by an old map showing several, possibly eight, natural gas wells located under or near what is now the southeast corner of the Main Manufacturing Building at KCP. Volatile organic compound contamination in the alluvial aquifer surrounding the gas wells might possibly contaminate the bedrock aquifer if the gas wells still exist as conduits. Several circumstances exist that make it doubtful that contamination is entering the bedrock aquifers: (1) because regional groundwater flow in the bedrock beneath the KCP is expected to be vertically upward, contaminants found in the alluvial aquifer should not migrate down the old wells; (2) because of the low hydraulic conductivity of the bedrock units, contaminant transport would be extremely slow if the contaminants were migrating down the wells; and (3) casing, apparently set through the alluvium in all of the wells, would have deteriorated and may have collapsed; if the casing collapsed, the silty clays in the alluvium would also collapse and seal the well. No definitive information has been discovered about the exact location of the wells. No further search for or consideration of the old gas wells is recommended.

Pickering, D.A.; Laase, A.D. [Oak Ridge National Lab., TN (United States); Locke, D.A. [Oak Ridge Inst. for Science and Education, TN (United States)

1993-05-01

364

Potential effect of natural gas wells on alluvial groundwater contamination at the Kansas City Plant  

SciTech Connect

This report is the result of a request for further information about several abandoned natural gas wells at the US Department of Energy's Kansas City Plant (KCP). The request was prompted by an old map showing several, possibly eight, natural gas wells located under or near what is now the southeast corner of the Main Manufacturing Building at KCP. Volatile organic compound contamination in the alluvial aquifer surrounding the gas wells might possibly contaminate the bedrock aquifer if the gas wells still exist as conduits. Several circumstances exist that make it doubtful that contamination is entering the bedrock aquifers: (1) because regional groundwater flow in the bedrock beneath the KCP is expected to be vertically upward, contaminants found in the alluvial aquifer should not migrate down the old wells; (2) because of the low hydraulic conductivity of the bedrock units, contaminant transport would be extremely slow if the contaminants were migrating down the wells; and (3) casing, apparently set through the alluvium in all of the wells, would have deteriorated and may have collapsed; if the casing collapsed, the silty clays in the alluvium would also collapse and seal the well. No definitive information has been discovered about the exact location of the wells. No further search for or consideration of the old gas wells is recommended.

Pickering, D.A.; Laase, A.D. (Oak Ridge National Lab., TN (United States)); Locke, D.A. (Oak Ridge Inst. for Science and Education, TN (United States))

1993-05-01

365

Using chemical, microbial and fluorescence techniques to understand contaminant sources and pathways to wetlands in a conservation site.  

PubMed

Nutrients and faecal contaminants can enter wetland systems in a number of ways, with both biological and potentially human-health implications. In this study we used a combination of inorganic chemistry, dissolved organic matter (DOM) fluorescence and Escherichia coli and total coliform (TC) count techniques to study the sources and multiple pathways of contamination affecting a designated sand dune site of international conservation importance, surrounded by agricultural land. Analysis of stream samples, groundwater and dune slack wetlands revealed multiple input pathways. These included riverbank seepage, runoff events and percolation of nutrients from adjacent pasture into the groundwater, as well as some on-site sources. The combined techniques showed that off-site nutrient inputs into the sand dune system were primarily from fertilisers, revealed by high nitrate concentrations, and relatively low tryptophan-like fulvic-like ratios <0.4Ramanunits (R.U.). The E. coli and TC counts recorded across the site confirm a relatively minor source of bacterial and nutrient inputs from on-site grazers. Attenuation of the nutrient concentrations in streams, in groundwater and in run-off inputs occurs within the site, restoring healthier groundwater nutrient concentrations showing that contaminant filtration by the sand dunes provides a valuable ecosystem service. However, previous studies show that this input of nutrients has a clear adverse ecological impact. PMID:25616189

Rhymes, J; Jones, L; Lapworth, D J; White, D; Fenner, N; McDonald, J E; Perkins, T L

2015-04-01

366

Ground-water resources and contamination at Roi-Namur Island, Kwajalein Atoll, Republic of the Marshall Islands, 1990-91  

USGS Publications Warehouse

A study was conducted on Roi-Namur Island, Kwajalein Atoll to define the extent of the freshwater lenses and recharge zones and to asses potential contaminant migration from known sources of contamination. Rainfall, which is the sole natural source of freshwater, is strongly seasonal and occasional multi-year droughts are capable of disrupting the island's water supply. The supply of freshwater is produced by a joint system of rain catchments and shallow wells. From 1980-91, rain- catchment yield and ground-water withdrawal average 22,632 and 5,829 gallons per day, respectively. Maps were produced showing the areal extent of freshwater, the thickness of the freshwater lenses, the water-table configuration and directions of ground-water flow, and contamination sites and potential migration pathways of contaminants. Sectional views of freshwater lens thicknesses and seasonal freshwater lens thickness changes were also constructed. The freshwater lens attains a maximum thickness of 23 feet beneath the central area of Roi where recharge is high. The estimated amount of water in the lenses with chloride concentrations less than 250 milligrams per liter underlying Roi and Namur is 226 million and 4.2 million gallons, respectively. The presence of thick vegetation on Namur increases evapotranspiration losses significantly producing a smaller freshwater lens. Freshwater thicknesses shrank and expanded in a seasonal cycle as much as 3 feet near withdrawal wells. The water table forms broad mounds beneath Roi and Namur and freshwater heads reach a maximum of 1.4 feet. Most known sites of contamination lie near the periphery of the island where ground-water flow patterns will carry contaminants away from the withdrawal wells toward the shore.

Gingerich, Stephen B.

1996-01-01

367

Mineralogical approach in elucidation of contamination mechanism for toxic trace elements in the environment: Special reference to arsenic contamination in groundwater  

NASA Astrophysics Data System (ADS)

Mineralogy and mineral-microbe interactions play a significant role in the environmental contamination of toxic trace elements in groundwater and wetland ecosystems. This review has described the importance of use of TEM that is an essential tool to study the environmental mineralogy and mineral-microbe interactions. Biomineralization process that can advance the succession and evolution of biosphere on the earth has also been summarized briefly. This study explained the role of minerals to control the mechanism of adsorption, desorption, mobility and transport of toxic trace elements, especially arsenic (As) in the groundwater. Finally, this review has explored the evolution of As contamination in groundwater of the Quaternary age deposits including the Holocene and Pleistocene with special reference to groundwater of Bangladesh, West Bengal (India), Vietnam and Inner Mongolia (China).

Akai, Junji; Anawar, Hossain Md

368

Application of Biostimulation for Remediation of Sulfate-Contaminated Groundwater at a Mining Site  

NASA Astrophysics Data System (ADS)

There is growing concern regarding sulfate contamination of groundwater. One innovative in-situ remediation option under investigation is biostimulation through addition of electron-donor amendments to enhance sulfate reduction. Two pilot-scale ethanol-injection tests were conducted at a former uranium mining site that is contaminated with sulfate and nitrate (with a lack of heavy metals), and for which there appears to be minimal natural attenuation of sulfate. The first test was a push-pull test that had a limited zone of influence, while the second test was a single-well injection test in which additional downgradient wells were monitored. For both tests, sulfate concentrations began to decline within a few weeks of injection, after nitrate concentrations were significantly reduced. Concomitantly, aqueous concentrations of manganese, iron, and hydrogen sulfide increased from background. Monitoring over many months revealed that the declines in sulfate concentration conformed to exponential decay, with first-order decay rates of approximately 0.01 /d. Analysis of sulfur stable isotope data indicated that the decrease in sulfate concentrations was microbially mediated. The results also indicated that sulfides formed during sulfate reduction may have undergone partial re-oxidation. This study illustrates the feasibility of using ethanol injection for remediation of sulfate-contaminated groundwater. However, re-oxidation of sulfides (both metal sulfide precipitates and hydrogen sulfide gas) is a potential issue of significance that would need to be addressed.

Miao, Z.; Carroll, K. C.; Carreon, C.; Brusseau, M. L.

2011-12-01

369

Evaluation of the atmosphere as a source of volatile organic compounds in shallow groundwater  

USGS Publications Warehouse

The atmosphere as a source of volatile organic compounds (VOCs) in shallow groundwater was evaluated over an area in southern New Jersey. Chloroform, methyl tertbutyl ether (MTBE), 1,1,1-trichloroethane, tetrachloroethylene (PCE), and carbon disulfide (not a VOC) were detected frequently at low-level concentrations in a network of 78 shallow wells in the surficial Kirkwood-Cohansey aquifer system. The atmosphere was sampled for these compounds and only MTBE concentrations were high enough to potentially explain frequent detection in shallow groundwater. A mathematical model of reactive transport through the unsaturated zone is presented to explain how variations in unsaturated properties across the study area could explain differences in MTBE concentrations in shallow groundwater given the atmosphere as the source. Even when concentrations of VOCs in groundwater are low compared to regulatory concentration limits, it is critical to know the source. If the VOCs originate from a point source(s), concentrations in groundwater could potentially increase over time to levels of concern as groundwater plumes evolve, whereas if the atmosphere is the source, then groundwater concentrations would be expected to remain at low-level concentrations not exceeding those in equilibrium with atmospheric concentrations. This is the first analysis of VOC occurrence in shallow groundwater involving colocated atmosphere data.The atmosphere as a source of volatile organic compounds (VOCs) in shallow groundwater was evaluated over an area in southern New Jersey. Chloroform, methyl tert-butyl ether (MTBE), 1,1,1-trichloroethane, tetrachloroethylene (PCE), and carbon disulfide (not a VOC) were detected frequently at low-level concentrations in a network of 78 shallow wells in the surficial Kirkwood-Cohansey aquifer system. The atmosphere was sampled for these compounds and only MTBE concentrations were high enough to potentially explain frequent detection in shallow groundwater. A mathematical model of reactive transport through the unsaturated zone is presented to explain how variations in unsaturated properties across the study area could explain differences in MTBE concentrations in shallow groundwater given the atmosphere as the source. Even when concentrations of VOCs in groundwater are low compared to regulatory concentration limits, it is critical to know the source. If the VOCs originate from a point source(s), concentrations in groundwater could potentially increase over time to levels of concern as groundwater plumes evolve, whereas if the atmosphere is the source, then groundwater concentrations would be expected to remain at low-level concentrations not exceeding those in equilibrium with atmospheric concentrations. This is the first analysis of VOC occurrence in shallow groundwater involving collocated atmosphere data.

Baehr, A.L.; Stackelberg, P.E.

1999-01-01

370

Mass spectrometric screening and identification of acidic metabolites in fulvic acid fractions of contaminated groundwater.  

PubMed

The anaerobic microbial degradation of aromatic and heterocyclic compounds is a prevalent process in contaminated groundwater systems. The introduction of functional groups into the contaminant molecules often results in aromatic and heterocyclic and succinic acids. These metabolites can be used as indicators for prevailing degradation processes. Therefore, there is a strong interest in developing analytical methods for screening and identification of these metabolites. In this study, neutral loss scans (NLS) by liquid chromatography-electrospray ionization/tandem mass spectrometry with losses of CO2 (NL ?m/z?=?44) and C2H4(CO2)2 (NL ?m/z?=?116) were applied for the first time successfully to screen selectively for acidic and succinic metabolites of aromatic and heterocyclic contaminants in two fulvic acid fractions from a contaminated site and a downstream region of a tar oil-polluted groundwater. Identification of these preselected signals was performed by high-resolution mass spectrometry with a liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry instrument. High-resolution mass and mass fragmentation data were then compared with a list of known metabolites from a literature search or matched with chemical databases supported with in silico fragmentation. Based on authentic analytical standards, several compounds from NLS were identified (e.g., 4-hydroxy-3-methylbenzoic acid, benzylsuccinic acid, naphthyl-2-methylsuccinic acid, 2-carboxyindane, and 2-carboxybenzothiophene) and tentatively identified (e.g., benzofuranmethylsuccinic acid and dihydrocarboxybenzothiophene) as aromatic, phenolic, heterocyclic, and succinic acids. The acidic metabolites were found exclusively in the contaminated region of the aquifer which indicates active biodegradation processes and no relevant occurrence of acidic metabolites in the downstream region. PMID:24714970

Jobelius, Carsten; Frimmel, Fritz H; Zwiener, Christian

2014-05-01

371

An integrated fuzzy-stochastic modeling approach for risk assessment of groundwater contamination.  

PubMed

An integrated fuzzy-stochastic risk assessment (IFSRA) approach was developed in this study to systematically quantify both probabilistic and fuzzy uncertainties associated with site conditions, environmental guidelines, and health impact criteria. The contaminant concentrations in groundwater predicted from a numerical model were associated with probabilistic uncertainties due to the randomness in modeling input parameters, while the consequences of contaminant concentrations violating relevant environmental quality guidelines and health evaluation criteria were linked with fuzzy uncertainties. The contaminant of interest in this study was xylene. The environmental quality guideline was divided into three different strictness categories: "loose", "medium" and "strict". The environmental-guideline-based risk (ER) and health risk (HR) due to xylene ingestion were systematically examined to obtain the general risk levels through a fuzzy rule base. The ER and HR risk levels were divided into five categories of "low", "low-to-medium", "medium", "medium-to-high" and "high", respectively. The general risk levels included six categories ranging from "low" to "very high". The fuzzy membership functions of the related fuzzy events and the fuzzy rule base were established based on a questionnaire survey. Thus the IFSRA integrated fuzzy logic, expert involvement, and stochastic simulation within a general framework. The robustness of the modeling processes was enhanced through the effective reflection of the two types of uncertainties as compared with the conventional risk assessment approaches. The developed IFSRA was applied to a petroleum-contaminated groundwater system in western Canada. Three scenarios with different environmental quality guidelines were analyzed, and reasonable results were obtained. The risk assessment approach developed in this study offers a unique tool for systematically quantifying various uncertainties in contaminated site management, and it also provides more realistic support for remediation-related decisions. PMID:16574309

Li, Jianbing; Huang, Gordon H; Zeng, Guangming; Maqsood, Imran; Huang, Yuefei

2007-01-01

372

Fresh Submarine Groundwater Discharge from a Contaminated Beach Aquifer is Enhanced During Neap Tide  

NASA Astrophysics Data System (ADS)

Experiments were carried out to assess the fortnightly effects of mixed semi-diurnal tides and tidally-induced aquifer overheight on the timing, magnitude, and quality of submarine groundwater discharge (SGD) from an unconfined beach aquifer impacted by septic tank effluent at Stinson Beach, California. Groundwater- and ocean elevations, salinity, and nutrient concentrations were monitored throughout a 14-day neap/spring cycle. A freshening of the surf zone coupled with an increase in nutrient concentrations was observed at neap tide and attributed to discharge of fresh, nutrient-rich groundwater during that part of the fortnight. Nutrient concentrations in the surf zone returned to near-offshore levels during the spring tide. Estimates of SGD were made with chemically- and physically-based methods. Fresh SGD was maximal during the neap tide although total SGD was maximal during the spring tide. An overheight of time-averaged piezometric head was observed in the aquifer near the beach face throughout the 14-day experiment. This overheight varied significantly with tidal range, thereby controlling the seaward hydraulic gradient across the fresh part of the aquifer and, thus, the flow of nutrient-rich fresh groundwater to the coastal ocean. We discuss the role of aquifer overheight in controlling submarine discharge of fresh groundwater and related non-point source pollution from unconfined aquifers in similar environments.

de Sieyes, N. R.; Yamahara, K. M.; Boehm, A. B.

2007-05-01

373

Update on the aquifer/wetlands restoration project at Utica, Nebraska, with recommendations for remapping of the carbon tetrachloride contamination in groundwater.  

SciTech Connect

In 1992-1993, Argonne National Laboratory investigated potential carbon tetrachloride contamination that might be linked to the former grain storage facility operated by the Commodity Credit Corporation (CCC) of the U.S. Department of Agriculture (USDA) at Utica, Nebraska. These initial studies identified carbon tetrachloride in a plume of contaminated groundwater, extending approximately 3,500 ft southeastward from the former CCC/USDA facility, within a shallow upper aquifer that had been used previously as a municipal water source by the town (Figure 1.1). A deeper aquifer used as the current municipal water source was found to be free of carbon tetrachloride contamination. Although the shallow aquifer was no longer being used as a source of drinking water at Utica, additional studies indicated that the carbon tetrachloride could pose an unacceptable health threat to potential future residents who might install private wells along the expected downgradient migration pathway of the plume. On the basis of these findings, corrective action was recommended to decrease the carbon tetrachloride concentrations in the upper aquifer to acceptable levels (Argonne 1993a,b, 1995). Initial discussions with the Utica village board indicated that any restoration strategies involving nonbeneficial discharge of treated groundwater in the immediate vicinity of Utica would be unacceptable to the town. To address this concern, the CCC/USDA and Argonne, in cooperation with multiple federal and state regulatory and environmental agencies (Table 1.1) proposed a treatment strategy for the Utica groundwater employing groundwater extraction coupled with the seasonal use of agricultural spray irrigation equipment to simultaneously (1) remove carbon tetrachloride from the groundwater (by volatilization to the atmosphere) and (2) discharge the treated groundwater to enhance the development of wetlands in the North Lake Basin Wildlife Management Area, just north of the town (Argonne 2000). To develop this treatment approach, additional groundwater sampling was conducted to update the distribution of carbon tetrachloride in groundwater identified in the preliminary studies in 1992-1993. In March 1998, detailed mapping of the carbon tetrachloride plume was performed by using the Argonne cone penetrometer (CPT) vehicle to collect groundwater samples for analyses for volatile organic compounds (VOCs) at 13 locations (PS01-PS09, PS12, PS16, PS17, PS19; Figure 1.2). The samples were collected in vertical profiles through the aquifer, at 10-ft intervals. The results of this 1998 study (Table 1.2) demonstrated that the three-dimensional distribution of carbon tetrachloride in the aquifer is complex, with multiple 'hot spots' occurring in the plume at various depths and distances along its length (Argonne 2000). In October 2002, the CCC/USDA requested that Argonne perform targeted groundwater sampling at Utica to document the migration of the carbon tetrachloride plume since the 1998 sampling event. In February 2003, vertical-profile groundwater sampling for VOCs analyses was conducted at 8 selected locations (PS01, PS04-PS07, PS12, PS19, PS20; Figure 1.2 and Table 1.3). The lateral and vertical configuration of the carbon tetrachloride plume, as identified in the 2003 study (Argonne 2003), is illustrated in Figures 1.3-1.7. On the basis of the 2003 groundwater sampling results, a remedial system employing four extraction wells (GWEX 1-GWEX 4), with groundwater treatment by spray irrigation and conventional air stripping, was implemented at Utica, with the concurrence of the CCC/USDA and the agencies identified in Table 1.1. The principal components of the Utica system (shown in Figure 1.8) are described briefly in Section 1.2. Operation of well GWEX4 and the associated air stripper began on October 29, 2004, and routine operation of wells GWEX1-GWEX3 and the spray irrigation treatment units began on November 22, 2004.

LaFreniere, L. M.; Environmental Science Division

2010-04-20

374

Alternative Endpoints and Approaches for the Remediation of Contaminated Groundwater at Complex Sites - 13426  

SciTech Connect

The goal of United States (U.S.) Department of Energy's (DOE)'s environmental remediation programs is to restore groundwater to beneficial use, similar to many other Federal and state environmental cleanup programs. Based on past experience, groundwater remediation to pre-contamination conditions (i.e., drinking water standards or non-detectable concentrations) can be successfully achieved at many sites. At a subset of the most complex sites, however, complete restoration is not likely achievable within the next 50 to 100 years using today's technology. This presentation describes several approaches used at complex sites in the face of these technical challenges. Many complex sites adopted a long-term management approach, whereby contamination was contained within a specified area using active or passive remediation techniques. Consistent with the requirements of their respective environmental cleanup programs, several complex sites selected land use restrictions and used risk management approaches to accordingly adopt alternative cleanup goals (alternative endpoints). Several sites used long-term management designations and approaches in conjunction with the alternative endpoints. Examples include various state designations for groundwater management zones, technical impracticability (TI) waivers or greater risk waivers at Superfund sites, and the use of Monitored Natural Attenuation (MNA) or other passive long-term management approaches over long time frames. 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 approaches for groundwater remediation at complex sites under a variety of Federal and state cleanup programs. 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 that illustrate the variety of approaches used at complex sites and the technical analyses used to predict and document cost, time frame, and potential remedial effectiveness. This presentation is intended to inform DOE program managers, state regulators, practitioners and other stakeholders who are evaluating technical cleanup challenges within their own programs, and establishing programmatic approaches to evaluating and implementing long-term management approaches. Case studies provide examples of long-term management designations and strategies to manage and remediate groundwater at complex sites. 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. Long-term management designations are not a way to 'do nothing' or walk away from a site. Instead, soil and groundwater within the zone is managed to be protective of human health and the environment. Understanding when and how to adopt a long-term management approach can lead to cost savings and the more efficient use of resources across DOE and at numerous other industrial and military sites across the U.S. This presentation provides context for assessing the use and appropriate role of alternative endpoints and supporting long-term management designations in final remedies. (authors)

Deeb, Rula A.; Hawley, Elisabeth L. [ARCADIS, U.S., 2000 Powell St., 7th Floor, Emeryville, California 94608 (United States)] [ARCADIS, U.S., 2000 Powell St., 7th Floor, Emeryville, California 94608 (United States)

2013-07-01

375

Integrated characterization of groundwater contamination in an alluvial system. Case study of Allier alluvial aquifer (Massif Central, France).  

NASA Astrophysics Data System (ADS)

Hydrogeology is an intrinsically multi-disciplinary field because of the critical role water plays in both human health and natural ecosystems. The NAA (Nappe Alluviale de l'Allier) project proposes an integrated research (hydrodynamic, hydrochemistry and biology) on the shallow aquifer of the Allier River (one of the main tributaries of the Loire River). This aquifer plays an important role in the regional water supply for it represents more than 60% of the total water abstraction. As an example, the sampling site, located near the city of Clermont-Ferrand (France) constitutes the major source of drinking water supply for more than 100 000 inhabitants and then plays a major role on the local socio-economy. A biweekly following sampling, that concerns hydrodynamical parameters, major ions and isotopes (oxygen-18, deuterium and carbon-13), has been achieved during two years on 2 rivers, 1 pond, 2 springs and 17 boreholes with the aim of defining the functioning of the aquifer in terms of quality and quantity of the water resources and then on the main processes that governs hydrodynamic and hydrochemistry. Preliminary results allowed discriminating different origins of groundwater with a part due to surface waters/groundwater interactions and a secondary origin that implies water circulating from the surrounding hills. A monthly following sampling of pesticides, pharmaceuticals and traces ions provides information on contaminants sources. In parallel, the dynamics of the microbial communities (bacteria, pico-cyanobacteria and pico-eukaryotes) was followed by flow cytometer. The bacterial diversity has been measured through PCR-DGGE analysis in order to evaluate the impact of the occurrence of contaminants.

Mohammed, Nabaz; Celle-Jeanton, Hélène; Batisson, Isabelle; Bardot, Corinne; Colombet, Jonathan; Huneau, Frédéric; Le Coustumer, Philippe; Clauzet, Marie-Laure; Lavastre, Véronique

2013-04-01

376

Application of artificial neural networks to assess pesticide contamination in shallow groundwater  

USGS Publications Warehouse

In this study, a feed-forward back-propagation neural network (BPNN) was developed and applied to predict pesticide concentrations in groundwater monitoring wells. Pesticide concentration data are challenging to analyze because they tend to be highly censored. Input data to the neural network included the categorical indices of depth to aquifer material, pesticide leaching class, aquifer sensitivity to pesticide contamination, time (month) of sample collection, well depth, depth to water from land surface, and additional travel distance in the saturated zone (i.e., distance from land surface to midpoint of well screen). The output of the neural network was the total pesticide concentration detected in the well. The model prediction results produced good agreements with observed data in terms of correlation coefficient (R = 0.87) and pesticide detection efficiency (E = 89%), as well as good match between the observed and predicted "class" groups. The relative importance of input parameters to pesticide occurrence in groundwater was examined in terms of R, E, mean error (ME), root mean square error (RMSE), and pesticide occurrence "class" groups by eliminating some key input parameters to the model. Well depth and time of sample collection were the most sensitive input parameters for predicting the pesticide contamination potential of a well. This infers that wells tapping shallow aquifers are more vulnerable to pesticide contamination than those wells tapping deeper aquifers. Pesticide occurrences during post-application months (June through October) were found to be 2.5 to 3 times higher than pesticide occurrences during other months (November through April). The BPNN was used to rank the input parameters with highest potential to contaminate groundwater, including two original and five ancillary parameters. The two original parameters are depth to aquifer material and pesticide leaching class. When these two parameters were the only input parameters for the BPNN, they were not able to predict contamination potential. However, when they were used with other parameters, the predictive performance efficiency of the BPNN in terms of R, E, ME, RMSE, and pesticide occurrence "class" groups increased. Ancillary data include data collected during the study such as well depth and time of sample collection. The BPNN indicated that the ancillary data had more predictive power than the original data. The BPNN results will help researchers identify parameters to improve maps of aquifer sensitivity to pesticide contamination. ?? 2006 Elsevier B.V. All rights reserved.

Sahoo, G.B.; Ray, C.; Mehnert, E.; Keefer, D.A.

2006-01-01