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1

Groundwater Contamination  

NSDL National Science Digital Library

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

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

2

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

3

Groundwater Contamination.  

National Technical Information Service (NTIS)

The reliable assessment of hazards or risks arising from groundwater contamination problems and the design of efficient and effective techniques to mitigate them require the ability to predict the behavior of contaminants in flowing groundwater. Increased...

1984-01-01

4

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

National Technical Information Service (NTIS)

Isotopes of several elements were measured in groundwater to provide a more complete characterization of contaminants. The additional species are expected to help identify contaminant sources and to aid interpretation of contaminant transport mechanisms b...

P. E. Dresel J. C. Evans O. T. Farmer

2002-01-01

5

Groundwater Contamination  

NSDL National Science Digital Library

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

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

2009-04-01

6

Sources of Nitrate Contamination in Groundwater Under Developing Asian Megacities  

Microsoft Academic Search

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

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

2008-01-01

7

Regional-scale assessment of non-point source groundwater contamination  

Microsoft Academic Search

Predictive assessments of non-point source (NPS) pollution can have great utility for environmentally focused land use decisions related to both the remediation of existing groundwater contamination and the regulation of current (and future) agrochemical use. At the regional scales associated with NPS agrochemical applications there are staggering data management problems in assessing potential groundwater vulnerability. Geographical information system (GIS) technology

Keith Loague; Dennis L. Corwin

1998-01-01

8

Emerging organic contaminants in groundwater: A review of sources, fate and occurrence.  

PubMed

Emerging organic contaminants (EOCs) detected in groundwater may have adverse effects on human health and aquatic ecosystems. This paper reviews the existing occurrence data in groundwater for a range of EOCs including pharmaceutical, personal care, 'life-style' and selected industrial compounds. The main sources and pathways for organic EOCs in groundwater are reviewed, with occurrence data for EOCs in groundwater included from both targeted studies and broad reconnaissance surveys. Nanogram-microgram per litre concentrations are present in groundwater for a large range of EOCs as well as metabolites and transformation products and under certain conditions may pose a threat to freshwater bodies for decades due to relatively long groundwater residence times. In the coming decades, more of these EOCs are likely to have drinking water standards, environmental quality standards and/or groundwater threshold values defined, and therefore a better understanding of the spatial and temporal variation remains a priority. PMID:22306910

Lapworth, D J; Baran, N; Stuart, M E; Ward, R S

2012-02-02

9

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

10

Assessment of groundwater chemistry in a coastal region (Kunsan, Korea) having complex contaminant sources: a stoichiometric approach  

Microsoft Academic Search

Groundwater chemistry in a coastal region (Kunsan, Korea) having complex contaminant sources was investigated. Water analysis data for 197 groundwater samples collected from the uniformly distributed sixty-six wells were used. Chemical analysis results indicate that groundwaters show wide concentration ranges in major inorganic ions, reflecting complex hydrochemical processes. Due to the complexity of groundwater chemistry, the samples were classified into

Kangjoo Kim; Natarajan Rajmohan; Hyun Jung Kim; Gab-Soo Hwang; Min Joe Cho

2004-01-01

11

Monitoring groundwater contamination and delineating source zones at industrial sites: Uncertainty analyses using integral pumping tests  

Microsoft Academic Search

Field-scale characterisations of contaminant plumes in groundwater, as well as source zone delineations, are associated with uncertainties that can be considerable. A major source of uncertainty in environmental datasets is due to variability of sampling results, as a direct consequence of the heterogeneity of environmental matrices. We develop a methodology for quantifying uncertainties in field-scale mass flow and average concentration

Jerker Jarsjö; Martí Bayer-Raich; Thomas Ptak

2005-01-01

12

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

PubMed

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

Farooqi, Abida; Masuda, Harue; Firdous, Nousheen

2006-06-13

13

Sources of Arsenic and Fluoride in Highly Contaminated Soils Causing Groundwater Contamination in Punjab, Pakistan  

Microsoft Academic Search

Highly contaminated groundwater, with arsenic (As) and fluoride (F?) concentrations of up to 2.4 and 22.8 mg\\/L, respectively, has been traced to anthropogenic inputs to the soil. In the present\\u000a study, samples collected from the soil surface and sediments from the most heavily polluted area of Punjab were analyzed to\\u000a determine the F? and As distribution in the soil. The surface

Abida Farooqi; Harue Masuda; Rehan Siddiqui; Muhammad Naseem

2009-01-01

14

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

NASA Astrophysics Data System (ADS)

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

Falta, R. W.

2004-05-01

15

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

PubMed

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

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

2012-09-14

16

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

17

Contamination of groundwaters  

Microsoft Academic Search

International experts have contributed key chapters to this major work in groundwater contamination. Section 1: Methodology and Modeling deals with both organic and inorganic contaminants, including those from agricultural operations. Section 2: Case Studies presents contamination scenarios with both inorganic and organic chemicals, including nitrates and PCBs. This book is a welcome addition to the literature and will enhance recent

D. C. Adriano; A. K. Iskandar; I. P. Murarka

1994-01-01

18

Bioremediation of contaminated groundwater  

DOEpatents

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  

SciTech Connect

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. 9 refs., 3 figs., 4 tabs.

Tase, Norio [Univ. of Tsukuba, Ibaraki (Japan)

1992-07-01

20

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

21

Reduction of nonpoint source contamination of surface water and groundwater by starch encapsulation of herbicides  

USGS Publications Warehouse

The loss of the preemergent herbicide atrazine in surface runoff from experimental field plots growing corn (Zea mays L.) was significantly reduced using a starchencapsulated formulation versus a conventional powdered formulation. Field edge losses of starch-encapsulated atrazine were described as following a Rayleigh distribution totaling 1.8% of applied herbicide compared to exponential powdered atrazine losses of 2.9% applied - a 40% decrease. This has important implications for the reduction of nonpoint source contamination of surface water by agricultural chemicals. Unsaturated zone release of starchencapsulated atrazine was gradual, but comparable weed control was maintained. Deethylatrazine was a major dealkylated metabolite from each formulation, and deisopropylatrazine was a minor metabolite. The determination of soil partition coefficients for deethylatrazine and deisopropylatrazine (0.4 and 0.3, respectively), aqueous solubilities (3200 and 670 mg/L, respectively), and melting points (133 and 177 ??C, respectively) confirmed that the dealkylated metabolites should move more rapidly through the soil profile to groundwater than atrazine.

Mills, M. S.; Thurman, E. M.

1994-01-01

22

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

NASA Astrophysics Data System (ADS)

Knowledge of the groundwater pollution source is of primary importance to define appropriate remediation strategies. Yet, the identification of the contamination sources remains a complicated task. A dual isotope approach has been used to provide information for tracing sources of nitrate in water. In this study, we used the naturally occurring stable isotopic composition of groundwater nitrate (1) to evaluate the origin of nitrate in the Brussels sands aquifer (Belgium) and (2) to study the temporal dynamics of the isotope signature of groundwater nitrate in this region. Potential N sources sampled in the region, including e.g. ammonium and nitrate mineral fertilizers, sewage and rain, had isotopic signatures that fell within the corresponding typical ranges found in literature. Some of them however deviated from the isotopic ranges corresponding to typical N sources, illustrating the impact of processes affecting the isotopic signature of the nitrate sources. During a pluri-annual sampling campaign, groundwater samples were collected at 10 moments between June 2007 and February of 2009 over 9 monitoring stations located in the western part of the study area. The isotopic data time series suggest that, most of the time, N applied on the soil has been cycled in the soil by micro-organisms before leaching to the groundwater, while the isotopic data and the high nitrate concentrations strongly suggests that nitrate of the groundwater sampled in January 2008 principally originates from mineral fertilizers. The isotopic data measured at some of the 114 monitoring stations across the study area strongly suggests that the sources of nitrate are mineral fertilizers used in agriculture and golf courses, manure leaching from unprotected stockpiles in farms, domestic gardening practices, cesspools and probably cemeteries. Isotopic data are particularly helpful when associated with other information like historical data about monitoring stations, land use, chemical parameters of water or statistical and deterministic models and must therefore be considered as one of the many elements of pollution sources identification.

Mattern, Samuel; Vanclooster, Marnik

2010-05-01

23

Bioremediation of contaminated groundwater  

DOEpatents

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

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

1994-01-01

24

[Construction of groundwater contamination prevention mapping system].  

PubMed

Groundwater contamination prevention mapping is an important component of groundwater contamination geological survey and assessment work, which could provide the basis for making and implementing groundwater contamination prevention planning. A groundwater contamination prevention mapping system was constructed in view of the synthetic consideration on nature perspective derived from groundwater contamination sources and aquifer itself, social-economic perspective, policy perspective derived from outside. During the system construction process, analytic hierarchy process and relevant overlaying principles were used to couple groundwater contamination risk assessment, groundwater value as well as wellhead protection area zoning. Data processing and visualization of mapping results were achieved in the GIS environment. The research on groundwater contamination prevention mapping in Beijing Plain indicated that the final groundwater prevention map was in accordance with the actual conditions and well reflected the priorities of groundwater prevention, which could play a guidance role in designing and implementing further practical prevention and supervision measures. Besides, because of the dynamical properties of the system components, it was suggested to analyze the update frequency of the mapping. PMID:23243867

Wang, Jun-Jie; He, Jiang-Tao; Lu, Yan; Liu, Li-Ya; Zhang, Xiao-Liang

2012-09-01

25

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

26

Groundwater Contamination from Refinery Operations. Final Report.  

National Technical Information Service (NTIS)

The focus of this project has been on examining all available sources for information on groundwater contamination from refining operations. Once the information was gathered, it was carefully researched with the following goals in mind. (1) To define the...

H. H. Comstock K. Q. Stirling

1986-01-01

27

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

NASA Astrophysics Data System (ADS)

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

Bullen, T.; Widory, D.

2009-05-01

28

Modeling the Impact of Cracking in Low Permeability Layers in a Groundwater Contamination Source Zone on Dissolved Contaminant Fate and Transport  

NASA Astrophysics Data System (ADS)

Dense Non-Aqueous Phase Liquids (DNAPLs), which are chemicals and chemical mixtures that are heavier than and only slightly soluble in water, are a significant source of groundwater contamination. Even with the removal or destruction of most DNAPL mass, small amounts of remaining DNAPL can dissolve into flowing groundwater and continue as a contamination source for decades. One category of DNAPLs is the chlorinated aliphatic hydrocarbons (CAHs). CAHs, such as trichloroethylene and carbon tetrachloride, are found to contaminate groundwater at numerous DoD and industrial sites. DNAPLs move through soils and groundwater leaving behind residual separate phase contamination as well as pools sitting atop low permeability layers. Recently developed models are based on the assumption that dissolved CAHs diffuse slowly from pooled DNAPL into the low permeability layers. Subsequently, when the DNAPL pools and residual DNAPL are depleted, perhaps as a result of a remediation effort, the dissolved CAHs in these low permeability layers still remain to serve as long-term sources of contamination, due to so-called "back diffusion." These recently developed models assume that transport in the low permeability zones is strictly diffusive; however field observations suggest that more DNAPL and/or dissolved CAH is stored in the low permeability zones than can be explained on the basis of diffusion alone. One explanation for these field observations is that there is enhanced transport of dissolved CAHs and/or DNAPL into the low permeability layers due to cracking. Cracks may allow for advective flow of water contaminated with dissolved CAHs into the layer as well as possible movement of pure phase DNAPL into the layer. In this study, a multiphase numerical flow and transport model is employed in a dual domain (high and low permeability layers) to investigate the impact of cracking on DNAPL and CAH movement. Using literature values, the crack geometry and spacing was varied to model and compare four scenarios: (1) CAH diffusion only into cracks, (2) CAH advection-dispersion into cracks, (3) separate phase DNAPL movement into the cracks, and (4) CAH diffusion into an uncracked low permeability clay layer. For each scenario, model simulations are used to show the evolution and persistence of groundwater contamination downgradient of the DNAPL source.

Sievers, K. W.; Goltz, M. N.; Huang, J.; Demond, A. H.

2011-12-01

29

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

30

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

Microsoft Academic Search

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 ?15N and ?18O) suggested that human waste via severe sewer leakage was the major source of

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

2008-01-01

31

Arsenic contamination in groundwater from parts of Ambagarh-Chowki block, Chhattisgarh, India: source and release mechanism  

NASA Astrophysics Data System (ADS)

Arsenic contamination in tube-well water in Ambagarh-Chowki block, central India, is restricted to local areas confined within the N-S trending Dongargarh rift zone. Affected areas are preferentially located in acid volcanics, close to shear zones and also in granites. Dug-wells even in severely contaminated areas generally have As concentration ?10 ?g/l. But in Kaurikasa area, several tube-wells and dug-wells are severely polluted. Weathered rocks and soils are also enriched in As from severely contaminated areas. As preferentially occurs in iron-enriched soil and similarly altered biotite, chlorite in granite. As sorbed in hydrated iron oxide (HFO) that preferably occurs in acid-leachable fraction and possibly as coatings on kaolinite, illite and goethite in soil or as coatings and along cleavage traces on weathered biotite and chlorite. Reductive dissolution of HFO released sorbed As to groundwater and enriched it in Fe. Pyrite in volcanic and shear zone rocks, although locally As-bearing is a minor source of As in groundwater.

Acharyya, S. K.; Shah, B. A.; Ashyiya, I. D.; Pandey, Y.

2005-11-01

32

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

33

Long-term Groundwater Contamination after Source Removal: Role of Sorbed Carbon and Nitrogen at Cape Cod, MA  

NASA Astrophysics Data System (ADS)

The consequences of groundwater contamination can remain long after a contaminant source has been removed. This can be the case even for constituents that are primarily water-soluble, such as treated wastewater. Yet, documentation of natural aquifer recoveries and empirical tools to predict recovery time frames and down-gradient impacts are generally lacking. We have been characterizing the long-term natural attenuation of a groundwater plume in a sand and gravel aquifer after the removal of the treated wastewater source on Cape Cod, Massachusetts. Although dissolved organic carbon (OC) and other soluble constituents have decreased substantially in concentration, after >14 years post source removal, the core of the plume remains anoxic, with extensive redox gradients and persistence of nitrate, ammonium, and phosphorus. Core material was collected from the former disposal site at several points in time and along a 0.4 km transect downgradient from the disposal site and correlated with changes in plume composition. Oxygen consumption capacity for the core material ranged from 12-54 nmol gr-1 day-1 and was positively correlated with both total and water-extractable OC. Total extractable OC ranged up to 2.9 µmol C (gr dry wt)-1. Extraction C/N ratios increased with time from 9 to >90, suggesting that OC degradation and oxygen consumption will become N-limited with time as the sorbed C and N pools separate by differential desorption. There was no quantifiable decrease in sorbed OC along the transect or with time, suggesting that the total sorbed carbon pool is large and will be impacting groundwater geochemistry for many decades. However, there is evidence of increased oxygen concentrations along the plume margins, which can provide upper limit estimates for in situ oxygen consumption kinetics and the relative rate of oxygen entrainment into the anoxic plume core.

Smith, R. L.; Repert, D.; Barber, L. B.; Fairchild, G.; Leblanc, D. R.

2010-12-01

34

Evaluating Potential Groundwater Contamination from Contaminated Soils.  

National Technical Information Service (NTIS)

Contamination of soils at toxic and hazardous waste sites can adversely affect groundwater and surface water. Water soluble materials can move in soil by leaching and percolation and by runoff. The project evaluated the toxicity of leachable toxicants fro...

J. R. Pratt P. V. McCormick K. W. Pontasch J. Cairns

1987-01-01

35

Source and fate of nitrate contamination in the groundwater along its flow in Kumamoto area, Japan using ?15NNO3 and ?18ONO3  

NASA Astrophysics Data System (ADS)

Kumamoto is a famous city for groundwater in Japan and its drinking water is fully dependent on groundwater. Groundwater nitrate-nitrogen contamination has increasingly been observed in the aquifer system of Kumamoto area. Actually, NO3-N concentrations in some groundwaters have been exceeding 10 mg/L. However, the cause of nitrate pollution has not yet been fully clarified and this issue needs to be addressed for sustainable utilization of groundwater in this region. The purpose of our study is to clarify the source and fate of nitrate contamination in Kumamoto groundwater by using ?15NNO3 and ?18ONO3. The main land-use is consisting of farm land in upland areas, rice paddies in the lowlands, and residential areas in the lowland area of the Kumamoto plain.Water samples for chemical and isotopic characterization were collected in October 2010 and January to March 2011 from 30 production wells. NO3-N concentrations in the groundwater were highest in highland areas where groundwater recharges in the agricultural zone. Dual nitrate isotope ratios clearly support the idea that nitrate contamination was due to the input of agricultural fertilizers applied in this recharge area. On the other hand, in the coastal area, where unoxic environment develops, significant denitrification effect was confirmed from the sample plot signature on concentration-?15NNO3 diagram. Our results should be important information to be used in the program of groundwater resource management of the Kumamoto City.

Tokunaga, T.; Shimada, J.; Hosono, T.; Nakata, H.; Kagabu, M.; Ono, M.; Orishikida, T.; Kumamoto Univ

2011-12-01

36

Groundwater pollution by organic compounds: a two-dimensional analysis of contaminant transport in stratified porous media with multiple sources of non-equilibrium partitioning  

Microsoft Academic Search

Transport of pollutants in soil and groundwater often occurs in stratified media under non-equilibrium conditions. Confined aquifers are usually bounded by low-permeability layers of soil which have been shown to exert a significant influence on the fate of contaminants in groundwater. Numerical solutions of transport equations have usually been restricted to single layers and have included single sources of non-equilibrium

Abbas H. Elzein; John R. Booker

1999-01-01

37

Contamination and restoration of groundwater aquifers.  

PubMed Central

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

Piver, W T

1993-01-01

38

Groundwater contamination: identification of source signal by time-reverse mass transport computation and filtering  

NASA Astrophysics Data System (ADS)

Source signal identification is a forensic task, within regulatory and legal activities. Estimation of the contaminant's release history by reverse-solution (stepping back in time) of the mass transport equation, partialC/partialt + u partialC/partialx = D partial^2C/ partialx^2, is an ill-posed problem (its solution is non-unique and unstable). For this reason we propose the recovery of the source signal from measured concentration profile data through a numerical technique that is based on the premise of advection-dominated transport. We derive an explicit numerical scheme by discretising the pure advection equation, partialC/ partialt + u partial C/partialx = 0, such that it also models gradient-transport by matching numerical diffusion (leading truncation error term) to physical dispersion. The match is achieved by appropriate choice of the scheme’s spatial weighting coefficient q as function of the grid Peclet number P = u ?x/D: ? = 0.5 - P-1. This is a novel and efficient direct solution approach for the signal identification problem at hand that can accommodate space-variable transport parameters as well. First, we perform numerical experiments to define proper grids (in terms of Courant {bf C} = u?t/?x and grid Peclet P numbers) for control of spurious oscillations (instability). We then assess recovery of source signals, from perfect as well as from error-seeded field data, considering field data resulting from single- and double-peaked source signals. With perfect data, the scheme recovers source signals with very good accuracy. With imperfect data, however, additional data conditioning is required for control of signal noise. Alternating reverse profile computation with Savitzky-Golay low-pass filtering allows the recovery of well-timed and smooth source signals that satisfy mass conservation very well. Current research focuses on: a) optimising the performance of Savitzky-Golay filters, through selection of appropriate parameters (order of least squares polynomial and number of filter points) for proper peak attenuation, b) working in the frequency domain, and c) combining reverse transport computation with complete signal optimisation [constrained to conserve mass with non-negative concentrations and minimising the sum of two criteria, for smoothness and for shape fidelity (objective function)].

Koussis, A. S.; Mazi, K.; Lykoudis, S.; Argyriou, A.

2003-04-01

39

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

40

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.

Bohlke, J. -K.

2002-01-01

41

Groundwater recharge and agricultural contamination  

NASA Astrophysics Data System (ADS)

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. Agricultural activities have directly or indirectly affected the concentrations of a large number of inorganic chemicals in groundwater, for example NO3 -, N2, Cl, SO4 2-, H+, P, C, K, Mg, Ca, Sr, Ba, Ra, and As, as well as 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, John-Karl

2002-02-01

42

Glycol Ethers As Groundwater Contaminants  

NASA Astrophysics Data System (ADS)

Ether derivatives of dihydroxy alcohols, which are formed from ethylene or propylene, comprise an important group of groundwater contaminants known as glycol ethers. Compounds in this group are used as solvents, cleaning agents, and emulsifiers in many chemical products and manufacturing operations. Glycol ethers have been associated with a variety of toxic effects, and some compounds in the group are relatively potent teratogens. The limited information available suggests that glycol ethers are contaminants in groundwater, especially in anaerobic plumes emanating from disposal of mixed industrial and household waste. Most methods used to analyze groundwater samples cannot adequately detect ?g/? (ppb) concentrations of glycol ethers, and the existing methods perform worst for the most widely used and toxic species. A new method capable of analyzing ?g/? concentrations of glycol ethers was recently developed, and its use is recommended for groundwater samples where glycol ethers are likely to be present.

Ross, Benjamin; Johannson, Gunnar; Foster, Gregory D.; Eckel, William P.

1992-01-01

43

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...

44

Groundwater: Contamination from Nitrogen Fertilizers  

Technology Transfer Automated Retrieval System (TEKTRAN)

High nitrate-nitrogen concentrations in water pose problems for human health and the environment. Groundwater is a major source for human water supplies and for contributing to surface water bodies. Leaching of N fertilizers is a major factor for high NO3-N concentrations in groundwater. Current ...

45

Glycol Ethers As Groundwater Contaminants  

Microsoft Academic Search

Ether derivatives of dihydroxy alcohols, which are formed from ethylene or propylene, comprise an important group of groundwater contaminants known as glycol ethers. Compounds in this group are used as solvents, cleaning agents, and emulsifiers in many chemical products and manufacturing operations. Glycol ethers have been associated with a variety of toxic effects, and some compounds in the group are

Benjamin Ross; Gunnar Johannson; Gregory D. Foster; William P. Eckel

1992-01-01

46

Arsenic Contamination of Groundwater at Zimapán, Mexiko  

NASA Astrophysics Data System (ADS)

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 has the highest concentrations. Two anthropogenic sources pollute the shallow wells. These result from the leaching of mine tailings and from the percolation of smelter fumes containing arsenic and which settled on the soil until the 1940's. The identification and evaluation of multiple sources of pollutants in aquifers are needed to establish reliable aquifer-remediation programs, especially in many arid regions, where groundwater in commonly the main or only source of drinking water.

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

1997-02-01

47

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

48

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

NASA Astrophysics Data System (ADS)

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

Adar, Eilon; Massoth, Sylvie

2013-04-01

49

Chemical barriers for controlling groundwater contamination  

Microsoft Academic Search

Chemical barriers are being explored as a low-cost means of controlling groundwater contamination. The barrier can intercept a contaminant plume and prevent migration by transferring contaminants from the groundwater to immobile solids. A chemical barrier can be emplaced in a landfill liner or in an aquifer cutoff wall or can be injected into a contaminant plume. Chemical barriers can be

S. J. Morrison; R. R. Spangler

1993-01-01

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

In situ biodegradation of TCE contaminated groundwater  

Microsoft Academic Search

Trichloroethylene (TCE) is one of the most widely used chlorinated solvents; it is also a common groundwater contaminant. TCE-contaminated groundwater is presently treated by transferring the solvent either to a solid (carbon adsorption) or to the atmosphere (air stripping). Biological treatment of the contaminated water is an alternative that causes complete destruction of the solvent. When performed within the aquifer

Michael J. Nelson; John V. Kinsella; Terry Montoya

1990-01-01

53

Screening for Groundwater Contaminants Discharging to Urban Streams  

NASA Astrophysics Data System (ADS)

Groundwater contaminated with urban pollutants can adversely affect freshwater aquatic ecosystems where it discharges to streams, lakes or wetlands. Generally such occurrences have been revealed following the discovery of contaminated groundwater plumes at a particular site or from wells in the area. Thus, this contaminant pathway tends to be dealt with on a site-specific and aquifer-focused basis. In contrast, surface water contaminant monitoring typically relies on bulk water concentrations from one or a small set of locations, thus ignoring the spatial variation in contaminant loading, potential losses to sediment or the atmosphere, and the full range of benthic components of the aquatic ecosystem. There are few studies outlining the extent of this contamination from the perspective of the surface water body's deeper benthic community, which might be expected to experience the greatest contaminant concentrations, on more than a local-scale. In this study, we report on an approach to stream-reach-screening for urban contaminants in discharging groundwater, with the focus on detection rather than accurate quantification. The methodology consists of a drive-point technique for sampling groundwater from below the stream bed (e.g. typically 50 cm) along a chosen reach at intervals of about 10 m. Groundwater samples were then analyzed for a wide range of common urban contaminants and general chemistry. This screening method was performed in three urban settings in Canada with known groundwater contamination, covering sections of about 140 to >500 m. The known contaminant plumes at each site were detected and roughly delineated. In addition, potential areas of previously-unknown groundwater contamination were also identified at each site. Contaminants included BTEX and other petroleum hydrocarbons, various chlorinated solvent compounds, nitrate, 1,4-dioxane, MTBE and elevated chloride (likely indicating road salt). These preliminary findings suggest that this approach may be useful for quickly assessing the cumulative threat to aquatic ecosystems of potentially multiple groundwater contaminant sources discharging to surface water bodies in urban settings.

Roy, J. W.; Bickerton, G.; Voralek, J.

2009-05-01

54

Monitoring network design to provide initial detection of groundwater contamination  

Microsoft Academic Search

The design of a monitoring network to provide initial detection of groundwater contamination at a waste disposal facility is complicated by uncertainty in both the characterization of the subsurface and the nature of the contaminant source. In addition, monitoring network design requires the resolution of multiple conflicting objections. A method is presented that incorporates system uncertainty in monitoring network design

Philip D. Meyer; Albert J. Valocchi; J. Wayland Eheart

1994-01-01

55

Identification of groundwater contamination sources of nitrate and sulfate in shallow alluvial aquifers using a dual-isotope approach in an agricultural area  

NASA Astrophysics Data System (ADS)

The elevated level of nitrate in groundwater is a serious problem in Korean agricultural areas. Yupori, a small agricultural area in Chuncheon (Korea), shows a rising level of NO3-N and displays multiple NO3-N sources from non-point and point sources in shallow aquifer groundwater. Numerous vegetable fields are located in the western part of the study area and fruit orchards dominate the landscape with only few vegetable fields in the eastern part of the study area. The source identification of groundwater contamination from overburden agricultural area was undertaken by analyzing hydrochemical data and stable isotopic compositions of dissolved nitrate and sulfate (¥ä15N-NO3-, ¥ä18O-NO3-, ¥ä34S-SO42-, and ¥ä18O-SO42-). The measurements of ¥ä15N- NO3- are in the range of 7.1 to 14.4¢¶ and the values of ¥ä18O-NO3- are in the range of -1.8 to 6.5¢¶. High ¥ä15N-NO3- values shown at low concentrations of nitrate in the eastern Yupori are characteristics of manure- derived nitrate and organic soil. The values of ¥ä34S-SO4-2 ranged from 2.9 to 9.9¢¶ and ¥ä18O-SO42- ranged from 2.5 to 4.7¢¶. At high concentrations of SO42- in the western Yupori, the value of ¥ä34S-SO42- are low around 3-4¢¶. The value of ¥ä34S-SO42- increased with decreasing SO42- concentration in the eastern Yupori. Groundwater quality and stable isotopic compositions of dissolved nitrate and sulfate seem to be significantly affected by agricultural land use pattern of the study site.

Kaown, D.; Koh, D.; Mayer, B.; Hyun, Y.; Bae, G.; Lee, K.

2007-12-01

56

Characterization of groundwater contamination using factor analysis  

NASA Astrophysics Data System (ADS)

The effluent contamination of groundwater at two industrial sites at Visakhapatnam, India, was studied using factor analysis. Thirty groundwater samples near a zinc smelter plant and 19 from the polymers plant were analyzed for specific conductance, chloride, bicarbonate, sulfate, calcium, magnesium, sodium, and potassium. The data were subjected to R-mode factor analysis and the factor scores transferred to areal maps. While magnesium and sulfate are the dominant contaminants at the zinc site, sodium, chloride, and bicarbonate from the effluent are affecting groundwater in the polymers area. Contour maps for each factor suggest the areal extension of the contaminants.

Subbarao, C.; Subbarao, N. V.; Chandu, S. N.

1996-12-01

57

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

58

Groundwater nitrate contamination: Factors and indicators  

PubMed Central

Identifying significant determinants of groundwater nitrate contamination is critical in order to define sensible agri-environmental indicators that support the design, enforcement, and monitoring of regulatory policies. We use data from approximately 1200 Austrian municipalities to provide a detailed statistical analysis of (1) the factors influencing groundwater nitrate contamination and (2) the predictive capacity of the Gross Nitrogen Balance, one of the most commonly used agri-environmental indicators. We find that the percentage of cropland in a given region correlates positively with nitrate concentration in groundwater. Additionally, environmental characteristics such as temperature and precipitation are important co-factors. Higher average temperatures result in lower nitrate contamination of groundwater, possibly due to increased evapotranspiration. Higher average precipitation dilutes nitrates in the soil, further reducing groundwater nitrate concentration. Finally, we assess whether the Gross Nitrogen Balance is a valid predictor of groundwater nitrate contamination. Our regression analysis reveals that the Gross Nitrogen Balance is a statistically significant predictor for nitrate contamination. We also show that its predictive power can be improved if we account for average regional precipitation. The Gross Nitrogen Balance predicts nitrate contamination in groundwater more precisely in regions with higher average precipitation.

Wick, Katharina; Heumesser, Christine; Schmid, Erwin

2012-01-01

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

Groundwater contamination assessment for sustainable water supply in Kathmandu Valley, Nepal  

Microsoft Academic Search

A study was carried out to assess the water quality situation of groundwater sources in Kathmandu Valley, Nepal. Groundwater has remained to be a major water supply source for a population of 1.5 million at present in the valley. The focus of this study was to evaluate the extent and sources of groundwater contamination. Water sampling was carried out in

N. R. Khatiwada; S. Takizawa; T. V. N. Tran; M. Inoue

2002-01-01

61

Groundwater Contamination from Refinery Operations: Final Report.  

National Technical Information Service (NTIS)

The objective of this research project has been to evaluate the problems of groundwater contamination which are attributable to refining operations and to produce a model that will describe the transport of the hydrocarbon phase through the unsaturated zo...

J. Wells D. Brinkman K. Q. Stirling

1988-01-01

62

Microbiological Cleanup of Pentachlorophenol-Contaminated Groundwater.  

National Technical Information Service (NTIS)

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

T. D. Frick R. L. Crawford

1986-01-01

63

Iron contamination in groundwater of Rostov region  

NASA Astrophysics Data System (ADS)

Peculiarities of iron distribution in groundwater of Rostov region didn't receive appropriate attention up to now. Due to mine closer there is a problem of iron contamination in Rostov region nowadays. Mine water is coming up and become a source of pollution for rivers. Moreover in oil and gas regions iron contamination can cause falling out in collectors. In the second half of the XX century an interesting data was collected due to oil and gas exploration of the region. Statistical exploration of this database give an opportunity to find out the iron genesis in different nature spheres. We explore iron distribution in groundwater in two regions, such as Rostov gas region and Northern Don oil and gas region. The depth of taking samples varies from 260 m to 547 m. Average depth is 399 m. Iron quantity varies from 0,27 to 86,6 mg/dm3 (Fe2+), and from 0 to 11,17 mg/dm3 (Fe3+), average quantity is 5,91 mg/dm3. The correlation between iron quantity and mineralization, other ions and depth wasn't found.

Nazarenko, Olesya

2010-05-01

64

Impact Of Groundwater Discharge On Contaminant Behavior In Sediments  

EPA Science Inventory

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

65

A Contamination Vulnerability Assessment for the Sacramento Area Groundwater Basin  

SciTech Connect

In response to concerns expressed by the California Legislature and the citizenry of the State of California, the State Water Resources Control Board (SWRCB), implemented a program to assess groundwater quality, and provide a predictive capability for identifying areas that are vulnerable to contamination. The program was initiated in response to concern over public supply well closures due to contamination by chemicals such as MtBE from gasoline, and solvents from industrial operations. As a result of this increased awareness regarding groundwater quality, the Supplemental Report of the 1999 Budget Act mandated the SWRCB to develop a comprehensive ambient groundwater-monitoring plan, and led to the initiation of the Ambient Groundwater Monitoring and Assessment (GAMA) Program. The primary objective of the GAMA Program is to assess the water quality and to predict the relative susceptibility to contamination of groundwater resources throughout the state of California. Under the GAMA program, scientists from Lawrence Livermore National Laboratory (LLNL) collaborate with the SWRCB, the U.S. Geological Survey, the California Department of Health Services (DHS), and the California Department of Water Resources (DWR) to implement the groundwater assessment program in cooperation with local water purveyors. In 2001 and 2002, LLNL carried out this vulnerability study in the groundwater basin of Sacramento suburban area, located to the north of the American River and to the east of the Sacramento River. The goal of the study is to provide a probabilistic assessment of the relative vulnerability of groundwater used for the public water supply to contamination from surface sources. This assessment of relative contamination vulnerability is made based on the results of two types of analyses that are not routinely carried out at public water supply wells: ultra low-level measurement of volatile organic compounds (VOCs), and groundwater age dating (using the tritium-helium-3 method). In addition, stable oxygen isotope measurements help determine the recharge water source. Interpreted together, and in the context of existing water quality and hydrogeologic data, these observable parameters help define the flow field of a groundwater basin, and indicate the degree of vertical communication between near-surface sources (or potential sources) of contamination, and deeper groundwater pumped at high capacity production wells.

Moran, J E; Hudson, G B; Eaton, G F; Leif, R

2004-03-10

66

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

Microsoft Academic Search

The arsenic (As) contamination of groundwater has increasingly been recognized as a major global issue of concern. As groundwater resources are one of most important freshwater sources for water supplies in Southeast Asian countries, it is important to investigate the spatial distribution of As contamination and evaluate the health risk of As for these countries. The detection of As contamination

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

2011-01-01

67

AGRICULTURAL CONTAMINANTS REMOVAL FROM GROUNDWATER BY CARBON AND REVERSE OSMOSIS  

EPA Science Inventory

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

68

A model of groundwater contaminant transport using the CVBEM  

NASA Astrophysics Data System (ADS)

The Complex Variable Boundary Element Method or CVBEM has been used to develop a simple but powerful numerical analog of contaminant transport in a saturated, confined groundwater aquifer. The presented numerical technique is based upon a mean-square fit of the boundary conditions which includes the effects of sources and sinks defined within the problem domain. The numerical analogue produces locations of streamlines and the time-evolution of the contaminant front location.

Hromadka, T. V.; Yen, C. C.

1986-06-01

69

In situ remediation of uranium contaminated groundwater  

SciTech Connect

In an effort to develop cost-efficient techniques for remediating uranium contaminated groundwater at DOE Uranium Mill Tailing Remedial Action (UMTRA) sites nationwide, Sandia National Laboratories (SNL) deployed a pilot scale research project at an UMTRA site in Durango, CO. Implementation included design, construction, and subsequent monitoring of an in situ passive reactive barrier to remove Uranium from the tailings pile effluent. A reactive subsurface barrier is produced by emplacing a reactant material (in this experiment various forms of metallic iron) in the flow path of the contaminated groundwater. Conceptually the iron media reduces and/or adsorbs uranium in situ to acceptable regulatory levels. In addition, other metals such as Se, Mo, and As have been removed by the reductive/adsorptive process. The primary objective of the experiment was to eliminate the need for surface treatment of tailing pile effluent. Experimental design, and laboratory and field results are discussed with regard to other potential contaminated groundwater treatment applications.

Dwyer, B.P.; Marozas, D.C.

1997-02-01

70

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

71

Probability-based nitrate contamination map of groundwater in Kinmen.  

PubMed

Groundwater supplies over 50 % of drinking water in Kinmen. Approximately 16.8 % of groundwater samples in Kinmen exceed the drinking water quality standard (DWQS) of NO3 (-)-N (10 mg/L). The residents drinking high nitrate-polluted groundwater pose a potential risk to health. To formulate effective water quality management plan and assure a safe drinking water in Kinmen, the detailed spatial distribution of nitrate-N in groundwater is a prerequisite. The aim of this study is to develop an efficient scheme for evaluating spatial distribution of nitrate-N in residential well water using logistic regression (LR) model. A probability-based nitrate-N contamination map in Kinmen is constructed. The LR model predicted the binary occurrence probability of groundwater nitrate-N concentrations exceeding DWQS by simple measurement variables as independent variables, including sampling season, soil type, water table depth, pH, EC, DO, and Eh. The analyzed results reveal that three statistically significant explanatory variables, soil type, pH, and EC, are selected for the forward stepwise LR analysis. The total ratio of correct classification reaches 92.7 %. The highest probability of nitrate-N contamination map presents in the central zone, indicating that groundwater in the central zone should not be used for drinking purposes. Furthermore, a handy EC-pH-probability curve of nitrate-N exceeding the threshold of DWQS was developed. This curve can be used for preliminary screening of nitrate-N contamination in Kinmen groundwater. This study recommended that the local agency should implement the best management practice strategies to control nonpoint nitrogen sources and carry out a systematic monitoring of groundwater quality in residential wells of the high nitrate-N contamination zones. PMID:23892715

Liu, Chen-Wuing; Wang, Yeuh-Bin; Jang, Cheng-Shin

2013-07-30

72

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

73

Contaminant Fate and Reactive Transport in Groundwater  

Microsoft Academic Search

\\u000a Understanding the complex, interacting processes that determine the fate and transport of contaminants in groundwater is a\\u000a major challenge for evaluating and predicting risks to clean water, human and ecological receptors and for designing effective\\u000a remediation plans. Different physical and biogeochemical processes including advection, hydrodynamic dispersion, dissolution,\\u000a sorption and biodegradation affect the migration of contaminants in saturated porous media like

Massimo Rolle; Ulrich Maier; Peter Grathwohl

74

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.

75

Leukemia and radium groundwater contamination  

SciTech Connect

In the August 2, 1985, issue of JAMMA, Lyman et al claim to have shown an association between leukemia incidence in Florida and radium in groundwater supplies. Although cautious in their conclusions, the authors imply that this excess in leukemia was in fact caused by radiation. The authors believe they have not presented a convincing argument for causation. The radiation doses at these levels of exposure could account for only a tiny fraction of the leukemia excess.

Tracy, B.L.; Letourneau, E.G.

1986-06-27

76

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.

77

CONTAMINANT TRANSPORT MODELS FOR GROUNDWATER QUALITY SIMULATION  

Microsoft Academic Search

Groundwater solute transport models are now capable of simulating the migration of contaminants in complex real-world systems when sufficient data are available. A variety of numerical methods have been applied successfully to solving the transport equation, and no single method is best for all problems. Over the past 10 to 15 years techniques have been developed to simulate chemical reactions

STEVEN M. GORELICK

78

A Technical Approach to Groundwater Contamination Problems  

Microsoft Academic Search

Argonne National Laboratory has been performing technical investigations at sites in Nebraska and Kansas that have identified groundwater contamination by carbon tetrachloride. This comprehensive program will ultimately provide the affected communities with safe drinking water. The first step in the program is to evaluate the available data and identify sites that will require an Alternate Water Supply Study (AWSS). The

Jacqueline C. Burton; Catherine Leser; Candace M. Rose

1993-01-01

79

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

National Technical Information Service (NTIS)

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 outl...

M. Bill M. Conrad

2008-01-01

80

Effect of groundwater flow on forming arsenic contaminated groundwater in Sonargaon, Bangladesh  

NASA Astrophysics Data System (ADS)

We examine the As-contaminated groundwater flow paths in the Blamaptra delta plain. Water recharged from ground surface moves vertically downward beneath flood plain. As-hotspot groundwaters are formed on the vertical groundwater flow paths. Reducing groundwater condition is not essential for the As-hotspot groundwaters.

Nakaya, Shinji; Natsume, Haruyasu; Masuda, Harue; Mitamura, Muneki; Biswas, Dipak Kumar; Seddique, Ashraf A.

2011-11-01

81

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

82

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

83

An anatomy of a groundwater contamination episode  

Microsoft Academic Search

Using the contamination episode at Price Landfill, New Jersey, as a case study, major analytical and informational issues characterizing groundwater pollution, with special emphasis on uncertainty associated with the environmental medium, especially solute-transport processes, and the valuation of health risks, principally dose-response relationships, are addressed. Alternative approaches to modeling the physical-chemical processes are described and subsequently coupled with mortality risk

Mordechai Shechter

1985-01-01

84

Modeling the Impact of Cracking in Low Permeability Layers in a Groundwater Contamination Source Zone on Dissolved Contaminant Fate and Transport.  

National Technical Information Service (NTIS)

The storage and transport of a dense non-aqueous phase liquid (DNAPL) was evaluated using a numerical model. Many DNAPLs are used as solvents by the DoD and industry. The improper disposal and handling of these chemicals has led to long term contamination...

K. W. Sievers

2012-01-01

85

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

86

Monitoring network design to provide initial detection of groundwater contamination  

SciTech Connect

The design of a monitoring network to provide initial detection of groundwater contamination at a waste disposal facility is complicated by uncertainty in both the characterization of the subsurface and the nature of the contaminant source. In addition, monitoring network design requires the resolution of multiple conflicting objections. A method is presented that incorporates system uncertainty in monitoring network design and provides network alternatives that are noninferior with respect to several objectives. Monte Carlo simulation of groundwater contaminant transport is the method of uncertainty analysis. The random inputs to the simulation are the hydraulic conductivity field and the contaminant source location. The design objectives considered are (1) minimize the number of monitoring wells, (2) maximize the probability of detecting a contaminant leak, and (3) minimize the expected area of contamination at the time of detection. The network design problem is formulated as a multiobjective, integer programming problem and is solved using simulated annealing. An application of the method illustrates the configurations of noninferior network solution and the trade-offs between objectives. The probability of detection can be increased either by using more monitoring wells or by locating the wells farther from the source. The latter case results in an increase in the average area of the detected contaminant plumes at the time of initial detection. If monitoring is carried out very close to the contaminant source to reduce the expected area of a detected plume, a large number of wells are required to provide a high probability of detection. A sensitivity analysis showed that the predicted performance of a given number of wells decreases significantly as the heterogeneity of the porous medium increases. In addition, a poor estimate of hydraulic conductivity was shown to result in optimistic estimates of network performance. 44 refs., 12 figs.

Meyer, P.D. (Pacific Northwest Lab., Richland, WA (United States)); Valocchi, A.J.; Eheart, J.W. (Univ. of Illinois, Urbana, IL (United States))

1994-09-01

87

Groundwater and Contaminant Transport Modelling at the Sydney Tar Ponds  

Microsoft Academic Search

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

Mark King

88

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

Microsoft Academic Search

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

T. Wang; R. Lenahan; M. Kanik

1985-01-01

89

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

90

Parallel Processing of a Groundwater Contaminant Code  

SciTech Connect

The U. S. Department of Energy’s Idaho National Engineering and Environmental Laboratory (INEEL) is conducting a field test of experimental enhanced bioremediation of trichoroethylene (TCE) contaminated groundwater. TCE is a chlorinated organic substance that was used as a solvent in the early years of the INEEL and disposed in some cases to the aquifer. There is an effort underway to enhance the natural bioremediation of TCE by adding a non-toxic substance that serves as a feed material for the bacteria that can biologically degrade the TCE.

Arnett, Ronald Chester; Greenwade, Lance Eric

2000-05-01

91

Designing optimal strategies for contaminated groundwater remediation  

NASA Astrophysics Data System (ADS)

The problem of locating pumps and setting pump rates to most effectively stabilize and remove a plume of contaminated groundwater at a hazardous waste site is examined. Nonlinear optimization methods are combined with convective-disperisve transport simulation in a unit response matrix type of optimization formulation. Constraints are used which guarantee that the contaminant plume is removed by limiting the concentrations at nodal points in the domain at a future time. Additional constraints explicitly require that concentrations not increase in the area outside the initial plume boundary. The effectiveness of alternative formulations are examined by performing numerical experiments using a hypothetical aquifer. The experiments show that computational costs are dominated by the repeated simulations required for computation of constraint gradients and are proportional to the number of pump sites under consideration. This characteristic of the formulation and algorithm used, limits the use of the approach to problems where the number of potential pump sites is relatively small.

Ahlfeld, David P.; Mulvey, John M.; Pinder, George F.

92

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

93

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

94

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

95

Potential groundwater contamination with toxic metals around refuse dumps in some parts of Lagos metropolis, Nigeria  

Microsoft Academic Search

Industrial evolution in developing countries, most especially Nigeria in the last century, has resulted in geometrical increase in waste generation compared to the arithmetic progress in management methods, thereby creating the problem of effective waste management and disposal. Wastes generated from industries have become a major source of pollution of groundwater when contaminants become leached into the groundwater. Water samples

E. A. Oluyemi; W. O. Makinde; A. A. Oladipo

2009-01-01

96

Groundwater contaminant plume ranking. [UMTRA Project  

SciTech Connect

Containment plumes at Uranium Mill Tailings Remedial Action (UMTRA) Project sites were ranked to assist in Subpart B (i.e., restoration requirements of 40 CFR Part 192) compliance strategies for each site, to prioritize aquifer restoration, and to budget future requests and allocations. The rankings roughly estimate hazards to the environment and human health, and thus assist in determining for which sites cleanup, if appropriate, will provide the greatest benefits for funds available. The rankings are based on the scores that were obtained using the US Department of Energy's (DOE) Modified Hazard Ranking System (MHRS). The MHRS and HRS consider and score three hazard modes for a site: migration, fire and explosion, and direct contact. The migration hazard mode score reflects the potential for harm to humans or the environment from migration of a hazardous substance off a site by groundwater, surface water, and air; it is a composite of separate scores for each of these routes. For ranking the containment plumes at UMTRA Project sites, it was assumed that each site had been remediated in compliance with the EPA standards and that relict contaminant plumes were present. Therefore, only the groundwater route was scored, and the surface water and air routes were not considered. Section 2.0 of this document describes the assumptions and procedures used to score the groundwater route, and Section 3.0 provides the resulting scores for each site. 40 tabs.

Not Available

1988-08-01

97

Potassium ferrate treatment of RFETS` contaminated groundwater  

SciTech Connect

The potassium ferrate treatment study of Rocky Flats Environmental Technology Site (RFETS) groundwater was performed under the Sitewide Treatability Studies Program (STSP). This study was undertaken to determine the effectiveness of potassium ferrate in a water treatment system to remove the contaminants of concern (COCS) from groundwater at the RFETS. Potassium ferrate is a simple salt where the iron is in the plus six valence state. It is the iron at the plus six valence state (Fe {sup +6}) that makes it an unique water treatment chemical, especially in waters where the pH is greater than seven. In basic solutions where the solubility of the oxides/hydroxides of many of the COCs is low, solids are formed as the pH is raised. By using ferrate these solids are agglomerated so they can be effectively removed by sedimentation in conventional water treatment equipment. The objective of this study was to determine the quality of water after treatment with potassium ferrate and to determine if the Colorado Water Quality Control Commission (CWQCC) discharge limits for the COCs listed in Table 1.0-1 could be met. Radionuclides in the groundwater were of special concern.

NONE

1995-01-01

98

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

99

RISK ASSESSMENT METHODOLOGY FOR DETERMINING GROUNDWATER CONTAMINATION FROM LANDFILL SLUDGE  

EPA Science Inventory

Contaminant concentration criteria are required to prevent contaminant infiltration from leading to conditions which exceed health criteria. A methodology of groundwater has been described which may be used to select those criteria and quantify concentrations associated with plac...

100

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

101

Optimization of Contaminant Loading Mass and Pumping Rates for Sustainable Groundwater Use in Agricultural Region  

NASA Astrophysics Data System (ADS)

Nowadays, governments in many countries having difficulty in supplying sufficient water resources have made significant efforts in sustainable use of groundwater. Groundwater is frequently used as the main water resources for irrigation and drinking in the agricultural region, but it can be susceptible to depletion caused by overuse and to contamination from fertilizer. In this study, a simulation-optimization model is used to work out the management strategy for sustainable groundwater use in the agricultural region. 1-D solute reactive transport models in unsaturated zone (analytical solutions and LEACHN) are used to estimate the contaminant loading mass on ground and simulate the contaminant transport in the unsaturated zone. The output of the 1-D unsaturated transport models, mass of the contaminants leached on water table, works as contaminant sources in the 3-D solute reactive transport model in saturated zone. This integrated simulation model is linked to genetic algorithm that searches the global optimum for the optimal management strategy. The management strategy involves obtaining the optimal pumping rates that are able not only to supply sufficient amount of the groundwater, but also to protect the groundwater from the contamination and excessive drawdown. It also controls the amount of contaminant loading mass by suggesting the maximum permissible contaminant loading mass. The application results from hypothetical domain and an agricultural region around Icheon-city in Korea present that the groundwater management methodology suggested in this study can be considerably efficient by obtaining the optimized the contaminant loading mass and pumping rates simultaneously.

Park, D.; Bae, G.; Lim, J.; Lee, K.

2008-12-01

102

Remediation of Groundwater Contaminated with Organics and Radionuclides--An Innovative Approach Eases Traditional Hurdles.  

National Technical Information Service (NTIS)

Traditional approaches to the remediation of contaminated groundwater, such as pump-and-treat, have been used for many years for the treatment of groundwater contaminated with various organics. However the treatment of groundwater contaminated with organi...

J. Scott N. Case K. Coltman

2003-01-01

103

TREATMENT OF HIGHLY CONTAMINATED GROUNDWATER: A SITE DEMONSTRATION PROJECT  

EPA Science Inventory

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

104

Groundwater recharge and agricultural contamination in alluvial fan of Eastern Kofu basin, JAPAN  

NASA Astrophysics Data System (ADS)

Agriculture has significant effects on the rate and composition of groundwater recharge. The chemical loading into groundwater have been dominated by the constituents derived directly or indirectly from agricultural practices and additives. The contamination of groundwater with nitrate is a major public health and environmental concern around the world. The inorganic constituents like, K+, Ca2+, Mg2+, SO42-, Cl- and variety of other minor elements of groundwater are often used as agricultural additives; and the natural occurrence of these elements are dominated by the agricultural sources. A recent study has reported that Kofu basin groundwater aquifer is contaminated by nitrate from agricultural areas because of the fertilizer application for the orchard (Kazama and Yoneyama, 2002; Sakamoto et al., 1997, Nakamura et al., 2007). The water-oxygen and hydrogen stable isotope (?18O and ?D) and nitrate-nitrogen stable isotope (?15N) of groundwater, river water and precipitation samples were investigated to identify the source of groundwater and nitrate nitrogen contamination in groundwater in the Fuefukigawa and Hikawa_Kanegawa alluvial fans in Kofu basin. The plot of ?D versus ?18O values of groundwater, river water and precipitation samples suggest that the groundwater is a mixture of precipitation and river water. And nitrate-nitrogen isotope values have suggested the nitrate contamination of groundwater is from agricultural area. The study revealed positive correlation between groundwater ?18O values and NO3-, Cl-, SO42-, Ca2+, Mg2+ concentration, which shows the agricultural contamination is carried by the recharge of groundwater from precipitation in alluvial fan. Whereas, NO3-, Cl-, SO42-, Ca2+, Mg2+ are diluted by the river water recharges. This study showed the quality of groundwater is resulted from the mixing of water from the different source during the groundwater recharge in the study area. References Kazama F, Yoneyama M (2002) Nitrogen generation in the Yamanashi prefecture and its effects on the groundwater pollution. Int. Envir. Science Vol. 15:293-298. (in Japanese) Sakamoto Y, Nakamura F, Kazama F (1990) Spatial Distribution of Nitrate Concentration in Groundwater-Derived Potable. Reports of the Faculty of Engineering Yamanashi University Vol.41:139-144. (in Japanese) Nakamura T, Satake H, Kazama F (2007) Effects of groundwater recharge on nitrate-nitrogen loadings. Journal of Water and Environment Technology Vol.5:87-93.

Nakamura, T.

2009-12-01

105

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

106

Assessment of groundwater contamination from fertilizers in the Delhi area based on 180, N0 3 ? and K + composition  

Microsoft Academic Search

Increasing application of nitrogen fertilizers in the irrigated lands of the studied area is likely to create a blanket non-point source of nitrate. Groundwater contamination from fertilizers, in this context, has been reported as derived from N03?, K+ and 180 composition of groundwater. The data suggest both point and non-point sources of groundwater pollution. Thirty-three percent of the groundwater samples

P. S. Datta; D. L. Deb; S. K. Tyagi

1997-01-01

107

What should be done to mitigate groundwater contamination?  

PubMed Central

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

Patrick, R

1990-01-01

108

Arsenic contamination in groundwater in the Southeast Asia region  

Microsoft Academic Search

The adverse impact of groundwater contaminated with arsenic (As) on humans has been reported worldwide, particularly in Asian\\u000a countries. In this study, we present an overview of the As crisis in the Southeast Asian region where groundwater is contaminated\\u000a with naturally occurring As and where contamination has become more widespread in recent years. In this region more than 100 million\\u000a people

Mohammad Mahmudur Rahman; R. Naidu; Prosun Bhattacharya

2009-01-01

109

Determination of Electron Donors by Comparing Reaction Rates for In Situ Bioremediation of Nitrate-Contaminated Groundwater  

Microsoft Academic Search

Groundwater contaminated by nitrates occurs frequently. In this research, fumarate, acetate, formate, lactate, propionate, ethanol, and methane were evaluated as a potential electron donor and carbon source by comparing the denitrification rate for the in situ bioremediation of nitrate contaminated groundwater. The denitrification rate for each substance was the quickest in the order of: fumarate > hydrogen > formate\\/Lactate >

SEONG-WOOK OA; GEONHA KIM; YOUNG KIM

2006-01-01

110

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

Microsoft Academic Search

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

Jya-Jyun Yu; Shinn-Yow Chou

2000-01-01

111

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

112

Catchment-scale vulnerability assessment of groundwater pollution from diffuse sources using the DRASTIC method: a case study  

Microsoft Academic Search

The catchment-scale groundwater vulnerability assessment that delineates zones representing different levels of groundwater susceptibility to contaminants from diffuse agricultural sources has become an important element in groundwater pollution prevention for the implementation of the EU Water Framework Directive (WFD). This paper evaluates the DRASTIC method using an ArcGIS platform for assessing groundwater vulnerability in the Upper Bann catchment, Northern Ireland.

Y. S. Yang; L. Wang

2010-01-01

113

Radioactive contamination and radionuclide migration in groundwater. (Latest citations from the NTIS bibliographic database). Published Search  

SciTech Connect

The bibliography contains citations concerning the contamination of groundwater with radionuclides and their subsequent migration. Monitoring surveys of existing sites with actual or potential radioactive groundwater contamination are included. Transport and migration models for radionuclides in groundwater are discussed. Natural radiation and accidental releases are considered in addition to anthropogenic sources of radioactive pollution such as waste storage and disposal. Contributions to radioactive pollution from uranium mining and processing are discussed in a separate bibliography. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

NONE

1997-12-01

114

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

115

Refurbishing tritium contaminated ion sources  

Microsoft Academic Search

Extended tritium experimentation on TFTR has necessitated refurbishing Neutral Beam Long Pulse Ion Sources (LPIS) which developed operational difficulties, both in the TFTR Test Cell and later, in the NE Source Refurbishment Shop. Shipping contaminated sources off-site for repair was not permissible from a transport and safety perspective. Therefore, the NE source repair facility was upgraded by relocating fixtures, tooling,

K. E. Wright; R. H. Carnevale; B. E. McCormack; T. Stevenson; A. von Halle

1995-01-01

116

Assessment of landfill leachate toxicity and contamination of groundwater in Iowa  

Microsoft Academic Search

Groundwater contamination is an emerging national environmental issue and has gained much attention in Iowa, as measured by the Iowa Groundwater Protection Act of 1987. Assessment of the extent, significance, and solutions to groundwater contamination from Iowa's landfills must be an integral part of any groundwater protection strategy. This work establishes a framework for assessing groundwater contamination from landfill leachates

Kross

1987-01-01

117

Contamination of groundwater by outdoor highway deicing agent storage  

NASA Astrophysics Data System (ADS)

This research quantifies the impact of outdoor highway deicing agent storage on groundwater quality. Data and theory realize the objective at a well characterized salt/premix storage facility on a glacial drumlin comprised of clayey sand till. Tritium and tritiogenic helium were observed in 17 monitoring wells in 2003, while chloride concentrations were measured in 43 monitoring wells from 1998 through 2004. The 3He/3H ratios confirm an analytical model of drumlin hydraulics (Ostendorf, D.W., DeGroot, D.J., Shelburne, W.M., and Mitchell, T.J., 2004. Hydraulic head in a clayey sand till over multiple timescales. Can. Geotech. J. 41, 89-105.), and support advective travel time estimates from the monitoring well screens back to the water table. An advective balance of recharge, precipitation, and surface runoff routes the water table Cl- concentrations inwards to the outdoor storage pile maintained at the site from the 1960s to the mid 1980s. Concentrations as high as 320 meq Cl-/L were observed in groundwater, although the deicing agent contamination had not yet reached the bottom of the drumlin in the study area. The travel time simulations yield a 200 meq Cl-/L water table isopleth in 1985 under the prior outdoor storage pile. The recharge concentration model matches the radial decrease of Cl- water table concentrations from the pile, and implies that 4400 kg of Cl- leached into the groundwater in 1985. This is about 0.3% of the deicing agent Cl- stored at the site each year. These results suggest that outdoor storage of highway deicing agents significantly impacted groundwater quality near the pile. The groundwater quality began to recover after source removal however: the leached Cl- flux dropped to 2,300 kg in 1992, more than 5 years after elimination of the outdoor storage pile.

Ostendorf, David W.; Hinlein, Erich S.; Rotaru, Camelia; Degroot, Don J.

2006-07-01

118

Unsaturated zone arsenic distribution and implications for groundwater contamination.  

PubMed

Arsenic compounds have been applied at the land surface as pesticides in agricultural areas globally. The purpose of this study was to evaluate the fate of anthropogenic arsenic applications related to agriculture, using arsenic applications on cotton in the southern High Plains (SHP), Texas, as a case study and examining possible linkages with contamination of the underlying Ogallala aquifer in this region, where 36% of wells exceed the new EPA 10 microg/L standard. Unsaturated zone soil samples were collected from boreholes beneath natural ecosystems (grassland/ shrubland) to provide a control (no arsenic application) (5 profiles) and cotton cropland (20 profiles) for analyses of water-extractable arsenic, vanadium, phosphate, chloride, and nitrate. Natural ecosystem profiles have high arsenic concentrations at depth (maximum of 7.2-69.6 microg As/ kg dry soil at 5.9-21.4 m depth) that are attributed to a geologic source. Most profiles beneath cotton cropland have high arsenic concentrations within the upper meter (profile means 1.7 to 31.6 microg/kg) that correlate with phosphate (r = 0.70, p < 0.01) and are attributed to anthropogenic arsenic application associated with phosphate fertilizer application. High arsenic concentrations at >1 m depth (profile means < or =36.3 microg/kg) found in cropland profiles are attributed to a geologic source because of similarity with profiles beneath natural ecosystems, lack of correlation with phosphate, and pore-water ages that predate anthropogenic arsenic application in many profiles. GIS analyses showed poor correlations between groundwater arsenic and percent cultivated land (r = -0.15, p < 0.01), groundwater nitrate (r = 0.30, p < 0.01), and water table depth (r= -0.31, p < 0.01), further supporting the idea that anthropogenic-derived arsenic in the shallow subsurface is not linked to groundwater arsenic contamination in this region. PMID:17993128

Reedy, Robert C; Scanlon, Bridget R; Nicot, Jean-Philippe; Tachovsky, J Andrew

2007-10-15

119

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

National Technical Information Service (NTIS)

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

1993-01-01

120

Federalism and the Prevention of Groundwater Contamination  

NASA Astrophysics Data System (ADS)

The federal government has increasingly come to predominate in environmental protection. The underlying policies behind that shift are still being debated in the context of groundwater protection. Many of the reasons that led to national statutory schemes for air, surface water, toxics and other environmental media are applicable to groundwater and a greater federal role in the protection of groundwater is appropriate.

Fort, Denise D.

1991-11-01

121

Soil and groundwater contamination by oil spills; problems and remedies  

Microsoft Academic Search

Large scale transport and storage of hydrocarbons constitute a threat to the soil ecosystems and to the ground?water reserves. To clean?up oil spilled on soils or polluting groundwaters, one has either to remove mechanically the soil impregnated with oil or to collect and remove by pumping the contaminated groundwater reserves. A third and ultimately more complete clean?up method consists of

R. Vanloocke; R. De Borger; J. P. Voets; W. Verstraete

1975-01-01

122

Persistence of Three Halogenated Aliphatic Groundwater Contaminants under Anoxic Conditions.  

National Technical Information Service (NTIS)

Three halogenated compounds that are common groundwater contaminants were observed to undergo no appreciable transformation by soil microorganisms and an enrichment culture grown on methanol and ethanol under anoxic conditions. Based upon these observatio...

R. B. Kapuscinski

1985-01-01

123

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...

124

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...

125

COLLOIDAL CONSIDERATIONS IN GROUNDWATER SAMPLING AND CONTAMINANT TRANSPORT PREDICTIONS  

EPA Science Inventory

The association of contaminants with suspended colloidal material in groundwater is a possible transport mechanism and a complicating factor for accurate estimations of the aqueous geochemistry of subsurface systems. esearch to date indicates colloidal facilitated transport of co...

126

Groundwater Arsenic Contamination in India: Vulnerability and Scope for Remedy  

Microsoft Academic Search

Arsenic contamination in groundwater in the Ganga- Brahmaputra fluvial plains in India and Padma-Meghna fluvial plains in Bangladesh and its consequences to the human health have been reported as one of the world's biggest natural groundwater calamities to the mankind. In India, seven states namely- West Bengal, Jharkhand, Bihar, Uttar Pradesh in the flood plain of the Ganga River; Assam

N. C. Ghosh; R. D. Singh

127

Modeling organic contaminant partitioning in ground-water systems  

Microsoft Academic Search

Effective management of a ground-water system requires description and prediction of the transport and fate of contaminants in that system. This can be facilitated by using mathematical models which accurately represent the physical phenomena operative in the system. One of the most significant phenomena impacting the transport of many organic pollutants is partitioning between the solid (soil) and aqueous (ground-water)

C. T. Miller; W. J. Jr. Weber

2009-01-01

128

A multilayer groundwater sampler for characterizing contaminant plumes  

SciTech Connect

This final report describes activities related to the design and initial demonstration of a passive multilayer groundwater sampling system. The apparatus consists of remotely controlled cylinders filled with deionized water which are connected in tandem. Vertical fine structure of contaminants are easily defined. Using the apparatus in several wells may lead to three dimensional depictions of groundwater contamination, thereby providing the information necessary for site characterization and remediation.

Kaplan, E.; Heiser, J.

1992-12-18

129

A multilayer groundwater sampler for characterizing contaminant plumes. Final report  

SciTech Connect

This final report describes activities related to the design and initial demonstration of a passive multilayer groundwater sampling system. The apparatus consists of remotely controlled cylinders filled with deionized water which are connected in tandem. Vertical fine structure of contaminants are easily defined. Using the apparatus in several wells may lead to three dimensional depictions of groundwater contamination, thereby providing the information necessary for site characterization and remediation.

Kaplan, E.; Heiser, J.

1992-12-18

130

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

131

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

132

Investigating a Real-Life Groundwater Contamination Event  

NSDL National Science Digital Library

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

Riemersma, Peter

133

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

PubMed

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

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

2012-08-08

134

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

135

Viability of longitudinal trenches for capturing contaminated groundwater.  

PubMed

Using a groundwater flow and mass transport model, this study compared the capability of trenches with permeable backfill for capturing hypothetical contaminant plumes in homogeneous and heterogeneous unconfined aquifers. Longitudinal (parallel to groundwater flow), as well as conventional transverse (perpendicular to groundwater flow) trench configurations were considered. Alternate trench configurations intercepted the leading tip of an initial contaminant plume and had identical length, equal to the cross-gradient width of the plume. A longitudinal trench required 31% less time than its transverse counterpart to remediate a homogeneous aquifer. By contrast, in simulated heterogeneous aquifers, longitudinal remediation timeframes ranged from 41% less to 33% more than transverse trenches. Results suggest that longitudinal trenches may be a viable alternative for narrow contaminant plumes under low-groundwater velocity conditions, but may be impractical for plumes with wide leading tips, or in complex heterogeneous aquifers with divergent flow. PMID:20237910

Hudak, Paul F

2010-03-17

136

A Contamination Vulnerability Assessment for the Santa Clara and San Mateo County Groundwater Basins  

SciTech Connect

In response to concerns expressed by the California Legislature and the citizenry of the State of California, the State Water Resources Control Board (SWRCB), implemented a program to assess groundwater quality, and provide a predictive capability for identifying areas that are vulnerable to contamination. The program was initiated in response to concern over public supply well closures due to contamination by chemicals such as MtBE from gasoline, and solvents from industrial operations. As a result of this increased awareness regarding groundwater quality, the Supplemental Report of the 1999 Budget Act mandated the SWRCB to develop a comprehensive ambient groundwater-monitoring plan, and led to the initiation of the Ambient Groundwater Monitoring and Assessment (GAMA) Program. The primary objective of the GAMA Program is to assess the water quality and to predict the relative susceptibility to contamination of groundwater resources throughout the state of California. Under the GAMA program, scientists from Lawrence Livermore National Laboratory (LLNL) collaborate with the SWRCB, the U.S. Geological Survey, the California Department of Health Services (DHS), and the California Department of Water Resources (DWR) to implement this groundwater assessment program. In 2001 and 2002, LLNL carried out this vulnerability study in the groundwater basins of Santa Clara County and San Mateo County, located to the south of the city of San Francisco. The goal of the study is to provide a probabilistic assessment of the relative vulnerability of groundwater used for the public water supply to contamination from surface sources. This assessment of relative contamination vulnerability is made based on the results of two types of analyses that are not routinely carried out at public water supply wells: ultra low-level measurement of volatile organic compounds (VOCs), and groundwater age dating (using the tritium-helium-3 method). In addition, stable oxygen isotope measurements help determine the recharge water source location. Interpreted together, and in the context of existing water quality and hydrogeologic data, these observable parameters help define the flow field of a groundwater basin, and indicate the degree of vertical communication between near-surface sources (or potential sources) of contamination, and deeper groundwater pumped at high capacity production wells.

Moran, J E; Hudson, G B; Eaton, G F; Leif, R

2004-01-06

137

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

138

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

SciTech Connect

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

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

1992-01-01

139

Limitations in recovering the history of a groundwater contaminant plume  

Microsoft Academic Search

Groundwater contaminant transport is a dispersive process and consequently there are limits to what may be learned about a contaminant's origins (history) from measurements of its present spatial distribution. The extent of these limitations in a particular case depends on a number of factors, including the dispersive properties of the transport medium, the accuracy of the measured plume, and the

Todd H. Skaggs; Z. J. Kabala

1998-01-01

140

Impact of groundwater contamination of public water supplies  

Microsoft Academic Search

The presence of a wide variety of organic contaminants in groundwater has required that additional treatment processes be added to the present treatment train in potable water treatment plants. Among the many contaminants identified, the most concern has been focused on the synthetic organic compounds. The Environmental Protection Agency's (EPA's) Carcinogen Assessment Group has identified 19 carcinogens. The Safe Drinking

Singley

1989-01-01

141

Modeling In Situ Bioremediation of Perchlorate-Contaminated Groundwater  

NASA Astrophysics Data System (ADS)

Perchlorate-contaminated groundwater is a significant national problem. An innovative technology was recently developed which uses a pair of dual-screened treatment wells to mix an electron donor into perchlorate- contaminated groundwater in order to effect in situ bioremediation of the perchlorate by indigenous perchlorate reducing bacteria (PRB) without the need to extract the contaminated water from the subsurface. The two treatment wells work in tandem to establish a groundwater recirculation zone in the subsurface. Electron donor is added and mixed into perchlorate-contaminated groundwater flowing through each well. The donor serves to stimulate biodegradation of the perchlorate by PRB in bioactive zones that form adjacent to the injection screens of the treatment wells. In this study, a model that simulates operation of the technology was calibrated using concentration data obtained from a field-scale technology evaluation project at a perchlorate-contaminated site. The model simulates transport of perchlorate, the electron donor (citrate, for this study), and competing electron acceptors (oxygen and nitrate) in the groundwater flow field induced by operation of the treatment well pair. A genetic algorithm was used to derive a set of best-fit model parameters to describe the perchlorate reduction kinetics in this field-scale evaluation project. The calibrated parameter values were then used to predict technology performance. The model qualitatively predicted the salient characteristics of the observed data. It appears the model may be a useful tool for designing and operating this technology at other perchlorate-contaminated sites.

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

2007-12-01

142

Sources of groundwater nitrate revealed using residence time and isotope methods  

Microsoft Academic Search

Nitrate concentrations approaching and greater than the maximum contaminant level (MCL) are impairing the viability of many groundwater basins as drinking water sources. 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

K B Moore; B Ekwurzel; B K Esser; G B Hudson; J E Moran

2004-01-01

143

Sources of groundwater nitrate revealed using residence time and isotope methods  

Microsoft Academic Search

Nitrate concentrations approaching and greater than the maximum contaminant level are impairing the viability of many groundwater basins as drinking water sources. Nitrate isotope data are effective in determining contaminant sources, especially when combined with other isotopic tracers such as stable isotopes of water and 3H–He ages to give insight into the routes and timing of NO3 inputs to the

Keara B. Moore; Brenda Ekwurzel; Bradley K. Esser; G. Bryant Hudson; Jean E. Moran

2006-01-01

144

Managing ground-water contamination from agricultural nitrates  

SciTech Connect

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

Halstead, J.M.

1989-01-01

145

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

146

Application of a groundwater contamination index in Finland and Slovakia  

Microsoft Academic Search

A methodology is presented for evaluating and mapping the degree of groundwater contamination by applying the contamination\\u000a index C\\u000a \\u000a d\\u000a . The applicability of the contamination index was tested in two distinctly different geological regions: the area between\\u000a Uusikaupunki and Ylne in southwestern Finland and the Brezno area in central Slovakia. The index takes into account both\\u000a the number of

B. Backman; D. Bodiš; P. Lahermo; S. Rapant; T. Tarvainen

1998-01-01

147

Toxic groundwater contaminants: an overlooked contributor to urban stream syndrome?  

PubMed

Screening for common groundwater contaminants was performed along eight urban stream reaches (100s-1000s of m) at approximately 25-75 cm below the streambeds. Four sites had known or suspected chlorinated-solvent plumes; otherwise no groundwater contamination was known previously. At each site, between 5 and 22 contaminants were detected at levels above guideline concentrations for the preservation of aquatic life, while several others were detected at lower levels, but which may still indicate some risk. Contaminants of greatest concern include numerous metals (Cd, Zn, Al, Cu, Cr, U), arsenic, various organics (chlorinated and petroleum), nitrate and ammonium, and chloride (road salt likely), with multiple types occurring at each site and often at the same sampling location. Substantial portions of the stream reaches (from 40 to 88% of locations sampled) possessed one or more contaminants above guidelines. These findings suggest that this diffuse and variable-composition urban groundwater contamination is a toxicity concern for all sites and over a large portion of each study reach. Synergistic toxicity, both for similar and disparate compounds, may also be important. We conclude that groundwater contaminants should be considered a genuine risk to urban stream aquatic ecosystems, specifically benthic organisms, and may contribute to urban stream syndrome. PMID:22201254

Roy, James W; Bickerton, Greg

2011-12-22

148

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.

149

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

150

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

NSDL National Science Digital Library

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

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

151

Measurement of Helium Isotopes in Soil Gas as an Indicator of Tritium Groundwater Contamination  

Microsoft Academic Search

This study was undertaken at the U. S. Department of Energy's Hanford Site in southeastern Washington State. The focus of this study was to define the shape and extent of tritium groundwater contamination emanating from the 618-11 burial ground and to identify vadose zone sources of tritium using helium isotopes (3He and 4He) in soil gas.

Khris B. Olsen; P EVAN. Dresel; John C. Evans; William J. Mcmahon; Robert Poreda

2006-01-01

152

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

153

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

154

Development of Chemical Indicators of Groundwater Contamination Near the Carcass Burial Site  

NASA Astrophysics Data System (ADS)

A serious outbreak of foot and mouth disease (FMD) and avian influenza (AI) led to the culling of millions of livestock in South Korea from late 2010 to earlier 2011. Because of the scale of FMD and AI epidemic in Korea and rapid spread of the diseases, mass burial for the disposal of carcass was conducted to halt the outbreak. The improper construction of the burial site or inappropriate management of the carcass burial facility can cause the contamination of groundwater mainly due to the discharges of leachate through the base of disposal pit. The leachate from carcass burial contains by products of carcass decay such as amino acids, nitrate, ammonia and chloride. The presence of these chemical components in groundwater can be used as indicators demonstrating contamination of groundwater with leachate from carcass. The major concern about using these chemical indicators is that other sources including manures, fertilizers and waste waters from human or animal activities already exist in farming area. However, we lack the understanding of how groundwater contamination due to mass burial of carcass can be differentiated from the contamination due to livestock manures which shows similar chemical characteristics. The chemical compositions of the leachate from carcass burial site and the wastewater from livestock manure treatment facilities were compared. The chemical compositions considered include total organic carbon (TOC), total nitrogen (TN), nitrate, organic nitrogen (Organic nitrogen =TN-Ammonium Nitrogen- Nitrate nitrogen), ammonia, chloride, sodium, potassium and amino acids (20 analytes). The ratios of concentrations of the chemical compositions as indicators of contamination were determined to distinguish the sources of contamination in groundwater. Indicators which showed a linear relationship between two factors and revealed a distinct difference between the carcass leachate and livestock manure were chosen. In addition, the background level of the indicators in groundwater which was presumed not to be contaminated with the leachate was also considered. The indicators selected from these step were TN/nitrate nitrogen, organic nitrogen/TN, organic nitrogen/Cl and organic nitrogen/Na. In a similar manner, concentrations and peak pattern of amino acids with LC-MSMS as indicators were also selected. One more step added to identify the source of a contaminant release was the consideration of the transport of 20 amino acids in the subsurface which could significantly change the peak pattern among different amino acids. Six group of amino acid as indicators were chosen and they were Isoleucine/Valine, Leucine/Tryptophane, Valine/Tryptophane, Lysine/Leucine, Lysine/Isoleucine and Methionine/Lysine. The use of chemical indicators was attempted in this study to distinguish the sources of contamination by considering both the concentration of contaminants and the unique patterns of contamination.

Kim, H.; Choi, J.; Kim, M.; Choi, J.; Lee, M.; Lee, H.; Jeon, S.; Bang, S.; Noh, H.; Yoo, J.; Park, S.; Kim, H.; Kim, D.; Lee, Y.; Han, J.

2011-12-01

155

Chlorinated organics removal from contaminated soil and groundwater by microorganisms  

SciTech Connect

This research has focused on the development of remedial technology to rehabilitate contaminated soil and groundwater. Biological treatment was chosen because it is environmentally sound and less costly than alternative methods involving physical-chemical treatment. Pentachlorophenol (PCP) was used as a model compound. PCP removal from contaminated groundwater and synthetic media was studied in batch tests. Complete removal and stoichiometric release of chloride ions was observed. The effects of different size sand particles on PCP biodegradation were tested to determine the rates of removal. Short and long sand columns were also tested to determine the rates of PCP removal in saturated and unsaturated flow conditions. The results show that the acclimated culture is capable of removing chlorinated organics from contaminated groundwater even in the presence of several hundred of mg/L of other organic pollutants.

Kim, C.J.

1986-01-01

156

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

157

Fluorine contamination in groundwater: a major challenge.  

PubMed

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

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

2010-03-30

158

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

159

Network design for predicting groundwater contamination  

Microsoft Academic Search

A new network design algorithm for improving the reliability of groundwater simulation model predictions is developed. The objective of the algorithm is to minimize the simulation model prediction variance by choice of new aquifer property measurement locations. This method, which uses parameter measurements to minimize prediction error, is different in concept from conventional parameter estimation or inverse methods which use

Daene C. McKinney; Daniel P. Loucks

1992-01-01

160

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

161

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

SciTech Connect

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

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

1993-04-01

162

Colloid-facilitated groundwater contaminant transport  

Microsoft Academic Search

Colliodal particles or dissolved organic matter (DOM) can act as carriers to enhance the transport of contaminants is goundwater by reducing retardation effects. When either of these materials is present, the system can be treated as consisting of three phases: an aqueous phase, a carrier phase, and the stationary solid matrix phase. The contaminant may be present in either or

M. Yavuz Corapcioglu; Shiyan Jiang

1993-01-01

163

Finite element analysis of contaminant transport in groundwater  

Microsoft Academic Search

In this paper, we focus on the development of a finite element model for predicting the contaminant concentration governed by the advective–dispersive equation. In this study, we take into account the first-order degradation of the contaminant to realistically model the transport phenomenon in groundwater. To solve the resulting unsteady advection–diffusion equation with production, a finite element model is constructed, which

Tony W. H. Sheu; Y. H. Chen

2002-01-01

164

Physical and numerical modeling results for controlling groundwater contaminants following shutdown of underground coal gasification processes  

SciTech Connect

Groundwater contamination has resulted from some of in-situ gasification field tests, and concern over groundwater contamination may hamper commercialization. When UCG recovery operations are terminated, energy remains stored as heat in the adjacent masses of rock and coal ash, and this energy is transferred into the coal seam. Coal continues to pyrolyze as a result of the transferred energy; the products of this coal pyrolysis are a source of groundwater contamination resulting from UCG. A laboratory simulator was developed, and six simulations of UCG postburn coal pyrolysis have been completed. The simulations show that the products of coal pyrolysis are the source of most contaminants associated with UCG operations. Injection of water directly into the UCG cavity can limit postburn coal pyrolysis and reduce the production of contaminants by cooling the masses of rubble and coal ash in the cavity. Water flow through the coal towards the cavity also limits postburn pyrolysis and subsequent contaminant generation; however, steam produced in the heated portions of the coal limits the rate of water flow. Simulation results indicate that UCG field tests should be operated so that the flow of pyrolysis liquids and gases into the formation is prevented and that the natural influx of water into the cavity is allowed. This can be accomplished by minimizing gas leakage to the formation during gasification, venting the cavity after the gasification process is complete, and maintaining low postburn cavity pressures. 11 refs., 17 figs., 17 tabs.

Boysen, J.E.; Mones, C.G.; Glaser, R.R.; Sullivan, S.

1987-03-01

165

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

Microsoft Academic Search

Working with Dr. Gilbert Hanson has allowed me to apply general mixing equations to identification of nonpoint sources of groundwater contamination. These methods have not commonly been used in hydrologic studies, as they involve a more classical petrologic approach, one which Dr. Hanson has pioneered. Our drinking water supplies are becoming more susceptible to contamination and knowing the chemistry of

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

2007-01-01

166

Performance comparison of interceptor trench configurations for extracting contaminated groundwater.  

PubMed

Computer simulations tested the capability of five alternative interceptor trench configurations to capture an enclave (plume) of contaminated groundwater. The configurations included a single linear segment and angled segments, at 90 degrees and 135 degrees, with a common endpoint. Alternative angled configurations both faced and opposed the contaminant plume. Each trench configuration had the same total length and was located the same average distance from the contaminant plume. The minimum pumping rate required to capture the plume and a surrounding buffer zone, within a prescribed time period, was determined for each trench configuration. The 90 degree plume-opposed trench performed best, requiring approximately one-third the pumping rate of the 90 degree plume-facing configuration. The plume-opposed configuration yielded a capture zone that best conformed to the actual shape of the contaminant plume, thereby reducing the amount of groundwater that had to be removed from the aquifer to remove the contaminant plume. Ironically, plume opposed configurations are rarely used in practice. Results of this study suggest that alternative interceptor trench configurations, including funnels with mouths opposed to contaminant plumes, should be tested with computer simulations when devising protocols for groundwater remediation. PMID:15137698

Hudak, Paul F

2004-01-01

167

PRACTICAL DIAGNOSIS OF BIOSTIMULATION FOR VOC CONTAMINATED SOIL AND GROUNDWATER  

NASA Astrophysics Data System (ADS)

Biostimulation has been widely used as a remediation of soil and groundwater contaminated by chlorinated volatile organic compounds (VOC). The chemical and biological systems in actual field are so complicated that it is hard to know the mathematical modeling parameters prior to laboratory tests using contaminated soil and groundwater sampled from specific site. The paper addresses an diagnostic method to evaluate the parameters controlling the lag time an d the chemical reaction rate which are essential to predict efficiency of biostimulation in actual field. In this paper, laboratory test results of thirtyseven sites are stochastically reanalyzed to make clear the dependency of the lag time and the chemical reaction rate on groundwater quality indices, such as DO, ORP, pH, etc.

Suzuki, Keiichi; Ando, Takuya; Ito, Yoshitaka; Sato, Takeshi

168

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

169

Field testing solar photocatalytic detoxification on TCE-contaminated groundwater  

Microsoft Academic Search

The Solar Detoxification Field Experiment was designed to investigate the photocatalytic decomposition of organic contaminants in groundwater at a Superfund site at Lawrence Livermore National Laboratory. The process uses ultraviolet (UV) energy available in sunlight in conjunction with a photocatalyst, titanium dioxide, to decompose organic chemicals into nontoxic compounds. The destruction mechanism, as in many other advanced oxidation processes, involves

Mark S. Mehos; Craig S. Turchi

1993-01-01

170

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....

171

Groundwater contamination assessment for sustainable water supply in Kathmandu Valley, Nepal.  

PubMed

A study was carried out to assess the water quality situation of groundwater sources in Kathmandu Valley, Nepal. Groundwater has remained to be a major water supply source for a population of 1.5 million at present in the valley. The focus of this study was to evaluate the extent and sources of groundwater contamination. Water sampling was carried out in selected deep wells and shallow sources. The level of pollution was evaluated by comparing the water quality results with WHO guidelines. The major problems with the dug wells, hand pumps and spouts were found to be the elevated nitrate and mercury contents. The deep wells located on the central aquifer were found to have a serious threat of ammonia pollution. Deep wells were also found to have iron, manganese and mercury concentrations exceeding the guideline values. Multivariate statistical analysis was carried out to cluster the sampling sources and identify the common factors describing the potential sources and possible mechanisms associated with the contaminants. The results suggested that disintegration of the sediment organic matter under strong reducing environment leads to the origin of the unusual water qualities at the central confined aquifer. This process may be microbially mediated and occurs with the simultaneous reduction of species such as arsenic, iron, manganese and sulfate. Both natural and anthropogenic water quality problems were observed in the groundwater system of Kathmandu valley. Attention should be focused to consider distinct strategies to address these problems. PMID:12448463

Khatlwada, N R; Takizawa, S; Tran, T V N; Inoue, M

2002-01-01

172

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

173

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

174

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

Microsoft Academic Search

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

Michael O Rivett; Stanley Feenstra; John A Cherry

2001-01-01

175

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

176

Estimating contaminant attenuation half-lives in alluvial groundwater systems.  

PubMed

One aspect of describing contamination in an alluvial aquifer is estimating changes in concentrations over time. A variety of statistical methods are available for assessing trends in contaminant concentrations. We present a method that extends trend analysis to include estimating the coefficients for the exponential decay equation and calculating contaminant attenuation half-lives. The conceptual model for this approach assumes that the rate of decline is proportional to the contaminant concentration in an aquifer. Consequently, the amount of time to remove a unit quantity of the contaminant inventory from an aquifer lengthens as the concentration decreases. Support for this conceptual model is demonstrated empirically with log-transformed time series of contaminant data. Equations are provided for calculating system attenuation half-lives for non-radioactive contaminants. For radioactive contaminants, the system attenuation half-life is partitioned into the intrinsic radioactive decay and the concentration reduction caused by aquifer processes. Examples are presented that provide the details of this approach. In addition to gaining an understanding of aquifer characteristics and changes in constituent concentrations, this method can be used to assess compliance with regulatory standards and to estimate the time to compliance when natural attenuation is being considered as a remediation strategy. A special application of this method is also provided that estimates the half-life of the residence time for groundwater in the aquifer by estimating the half life for a conservative contaminant that is no longer being released into the aquifer. Finally, the ratio of the half-life for groundwater residence time to the attenuation half-life for a contaminant is discussed as a system-scale retardation factor which can be used in analytical and numerical modeling. PMID:17344953

Tardiff, Mark F; Katzman, Danny

2007-02-09

177

Structural diversity of organochlorine compounds in groundwater affected by an industrial point source  

Microsoft Academic Search

Groundwater samples contaminated by an industrial point source were analysed in order to reveal the structural diversity of halogenated organic contaminants. Particular focus was laid on the metabolites and derivatives related to the pesticides DDT (2,2-bis(chlorophenyl)-1,1,1-trichlorethane) and lindane (?-hexachlorocyclohexane). Additionally, a wide range of chlorinated and brominated xenobiotics were identified. These results represent a high degree of contamination with organochlorine

Kerstin Frische; Jan Schwarzbauer; Mathias Ricking

2010-01-01

178

Quantification of groundwater contamination in an urban area using integral pumping tests.  

PubMed

In this paper, the integral groundwater investigation method is used for the quantification of PCE and TCE mass flow rates at an industrialized urban area in Linz, Austria. In this approach, pumping wells positioned along control planes perpendicular to the groundwater flow direction are operated for a time period on the order of days and sampled for contaminants. The concentration time series of the contaminants measured during operation of the pumping wells are then used to determine contaminant mass flow rates, mean concentrations and the plume shapes and positions at the control planes. The three control planes used in Linz were positioned downstream of a number of potential source zones, which are distributed over the field site. By use of the integral investigation method, it was possible to identify active contaminant sources, quantify the individual source strength in terms of mass flow rates at the control planes and estimate the contaminant plume position relative to the control planes. The source zones emitting the highest PCE and TCE mass flow rates could be determined, representing the areas where additional investigation and remediation activities will be needed. Additionally, large parts of the area investigated could be excluded from further investigation and remediation activities. PMID:15610900

Bauer, S; Bayer-Raich, M; Holder, T; Kolesar, C; Müller, D; Ptak, T

2004-12-01

179

Assessing Groundwater Contamination Vulnerability at Public Water Supply Wells in California  

NASA Astrophysics Data System (ADS)

The California Aquifer Susceptibility project, sponsored by the California State Water Resources Control Board, uses a probabilistic approach to assess the vulnerability of public water supply wells to contamination by anthropogenic compounds. Sources of contamination to groundwater occur near the earth's surface, and have been present mostly since WWII. Therefore, wells that receive water that has recharged in the recent past are more likely to intercept contaminants transported by advection. The parameters that the study uses to rank wells according to vulnerability are groundwater age dates (using the tritium/helium method), stable isotopes of the water molecule (for water source determination), and analysis of low level Volatile Organic Compounds (VOCs). Results of a pilot project in which 300 public water supply wells were tested for vulnerability will be presented. Basins sampled for the study include the Livermore Valley, Santa Clara Valley, and the Sacramento Basin. Methyl-tertiary-Butyl Ether (MTBE) may be a useful time marker in groundwater basins, with water recharged after the 1980's showing traces of MTBE. Low-level detections of other VOCs such as TCE and PCE can give an early warning of a contaminant plume. When employed on a basin-scale, groundwater ages are an effective tool for identifying recharge areas, defining flowpaths, and determining the rate of transport of water and associated contaminants. Examination of these parameters also helps identify 'short circuits', whereby e.g., loss of integrity in well casing allows near surface contamination to reach 'old' (recharged >50 years ago) water. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48.

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

2001-12-01

180

Vapor Pressure Characterization to Predict Contaminant Releases from MGP Site Source Area Soils  

Microsoft Academic Search

Risk-based management of contaminated sites often requires timely screening and identification of source areas that release contaminants to groundwater and other reception of concern. Over-reliance on total concentrations often results in costly site characterization, delays in remediation, and overestimation of the soil volumes targeted for removal or treatment. Advances in diagnostic tools to accelerate source area characterization will improve the

Thomas D. Hayes; Bhupendra K. Soni

2006-01-01

181

Groundwater protection from cadmium contamination by permeable reactive barriers.  

PubMed

This work studies the reliability of an activated carbon permeable reactive barrier in removing cadmium from a contaminated shallow aquifer. Laboratory tests have been performed to characterize the equilibrium and kinetic adsorption properties of the activated carbon in cadmium-containing aqueous solutions. A 2D numerical model has been used to describe pollutant transport within a groundwater and the pollutant adsorption on the permeable adsorbing barrier (PRB). In particular, it has been considered the case of a permeable adsorbing barrier (PAB) used to protect a river from a Cd(II) contaminated groundwater. Numerical results show that the PAB can achieve a long-term efficiency by preventing river pollution for several months. PMID:18448247

Di Natale, F; Di Natale, M; Greco, R; Lancia, A; Laudante, C; Musmarra, D

2008-03-12

182

Groundwater contaminations and health perspectives in developing world case study: Gaza Strip  

Microsoft Academic Search

Groundwater is the only source of water in the Gaza Strip. The results of a 10-year monitoring program revealed that more\\u000a than 90% of the available water is not suitable for drinking purposes as a result of elevated chemical contaminants as well\\u000a as microbiological organisms. The archives of the local hospitals showed catastrophic records on diseases caused by water\\u000a directly

B. Shomar

2011-01-01

183

Impacts of antropogenic contaminants on vegetation and groundwater chemistry in a fen complex (IL)  

Microsoft Academic Search

Residential development within the watershed of a fen complex has resulted in encroachment of ground-water borne anthropogenic contaminants into 3 high quality fens. Groundwater samples were collected from peat and marl and analyzed for inorganic constituents. Height and density of Typha angustifolia L. and Scirpus acutus Muhl. were recorded in belt transects coincident with ground-water samples. Contaminant plumes from septic

V. A. Nuzzo; B. Hensel; S. Panno; K. Cartwright; I. Krapac

1993-01-01

184

Groundwater: Nature's Hidden Treasure  

NSDL National Science Digital Library

Materials presented here outline basic concepts related to groundwater, answering questions like "What is groundwater?" and "What is an aquifer?" More detailed topics include groundwater quality, sources of contamination, engineering problems presented by groundwater, and safeguards to the groundwater supply. A bibliography and links to other water-related sites are included. A French translation is available.

2001-10-05

185

Groundwater pollution source characterization of an old landfill  

Microsoft Academic Search

Only a few landfill investigations have focused on both the quantity and the quality of leachate as a source of groundwater pollution. The investigation of Vejen Landfill in Denmark included an introductionary historical survey (old maps, aerial photographs, interviews, etc.), leachate quality analysis, potential mapping of the groundwater surface below the landfill and leachate flow to surface waters and groundwater.

Peter Kjeldsen

1993-01-01

186

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

187

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 (>1mg/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

2013-07-23

188

Uranium removal from contaminated groundwater by synthetic resins.  

PubMed

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

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

2007-07-14

189

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

190

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

2012-10-30

191

Modeling the Fate of Groundwater Contaminants Resulting from Leakage of Butanol-blended Fuel.  

National Technical Information Service (NTIS)

Fuel spills and leaks from storage tanks can contaminate groundwater. Typically in groundwater, hazardous aromatic hydrocarbons like benzene are attenuated through natural processes. However, it is possible that adding butanol to gasoline will interfere w...

K. H. Vuong

2010-01-01

192

Groundwater monitoring and remediation  

SciTech Connect

Groundwater samplers are literally an effective measure of groundwater. Samples taken from groundwater reserves are analyzed in laboratories to obtain information on what pollutants, if any, are found in the source. Groundwater modeling is a computer-based method of tracking and calculating pollutant flow and migration. An emerging facet is the inclusion of risk assessment. Remediation of contaminated groundwaters is a burgeoning industry, with several remediation methods available. Air sparging is the injection of air into the contaminated groundwater, allowing release of the contaminants by aeration. Bioremediation is the process of using microorganisms or contaminant-specific organisms to render the contaminants innocuous.

Hodson, C.O.; Kilbourne, A.

1996-07-01

193

Origin of a mixed brominated ethene groundwater plume: contaminant degradation pathways and reactions.  

PubMed

On the basis of a combination of laboratory microcosm experiments, column sorption experiments, and the current spatial distribution of groundwater concentrations, the origin of a mixed brominated ethene groundwater plume and its degradation pathway were hypothesized. The contaminant groundwater plume was detected downgradient of a former mineral processing facility, and consisted of tribromoethene (TriBE), cis-1,2-dibromoethene (c-DBE), trans-1,2-dibromoethene (t-DBE), and vinyl bromide (VB). The combined laboratory and field data provided strong evidence that the origin of the mixed brominated ethene plume was a result of dissolution of the dense non-aqueous-phase liquid 1,1,2,2-tetrabromoethane (TBA) atthe presumed source zone, which degraded rapidly (half-life of 0.2 days) to form TriBE in near stoichiometric amounts. TriBE then degraded (half-life of 96 days) to form c-DBE, t-DBE, and VB via a reductive debromination degradation pathway. Slow degradation of c-DBE (half-life >220 days), t-DBE (half-life 220 days), and VB (half-life >220 days) coupled with their low retardation coefficients (1.2, 1.2, and 1.0 respectively) resulted in the formation of an extensive mixed brominated ethene contaminant plume. Without this clearer understanding of the mechanism for TBA degradation, the origin of the mixed brominated ethene groundwater contamination could have been misinterpreted, and inappropriate and ineffective source zone and groundwater remediation techniques could be applied. PMID:17593741

Patterson, Bradley M; Cohen, Elizabeth; Prommer, Henning; Thomas, David G; Rhodes, Stuart; McKinley, Allan J

2007-02-15

194

Establishing indices for groundwater contamination risk assessment in the vicinity of hazardous waste landfills in China.  

PubMed

Groundwater contamination by leachate is the most damaging environmental impact over the entire life of a hazardous waste landfill (HWL). With the number of HWL facilities in China rapidly increasing, and considering the poor status of environmental risk management, it is imperative that effective environmental risk management methods be implemented. A risk assessment indices system for HWL groundwater contamination is here proposed, which can simplify the risk assessment procedure and make it more user-friendly. The assessment framework and indices were drawn from five aspects: source term, underground media, leachate properties, risk receptors and landfill management quality, and a risk assessment indices system consisting of 38 cardinal indicators was established. Comparison with multimedia models revealed that the proposed indices system was integrated and quantitative, that input data for it could be easily collected, and that it could be widely used for environmental risk assessment (ERA) in China. PMID:22410106

Li, Ying; Li, Jinhui; Chen, Shusheng; Diao, Weihua

2012-03-10

195

Soil Activation and Groundwater Contamination at Brookhaven National Laboratory, Upton, New York  

SciTech Connect

In November 1999, tritium (H-3) was detected in the groundwater near one of Brookhaven National Laboratory's (BNL) accelerator experiments at concentrations above the 20,000 pico curie per liter (pCi/L) Maximum Contaminant Level (MCL). Sodium-22 (Na-22) was also detected in the groundwater, but at concentrations well below the 400 pCi/L MCL. An investigation into the source of the contamination revealed that the tritium and sodium-22 originated from activated soil shielding located adjacent to the g-2 target building where approximately five percent of the beam was inadvertently striking one of the beam-line magnets. Rainwater was able to infiltrate the activated soils and carry the tritium and sodium-22 into the groundwater. The highest tritium level detected in groundwater during the 1999 investigation was nearly 1.8 million pCi/L. To prevent additional rainwater infiltration into the activated soil shielding, a concrete cap was constructed over the soil shielding in December 1999. Other corrective actions included refocusing the beam and improved beam loss monitoring to reduce additional soil activation, storm-water management improvements, and additional groundwater monitoring. From 2001 through 2004, three high concentration zones (or slugs) of tritium were observed passing through the groundwater monitoring well network immediately down-gradient of the source area, with a maximum observed concentration of 3.4 million pCi/L. Some of the tritium that was previously leached from the activated soil was trapped in the vadose (unsaturated) zone soils directly above the water table after then cap was installed. A portion of this residual tritium was later mobilized into the groundwater during periods of high groundwater table elevations, which can occur following heavy seasonal rainfall. Monitoring results for the past two years indicate that the amount of tritium being released from the vadose zone is decreasing, with tritium concentrations consistently below 100,000 pCi/L. The tritium plume is currently 550 meters long, and is located entirely in the central portion of the BNL site. The plume has not impacted any of the Laboratory's drinking water supply wells. Contaminant transport modeling suggests that the tritium plume will attenuate entirely in the central portion of the BNL site by years 2010-2015. (authors)

Paquette, D.E.P.G. [Brookhaven National Laboratory, Upton, NY (United States); Chek Beng, Ng P.E. [New York State Department of Environmental Conservation, Albany, NY (United States); Penny, G. [Federal Project Director, United States Department of Energy - Brookhaven Site Office, Upton, NY (United States)

2008-07-01

196

A Quasi3D transport model for simulation of non-point source contamination in large domains  

Microsoft Academic Search

In this study we propose a computationally efficient model to predict Non-Point Source (NPS) contamination in large groundwater bodies. The model consists of a 3D, highly detailed, groundwater flow model, combined with a quasi-3D contaminant transport model. In order to calculate a detailed groundwater flow field for large domains (i.e. >30 km2) we developed a two-step modeling approach: First the

G. Kourakos; F. Klein; T. Harter

2010-01-01

197

Phytoremediation of contaminated soils and groundwater: lessons from the field  

SciTech Connect

The use of plants and associated microorganisms to remove, contain, inactivate, or degrade harmful environmental contaminants (generally termed phytoremediation) and to revitalize contaminated sites is gaining more and more attention. In this review, prerequisites for a successful remediation will be discussed. The performance of phytoremediation as an environmental remediation technology indeed depends on several factors including the extent of soil contamination, the availability and accessibility of contaminants for rhizosphere microorganisms and uptake into roots (bioavailability), and the ability of the plant and its associated microorganisms to intercept, absorb, accumulate, and/or degrade the contaminants. The main aim is to provide an overview of existing field experience in Europe concerning the use of plants and their associated microorganisms whether or not combined with amendments for the revitalization or remediation of contaminated soils and undeep groundwater. Contaminations with trace elements (except radionuclides) and organics will be considered. Because remediation with transgenic organisms is largely untested in the field, this topic is not covered in this review. Brief attention will be paid to the economical aspects, use, and processing of the biomass. It is clear that in spite of a growing public and commercial interest and the success of several pilot studies and field scale applications more fundamental research still is needed to better exploit the metabolic diversity of the plants themselves, but also to better understand the complex interactions between contaminants, soil, plant roots, and microorganisms (bacteria and mycorrhiza) in the rhizosphere. Further, more data are still needed to quantify the underlying economics, as a support for public acceptance and last but not least to convince policy makers and stakeholders (who are not very familiar with such techniques).

Vangronsveld, J.; van der Lelie, D.; Herzig, R.; Weyens, N.; Boulet, J.; Adriaensen, K.; Ruttens, A.; Thewys, T.; Vassilev, A.; Meers, E.; Nehnevajova, E.; Mench, M.

2009-11-01

198

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

NASA Astrophysics Data System (ADS)

The aim of the project is to clarify and characterize the probable sources of increased selenium contamination in groundwater at Suchomasty Village located 35 km SW of Prague. The village is supplied by drinking water from a 25 m deep bore-hole with catchment formed by Ordovician to Devonian mostly sedimentary rocks of the Prague Basin. The selenium concentrations have suddenly exceeded limit 10 ?g/l up to 123 ?g/l since 2007. Several possible selenium sources were predicted in the bore-hole catchment: (i) Paleozoic bedrock, (ii) ash from coal power stations used for arable soil improvement, (iii) selenium-accumulating plants used as manure and (iv) an old rubbish dump. Samples of bedrock, soil and anthropogenic deposits were collected for selenium concentration analyses from five excavated test-holes up to 2.5 m deep. Concentration of selenium was analyzed in month intervals in the water from the bore-hole and from a shallow well. Groundwater residence time was determined using tritium and SF6. Oxygen isotopic composition could help us to better understanding of groundwater dynamics. The AAS and ICP-OES analyses of bedrock and soils revealed no distinct increased selenium concentrations. Devonian limestone contains 5 mg/kg, field soil with ash up to 25 mg/kg and selenium-accumulating plants 6 mg/kg. The highest selenium concentration was found in material from the dump (up to 45 mg/kg) stored in abandoned quarry located 1 km away from the bore-hole. We assume the dump is a main potential source of selenium contamination. Although the average groundwater residence time is up to 20 years, the selenium contamination has reached the bore-hole in 18 month since dump reclamation. It is possible that the fast groundwater circulation has been using more karstified rock. Based on obtained data the selenium is hold in suspension transported by groundwater. Filtration of drinking water should help in a case of continuing long-term increase of selenium contamination. Project is supported by the Ministry of the Environment CR (SP/2e1/153/07).

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

2010-05-01

199

Bacterial sulfate reduction limits natural arsenic contamination in groundwater  

NASA Astrophysics Data System (ADS)

Natural arsenic contamination of groundwater, increasingly recognized as a threat to human health worldwide, is characterized by arsenic concentrations that vary sharply over short distances. Variation in arsenic levels in the Mahomet aquifer system, a regional glacial aquifer in central Illinois, appears to arise from variable rates of bacterial sulfate reduction in the subsurface, not differences in arsenic supply. Where sulfate-reducing bacteria are active, the sulfide produced reacts to precipitate arsenic, or coprecipitate it with iron, leaving little in solution. In the absence of sulfate reduction, methanogenesis is the dominant type of microbial metabolism, and arsenic accumulates to high levels.

Kirk, Matthew F.; Holm, Thomas R.; Park, Jungho; Jin, Qusheng; Sanford, Robert A.; Fouke, Bruce W.; Bethke, Craig M.

2004-11-01

200

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

201

Effects of hydrogeological characteristics on the attenuation of TCE- contaminated groundwater plume in Wonju, Korea  

NASA Astrophysics Data System (ADS)

Key attributes to temporal and seasonal variation of TCE and its daughter products at an industrial complex, Wonju, Korea were evaluated using groundwater monitoring data along with data from field investigations. The purpose of this study is to analyze the hydrogeological characteristics and seasonal variations associated with the plume attenuation of TCE and its daughter products. Study site is underlain by Jurassic biotite granite which is covered by quarternary alluvium. Average hydraulic conductivities of alluvial layer and bed rock are 2.4*10-3 and 2.0*10-4 cm/sec, respectively. The alluvial layer acts as a main layer for TCE contaminated groundwater flow. Average annual rainfall in this study area is 1,414 mm/year and over 65% of annual precipitation is concentrated in July, August and September. Seasonal variation of TCE contaminant plume shape near the source area and downgradient area are different depending on the surface recharge characteristics. The downgradient area is not much affected by seasonal rainfalls, but TCE contaminant concentration in the source area is greatly affected by the seasonal rainfalls. The water table fluctuation at the source area was maximally 1.95 m but the downgradient at industrial complex area was 0.9 m during concentrated rainfall events. General tendency of TCE contaminant concentrations at source zone was highly fluctuated and temporally increased due to rainfall events. As a result, due to the limited recharge and time-lag of the impact of precipitation in summer season, the TCE contaminant plume distribution and the impact of seasonal effect diminish as the distance from the source area increases. Keywords : TCE, recharge, precipitation, plume attenuation, seasonal variation

Lee, H.; Yang, J.; Lee, K.

2010-12-01

202

Large scale modelling of groundwater contamination from nitrate leaching  

Microsoft Academic Search

Groundwater pollution from non-point sources, such as nitrate from agricultural activities, is a problem of increasing concern. Comprehensive modelling tools of the physically based type are well proven for small-scale applications with good data availability, such as plots or small experimental catchments. The two key problems related to large-scale simulation are data availability at the large scale and model upscaling\\/aggregation

J. C. Refsgaard; M. Thorsen; J. B. Jensen; S. Kleeschulte; S. Hansen

1999-01-01

203

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

204

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

2011-07-20

205

Hexavalent chromium contamination in groundwaters of Thiva Basin, central Greece.  

PubMed

There is an increasing concern regarding elevated levels of Cr(VI) in the environment due to its higher mobility and toxicity compared to the trivalent form. Anomalous hexavalent chromium concentrations (up to 212 ?g/L) were determined in irrigated groundwaters from the wider area of Thiva Basin (central Greece), frequently exceeding the permissible limit for human consumption (50 ?g/L for total Cr). Based on the spatial distribution of Cr(VI) values, two groups of groundwater samples were distinguished, possibly reflecting different natural and/or anthropogenic factors that govern the levels of contamination. The first group is spatially located northwards of Thiva town and is consisted of concentrations that range from 13 to 212 ?g/L (median 58 ?g/L), while the second group is located near Mouriki village and Cr(VI) values range from <9 to 14 ?g/L. The Cr(VI) chemical anomalies represent an important social problem because the agricultural products of this region are a major vegetable supply for Greece, bringing up the urgent need to evaluate the health effects associated with Cr(VI) exposure by ingesting the potentially contaminated foods. PMID:22996651

Tziritis, Evangelos; Kelepertzis, Efstratios; Korres, George; Perivolaris, Dimitrios; Repani, Stella

2012-09-21

206

Contamination of Groundwater in California by MTBE: How Do We Constrain the Problem?  

NASA Astrophysics Data System (ADS)

The purpose of this project is to characterize and assess the contamination of groundwater in California by methyl tertiary-butyl ether (MTBE). Field data were collected by reviewing 85 leaking underground storage tank cases in Orange County, California in the Santa Ana Regional Quality Control Board Region 8. Our analytical study shows that the concentration of MTBE ranged from a minimum of 370 ppb to a maximum of 1,200,000 ppb contamination levels. The state of California considers levels >5 ppb of MTBE to be a concern. In order to estimate the length of the MTBE plumes, MTBE concentrations from the source well and one or more down-gradient monitoring wells were integrated into an Excel program based on the Domenico analytical model (1987). After the calibrations were estimated by adjusting values in longitudinal dispersivity, groundwater velocity and degradation rate constant, the horizontal MTBE plume length (maximum distance between source well and plume edge with a MCL <5pbb) was predicted. The data collected produced plume lengths ranging from 69 feet to 2790 feet. The mean calculated plume length was 760 feet. The future objective of the project is to present a comparative analysis of MTBE groundwater contamination between different hydrogeologic settings (e.g., fractured-controlled vs. alluvial-controlled) by reviewing underground storage tank cases in several regions across the state (e.g., California State Water Resources Control Regional Boards 1 (North Coast), 2 (San Francisco Bay), 5 (Central Valley), 6 (Lahontan), 8 (Santa Ana), and 9 (San Diego). The results from this project will (1) further characterize the nature of MTBE plumes, (2) provide data that can be used in future investigation, remediation and monitoring of MTBE plume sites, and (3) lead to refinement of groundwater transport models for MTBE plumes.

Nugal, K. A.; Tong, W.; McNulty, B. A.

2006-12-01

207

Vapor intrusion from entrapped NAPL sources and groundwater plumes  

NASA Astrophysics Data System (ADS)

Volatile organic compounds (VOC) are commonly found entrapped as non-aqueous phase liquids (NAPLs) in the soil pores or dissolved in groundwater at industrial waste sites and refineries. Vapors emitted from these contaminant sources readily disperse into the atmosphere, into air-filled void spaces within the soil, and migrate below surface structures, leading to the intrusion of contaminant vapors into indoor air through basements and other underground structures. This process referred to as vapor intrusion (VI) represents a potential threat to human health, and is a possible exposure pathway of concern to regulatory agencies. To assess whether this exposure pathway is present, remediation project managers often rely in part on highly simplified screening level models that do not take into consideration the complex flow dynamics controlled by subsurface heterogeneities and soil moisture conditions affected by the mass and heat flux boundary conditions at the land/atmospheric interface. A research study is under way to obtain an improved understanding of the processes and mechanisms controlling vapor generation from entrapped NAPL sources and groundwater plumes, their subsequent migration through the subsurface, and their attenuation in naturally heterogeneous vadose zones under various natural physical, climatic, and geochemical conditions. Experiments conducted at multiple scales will be integrated with analytical and numerical modeling and field data to test and validate existing VI theories and models. A set of preliminary experiments where the fundamental process of vapor generation from entrapped NAPL sources and dissolved plumes under fluctuating water were investigated in small cells and two-dimensional test tanks. In another task, intermediate scale experiments were conducted to generate quantitative data on how the heat and mass flux boundary conditions control the development of dynamic VI pathways. The data from the small cell and tank experiments were used to test whether the equilibrium mass transfer assumption is valid under normal pressure gradients generated from atmospheric pressure variations and fluctuations of pressure in the building. The data from the intermediate scale airflow experiments were used to validate a numerical models based on a multi-physics simulator. These analyses will help us to evaluate the significance of the boundary conditions at the land/ atmospheric interface on the development of dynamic air pathways that transmit vapors from contaminant sources to buildings. The experimental findings and models are used to design a set of experiments in a coupled wind tunnel/ porous media test facility where integrated models of atmospheric and shallow subsurface interaction and up-scaling theories will be tested and validated.

Illangasekare, Tissa H.; Sakaki, Toshihiro; Christ, John; Petri, Bejamin; Sauck, Carolyn; Cihan, Abdullah

2010-05-01

208

Chaotic Advection, Fluid Spreading, and Groundwater Contaminant Plumes  

NASA Astrophysics Data System (ADS)

In situ remediation of contaminated groundwater requires degradation reactions at the interface between the contaminant plume and an injected treatment solution containing chemical or biological amendments. Therefore a promising approach to accelerate in situ remediation is to elongate the interface between the contaminant plume and treatment solution through fluid spreading. The literature on chaotic advection describes how to accomplish spreading in laminar flows, which lack the turbulent eddies that provide spreading in streams or engineered reactors. A key result from the literature on chaotic advection is that spreading is inherent in the vicinity of certain periodic points, which are points to which fluid particles return in successive iterations of chaotic flows. Specifically, spreading is enhanced near the stable and unstable manifolds associated with hyperbolic periodic points. We investigate the transient flow created with a four-well system in which wells are operated sequentially as either injection wells or extraction wells. In particular, we identify the periodic points and demonstrate that fluid spreading occurs nearby. For appropriately designed injection and extraction sequences, the periodic points are located near the interface between the contaminant plume and treatment solution, leading to elongation of the interface, with expected benefits of enhanced reaction and accelerated remediation.

Neupauer, R. M.; Mays, D. C.

2011-12-01

209

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

210

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

PubMed Central

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

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

2006-01-01

211

Application of Principal Component Analysis and Clustering to Spatial Allocation of Groundwater Contamination  

Microsoft Academic Search

This paper presented a case study that conventional statistical methods were applied to mining environmental monitoring database to extract the patterns of groundwater contamination. Eighty-four monitoring wells located at Chianan Plain groundwater subregion in Taiwan were selected as study area, and lab data of routine groundwater analysis including pH, EC, hardness, TDS, TOC, ammonia, nitrate, chloride, sulfate, Fe, Mn, As,

Ting-nien Wu; Chiu-sheng Su

2008-01-01

212

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

PubMed

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

Bedekar, Vivek; Neville, Christopher; Tonkin, Matthew

2012-06-20

213

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

USGS Publications Warehouse

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

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

2002-01-01

214

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

Microsoft Academic Search

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

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

2010-01-01

215

Physical and numerical modeling results for controlling groundwater contaminants following shutdown of underground coal gasification processes  

Microsoft Academic Search

Groundwater contamination has resulted from some of in-situ gasification field tests, and concern over groundwater contamination may hamper commercialization. When UCG recovery operations are terminated, energy remains stored as heat in the adjacent masses of rock and coal ash, and this energy is transferred into the coal seam. Coal continues to pyrolyze as a result of the transferred energy; the

J. E. Boysen; C. G. Mones; R. R. Glaser; S. Sullivan

1987-01-01

216

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

217

Groundwater contamination by nitrates associated with intensive potato culture in Québec  

Microsoft Academic Search

In rural areas, groundwater contamination by nitrates is a problem related to the spreading of organic and chemical fertilizers by farmers and, to some extent, to effluents from domestic sewage systems. Health effects of groundwater contamination by nitrates have been assessed several times and may lead to important consequences for infants. Following pressures from citizens in 1990, a survey of

P Levallois; M Thériault; J Rouffignat; S Tessier; R Landry; P Ayotte; M Girard; S Gingras; D Gauvin; C Chiasson

1998-01-01

218

Assessment of groundwater contamination by nitrate leaching from intensive vegetable cultivation using geographical information system  

Microsoft Academic Search

This study employed the Geographical Information System (GIS) technology to investigate nitrate contamination of groundwater by agrochemical fertilizers in the Kakamigahara Heights, Gifu Prefecture, central Japan. Thematic information and chemical data of groundwater from the Heights were analyzed in a GIS environment to study the extent and variation of nitrate contamination and to establish spatial relationships with responsible land use

Insaf S. Babiker; Mohamed A. A. Mohamed; H. Terao; Kikuo Kato; Keiichi Ohta

2004-01-01

219

PERMEABLE REACTIVE BARRIER STRATEGIES FOR REMEDIATION OF ARSENIC-CONTAMINATED GROUNDWATER  

EPA Science Inventory

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

220

Evaluation of groundwater contamination in a coastal area of south-eastern Sicily  

Microsoft Academic Search

This investigation was under taken to evaluate the groundwater resources contamination due to intensive agricultural practices (particularly greenhouses). The study-area is located in the coastal area of the Ragusa province (South-East Sicily), where numerous existing greenhouses may cause the contamination of groundwater systems (unconfined and confined aquifers) beneath the cropped land. The pollution risk is mainly related with the seepage

Feliciana Licciardello; Maria Lucia Antoci; Luana Brugaletta; Giuseppe Luigi Cirelli

2011-01-01

221

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

Microsoft Academic Search

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

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

2007-01-01

222

Nitrogen Transport from Atmospheric Deposition and Contaminated Groundwater to Surface Waters on a Watershed Scale.  

NASA Astrophysics Data System (ADS)

Increasing nitrate contamination of surface water and groundwater is a problem in regions of intensive agriculture and near urban wastewater treatment facilities that land-apply biosolids. The 15N composition of groundwater nitrate has been used to assess potential sources of nitrogen contamination. But because of transformations of nitrogen within the hydrological system, contaminant source tracing with nitrogen isotopes has been complicated. We have used multiple isotope tracers of nitrate (15N, 17O, 18O) to distinguish between different N contamination sources, areas of extensive denitrification, and areas of atmospheric N deposition on the NC coastal plain and piedmont. Areas of extensive denitrification are often associated with hydric soils. The distribution of hydric soils on field and watershed scales correlates with surface and ground water quality degradation. The distribution of hydric soils may thus be an important element in prediction of environmental impacts of agriculture. Transport of atmospheric nitrogen into surface waters as indicated by the 17O of nitrate is event driven. Most surface waters in our study area have low concentrations of nitrate 17O, indicating that the importance of atmospheric N has been overestimated in riverine N flux from watersheds. However, when the atmospheric N flux is integrated over a discharge event, atmospheric N can approach 25 % of the total N riverine flux in urban areas. More work needs to be completed with multiple isotopic tracers and GIS analysis on watershed scales. Using a GIS / isotope approach, areas where the isotopic signature has been affected by denitrification can be predicted, and remediation efforts can be focused on potential areas of N contamination where extensive denitrification is unlikely to occur.

Showers, W. J.; Demaster, D.

2005-12-01

223

EFFECTS OF GROUNDWATER VELOCITY ON SAMPLING INTERVALS FOR CONTAMINANT-DETECTION NETWORKS IN AQUIFERS  

Microsoft Academic Search

This study evaluated how groundwater velocity affects the sampling interval of a groundwater monitoring network and its ability to intercept contaminant plumes before reaching a buffer zone boundary. A computer simulation model tested the detection capability of a groundwater-monitoring network in different groundwater velocity settings. A 0.4-m\\/d velocity registered a maximum sampling interval of four months. By comparison, decreasing the

Paul F. Hudak

2001-01-01

224

PRIORITIZATION OF GROUND WATER CONTAMINANTS AND SOURCES  

EPA Science Inventory

The objective of this research was to identify chemical, physical, bacteriological, and viral contaminants, and their sources, which present the greatest health threat in public ground water supplies in the USA; and to classify (prioritize) such contaminants and relative to their...

225

Groundwater contamination by nitrates associated with intensive potato culture in Québec.  

PubMed

In rural areas, groundwater contamination by nitrates is a problem related to the spreading of organic and chemical fertilizers by farmers and, to some extent, to effluents from domestic sewage systems. Health effects of groundwater contamination by nitrates have been assessed several times and may lead to important consequences for infants. Following pressures from citizens in 1990, a survey of well water quality around potato fields of the Portneuf county (Québec) found that nitrate contamination was frequently above the 10 mg-N/1 standard. Because this first survey was limited to areas of intensive potato culture, it was not possible to evaluate the real impact on the groundwater quality for the whole county and the subsequent public health intervention was spread over the entire region. A second survey was carried out in 1995 to reevaluate the situation using random sampling methods. This latter study took into account drinking water habits of the population, the relative importance of potato culture as a source of nitrogen loading, the effects of soil types, and waste-water disposal systems as well as land use on nitrate concentration in private well water. The data analysis was carried out by combining GIS and statistical methods to test hypotheses about the spatial relationship linking measured nitrate concentrations with their immediate environment. This paper presents the major findings from this second study which confirm the impact of intensive potato culture on groundwater nitrate concentrations, mainly localized in sandy soil areas within 2 km of fields. Finally, it illustrates the usefulness of GIS to focus public health interventions. PMID:9695174

Levallois, P; Thériault, M; Rouffignat, J; Tessier, S; Landry, R; Ayotte, P; Girard, M; Gingras, S; Gauvin, D; Chiasson, C

1998-06-30

226

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.

227

Modeling uranium transport in acidic contaminated groundwater with base addition  

SciTech Connect

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

Zhang, Fan [Institute of Tibetan Plateau Research, Chinese Academy of Sciences; Luo, Wensui [ORNL; Parker, Jack C. [University of Tennessee, Knoxville (UTK); Brooks, Scott C [ORNL; Watson, David B [ORNL; Jardine, Philip [University of Tennessee, Knoxville (UTK); Gu, Baohua [ORNL

2011-01-01

228

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

229

Risk Management of Groundwater Contamination in a Multiobjective Framework  

NASA Astrophysics Data System (ADS)

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

Kaunas, John R.; Haimes, Yacov Y.

1985-11-01

230

40 CFR 257.22 - Ground-water monitoring systems.  

Code of Federal Regulations, 2010 CFR

...detection of ground-water contamination in the uppermost aquifer...including other sources of contamination and their cumulative...that ensures detection of groundwater contamination in the uppermost...

2010-07-01

231

40 CFR 257.22 - Ground-water monitoring systems.  

Code of Federal Regulations, 2010 CFR

...detection of ground-water contamination in the uppermost aquifer...including other sources of contamination and their cumulative...that ensures detection of groundwater contamination in the uppermost...

2009-07-01

232

MDL Groundwater software: Laplace transforms and the De Hoog algorithm to solve contaminant transport equations  

Microsoft Academic Search

The Modeling with De Hoog and Laplace (MDL) Groundwater software is a contaminant transport-modeling program offering a suite of models suitable for simulating subsurface transport of contaminants (i.e., chromium and organics), biotracers, and microorganisms. The MDL Groundwater software provides solutions to a wide range of contaminant transport models that do not have closed-form analytical solutions. The models are solved in

Khansith Boupha; Jennifer M. Jacobs; Kirk Hatfield

2004-01-01

233

MDL Groundwater software: Laplace transforms and the De Hoog algorithm to solve contaminant transport equations  

Microsoft Academic Search

The Modeling with De Hoog and Laplace (MDL) Groundwater software is a contaminant transport-modeling program offering a suite of models suitable for simulating subsurface transport of contaminants (i.e., chromium and organics), biotracers, and microorganisms. The MDL Groundwater software provides solutions to a wide range of contaminant transport models that do not have closed-form analytical solutions. The models are solved in

Jennifer M. Jacobs; Kirk Hatfield

234

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

USGS Publications Warehouse

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

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

2006-01-01

235

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

236

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

237

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

PubMed

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

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

2012-01-01

238

URBAN GROUNDWATER POLLUTION IN TURKEY  

Microsoft Academic Search

Groundwater pollution in Turkey is examined. Important natural sources of groundwater pollution identified include seawater intrusion, discharges from contaminated lakes and streams, geothermal waters, and dissolution of minerals. The major sources of anthropogenic groundwater contamination identified are: agricultural pesticides and fertilizers; mining waste products; industrial waste; on?site septic tank systems; and pollution from poorly constructed wells. Although industrial waste and

Alper Baba; Onder Ayyildiz

239

Assessment of groundwater quality and contamination problems ascribed to an abandoned uranium mine (Cunha Baixa region, Central Portugal)  

NASA Astrophysics Data System (ADS)

The assessment of groundwater quality and its environmental implications in the region of the abandoned Cunha Baixa uranium mine (Central Portugal) was carried out from 1995 to 2004. Shallow groundwater is the major water supply source for irrigation in the neighbourhood of Cunha Baixa village. Water samples from the mine site as well as from private wells were collected in order to identify the mining impact on water composition, the extent of contamination and the seasonal and temporal groundwater quality variations. Some of the sampled private wells contain waters having low pH (<4.5 5) and high values of EC, TDS, SO4, F, Ca, Mg, Al, Mn, Ni, U, Zn and 226Ra. The wells located through the ESE WSE groundwater flow path (1 km down gradient of the mining site) display the most contaminated water. In the summer season, the levels of SO4, Al, Mn, and U were 50 120 times higher than those registered for uncontaminated waters and exceeded the quality limits for irrigation purposes, presenting soil degradation risks. Nevertheless, this study indicates that groundwater contamination suffered a small decrease from 1999 to 2004. The bioaccumulation of toxic metals such as Al, Mn, and U within the food chain may cause a serious health hazard to the Cunha Baixa village inhabitants.

Neves, O.; Matias, M. J.

2008-02-01

240

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

241

A multivariate statistical approach to spatial representation of groundwater contamination using hydrochemistry and microbial community profiles.  

PubMed

Managers of landfill sites are faced with enormous challenges when attempting to detect and delineate leachate plumes with a limited number of monitoring wells, assess spatial and temporal trends for hundreds of contaminants, and design long-term monitoring (LTM) strategies. Subsurface microbial ecology is a unique source of data that has been historically underutilized in LTM groundwater designs. This paper provides a methodology for utilizing qualitative and quantitative information (specifically, multiple water quality measurements and genome-based data) from a landfill leachate contaminated aquifer in Banisveld, The Netherlands, to improve the estimation of parameters of concern. We used a principal component analysis (PCA) to reduce nonindependent hydrochemistry data, Bacteria and Archaea community profiles from 16S rDNA denaturing gradient gel electrophoresis (DGGE), into six statistically independent variables, representing the majority of the original dataset variances. The PCA scores grouped samples based on the degree or class of contamination and were similar over considerable horizontal distances. Incorporation of the principal component scores with traditional subsurface information using cokriging improved the understanding of the contaminated area by reducing error variances and increasing detection efficiency. Combining these multiple types of data (e.g., genome-based information, hydrochemistry, borings) may be extremely useful at landfill or other LTM sites for designing cost-effective strategies to detect and monitor contaminants. PMID:16245827

Mouser, Paula J; Rizzo, Donna M; Röling, Wilfred F M; Van Breukelen, Boris M

2005-10-01

242

In-situ characterization of wastewater flow and transport from at-grade line sources to shallow groundwater  

NASA Astrophysics Data System (ADS)

A better understanding of multidimensional unsaturated and saturated flow and transport under boundary conditions typical of on-site wastewater disposal systems is required to assess the risk to groundwater contamination. The main objective of this research is to characterize in-situ wastewater flow and transport from at-grade line sources on a shallow groundwater conditions. The research site was conducted at Wetaskiwin Rest Stop, Alberta, Canada, where ultraviolet disinfected wastewater has been disposed off to the ground via pressurized at-grade line sources since 2007. The site was characterized for wastewater plume and temporal groundwater fluctuation by using Electromagnetic induction (EM31) and (EM38); and by grid of 74 water table wells, 14 piezometers and 11 transducers. Groundwater was analyzed for selected tracers (pH, EC and Cl) and some microbiology (e.g. E. coli). From the results wastewater plume was identified; and wastewater plume center of mass and average flow direction were estimated. Along the horizontal plume center of mass, 30 monitoring wells in 10 nests and 31 temperature sensors in 5 nests were installed to get vertical resolution of the wastewater plume and to track contaminant transport over time. Results, implications and plans for future investigations will be presented. The research output will benefit future research on contaminant fate and transport and groundwater risk assessment plans. Key words: On-site wastewater treatment/disposal system, Wastewater plume, Groundwater contamination.

Weldeyohannes, A. O.; Kachanoski, R. G.; Dyck, M. F.

2011-12-01

243

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

PubMed

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

Wang, Xiaolin; Deshusses, Marc A

2006-05-30

244

Application of multi-isotope ratios to study the source and quality of urban groundwater in Metro Manila, Philippines  

Microsoft Academic Search

To characterize water quality in terms of dissolved elements and to investigate both the origin of the water and the source and behavior of groundwater contaminants in Metro Manila, 33 water (groundwater and surface water) samples were analyzed for ion and element concentrations, H and O isotope ratios (?D-H2O and ?18O-H2O), SO42- isotope ratios (?34S-SO42- and ?18O-SO42-), and Sr isotope

Takahiro Hosono; Fernando Siringan; Tsutomu Yamanaka; Yu Umezawa; Shin-ichi Onodera; Takanori Nakano; Makoto Taniguchi

2010-01-01

245

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

Microsoft Academic Search

Alluvial groundwaters in the area where intensive agricultural activity takes place were geochemically investigated to evaluate factors regulating groundwater quality of alluvial aquifers. For this study, 55 groundwater samples were taken from the uniformly distributed irrigation wells and were classified into three distinct groups according to their geochemical characteristics. This study reveals that the groundwater quality and the geochemical characteristics

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

2004-01-01

246

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

247

Discussion Regarding Sources and Ages of Groundwater in Southeastern California  

SciTech Connect

A planned groundwater storage project for future drought relief has been assessed in the Fenner Gap area of the Fenner, Cadiz, and Bristol watershed region of southeastern California. Questions regarding the source and age of groundwater beneath the proposed project area were resolved using natural isotope abundances measured at LLNL. The report presents data, briefly summarizes conclusions of that data, and records correspondence with the sponsor Geosciences Support Services Inc.

Davisson, M.L.

2000-03-03

248

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

249

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

250

Assessment of nitrogen contamination of groundwater in paddy and upland fields  

Microsoft Academic Search

This study aims to assess the nitrogen contamination of groundwater in paddy and upland fields. A reactive chemical transport\\u000a model PHREEQC and a variable saturated groundwater flow and transport model FEMWATER were used to evaluate the vertical transport\\u000a of nitrogen compound in various soil types of paddy and upland. The shallow groundwater quality monitoring data of 2003, 2006,\\u000a 2009 in

Y. H. Kao; C.-W. Liu; C. S. Jang; S. W. Zanh; K. H. Lin

2011-01-01

251

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...

252

Pilot-scale study of the solar detoxification of VOC-contaminated groundwater.  

National Technical Information Service (NTIS)

The Solar Detoxification Field Experiment was designed to investigate the photocatalytic decomposition of organic contaminants in groundwater at a Superfund site at Lawrence Livermore National Laboratory (LLNL). The process uses ultraviolet (UV) energy, a...

M. Mehos C. Turchi J. Pacheco A. J. Boegel T. Merrill

1992-01-01

253

Methods of Minimizing Ground-Water Contamination from In situ Leach Uranium Mining: Final Report.  

National Technical Information Service (NTIS)

This is the final report of a research project dealing with methods of minimizing ground-water contamination from in situ leach uranium mining. Field work and laboratory experiments were conducted to identify excursion indicators for monitoring purposes d...

W. J. Deutsch W. J. Martin L. E. Eary R. J. Serne

1985-01-01

254

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

EPA Science Inventory

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

255

Development and Applications of Two Finite Element Groundwater Flow and Contaminant Transport Models: FEWA And FEMA.  

National Technical Information Service (NTIS)

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 (F...

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

1985-01-01

256

Biodegradation of Creosote and Pentachlorophenol in Contaminated Groundwater: Chemical and Biological Assessment.  

National Technical Information Service (NTIS)

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...

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

1991-01-01

257

In Situ Chemical Oxidation for Remediation of Contaminated Groundwater. Frequently Asked Questions.  

National Technical Information Service (NTIS)

This document contains a set of frequently asked questions (FAQ) along with short answers concerning the application of in situ chemical oxidation (ISCO) for remediation of contaminated groundwater. This FAQ guide is designed to provide an overview of the...

M. Crimi

2010-01-01

258

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...

259

BIODEGRADATION OF CREOSOTE AND PCP IN CONTAMINATED GROUNDWATER: CHEMICAL AND BIOLOGICAL ASSESSMENT  

EPA Science Inventory

Shake flask studies examined 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 (ACW) superfund site, Pensacola, Florida. he ability of soil microorgani...

260

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

Microsoft Academic Search

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

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

1985-01-01

261

Granular activated carbon pilot treatment studies for explosives removal from contaminated groundwater  

Microsoft Academic Search

Manufacturing activities at Army Ammunition Plants (AAPs) result in the production of organic wastewaters that contain both explosive residues and other organic chemicals. As a result of past waste practices at such plants, explosive residues may leach through the soil and contaminate groundwater. Two pilot studies were performed to evaluate the use of granular activated carbon (GAC) to treat groundwater

W. J. Wujcik; W. L. Lowe; P. J. Marks; W. E. Sisk

1992-01-01

262

Quantification of groundwater contamination in an urban area using integral pumping tests  

Microsoft Academic Search

In this paper, the integral groundwater investigation method is used for the quantification of PCE and TCE mass flow rates at an industrialized urban area in Linz, Austria. In this approach, pumping wells positioned along control planes perpendicular to the groundwater flow direction are operated for a time period on the order of days and sampled for contaminants. The concentration

S. Bauer; M. Bayer-Raich; T. Holder; C. Kolesar; D. Müller; T. Ptak

2004-01-01

263

Chemical modifications of groundwater contaminated by recharge of treated sewage effluent  

Microsoft Academic Search

Long-term monitoring of the chemical composition of recharge sewage effluent and associated contaminated groundwater from the Dan Region Sewage Reclamation Project shows, after 16 years of recharge operation, the presence of a distinct saline plume (up to 400 mg\\/l Cl), extending 1600 m downgradient in the Coastal Plain aquifer of Israel. The recorded electrolyte composition of groundwater in the vicinity

Avner Vengosh; Rami Keren

1996-01-01

264

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

Microsoft Academic Search

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

Xiaodong Zhang; Christine W. Chan; Gordon Huang

2005-01-01

265

Groundwater redox conditions and conductivity in a contaminant plume from geoelectrical investigations  

Microsoft Academic Search

Accurate mapping of the electrical conductivity and of the redox potential of the groundwater is important in delineating the shape of a contaminant plume. A map of redox potential in an aquifer is indicative of biodegradation of organic matter and of concentrations of redox-active components; a map of electrical conductivity provides information on the mineralisation of the groundwater. Both maps

V. Naudet; A. Revil; E. Rizzo; J.-Y. Bottero; P. Bégassat

2004-01-01

266

Characterization of Microbial Communities from Pristine and Chlorinated-Ethene-Contaminated Landfill Groundwater  

SciTech Connect

Molecular, phospholipid fatty acid analysis (PLFA), and substrate utilization (BIOLOG) techniques were used to assess structural and functional differences between microbial communities from a chlorinated-ethene (CE)-contaminated groundwater at a sanitary landfill. The information will be used to evaluate natural attenuation of the associated CE plume. Two groundwater-monitoring wells were tested.

Brigmon, R.L.

2002-05-17

267

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

268

A statistical F test for the natural attenuation of contaminants in groundwater.  

PubMed

Natural attenuation (NA) is a catchall explanation for the overall decay and slowed movement of the contaminants in the subsurface. One direct support to NA is to demonstrate that contaminant concentrations from monitoring wells located near the source are decreasing over time. The decrease is summarily expressed in terms of an apparent half-life that is determined from the line best fitting the observed log-transformed concentration data and time. This simple (time-only) decay model assumes other factors are invariant, and so is flawed when complicating factors--such as a fluctuating water table--are present. A history of the water-table fluctuation can track changes in important NA factors like recharge, groundwater flow direction and velocity, as well as other non-NA factors like volume of water in and purged from the well before a sample is collected. When the trend in the concentrations is better associated with the water table rising or falling, any conclusion about degradation rate may be premature. We develop simple regressions to predict contaminant concentration (c) by two line models: one involving time (c approximately c(t)), and another involving groundwater elevation (c approximately c(z)). We develop a third model that includes both factors (c approximately c(t, z)). Using an F-test to compare the fits to the models, we determine which model is statistically better in explaining the observed concentrations. We applied the test to sites where benzene degradation rates had previously been estimated. The F-test can be used to determine the suitability of applying non-parametric statistics, like the Mann-Kendall, to the concentration data, because the result from the F-test can indicate instability of the contaminant plume that may be masked when the water table fluctuates. PMID:12666721

Pelayo, Aristeo M; Evangelista, Fe S

2003-03-01

269

Geochemical interpretation of groundwater flow in the southern Great Basin  

Microsoft Academic Search

The study of geochemical processes and integrated water flow can help identify groundwater sources and improve predic- tions of contaminant fate and transport in groundwater systems. Understanding groundwater flow paths in and around the Nevada Test Site (NTS) is important due to the possible migration of contaminated groundwater to the neighboring communi- ties. A total of 118 groundwater samples from

J. E. Koonce; I. M. Farnham; K. J. Stetzenbach

2006-01-01

270

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

SciTech Connect

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

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

2010-07-01

271

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

272

Identification and simulation of contaminant source architecture  

NASA Astrophysics Data System (ADS)

At many hazardous waste sites and accidental spills, dense non-aqueous phase liquids (DNAPLs) such as TCE, PCE, or TCA have been released into the subsurface. Once a DNAPL is released into the subsurface it migrates through the porous medium, forming a complex pattern of residual saturation (ganglia and blobs) and high saturation (pools at permeability and capillary barriers). Entrapped DNAPLs serve as persistent sources of dissolved-phase contamination. Although fine-scale geometric and topological contaminant source characteristics provide essential information for predicting subsurface contaminant transport, they are commonly paid too little attention. In absence of better knowledge or sufficient data, strong assumptions on contaminant source architecture (CSA), such as geometry, intensity, and location, are frequently accepted. Yet, such assumptions may cause severe prediction errors, since CSA controls mass release kinetics, downstream mass fluxes, source depletion times, and the initial conditions for mixing with oxygen-rich ambient water that is often limiting natural attenuation. This work conceptualizes and resolves fine-scale heterogeneities of DNAPL distributions and accounts for data scarcity when inferring CSA characteristics from field data. We lay out the theory for inferring CSA via Bayesian updating, present an efficient reverse-inverse methodology and provide results from a series of synthetic test cases. The prime objectives are to infer CSA from soil, head, and concentration measurements and to point out the role of CSA in predicting contaminant transport. To this end, we conceptualize contaminant source zones (CSZ) as random space functions which are then inferred with stochastic inverse modeling. A fully Bayesian geostatistical approach is chosen in order to cope with the issue of sparse and noisy data and uncertainty in aquifer structures. We introduce a reverse technique in a Lagrangian framework along with a swift transfer function that dramatically reduces the computational burden of common inverse models. With improved knowledge of CSA, better estimates and confidence intervals of contaminant mass flux, total mass, and source depletion times are possible. These are crucial metrics for risk assessment and to determine optimal remediation strategies.

Koch, J.; Nowak, W.; Bardossy, A.

2011-12-01

273

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

USGS Publications Warehouse

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

Ragone, S. E.

1986-01-01

274

Nonpoint Source Groundwater Solute Transport Using Unit Response Functions  

NASA Astrophysics Data System (ADS)

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

Klein, F.; Harter, T.

2009-12-01

275

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

SciTech Connect

In the mid-1990s, a groundwater plume of uranium (U) was detected in monitoring wells in the B-BX-BY Waste Management Area (WMA) 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 (MC ICPMS) high precision uranium isotopic analyses were conducted of samples of vadose zone contamination and of groundwater. The ratios {sup 236}U/{sup 238}U, {sup 234}U/{sup 238}U and {sup 238}U/{sup 235}U are used to distinguish contaminant sources. Based on 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 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 {approx}0.7-0.8 m/day showing slight retardation relative to a ground water flow of {approx}1 m/day.

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

2004-03-30

276

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

National Technical Information Service (NTIS)

A calibrated groundwater flow model for a contaminated site can provide substantial information for assessing and improving hydraulic measures implemented for remediation. A three-dimensional transient groundwater flow model was developed for a contaminat...

Q. Zhou J. T. Birkholzer I. Javandel P. D. Jordan

2005-01-01

277

Waste and cost reduction using dual wall reverse circulation drilling with multi-level groundwater sampling for contaminant plume delineation.  

National Technical Information Service (NTIS)

This paper describes the drilling and sampling methods used to delineate a groundwater contaminant plume at the Paducah Gaseous Diffusion Plant (PGDP) during the Groundwater Monitoring IV characterization. The project was unique in that it relied upon dua...

D. R. Smuin

1995-01-01

278

Remediation of Groundwater Contaminated with Organics and Radionuclides - An Innovative Approach Eases Traditional Hurdles  

SciTech Connect

Traditional approaches to the remediation of contaminated groundwater, such as pump-and-treat, have been used for many years for the treatment of groundwater contaminated with various organics. However the treatment of groundwater contaminated with organics and radionuclides has been considerably more challenging. Safety and Ecology Corporation (SEC) was recently faced with these challenges while designing a remediation system for the remediation of TCE-contaminated groundwater and soil at the RMI Extrusion Plant in Ashtabula, OH. Under contract with RMI Environmental Services (RMIES), SEC teamed with Regenesis, Inc. to design, implement, and execute a bioremediation system to remove TCE and associated organics from groundwater and soil that was also contaminated with uranium and technetium. The SEC-Regenesis system involved the injection of Hydrogen Release Compound (HRC), a natural attenuation accelerant that has been patented, designed, and produced by Regenesis, to stimulate the reductive dechlorination and remediation of chlorinated organics in subsurface environments. The compound was injected using direct-push Geoprobe rods over a specially designed grid system through the zone of contaminated groundwater. The innovative approach eliminated the need to extract contaminated groundwater and bypassed the restrictive limitations listed above. The system has been in operation for roughly six months and has begun to show considerable success at dechlorinating and remediating the TCE plume and in reducing the radionuclides into insoluble precipitants. The paper will provide an overview of the design, installation, and initial operation phase of the project, focusing on how traditional design challenges of remediating radiologically contaminated groundwater were overcome. The following topics will be specifically covered: a description of the mechanics of the HRC technology; an assessment of the applicability of the HRC technology to contaminated groundwater plumes and other potential remediation opportunities; a discussion of how the implementation of the HRC technology eased permitting issues and other challenges of remediating groundwater contaminated with radionuclides and organics; an overview of the remedial design and installation of the design including the inputs required to design the remediation system; a summary of results achieved to date and a forecast of future results; and a discussion of future needs and lessons learned.

Scott, J.; Case, N.; Coltman, K.

2003-02-25

279

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

SciTech Connect

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

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

2004-01-14

280

Superfund Record of Decision (EPA Region 4): Bypass 601 Groundwater Contamination Site, Operable Unit 2, Concord, NC, April 1993  

SciTech Connect

The decision document presents the selected remedial action for the Bypass 601 Groundwater Contamination Site in Concord, Cabarrus County, North Carolina. This remedy addresses the principle threats posed by the Site. The major threat is the contaminated groundwater emanating from beneath the Site. This remedial action will also address the threat from soil contamination.

Not Available

1993-04-01

281

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

Microsoft Academic Search

A calibrated groundwater flow model for a contaminated site can provide substantial information for assessing and improving hydraulic measures implemented for remediation. A three-dimensional transient groundwater flow model was developed for a contaminated mountainous site, at which interim corrective measures were initiated to limit further spreading of contaminants. This flow model accounts for complex geologic units that vary considerably in

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

2004-01-01

282

Beneficial effects of plants in the remediation of soil and groundwater contaminated with organic materials  

Microsoft Academic Search

The use of plants in remediation of soil and unconfined groundwater contaminated with organic materials is appealing for a variety of reasons: (1) plants provide a remediation strategy that utilizes solar energy; (2) vegetation is aesthetically pleasing; (3) plant samples can be harvested and tested as indicators of the level of remediation; (4) plants help contain the region of contamination

J. F. Shimp; J. C. Tracy; L. C. Davis; E. Lee; W. Huang; L. E. Erickson; J. L. Schnoor

1993-01-01

283

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

284

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...

285

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

EPA Science Inventory

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

286

Mapping groundwater contamination using dc resistivity and VLF geophysical methods -- A case study  

Microsoft Academic Search

Geophysical methods can be helpful in mapping areas of contaminated soil and groundwater. Electrical resistivity and very low-frequency electromagnetic induction (VLF) surveys were carried out at a site of shallow hydrocarbon contamination in Utah County, Utah. Previously installed monitoring wells facilitated analysis of water chemistry to enhance interpretation of the geophysical data. The electrical resistivity and VLF data correlate well,

Alvin K. Benson; Kelly L. Payne; M. A. Stubben

1997-01-01

287

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 ...

288

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

289

A kinetic approach to modeling mobile bacteria-facilitated groundwater contaminant transport  

Microsoft Academic Search

Mobile bacterial particles can act as carriers and enhance the transport of hydrophobic contaminants in groundwater by reducing retardation effects. Because of their colloidal size and favorable surface conditions, bacteria act as efficient contaminant carriers. When such carriers exist in a water-saturated porous medium, the system can be thought of as three phases: an aqueous phase, a carrier phase, and

Seunghyun Kim; M. Yavuz Corapcioglu

1996-01-01

290

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

291

Analysis of uncertainty in optimal groundwater contaminant capture design  

Microsoft Academic Search

A three-dimensional groundwater management model is developed for a shallow, unconfirmed sandy aquifer at a Superfund site at which a vinyl chloride plume is migrating toward Lake Michigan. We use nonlinear simulation-regression applied to a transient groundwater flow model to estimate parameter values and their uncertainties and use steady state flow path analyses to confirm the model's consistency with the

Claire Tiedeman; Steven M. Gorelick

1993-01-01

292

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

SciTech Connect

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

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

2004-03-01

293

Use of pesticide simulation models for assessing pesticide contamination of surface and groundwater  

SciTech Connect

Two field scale hydrologic and pesticide routing models, CREAMS (Chemicals, Runoff, and Erosion in Agricultural Management Systems) and PRZM (Pesticide Root Zone Model) were used to predict average pesticide concentrations in storm flow and unsaturated subsurface flow after application of forestry herbicides and insecticides. Forest regions in the mountain, Piedmont, and coastal plain physiographic provinces of the South provide important stream sources and groundwater recharge zones for municipal water supplies. Increasing use of herbicides and insecticides in forest management has raised concerns about maintaining future water quality. Thus tools for assessing potential contamination from pesticide use are needed. CREAMS accurately predicted herbicide concentrations in storm flow in mountain watersheds for 2 months. But it is underestimated concentrations for the next 4 months when transport processes not accounted for in the model dominated actual residue movement. PRZM was likewise tested with actual field data on subsurface movement of herbicides in mountain regions and insecticides in deep sands of the coastal plain.

Nutter, W.L.; Bush, P.B.; Neary, D.G.; Dowd, J.F.

1985-01-01

294

What Carbon Sources Support Groundwater Microbial Activity in Riparian Forests?  

NASA Astrophysics Data System (ADS)

A major question in riparian research is the source of energy to support subsurface microbial denitrification activity. The supply of microbially-available carbon frequently limits microbial activity in the subsurface. Therefore, identifying the relative importance of carbon sources in the riparian subsurface helps explain the sustainability and spatial heterogeneity of denitrification rates. We have investigated the importance of buried, carbon-rich soil horizons, deep roots and dissolved organic carbon as potential carbon sources to support groundwater denitrification in riparian forests in Rhode Island. We used field observations, laboratory incubations and in-situ experiments to evaluate these sources at four sites in different geomorphic settings. In particular, we measured the 14C-DIC signature and DIC concentration of ambient groundwater and groundwater that had been degassed, re-introduced into the well, and incubated in-situ. Buried horizons appear to be an important source of carbon in the subsurface, as shown by active respiration in laboratory incubations; greater microbial biomass in buried carbon-rich soils compared to surrounding carbon-poor soils; and the presence of very old carbon (>1,000 ybp) in DIC 225 cm beneath the surface. DIC collected from shallower wells showed no clear evidence of ancient carbon. Roots also appear to be important, creating hotspots of carbon availability and denitrification in the generally carbon poor subsurface matrix. Dissolved organic carbon did not stimulate denitrification in aquifer microcosms in the laboratory, suggesting that this was not an important carbon source for denitrification in our sites. Determining which carbon source is fueling denitrification has practical implications. Where buried horizons are the key source, surface management of the riparian zone will likely have little direct influence on groundwater denitrification. Where roots are the key source, changes in the plant community are likely to influence denitrification capacity in the subsurface.

Gurwick, N. P.; Groffman, P. M.; McCorkle, D. C.; Stolt, M. H.; Kellogg, D. Q.; Gold, A. J.

2004-05-01

295

Performance of semipermeable membrane devices for sampling of organic contaminants in groundwater.  

PubMed

Lipid-filled semipermeable membrane devices (SPMDs) are receiving increasing attention as passive, in situ samplers for the assessment of environmental pollutant exposure. Although SPMDs have been successfully used in a variety of field studies in surface waters, only a few studies have addressed their characteristics as groundwater samplers. In this study, the performance of the SPMDs for monitoring organic contaminants in groundwater was evaluated in a pilot field application in an area severely contaminated by chemical waste, especially by chlorinated hydrocarbons. The spatial distribution of hydrophobic groundwater contaminants was assessed using a combination of passive sampling with SPMDs and non-target semiquantitative GC-MS analysis. More than 100 contaminants were identified and semiquantitatively determined in SPMD samples. Along the 6 field sites under investigation, a large concentration gradient was observed, which confirms a very limited mobility of hydrophobic substances in dissolved form in the aquifer. The in situ extraction potential of the SPMD is limited by groundwater flow, when the exchange volume of well water during an exposure is lower than the SPMD clearance volume for the analytes. This study demonstrates that SPMDs present a useful tool for sampling and analyzing of groundwater polluted with complex mixtures of hydrophobic chemicals and provides guidance for further development of passive sampling technology for groundwater. PMID:15877173

Vrana, Branislav; Paschke, Heidrun; Paschke, Albrecht; Popp, Peter; Schuurmann, Gerrit

2005-03-22

296

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

PubMed

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

Zamani, Abbas Ali; Yaftian, Mohammad Reza; Parizanganeh, Abdolhossein

2012-12-17

297

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.

2012-01-01

298

QUALITY ASSURANCE IN COMPUTER SIMULATIONS OF GROUNDWATER CONTAMINATION  

EPA Science Inventory

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

299

Groundwater arsenic contamination in Manipur, one of the seven North-Eastern Hill states of India: a future danger  

NASA Astrophysics Data System (ADS)

Manipur State, with a population of 2.29 million, is one of the seven North-Eastern Hill states in India, and is severely affected by groundwater arsenic contamination. Manipur has nine districts out of which four are in Manipur Valley where 59% of the people live on 10% of the land. These four districts are all arsenic contaminated. We analysed water samples from 628 tubewells for arsenic out of an expected total 2,014 tubewells in the Manipur Valley. Analyzed samples, 63.3%, contained >10 ?g/l of arsenic, 23.2% between 10 and 50 ?g/l, and 40% >50 ?g/l. The percentages of contaminated wells above 10 and 50 ?g/l are higher than in other arsenic affected states and countries of the Ganga-Meghna-Brahmaputra (GMB) Plain. Unlike on the GMB plains, in Manipur there is no systematic relation between arsenic concentration and the depth of tubewells. The source of arsenic in GMB Plain is sediments derived from the Himalaya and surrounding mountains. North-Eastern Hill states were formed at late phase of Himalaya orogeny, and so it will be found in the future that groundwater arsenic contamination in the valleys of other North-Eastern Hill states. Arsenic contaminated aquifers in Manipur Valley are mainly located within the Newer Alluvium. In Manipur, the high rainfall and abundant surface water resources can be exploited to avoid repeating the mass arsenic poisoning that has occurred on the GMB plains.

Chakraborti, Dipankar; Singh, E. Jayantakumar; Das, Bhaskar; Shah, Babar Ali; Hossain, M. Amir; Nayak, Bishwajit; Ahamed, Sad; Singh, N. Rajmuhon

2008-11-01

300

Heavy metal contamination from geothermal sources.  

PubMed

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

1975-12-01

301

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

Microsoft Academic Search

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

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

2009-01-01

302

STIMULATION OF IN SITU BIOPRECIPITATION FOR THE REMOVAL OF HEXAVALENT CHROMIUM FROM CONTAMINATED GROUNDWATER  

Microsoft Academic Search

The groundwater chemistry of an industrial site near the centre of a historical town in Flanders is characterized by chromium(VI) contamination. Since the potential for natural attenuation was not sufficient to control the groundwater plume as observed from different analyses like pH, Eh, soil oxidation and reduction capacity, the feasibility of site remediation based on in-situ bioprecipitation of Cr was

K. Vanbroekhoven; Y. Vermoortel; L. Diels; J. Gemoets

303

Human impacts on groundwater flow and contamination deduced by multiple isotopes in Seoul City, South Korea.  

PubMed

The influence of human activities on the flow system and contamination of groundwater were investigated in Seoul City, South Korea, one of the largest Asian cities, using a combination of isotopes (deltaD, T, delta15N, delta18O, delta34S, and 87Sr/86Sr). Eighteen representative groundwater and river water samples, which were collected over a wide area of the city, were compared with previously reported data. The distribution of stable isotopes (deltaD and delta18O) with groundwater potential data shows that recharged groundwater from either the surrounding mountainous area as well as the Han River and other surface streams discharged towards the northern-central part of the city, where a subway tunnel pumping station is located. It is suggested from T values (3.3 to 5.8 T.U.) that groundwater was recharged in the last 30 to 40 years. The delta34S and delta15N of SO4(2-) and NO3- data were efficiently used as indicators of contamination by human activities. These isotopes clarified that the contribution of anthropogenic contaminants i.e., industrial and household effluents, waste landfills, and fertilizers, are responsible for the enrichment by SO4(2-) (>30 ppm as SO4(2-)) and NO3- (>20 ppm as NO3-) of groundwater. The 87Sr/86Sr values of groundwater vary (0.71326 to 0.75058) in accordance with the host rocks of different origins. Mineral elements such as Ca are also suggested to be derived naturally from rocks. The groundwater under Seoul City is greatly affected by transportation of pollutants along the groundwater flow controlled by subway tunnel pumping, contributing to the degradation of water quality in urbanized areas. PMID:18495214

Hosono, Takahiro; Ikawa, Reo; Shimada, Jun; Nakano, Takanori; Saito, Mitsuyo; Onodera, Shin-ichi; Lee, Kang-Kun; Taniguchi, Makoto

2008-05-20

304

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

National Technical Information Service (NTIS)

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...

1993-01-01

305

Evaluating the source and residence times of groundwater seepage to streams, New Jersey Coastal Plain  

Microsoft Academic Search

A conceptual model of the patterns and residence times of groundwater seepage to gaining streams indicates that groundwater seepage originates from sources that are both near and far from the stream. Consequently, the age of groundwater seepage across a stream-channel transect increases from its banks to its center and becomes progressively older with distance downstream. A groundwater flow model and

E. Modica; H. T. Buxton; L. N. Plummer

1998-01-01

306

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

307

[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

308

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

309

Estimating contaminant attenuation half-lives in alluvial groundwater systems  

SciTech Connect

One aspect of describing contamination in an alluvial aquifer is estimating changes in concentrations over time. A variety of statistical methods are available for assessing trends in contaminant concentrations. We present a method that extends trend analysis to include estimating the coefficients for the exponential decay equation and calculating contaminant attenuation half-lives. The conceptual model for this approach assumes that the rate of decline is proportional to the contaminant concentration in an aquifer. Consequently, the amount of time to remove a unit quantity of the contaminant inventory from an aquifer lengthens as the concentration decreases. Support for this conceptual model is demonstrated empirically with log-transformed time series of contaminant data. Equations are provided for calculating system attenuation half-lives for non-radioactive contaminants.

Tardiff, Mark F.; Katzman, Danny

2007-03-13

310

Rhizofiltration using sunflower ( Helianthus annuus L.) and bean ( Phaseolus vulgaris L. var. vulgaris) to remediate uranium contaminated groundwater  

Microsoft Academic Search

The uranium removal efficiencies of rhizofiltration in the remediation of groundwater were investigated in lab-scale experiments. Sunflower (Helianthus annuus L.) and bean (Phaseolus vulgaris L. var. vulgaris) were cultivated and an artificially uranium contaminated solution and three genuine groundwater samples were used in the experiments. More than 80% of the initial uranium in solution and genuine groundwater, respectively, was removed

Minhee Lee; Minjune Yang

2010-01-01

311

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

312

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

313

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

SciTech Connect

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

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

2004-03-01

314

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

315

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

316

Impact of climate change on natural attenuation potential of flooded wetlands for contaminants in groundwater  

NASA Astrophysics Data System (ADS)

Reduction of a solute concentration during its passage through flooded wetlands has been observed implying potential of the flooded wetlands as a natural attenuator of groundwater contaminants. Analyzing this process will contribute to an understanding of solute transport from subsurface to groundwater and further to risk management of groundwater contaminants. In this study, one dimensional column model is built to analyze the role of flooded wetland in natural attenuation of contaminants in groundwater. Among many factors controlling the attenuation process, rainfall and soil moisture conditions are of special interest since the recent climate change will bring a change in rainfall pattern and subsurface soil moisture condition. Contaminant loading to wetlands is dependent on rainfall pattern and irrigation event, while its reduction in concentration during passage through wetlands is on soil moisture condition of subsurface. Change in rainfall pattern and soil moisture condition will bring subsequent change in natural attenuation potential of flooded wetlands. Future scenarios with different rainfall pattern and soil moisture conditions are given as inputs to the column model, and its impact on attenuation of contaminants through flooded wetland is compared.

Lim, J.; Hyun, Y.; Lee, K.

2009-12-01

317

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

318

GIS techniques applied to non-point contamination predictions in Illinois groundwater  

SciTech Connect

The Illinois State Water Survey and the Illinois State Geological Survey, parts of the Illinois Department of Energy and Natural Resources, as part of the mandates of the Illinois Groundwater Protection Act, undertook a project to determine the potential for vulnerability to contamination by agricultural chemicals in private domestic wells throughout the State. GIS techniques were heavily relied upon to establish four categories of potential vulnerability to such contamination. Information from several sources, Federal, State and Local, were used to develop the coverages which were finally overlain to create the map. Criteria for the evaluation of the potential for vulnerability included location with respect to agricultural chemical application, storage, and preparation, urban vs. rural setting land use, depth below surface to aquifer materials, and soils information. Illinois has more in-depth information on these kinds of information than many of the States, and still there were problems in accumulating the needed data. These included, lack of availability, poor documentation of data collection and storage protocols, and the lack of adequate detail within datasets. Supplementation of information before the application of GIS techniques was needed.

Schock, S.C. (Environmental Protection Agency, Cincinnati, OH (United States)); Keefer, D.; Mehnert, E. (Illinois State Geological Survey, Champaign, IL (United States)); Ray, C. (Illinois State Water Survey, Champaign, IL (United States))

1994-03-01

319

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

320

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

2005-08-01

321

Subsurface characterization of groundwater contaminated by landfill leachate using microbial community profile data and a nonparametric decision-making process  

Microsoft Academic Search

Microbial biodiversity in groundwater and soil presents a unique opportunity for improving characterization and monitoring at sites with multiple contaminants, yet few computational methods use or incorporate these data because of their high dimensionality and variability. We present a systematic, nonparametric decision-making methodology to help characterize a water quality gradient in leachate-contaminated groundwater using only microbiological data for input. The

Andrea R. Pearce; Donna M. Rizzo; Paula J. Mouser

2011-01-01

322

Assessment of potential impacts of major groundwater contaminants to fall chinook salmon (Oncorhynchus tshawytscha) in the Hanford Reach, Columbia River  

Microsoft Academic Search

Past operations of Hanford Site facilities have contaminated the groundwater adjacent to the Hanford Reach of the Columbia River, Washington, with various chemical and radiological constituents. The groundwater is hydraulically connected to the river and contains concentrations of contaminants that sometimes exceed federal and\\/or state drinking water standards or standards for the protection of aquatic life. For example, concentrations of

D. R. Geist; T. M. Poston; D. D. Dauble

1994-01-01

323

Evaluating system for ground-water contamination hazards due to gas-well drilling on the Glaciated Appalachian Plateau  

Microsoft Academic Search

Recent drilling for natural gas in the Glaciated Appalachian Plateau area of NW Pennsylvania has caused limited, but increasing ground-water contamination. By evaluating hydrogeologic parameters at a proposed gas well site, such as the ground-water flow system, permeability of surficial sediments, and the presence of fractures zones, the contamination hazard of the site can be assessed. Three case studies document

2009-01-01

324

Contamination of groundwater by outdoor highway deicing agent storage  

Microsoft Academic Search

This research quantifies the impact of outdoor highway deicing agent storage on groundwater quality. Data and theory realize the objective at a well characterized salt\\/premix storage facility on a glacial drumlin comprised of clayey sand till. Tritium and tritiogenic helium were observed in 17 monitoring wells in 2003, while chloride concentrations were measured in 43 monitoring wells from 1998 through

David W. Ostendorf; Erich S. Hinlein; Camelia Rotaru; Don J. DeGroot

2006-01-01

325

Biodegradation of Trichloroethylene and Dichloromethane in Contaminated Soil and Groundwater  

Microsoft Academic Search

Soil column and serum bottle microcosm experiments were conducted to investigate the potential for in situ anaerobic bioremediation of trichloroethy lene (TCE) and dichloromethane (DCM) at the Pinellas site near Largo, Florida. Soil columns with continuous groundwater recycle were used to evaluate treatment with complex nutrients (casamino acids, methanol, lactate, sulfate); benzoate and sulfate; and methanol. The complex nutrients drove

Kim A. DeWeerd; William P. Flanagan; Michael J. Brennan; Jan M. Principe; James L. Spivack

1998-01-01

326

Characterization of redox conditions in groundwater contaminant plumes  

Microsoft Academic Search

Evaluation of redox conditions in groundwater pollution plumes is often a prerequisite for understanding the behaviour of the pollutants in the plume and for selecting remediation approaches. Measuring of redox conditions in pollution plumes is, however, a fairly recent issue and yet relative few cases have been reported. No standardised or generally accepted approach exists. Slow electrode kinetics and the

Thomas H Christensen; Poul L Bjerg; Steven A Banwart; Rasmus Jakobsen; Gorm Heron; Hans-Jørgen Albrechtsen

2000-01-01

327

REMEDIATION OF NITRATE-CONTAMINATED GROUNDWATER USING A BIOBARRIER  

Microsoft Academic Search

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

B. A. Strietelmeier; M. L. Espinosa

2001-01-01

328

Methodology for setting risk-based concentrations of contaminants in soil and groundwater and application to a model contaminated site.  

PubMed

In Japan, environmental standards for contaminants in groundwater and in leachate from soil are set with the assumption that they are used for drinking water over a human lifetime. Where there is neither a well nor groundwater used for drinking, the standard is thus too severe. Therefore, remediation based on these standards incurs excessive effort and cost. In contrast, the environmental-assessment procedure used in the United States and the Netherlands considers the site conditions (land use, existing wells, etc.); however, a risk assessment is required for each site. Therefore, this study proposes a new framework for judging contamination in Japan by considering the merits of the environmental standards used and a method for risk assessment. The framework involves setting risk-based concentrations that are attainable remediation goals for contaminants in soil and groundwater. The framework was then applied to a model contaminated site for risk management, and the results are discussed regarding the effectiveness and applicability of the new methodology. PMID:21978276

Fujinaga, Aiichiro; Uchiyama, Iwao; Morisawa, Shinsuke; Yoneda, Minoru; Sasamoto, Yuzuru

2011-10-06

329

Backward probabilistic model of groundwater contamination in non-uniform and transient flow  

Microsoft Academic Search

Backward location and travel time probabilities, which provide information about the former location of contamination in an aquifer, can be used to identify unknown contamination sources. Backward location probability describes the possible upgradient positions of contamination at a known time in the past, and backward travel time probability describes the time required for contamination to travel from a known upgradient

R. M. Neupauer; J. L. Wilson

2002-01-01

330

ELECTROCHEMICAL DEGRADATION OF CHLORINATED CONTAMINANTS IN SEDIMENTS AND GROUNDWATER  

EPA Science Inventory

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

331

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...

332

MONITORED NATURAL ATTENUATION FOR INORGANIC CONTAMINANT REMEDIATION IN GROUNDWATER  

EPA Science Inventory

Monitored natural attenuation (MNA) has been applied as a knowledge-based remediation technology for organic contaminants in ground water. Development of a site-specific assessment of biotic and abiotic processes that lead to organic contaminant degradation provides the technica...

333

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

334

Status of groundwater arsenic contamination in Bangladesh: a 14-year study report.  

PubMed

Since 1996, 52,202 water samples from hand tubewells were analyzed for arsenic (As) by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) from all 64 districts of Bangladesh; 27.2% and 42.1% of the tubewells had As above 50 and 10 ?g/l, respectively; 7.5% contained As above 300 ?g/l, the concentration predicting overt arsenical skin lesions. The groundwater of 50 districts contained As above the Bangladesh standard for As in drinking water (50 ?g/l), and 59 districts had As above the WHO guideline value (10 ?g/l). Water analyses from the four principal geomorphological regions of Bangladesh showed that hand tubewells of the Tableland and Hill tract regions are primarily free from As contamination, while the Flood plain and Deltaic region, including the Coastal region, are highly As-contaminated. Arsenic concentration was usually observed to decrease with increasing tubewell depth; however, 16% of tubewells deeper than 100 m, which is often considered to be a safe depth, contained As above 50 ?g/l. In tubewells deeper than 350 m, As >50 ?g/l has not been found. The estimated number of tubewells in 50 As-affected districts was 4.3 million. Based on the analysis of 52,202 hand tubewell water samples during the last 14 years, we estimate that around 36 million and 22 million people could be drinking As-contaminated water above 10 and 50 ?g/l, respectively. However for roughly the last 5 years due to mitigation efforts by the government, non-governmental organizations and international aid agencies, many individuals living in these contaminated areas have been drinking As-safe water. From 50 contaminated districts with tubewell As concentrations >50 ?g/l, 52% of sampled hand tubewells contained As <10 ?g/l, and these tubewells could be utilized immediately as a source of safe water in these affected regions provided regular monitoring for temporal variation in As concentration. Even in the As-affected Flood plain, sampled tubewells from 22 thanas in 4 districts were almost entirely As-safe. In Bangladesh and West Bengal, India the crisis is not having too little water to satisfy our needs, it is the challenge of managing available water resources. The development of community-specific safe water sources coupled with local participation and education are required to slow the current effects of widespread As poisoning and to prevent this disaster from continuing to plague individuals in the future. PMID:20684969

Chakraborti, Dipankar; Rahman, Mohammad Mahmudur; Das, Bhaskar; Murrill, Matthew; Dey, Sankar; Chandra Mukherjee, Subhas; Dhar, Ratan Kumar; Biswas, Bhajan Kumar; Chowdhury, Uttam Kumar; Roy, Shibtosh; Sorif, Shahariar; Selim, Mohammad; Rahman, Mahmuder; Quamruzzaman, Quazi

2010-06-30

335

Long-term fate of organic micropollutants in sewage-contaminated groundwater  

Microsoft Academic Search

Disposal of secondary sewage effluent by rapid infiltration has produced a plume of contaminated groundwater over 3500 m long near Falmouth, MA. Approximately 50 volatile organic compounds were detected and identified in the plume, at concentrations ranging from 10 ng\\/L to 500 μg\\/L, by closed-loop stripping and purge-and-trap in conjunction with gas chromatography-mass spectrometry. The dominant contaminants were di-, tri-

Larry B. Barber; E. Michael. Thurman; Michael P. Schroeder; Denis R. LeBlanc

1988-01-01

336

On the potential of biological treatment for arsenic contaminated soils and groundwater  

Microsoft Academic Search

Bioremediation of arsenic contaminated soils and groundwater shows a great potential for future development due to its environmental compatibility and possible cost-effectiveness. It relies on microbial activity to remove, mobilize, and contain arsenic through sorption, biomethylation–demethylation, complexation, coprecipitation, and oxidation–reduction processes. This paper gives an evaluation on the feasibility of using biological methods for the remediation of arsenic contaminated soils

Suiling Wang; Xiangyu Zhao

2009-01-01

337

A Mathematical Model of Phenolic Groundwater Contamination at a Brownfield Site Based on Few Available Data  

Microsoft Academic Search

Phenolic chemicals form multi-substance systems. They can pollute aquifers by the leacheate from tar residues and their concentrations\\u000a which vary in space and time and require quantitative models of composition, spatial distribution and temporal alteration\\u000a of the contaminants for monitoring and remediation. Mathematical models for groundwater flow, contaminant transport or mass\\u000a balances and numerous unspecific multivariate-statistical methods cannot be applied

Hannes Thiergärtner

2006-01-01

338

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

SciTech Connect

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

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

1996-02-01

339

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

National Technical Information Service (NTIS)

Dual wall reverse circulation (DWRC) drilling was used to drill 48 borings during a groundwater contaminant investigation at the Paducah Gaseous Diffusion Plant, Paducah, Kentucky. This method was selected as an alternative to conventional hollow stem aug...

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

1995-01-01

340

Factors Affecting the Sustainability of Groundwater-Source Cooling  

NASA Astrophysics Data System (ADS)

The use of groundwater in thermal applications has grown in popularity due to increases in environmental awareness and rising energy costs. While this source of energy is generally seen as beneficial to the environment, changes in subsurface temperatures resulting from thermal development and other factors may make this practice unsustainable. An example of such changes in subsurface temperatures has been observed in Winnipeg, Manitoba, where groundwater is extensively used for cooling applications. Temperatures in a regional aquifer beneath the city were found to be as much as ten degrees Celsius greater than those measured in surrounding rural areas. Numerical modeling indicates increases in temperature of up to 5 degrees Celsius can be attributed to downward heat flow originating in buildings in many cases. Areas where increases in temperature were found to be greater corresponded to areas where water is being injected into the aquifer. This water is being produced in the process of using groundwater for cooling applications, such as air conditioning and industrial cooling, and is being injected back into the aquifer to maintain hydraulic head and reduce the demand on Winnipeg's sewer system. In most cases, the heat introduced by injecting this water is significantly affecting temperatures at the production well of the same system and numerical modeling indicates that this is inevitable with the current method of development. The combination of heat loss from buildings and injection of heated water is largely responsible for a reduction in the efficiency of groundwater as a coolant and may eventually make the use of groundwater in cooling applications unsustainable.

Ferguson, G. A.; Woodbury, A. D.

2004-12-01

341

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

342

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

Microsoft Academic Search

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

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

1998-01-01

343

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...

344

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 ...

345

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

Microsoft Academic Search

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

HASHIM MOHD KASSIM

346

Boundary-conforming coordinate system for groundwater and contaminant transport modeling  

Microsoft Academic Search

In order to understand the behavior of flow and contaminant transport in heterogeneous porous media with semipermeable clay lenses, a conceptual two-dimensional mathematical model has been developed. The model is based on Darcy's law, the groundwater continuity equation, and the advection-dispersion transport equation. To deal with the existence of arbitrarily shaped clay lenses, the numerical grid generation techniques and the

Zhao; Xiaoxia

1991-01-01

347

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

348

GIS techniques applied to non-point contamination predictions in Illinois groundwater  

Microsoft Academic Search

The Illinois State Water Survey and the Illinois State Geological Survey, parts of the Illinois Department of Energy and Natural Resources, as part of the mandates of the Illinois Groundwater Protection Act, undertook a project to determine the potential for vulnerability to contamination by agricultural chemicals in private domestic wells throughout the State. GIS techniques were heavily relied upon to

S. C. Schock; D. Keefer; E. Mehnert; C. Ray

1994-01-01

349

Evaluation of groundwater contamination and protection measures in a rural area  

Microsoft Academic Search

Clean drinking water plays a very important role in the health of a community. Providing safe drinking water to the people has been a major challenge for Romanian Government in order to achieve the goal of accession into the EU by 2007. The main purpose of this research was to investigate the chemical contamination of groundwater in a rural region

D. Curseu; M. Popa; D. Sirbu; Z. Moldovan

2008-01-01

350

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

SciTech Connect

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

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

1998-08-31

351

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

352

Methods of minimizing ground-water contamination from in situ leach uranium mining. Final report  

Microsoft Academic Search

This is the final report of a research project designed to study methods of minimizing ground-water contamination from in situ leach uranium mining. Fieldwork and laboratory experiments were conducted to identify excursion indicators for monitoring purposes during mining, and to evaluate effective aquifer restoration techniques following mining. Many of the solution constituents were found to be too reactive with the

W. J. Deutsch; W. J. Martin; L. E. Eary; R. J. Serne

1985-01-01

353

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...

354

Description of work for the 200UP1 groundwaters contaminant vertical profiling activity. Revision 1  

Microsoft Academic Search

This description of work (DOW) details the field activities associated with assessing the vertical extent of groundwater contamination in the uppermost unconfined and confined aquifers beneath the southeastern portion of the 200 West area. The document serves as the test plan for those performing the work. It should be used in conjunction with the Remedial Investigation\\/Feasibility Study Work Plan for

Ford

1993-01-01

355

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

356

Rooftop Runoff as a Source of Contamination: A Review  

EPA Science Inventory

Scientific reports concerning chemical and microbiological contaminant levels of rainwater runoff from rooftop collection in both urban and rural areas are reviewed. This alternative source of water has been documented to often contain substantial amounts of contaminants. Studi...

357

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

358

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 ...

359

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

NASA Astrophysics Data System (ADS)

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

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

2004-05-01

360

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

361

Structural diversity of organochlorine compounds in groundwater affected by an industrial point source.  

PubMed

Groundwater samples contaminated by an industrial point source were analysed in order to reveal the structural diversity of halogenated organic contaminants. Particular focus was laid on the metabolites and derivatives related to the pesticides DDT (2,2-bis(chlorophenyl)-1,1,1-trichlorethane) and lindane (?-hexachlorocyclohexane). Additionally, a wide range of chlorinated and brominated xenobiotics were identified. These results represent a high degree of contamination with organochlorine compounds illustrating a considerable structural diversity in groundwater in the vicinity of the industrial plant. The polar DDT-metabolite DDA (2,2-bis(chlorophenyl)acetic acid), which has been neglected in water studies widely, represents the main DDT metabolite analysed in the water samples. Besides DDA, some unknown substances with structural relation to DDA and DDT were detected and identified, in detail 2,2-bis(4-chlorophenyl)acetic acid N-methyl amide (DDAMA) and 2,2-bis(4-chlorophenyl)acetic acid n-butyl ester (DDABE). As an overall implication of this study it has to be demanded that analysis of industrially affected ground waters have to be based on screening analysis for a comprehensive view on the state of pollution. PMID:20810145

Frische, Kerstin; Schwarzbauer, Jan; Ricking, Mathias

2010-09-01

362

Adjoint method for obtaining backward-in-time location and travel time probabilities of a conservative groundwater contaminant  

NASA Astrophysics Data System (ADS)

Backward location and travel time probabilities can be used to determine the prior location of contamination in an aquifer. For a contaminant particle that was detected in an aquifer, the backward location probability is the probability of where the particle was located at some prior time. Backward travel time probability is the probability of when the particle was located at some position upgradient of the detection. These probabilities can be used to improve characterization of known sources of groundwater contamination, to identify previously unknown contamination sources, and to delineate capture zones. For simple model domains, backward probabilities can be obtained heuristically from a forward model of contaminant transport. For multidimensional problems and complex domain geometries, the heuristic approach is difficult to implement and verify. The adjoint method provides a formal approach for obtaining backward probabilities for all model domains and geometries. We formally show that the backward model probabilities are adjoint states of resident concentration. We provide a methodology for obtaining the governing equations and boundary and final conditions for these probabilities. The approach is illustrated using a one-dimensional, semi-infinite domain that mimics flow to a production well, and these results are compared to equivalent probabilities derived heuristically.

Neupauer, Roseanna M.; Wilson, John L.

1999-11-01

363

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

364

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

SciTech Connect

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

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

1997-04-01

365

Mapping groundwater contamination using dc resistivity and VLF geophysical methods -- A case study  

SciTech Connect

Geophysical methods can be helpful in mapping areas of contaminated soil and groundwater. Electrical resistivity and very low-frequency electromagnetic induction (VLF) surveys were carried out at a site of shallow hydrocarbon contamination in Utah County, Utah. Previously installed monitoring wells facilitated analysis of water chemistry to enhance interpretation of the geophysical data. The electrical resistivity and VLF data correlate well, and vertical cross-sections and contour maps generated from these data helped map the contaminant plume, which was delineated as an area of high interpreted resistivities.

Benson, A.K.; Payne, K.L.; Stubben, M.A. [Brigham Young Univ., Provo, UT (United States). Dept. of Geology and Geophysics

1997-01-01

366

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

SciTech Connect

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

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

2008-01-31

367

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

PubMed

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

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

2012-11-01

368

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

369

Contaminated groundwater remediation design using simulation, optimization, and sensitivity theory, 1. Model development  

NASA Astrophysics Data System (ADS)

The problem of designing contaminated groundwater remediation systems using hydraulic control is addressed. Two nonlinear optimization formulations are proposed which model the design process for the location and pump rates of injection and extraction wells in an aquifer cleanup system. The formulations are designed to find a pumping system which (1) removes the most contaminant over a fixed time period and (2) reduces contaminant concentration to specified levels by the end of a fixed time period at least cost. The formulations employ a two-dimensional Galerkin finite element simulation model of steady state groundwater flow and transient convective-dispersive transport. To make the optimization problems computationally tractable sensitivity theory is used to derive a general relationship for computing the derivatives of an arbitrary function of the simulation outputs with respect to model inputs. This relationship is then applied to the convective-dispersive transport equation.

Ahlfeld, David P.; Mulvey, John M.; Pinder, George F.; Wood, Eric F.

1988-03-01

370

Second moment method for evaluating human health risks from groundwater contaminated by trichloroethylene.  

PubMed Central

Pollutants in groundwater aquifers may constitute a significant human health risk. A large variation in response may result among human populations experiencing the same level and duration of exposure to pollutants. Variability in response, as a result of exposure to a carcinogenic contaminant such as trichloroethylene (TCE), can be represented by a distribution function of safe doses. Spatial variability in aquifer characteristics and contaminant transport parameters requires the use of stochastic transport models to quantify variability in exposure concentrations. A second moment method is used to evaluate the probability of exceeding safe dose levels for a contaminated aquifer. The name of this method stems from the fact that the formulation is based on the first and second moments of the random variables. With this method, the probability is a function of the variability of contaminant concentration (which incorporates variability in hydrogeologic parameters such as hydraulic conductivity) and the variability in response in the human population. In this manner, the severity of the health risk posed by a contaminated aquifer and the evaluation of appropriate strategies and technologies for aquifer remediation are a function of contaminant concentrations and human health risks. The applicability and limitations of this method are demonstrated with data on groundwater contaminated by TCE at Hill Air Force Base, Utah. Images Figure 1. Figure 2. Figure 3. Figure 4.

Jacobs, T L; Warmerdam, J M; Medina, M A; Piver, W T

1996-01-01

371

Assessment of groundwater contamination caused by uncontrolled dumping in old gravel quarries in the Besòs aquifers (Barcelona, Spain).  

PubMed

The contamination of groundwater in the aquifer of the La Llagosta basin (Besòs river basin) due to waste disposal in quarries formerly used for the extraction of dry raw materials has led to the cessation of groundwater extraction for public water supply. The mobilization of pollutants was largely caused by fluctuations in piezometric levels, which led to the washing of buried waste. The hydrogeochemical processes associated with uncontrolled waste disposal in these landfilled areas of the La Llagosta basin aquifer were studied along a flow path that crosses the contaminated area. The PHREEQC code was used to establish the reactions associated with the different mineral phases through inverse modeling. This transport code, ionic exchange phenomena, surface reactions and balance (mineral phase) reactions were used to simulate the dilution phenomenon associated with the pollution after the potential removal of the sources of contamination. One-dimensional advective-dispersive modeling indicates a substantial reduction in Ca, Mg, Na and SO2(4-) within one year and stabilization within four years. PMID:17879130

Navarro, Andrés; Carbonell, Montserrat

2008-06-01

372

In situ disinfection of sewage contaminated shallow groundwater: a feasibility study.  

PubMed

Sewage-contaminated shallow groundwater is a potential cause of beach closures and water quality impairment in marine coastal communities. In this study we set out to evaluate the feasibility of several strategies for disinfecting sewage-contaminated shallow groundwater before it reaches the coastline. The disinfection rates of Escherichia coli (EC) and enterococci bacteria (ENT) were measured in mixtures of raw sewage and brackish shallow groundwater collected from a coastal community in southern California. Different disinfection strategies were explored, ranging from benign (aeration alone, and aeration with addition of brine) to aggressive (chemical disinfectants peracetic acid (PAA) or peroxymonosulfate (Oxone)). Aeration alone and aeration with brine did not significantly reduce the concentration of EC and ENT after 6 h of exposure, while 4-5 mg L(-1) of PAA or Oxone achieved >3 log reduction after 15 min of exposure. Oxone disinfection was more rapid at higher salinities, most likely due to the formation of secondary oxidants (e.g., bromine and chlorine) that make this disinfectant inappropriate for marine applications. Using a Lagrangian modeling framework, we identify several factors that could influence the performance of in-situ disinfection with PAA, including the potential for bacterial regrowth, and the non-linear dependence of disinfection rate upon the residence time of water in the shallow groundwater. The data and analysis presented in this paper provide a framework for evaluating the feasibility of in-situ disinfection of shallow groundwater, and elucidate several topics that warrant further investigation. PMID:21906774

Bailey, Morgan M; Cooper, William J; Grant, Stanley B

2011-08-22

373

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...

374

Detecting groundwater contamination of a river in Georgia, USA using baseflow sampling  

NASA Astrophysics Data System (ADS)

Algal blooms and fish kills were reported on a river in coastal Georgia (USA) downstream of a poultry-processing plant, prompting officials to conclude the problems resulted from overland flow associated with over-application of wastewater at the plant’s land application system (LAS). An investigation was undertaken to test the hypothesis that contaminated groundwater was also playing a significant role. Weekly samples were collected over a 12-month period along an 18 km reach of the river and key tributaries. Results showed elevated nitrogen concentrations in tributaries draining the plant and a tenfold increase in nitrate in the river between the tributary inputs. Because ammonia concentrations were low in this reach, it was concluded that nitrate was entering via groundwater discharge. Data from detailed river sampling and direct groundwater samples from springs and boreholes were used to isolate the entry point of the contaminant plume. Analysis showed two separate plumes, one associated with the plant’s unlined wastewater lagoon and another with its LAS spray fields. The continuous discharge of contaminated groundwater during summer low-flow conditions was found to have a more profound impact on river-water quality than periodic inputs by overland flow and tributary runoff.

Reichard, James S.; Brown, Chandra M.

2009-05-01

375

CONTAMINATION OF GROUNDWATER WITH HEAVY METALS IN GAZA STRIP  

Microsoft Academic Search

This study characterized the chemical contamination of drinking water in Gaza Strip. Twenty one fresh samples from different supply site s were analyzed for metals and anions concentration. Results showed that samples c ontained higher level of nitrates than the EPA standards. Concentrations of sodium, p otassium, calcium, magnesium salts are high in several water supply sites but th ey

Yasser El-Nahhal

376

Evidence for Groundwater Contamination Vulnerability in California?s Central Valley  

SciTech Connect

The California Water Resources Control Board, in collaboration with the US Geological Survey and Lawrence Livermore National Laboratory, has implemented a program to assess the susceptibility of groundwater resources. Advanced techniques such as groundwater age dating using the tritium-helium method, extensive use of oxygen isotopes of the water molecule ({delta}{sup 18}O) for recharge water provenance, and analysis of common volatile organic compounds (VOCs) at ultra-low levels are applied with the goal of assessing the contamination vulnerability of deep aquifers, which are frequently used for public drinking water supply. Over 1200 public drinking water wells have been tested to date, resulting in a very large, tightly spaced collection of groundwater ages in some of the heavily exploited groundwater basins of California. Smaller scale field studies that include shallow monitoring wells are aimed at assessing the probability that nitrate will be transported to deep drinking water aquifers. When employed on a basin-scale, groundwater ages are an effective tool for identifying recharge areas, defining flowpaths, and determining the rate of transport of water and entrained contaminants. De-convolution of mixed ages, using ancillary dissolved noble gas data, gives insight into the water age distribution drawn at a well, and into the effective dilution of contaminants such as nitrate at long-screened production wells. In combination with groundwater ages, low-level VOCs are used to assess the impact of vertical transport. Special studies are focused on the fate and transport of nitrate with respect to vulnerability of aquifers in agricultural and formerly agricultural areas.

Moran, J E; Leif, R; Esser, B K; Singleton, M J

2005-12-13

377

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

PubMed Central

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

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

2007-01-01

378

An analytical model of contaminant transport from diffuse sources in saturated porous media  

NASA Astrophysics Data System (ADS)

An analytical two-dimensional model of solute transport along a vertical cross section of an aquifer is described. The model extends analytical methods to two-dimensional dispersive solute transport in a two-dimensional flow field which until now has been the exclusive province of numerical models. This avoids the very significant problems of numerical instability and numerical dispersion facing the application of numerical transport models at a regional scale. Furthermore, the model is simple and very fast. A novel feature is the segregation of longitudinal and transverse transport components. The model is intended for preliminary evaluation of groundwater quality on a regional scale in areas subject to diffuse sources of contamination. It gives vertical resolution of contaminant concentrations through the aquifer thickness. Results compare favorably with finite element model results for a case involving a strip source of contaminants. It has been useful in predicting the impact of diffuse source nitrate contamination on groundwater quality in the Lower South East of South Australia.

Dillon, P. J.

1989-06-01

379

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

380

Groundwater contamination by volatile halogenated alkanes: abiotic formation of volatile sulfur compounds under anaerobic conditions  

SciTech Connect

The investigation of a groundwater contamination caused by a leaking wastewater tank of a chemical plant revealed that in groundwaters, under highly reducing conditions in the presence of hydrogen sulfide, certain volatile bromo- and chloroalkanes may undergo second-order nucleophilic substitution reactions yielding very persistent and hazardous volatile sulfur-containing compounds including dialkyl sulfides. Rate constants determined in the laboratory indicate that these nucleophilic substitution reactions may compete with hydrolysis, even at the low hydrogen sulfide concentrations typically encountered in the aquatic environment.

Schwarzenbach, R.P.; Giger, W.; Schaffner, C.; Wanner, O.

1985-01-01

381

Hydrogeochemical controls on removal of Cr(VI) from contaminated groundwater by anion exchange  

Microsoft Academic Search

Column experiments using strongly basic anion exchange resin under acidic conditions of pH (3.6–5) and conducted with groundwater sources having strong acidic anions (Cl? and SO42-) in excess of weak acidic anions (HCO3- and CO32-) but with markedly different Cr(VI) concentrations demonstrate that the anion chemistry of groundwater controls the efficacy of the ion exchange process for removing dissolved oxyanions

Biswajit Mukhopadhyay; Jon Sundquist; Eric White

2007-01-01

382

Tracing the Sources and History of Subsurface Contamination at the Hanford Site in Washington Using High-Precision Uranium Isotopic Measurements  

NASA Astrophysics Data System (ADS)

Groundwater contamination at the Hanford Site, Washington, resulted from decades of nuclear fuel production and processing. Understanding the fate and transport of contaminants has been complicated by the presence of multiple potential sources within relatively small areas. The contrasts in isotopic composition between natural and anthropogenic uranium promotes the measurement of uranium isotopic composition as a fingerprint and tracer of uranium contamination in the environment. In this study we focused on a uranium groundwater plume and two vadose zone U plumes associated with the B-BX-BY waste management area, used since the late 1940's for the storage of high-level radioactive waste. Groundwater U contamination was first detected in monitoring wells in the early 1990's. The groundwater plume (>30 ppb U) is currently approximately 250 m wide, at least 900 m long with U concentrations up to 525 ppb. The exact origin and history of this contamination is not well understood, since a number of tanks and incidents are potential sources. Using multiple collector ICPMS (Micromass IsoProbe) high precision uranium isotopic analyses were conducted of samples of vadose zone contamination and of groundwater. The measured isotopic compositions (234U/238U, 235U/238U and 236U/238U) are used to distinguish contaminant sources, and are compared to a history of processed U fuel rod compositions. Based on the isotopic data, the groundwater plume appears to be related to a tank overflow event in 1951 that spilled high-level waste into the vadose zone. A second zone of identified vadose zone contamination does not seem to be an important contributor to the groundwater U plume. The variation in U isotopic composition of the groundwater samples is a result of mixing of contaminant U from the 1951 event and natural background U. The identified vadose zone contamination source is horizontally displaced from the initial locus of groundwater contamination, indicating that lateral migration within the vadose was at least 8 times greater than vertical migration. The time evolution of the groundwater plume suggests an average U migration rate of ˜0.7 m/day showing slight retardation relative to groundwater flow of ˜1 m/day.

Christensen, J. N.; Dresel, P. E.; Conrad, M. E.; Maher, K.; Depaolo, D. J.

2003-12-01

383

Pseudomonadaceae as a Source of Bacterial Contamination in Tissue Culture  

Microsoft Academic Search

THE pleuro-pneumonia-like organisms cause considerable difficulty in tissue culture work, as many lines of cell cultures are contaminated with these organisms1. I have found that members of the Pseudomonadaceae could play a part as contaminants of tissue culture. It is well known that these bacteria are frequently a source of bacterial contamination in stored blood and blood derivatives2.

M. Likar

1961-01-01

384

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

2013-07-11

385

Linking Groundwater Quality and Quantity: An Assessment of Satellite-Based Groundwater Storage Anomalies From GRACE Against Ground Measurements of Contaminants in California  

NASA Astrophysics Data System (ADS)

Groundwater comprises a large portion of irrigation for California's agriculture, and sustains a wide diversity of ecosystems as well as consumptive use, but pumping is occurring faster than replenishment. At the same time, contaminants from fertilizers and pesticides are infiltrating into the groundwater, becoming increasingly concentrated as water is extracted. We compared space-based observations of groundwater anomalies from California's San Joaquin Valley using the Gravity Recovery and Climate Experiment (GRACE) against measurements of 42 organic and inorganic chemicals from 41,667 wells in the valley from 2003 to 2010. Preliminary results show both strong and weak correlations with groundwater depletion against increasing chlorine (r2=0.78), boron (r2=0.88), but no relationship with benzene (r2=0.03). These results are the first to link space-based groundwater quantity with groundwater quality.

Rezaie Boroon, M.; Fisher, J. B.

2011-12-01

386

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

387

Characterization of contaminated soil and groundwater surrounding an illegal landfill (S. Giuliano, Venice, Italy) by principal component analysis and kriging  

Microsoft Academic Search

The characterization of a hydrologically complex contaminated site bordering the lagoon of Venice (Italy) was undertaken by investigating soils and groundwaters affected by the chemical contaminants originated by the wastes dumped into an illegal landfill. Statistical tools such as principal components analysis and geostatistical techniques were applied to obtain the spatial distribution of chemical contaminants. Dissolved organic carbon (DOC), SO42?

Andrea Critto; Claudio Carlon; Antonio Marcomini

2003-01-01

388

Groundwater Contamination by Chlorinated Solvents: History, Remediation Technologies and Strategies  

Microsoft Academic Search

\\u000a Chlorinated solvents have seen broad usage for a wide variety of purposes, from cleaning of machinery, clothes and electronic\\u000a parts to use in chemical manufacturing. However, through general dispersal, during normal usage and also as a result of indiscriminate\\u000a disposal, chlorinated solvents have caused a variety of environmental problems. One such problem of great concern is the contamination\\u000a of soil

Perry L. McCarty

389

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

PubMed

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

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

2005-11-01

390

Co-contamination of arsenic and fluoride in the groundwater of unconsolidated aquifers under reducing environments.  

PubMed

The co-contamination of arsenic (As) and fluoride (F(-)) in shallow aquifers is frequently observed worldwide, and the correlations between those contaminants are different according to the redox conditions. This study geochemically explores the reasons for the co-contamination and for the redox-dependent correlations by investigating the groundwater of an alluvial aquifer in Korea. Geochemical signatures of the groundwater in the study area show that the As concentrations are enriched by the reductive dissolution of Fe-(hydr)oxides, and the correlations between As and F(-) concentrations are poor comparatively to those observed in the oxidizing aquifers. However, F(-) concentrations are strongly dependent on pH. Desorption/adsorption experiments using raw soils and citrate-bicarbonate-dithionite treated soils indicated that Fe-(hydr)oxides are the important As and F(-) hosts causing the co-contamination phenomenon. The weaker correlation between F(-) and As in reducing aquifers is likely to be associated with sulfate reduction, which removes As from groundwater without changing the F(-) concentration. PMID:22325979

Kim, Seok-Hwi; Kim, Kangjoo; Ko, Kyung-Seok; Kim, Yeongkyoo; Lee, Kwang-Sik

2012-02-10

391

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

392

Numerical simulation of contaminant transport problems in groundwater using the finite element method  

SciTech Connect

In this investigation, a Galerkin finite element model in two dimensions was developed to study the phenomena of mass transfer in porous media. In particular, the problems of the saltwater encroachment in coastal aquifers and the transport of hazardous wastes in groundwater environment are studied for a wide range of aquifer parameters. The coupled governing partial differential equations are nondimensionalized and solved for a two-dimensional, saturated aquifer in the vertical plane for both steady state and transient conditions using an iterative solution procedure. The flow transport is represented either in terms of the stream function or the freshwater hydraulic head and the respective models are termed as the Stream Function Model and the Hydraulic Head Model. It was found, in the analyses conducted with the Stream Function Model for isotropic conditions, that the selection of an appropriate mesh is extremely important to obtain correct solutions in the saltwater intrusion problem. In addition, the selection of an appropriate region size is necessary to properly satisfy the boundary condition C = 0 at the freshwater face. Contaminant transport episodes are simulated for anisotropic conditions with the Hydraulic Head Model. Results obtained with a coarse mesh show that negative concentration values appear at large values of d/sub L/ and low values of the piezometric gradient. These negative concentrations are removed when a refined mesh, near the pollutant source, is utilized.

Pandit, A.

1982-01-01

393

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

PubMed Central

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

Freni, S C; Phillips, D L

1987-01-01

394

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

395

The implications of groundwater velocity variations on microbial transport and wellhead protection – review of field evidence  

Microsoft Academic Search

Current strategies to protect groundwater sources from microbial contamination (e.g., wellhead protection areas) rely upon natural attenuation of microorganisms between wells or springs and potential sources of contamination and are determined using average (macroscopic) groundwater flow velocities defined by Darcy's Law. However, field studies of sewage contamination and microbial transport using deliberately applied tracers provide evidence of groundwater flow paths

Richard Taylor; Aidan Cronin; Steve Pedley; John Barker; Tim Atkinson

2004-01-01

396

An isotope study of the sources of nitrate in Malta's groundwater  

NASA Astrophysics Data System (ADS)

Examines sources of nitrate in some of Europe's highest nitrate groundwaters. Measures, rather than assumes isotope composition of potential sources. Indicates soil nitrification as the most likely source. Examines implications for a country with a long history of cultivation.

Heaton, Tim H. E.; Stuart, Marianne E.; Sapiano, Manuel; Micallef Sultana, Miriam

2012-01-01

397

GROUNDWATER QUALITY MONITORING OF WESTERN COAL STRIP MINING: PRELIMINARY DESIGNS FOR ACTIVE MINE SOURCES OF POLLUTION  

EPA Science Inventory

Three potential pollution source categories have been identified for Western coal strip mines. These sources include mine stockpiles, mine waters, and miscellaneous active mine sources. TEMPO's stepwise monitoring methodology (Todd et al., 1976) is used to develop groundwater qua...

398

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

NASA Astrophysics Data System (ADS)

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, Judith M.; McKenna, Thomas E.; Ullman, William J.

2010-12-01

399

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

PubMed

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

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

2011-06-01

400

California GAMA Program: Sources and Transport of Nitrate in Shallow Groundwater in the Llagas Basin of Santa Clara County, California.  

National Technical Information Service (NTIS)

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 t...

2005-01-01

401

Bat groundwater monitoring system in contaminant studies. Doctoral thesis  

SciTech Connect

The purpose of this study is to provide an in-depth, comprehensive study to compare results from the BAT probe and Teflon bailers from nearby monitoring wells. Volatile organic compounds are typically the most difficult contaminants to sample. The research was performed by taking samples within a small radius around monitoring wells at two leaking underground storage tank sites and taking bailer samples from the monitoring wells. BAT sampling will also be performed inside the monitoring wells to ensure basically the same water is being sampled.

Mines, B.S.

1992-01-01

402

Remediation of Contaminated Groundwater Using Nano-Carbon Colloids  

NASA Astrophysics Data System (ADS)

The paper deals with a novel method of obtaining nano-carbon colloids (NCC). The method allows synthesizing aqueous dispersions of NCC with the sizes in the range of 1-100 nm, concentration of 150-400 ppm and pH of 2.8-3.1. Due to functional carboxyl groups the ion exchange capacity of carbon colloids obtained is very high — 7.4 mmol/g for a monovalent cation. NCC can be used for effective removal of metal ions (Zn, Ni, Cu, Sb, Co, Cd, Cr, etc.) from contaminated water.

Khaydarov, R. R.; Khaydarov, R. A.; Gapurova, O.

403

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

PubMed

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

Adel, Miah M

2005-12-01

404

The effect of ionic strength and hardness of trichloroethylene-contaminated synthetic groundwater on remediation using granular activated carbon  

Microsoft Academic Search

The objective of this study is to evaluate the effect of ionic strength and hardness of trichloroethylene (TCE)-contaminated\\u000a synthetic groundwater on remediation using granular activated carbon (GAC). The TCE sorption rate onto GAC in synthetic groundwater\\u000a was observed by batch experiments and ranged from 86.2% to 100%. As the ionic strength and hardness of the synthetic groundwater\\u000a increased, the TCE

Joong-Hyeok Heo; Dal-Heui Lee; Dong-Chan Koh; Ho-Wan Chang

2007-01-01

405

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

PubMed

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. PMID:16572769

Repert, Deborah A; Barber, Larry B; Hess, Kathryn M; Keefe, Steffanie H; Kent, Douglas B; LeBlanc, Denis R; Smith, Richard L

2006-02-15

406

Granular activated carbon pilot treatment studies for explosives removal from contaminated groundwater  

SciTech Connect

Manufacturing activities at Army Ammunition Plants (AAPs) result in the production of organic wastewaters that contain both explosive residues and other organic chemicals. As a result of past waste practices at such plants, explosive residues may leach through the soil and contaminate groundwater. Two pilot studies were performed to evaluate the use of granular activated carbon (GAC) to treat groundwater contaminated with explosives at Badger AAP and Milan AAP. An additional goal of the Badger AAP study was to examine the potential discharge of explosives 2,4-DNT and 2,6-DNT from a packed column air stripper used to remove volatile organic compounds from groundwater. A laboratory method was developed for the BAAP study to permit lower detection levels for 2,4-DNT and 2,6-DNT (0.46[mu]g/L and 0.017 [mu]g/L, respectively). The studies concluded that removal of explosives from groundwater using continuous flow GAC is feasible. 14 refs., 10 figs., 11 tabs.

Wujcik, W.J.; Lowe, W.L.; Marks, P.J. (Roy F. Weston, Inc., West Chester, PA (United States)); Sisk, W.E. (USATHAMA, Edgewood, MD (United States))

1992-08-01

407

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.