Groundwater Contamination In Areas Research Articles

Water Policy of Korea for Supplying Safe Groundwater in Rural Areas

According to a 2015 study conducted by the Ministry of Environment of Korea, municipal water is supplied to 96.1% of the total Korean population, but 3.9% of the total population (~2.14 million people) in rural myeon or villages, drink groundwater from old and/or unregistered wells that are not a part of the municipal water system. Additionally, accurate statistics are not reported without regular water quality tests, so safety measures alone are insufficient to improve water quality. In this situation, the Korean government is responsible for verifying the quality of groundwater and identifying the cause of groundwater contamination in areas with no municipal water supply. The National Institute of Environmental Research (NIER) under the Ministry of Environment of Korea, conducted the ‘Safe Groundwater Supply Project (SGSP)’ between 2012 and 2016 to secure groundwater quality stability in areas without the benefit of municipal water. This survey identified groundwater quality using a detailed water quality survey and gave recommendations for supplying safe groundwater and providing future improvements and countermeasures in cases of groundwater pollution. This paper presents the SGSP and consists of water quality analysis, the exploration and exploitation of drinking water facilities, the selection of a pilot project area among high-pollution areas, and improvement measures for water quality in the pilot project area.

Temporal variation in groundwater quality in the Permian Basin of Texas, a region of increasing unconventional oil and gas development

The recent expansion of natural gas and oil extraction using unconventional oil and gas development (UD) practices such as horizontal drilling and hydraulic fracturing has raised questions about the potential for environmental impacts. Prior research has focused on evaluations of air and water quality in particular regions without explicitly considering temporal variation; thus, little is known about the potential effects of UD activity on the environment over longer periods of time. Here, we present an assessment of private well water quality in an area of increasing UD activity over a period of 13months. We analyzed samples from 42 private water wells located in three contiguous counties on the Eastern Shelf of the Permian Basin in Texas. This area has experienced a rise in UD activity in the last few years, and we analyzed samples in four separate time points to assess variation in groundwater quality over time as UD activities increased. We monitored general water quality parameters as well as several compounds used in UD activities. We found that some constituents remained stable over time, but others experienced significant variation over the period of study. Notable findings include significant changes in total organic carbon and pH along with ephemeral detections of ethanol, bromide, and dichloromethane after the initial sampling phase. These data provide insight into the potentially transient nature of compounds associated with groundwater contamination in areas experiencing UD activity.

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

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.

Surveying Upstate NY Well Water for Pesticide Contamination: Cayuga and Orange Counties

Private wells in Cayuga and Orange counties in New York were sampled to determine the occurrence of pesticide contamination of groundwater in areas where significant pesticide use coincides with shallow or otherwise vulnerable groundwater. Well selection was based on local groundwater knowledge, risk modeling, aerial photo assessments, and pesticide application database mapping. Single timepoint samples from 40 wells in each county were subjected to 93‐compound chromatographic scans. All samples were nondetects (reporting limits ≤1 μg/L), thus no wells from either county exceeded any of 15 state groundwater standards or guidance values. More sensitive enzyme‐linked immunosorbent assays (ELISA) found two wells with quantifiable atrazine in each county (0.1–0.3 μg/L), one well with quantifiable diazinon (0.1 μg/L) in Orange County, and one well with quantifiable alachlor (0.2 μg/L) in Cayuga County. Trace detections (<0.1 μg/L) in Cayuga County included atrazine (five wells), metolachlor (six wells), and alachlor (one well), including three wells with multiple detections. All 12 Cayuga County wells with ELISA detections had either corn/grain or corn/forage rotations as primary surrounding land uses (although 20 other wells with the same land uses had no detections) and all quantified detections and most trace detections occurred in wells up to 9‐m deep. Orange County trace (<0.1 μg/L) ELISA detections (atrazine three wells, diazinon one well, and metolachlor five wells) and quantified detections were only generally associated with agricultural land uses. Finding acceptable drinking water quality in areas of vulnerable groundwater suggests that water quality in less vulnerable areas will also be good.

Effects of pH and Manure on Transport of Sulfonamide Antibiotics in Soil

Sulfonamide antibiotics are a commonly used group of compounds in animal husbandry. They are excreted with manure, which is collected in a storage lagoon in certain types of confined animal feeding operations. Flood irrigation of forage fields with this liquid manure creates the potential risk of groundwater contamination in areas with shallow groundwater levels. We tested the hypothesis that-in addition to the soil characteristics-manure as cosolute and manure pH are two major parameters influencing sulfonamide transport in soils. Solute displacement experiments in repacked, saturated soil columns were performed with soil (loamy sand) and manure from a dairy farm in California. Breakthrough of nonreactive tracer and sulfadimethoxine, sulfamethazine, and sulfamethoxazole at different solution pH (5, 6.5, 8.5) with and without manure was modeled using Hydrus-1D to infer transport and reaction parameters. Tracer and sulfonamide breakthrough curves were well explained by a model concept based on physical nonequilibrium transport, equilibrium sorption, and first-order dissipation kinetics. Sorption of the antibiotics was low ( K₄ ≤ 0.7 L kg) and only weakly influenced by pH and manure. However, sulfonamide attenuation was significantly affected by both pH and manure. The mass recovery of sulfonamides decreased with decreasing pH, e.g., for sulfamethoxazole from 77 (pH 8.5) to 56% (pH 5). The sulfonamides were highly mobile under the studied conditions, but manure application increased their attenuation substantially. The observed attenuation was most likely caused by a combination of microbial transformation and irreversible sorption to the soil matrix.

Integrated techniques to identify groundwater vulnerability to pollution in a highly industrialized terrain, Tamilnadu, India

Investigation has been made to identify groundwater vulnerability to pollution by using geoelectric and hydrochemical investigations in an important industrial town Mettur located in Tamilnadu state of India. Schlumberger vertical electric soundings were carried out in 23 locations and groundwater samples collected from bore wells in the same locations. The resistivity value with <20 Ωm up to a depth of 36 m indicate contamination of groundwater in areas influenced by sewages from industries, domestic and agricultural practices in the central and southern part of the study area. The calculated specific conductance was noted higher than EC in central and southern part of the study area with low resistivity indicating the contaminated nature of groundwater. Concentrations of Ca, Na, Mg and K along with Cl, HCO(3), SO(4) and NO(3) were higher in certain locations when compared with WHO and ISI standards. The facies concept demarcated four groups based on the nature of groundwater contamination. The trace elements Fe and Pb were higher in locations confined to industrial zones and Zn and Cu were within the prescribed limit in all the samples.

Movement of trichloroethene in a discontinuous permafrost zone

At a site with discontinuous permafrost in Fairbanks, Alaska, releases of trichloroethene (TCE), an industrial solvent, have caused contamination of the groundwater. The objective of this study was to investigate the relationship between the migration pathway of the TCE groundwater plume and the distribution of the discontinuous permafrost at the site. The TCE plume configuration is substantially different than what regional hydrology trends would predict. Using GIS, we conducted a geostatistical analysis of field data collected during soil-boring installations and groundwater monitoring well sampling. With the analysis results, we constructed maps of the permafrost-table elevation (top of permafrost) and of the groundwater gradients and TCE concentrations from multiyear groundwater sampling events. The plume concentrations and groundwater gradients were overlain on the permafrost map to correlate permafrost locations with groundwater movement and the spatial distribution of TCE moving with groundwater. Correlation of the overlay maps revealed converging and diverging groundwater flow in response to the permafrost-table distribution, the absence of groundwater contamination in areas with a high permafrost-table elevation, and channeling of contaminants and water between areas of permafrost. In addition, we measured groundwater elevations in nested wells to quantify vertical gradients affecting TCE migration. At one set of nested wells down gradient from an area of permafrost we measured an upward vertical gradient indicating recharge of groundwater from the subpermafrost region of the aquifer causing dilution of the plume. The study indicates that the variable distribution of the permafrost is affecting the way groundwater and TCE move through the aquifer. Consequently, changes to the permafrost configuration due to thawing would likely affect both groundwater movement and TCE migration, and areas that were contaminant-free may become susceptible to contamination.

Nitrate contamination of groundwater in an agroecosystem in Zhangye Oasis, Northwest China

In order to assess the extent of groundwater contamination by nitrate (NO3 −–N) and to provide information about the deterioration of the groundwater quality in Zhangye Oasis, Northwest China, a study was conducted in this area. The mean value of NO3 −–N concentrations in groundwater samples was 10.66 ± 0.19 mg l−1. NO3 −–N concentrations exceeding 10 mg l−1 (the threshold for drinking water set by the World Health Organization) were found in 32.4% of 71 wells, and were 13, 33.3, 52.4 and 50.0% in the groundwater samples from drinking wells, irrigation wells, hand-pumping wells and groundwater table observation wells, respectively. The result showed that the groundwater samples that had NO3 −–N concentrations exceeding the threshold for drinking water were mostly collected from a depth of less than 20 m. Groundwater NO3 −–N concentrations in areas used for the cultivation of vegetables, seed maize and intercropped maize were significantly higher than those in urban or paddy areas. NO3 −–N contamination of groundwater in areas with sandy soil was more severe than in those with loam soil.

Long-term corrosion and leaching of depleted uranium (DU) in soil

Corrosion and leaching of depleted uranium (DU) was investigated for 3 years using six DU munitions (145-264 g DU) each buried in a column with a soil core of about 3.3 kg dry soil mass. The columns were installed in an air-conditioned laboratory. Each week they were irrigated and (238)U was determined in the effluents by inductively coupled plasma mass spectrometry. In addition, (235)U was measured occasionally to assure that the (238)U was predominantly from the DU munition. On average, 14.5 g corresponding to 7.9% of the initial DU mass was corroded after 3 years, indicating an increased corrosion as compared to the first year of observation. The leaching rates increased much stronger than the corrosion rates by factors of more than 100, resulting in a mean total amount of leached (238)U of 13 mg as compared to 0.03 mg after the first year. Uranium species identified in the seepage water by time-resolved laser-induced fluorescence spectroscopy were mainly hydroxo and carbonate compounds, while those in the corroded material were phosphate compounds. It is concluded that the dramatic increase of the leaching and its large temporal variability do not allow any extrapolation for the future. However, the high (238)U concentrations observed in the seepage water highlight the need for further investigations on the transport of (238)U through soil, in particular with regard to the potential future (238)U contamination of groundwater in areas affected by DU weapons.

Biosolid Colloid‐Mediated Transport of Copper, Zinc, and Lead in Waste‐Amended Soils

Increasing land applications of biosolid wastes as soil amendments have raised concerns about potential toxic effects of associated metals on the environment. This study investigated the ability of biosolid colloids to transport metals associated with organic waste amendments through subsurface soil environments with leaching experiments involving undisturbed soil monoliths. Biosolid colloids were fractionated from a lime-stabilized, an aerobically digested, and a poultry manure organic waste and applied onto the monoliths at a rate of 0.7 cm/h. Eluents were monitored for Cu, Zn, Pb, and colloid concentrations over 16 to 24 pore volumes of leaching. Mass-balance calculations indicated significantly higher (up to 77 times) metal elutions in association with the biosolid colloids in both total and soluble fractions over the control treatments. Eluted metal loads varied with metal, colloid, and soil type, following the sequences Zn = Cu > Pb, and ADB > PMB > LSB colloids. Colloid and metal elution was enhanced by decreasing pH and colloid size, and increasing soil macroporosity and organic matter content. Breakthrough curves were mostly irregular, showing several maxima and minima as a result of preferential macropore flow and multiple clogging and flushing cycles. Soil- and colloid-metal sorption affinities were not reliable predictors of metal attenuation/elution loads, underscoring the dynamic nature of transport processes. The findings demonstrate the important role of biosolid colloids as contaminant carriers and the significant risk they pose, if unaccounted, for soil and ground water contamination in areas receiving heavy applications of biosolid waste amendments.

Subsurface transport of Cd, Cr, and Mo mediated by biosolid colloids

The potential of biosolid colloids to transport metals associated with organic-waste amendments through subsurface soil environments was investigated with leaching experiments involving undisturbed soil monoliths. The monoliths (25 cm in height and 18 cm in diameter) were carved from the upper solum of an Alfisol, a Mollisol, and an Entisol in the Bluegrass region of Kentucky. Biosolid colloids were fractionated from two municipal wastes (lime-stabilized/LSB, and aerobically-digested/ADB), and a poultry-manure (PMB) organic waste and applied onto the monoliths at a rate of ∼0.7 cm/h. Eluents were monitored for soluble and sorbed Cd, Cr, and Mo concentrations over 16–24 pore volumes of leaching. Colloid-free solutions with metal concentrations similar to those of the biosolid colloids were used as controls. The results indicated significantly ( P<0.05) higher (up to 4 orders of magnitude) cationic and anionic metal elutions in association with the biosolid colloids in both, total and soluble fractions, over the control treatments. The elution of significant soluble metal loads in association with the biosolid colloids is attributed to increasing organic-metal complexation and exclusion processes, and emphasizes their importance as contaminant carriers and facilitators. Eluted metal loads varied with metal, colloid, and soil type, following the sequences Mo>Cd>Cr for the metals, and ADB>PMB>LSB (Cd and Cr) or ADB>LSB>PMB (Mo) for the colloids. Metal elution was generally enhanced by soil macroporosity and increasing OM content, while pH and Fe-Al oxides had significant, but opposite effects for the elution of cationic and anionic metal forms. Colloid and metal breakthrough curves were correlated well, being mostly asymmetrical with several maxima and minima caused by multiple clogging and flushing cycles. Soil- and colloid-metal sorption affinities were not reliable predictors of metal attenuation/elution loads, underscoring the dynamic nature of transport processes. The findings demonstrate the important role of biosolid colloids as contaminant carriers and the significant risk they pose, if unaccounted, for soil and ground water contamination in areas receiving heavy applications of biosolid waste amendments.

Environmental assessment: contamination of phreatic aquifer in areas impacted by waste from coal processing activities

The objective of the present work was to evaluate the degree of contamination of groundwater in areas under influence of inadequate disposal of residues from coal-processing activities. Charqueadas and São Jerônimo Counties were selected for the study. The contamination of groundwater from the phreatic aquifer was evaluated in a sequence of steps: initially, the target area was selected; then, the piezometers were installed and groundwater was sampled. The location of piezometers was based on the results obtained from the mapping of pollution sources, geophysical and hydrogeological studies. The results showed that the groundwater (phreatic aquifer) from the region studied is influenced, in variables degrees of intensity, by the type and characteristics of residues, the lithological profile of the site and the distance from the pollution sources. Physical and chemical characterization revealed that coal waste influenced more significantly groundwater contamination, evidenced by acidic pH values, as well as high values of conductivity, total dissolved solids (TDS), sulfates, ferrous iron and metals (Ni, Fe, Co, Cr and Mn). The statistical analysis applied to the variables studied gave a General Groundwater Index for each well. By the application of this index, it was possible to highlight the kind of residues and variables that are affecting the groundwater quality.

Clinical manifestations of arteriosclerotic disease: Evans, G.: Practitioner 153: 129, 1944

The potential of biosolid colloids to transport metals associated with organic-waste amendments through subsurface soil environments was investigated with leaching experiments involving undisturbed soil monoliths. The monoliths (25 cm in height and 18 cm in diameter) were carved from the upper solum of an Alfisol, a Mollisol, and an Entisol in the Bluegrass region of Kentucky. Biosolid colloids were fractionated from two municipal wastes (lime-stabilized/LSB, and aerobically-digested/ADB), and a poultry-manure (PMB) organic waste and applied onto the monoliths at a rate of ∼0.7 cm/h. Eluents were monitored for soluble and sorbed Cd, Cr, and Mo concentrations over 16–24 pore volumes of leaching. Colloid-free solutions with metal concentrations similar to those of the biosolid colloids were used as controls. The results indicated significantly (P<0.05) higher (up to 4 orders of magnitude) cationic and anionic metal elutions in association with the biosolid colloids in both, total and soluble fractions, over the control treatments. The elution of significant soluble metal loads in association with the biosolid colloids is attributed to increasing organic-metal complexation and exclusion processes, and emphasizes their importance as contaminant carriers and facilitators. Eluted metal loads varied with metal, colloid, and soil type, following the sequences Mo>Cd>Cr for the metals, and ADB>PMB>LSB (Cd and Cr) or ADB>LSB>PMB (Mo) for the colloids. Metal elution was generally enhanced by soil macroporosity and increasing OM content, while pH and Fe-Al oxides had significant, but opposite effects for the elution of cationic and anionic metal forms. Colloid and metal breakthrough curves were correlated well, being mostly asymmetrical with several maxima and minima caused by multiple clogging and flushing cycles. Soil- and colloid-metal sorption affinities were not reliable predictors of metal attenuation/elution loads, underscoring the dynamic nature of transport processes. The findings demonstrate the important role of biosolid colloids as contaminant carriers and the significant risk they pose, if unaccounted, for soil and ground water contamination in areas receiving heavy applications of biosolid waste amendments.