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At least 19 recordsLinked to original sources
PubMed1999

Environmental behavior of explosives in groundwater from the Milan Army Ammunition Plant in aquatic and wetland plant treatments. Removal, mass balances and fate in groundwater of TNT and RDX.

Phytoremediation of 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in groundwater using constructed wetlands is a potentially economical remediation alternative. To evaluate Explosives removal and fate was evaluated using hydroponic batch incubations of plant and substrate treatments with explosives-contaminated groundwater amended with [U-14C]-TNT or [U-14C]-RDX. Plants and substrates were collected from a small-scale wetland constructed for explosives removal, and groundwater originated from a local aquifer at the Milan Army Ammunition Plant. The study surveyed three aquatic, four wetland plant species and two substrates in independent incubations of 7 days with TNT and 13 days with RDX. Parent compounds and transformation products were followed using 14C and chemical (HPLC) analyses. Mass balance of water, plants, substrates and air was determined. It was demonstrated that TNT disappeared completely from groundwater incubated with plants, although growth of most plants except parrot-feather was low in groundwater amended to contain 1.6 to 3.4 mg TNT L-1. Highest specific removal rates were found in submersed plants in water star-grass and in all emergent plants except wool-grass. TNT declined less with substrates, and least in controls without plants. Radiolabel was present in all plants after incubation. Mineralization to 14CO2 was very low, and evolution into 14C-volatile organics negligible. RDX disappeared less rapidly than TNT from groundwater. Growth of submersed plants was normal, but that of emergent plants reduced in groundwater amended to contain 1.5 mg RDX L-1. Highest specific RDX removal rates were found in submersed plants in elodea, and in emergent plants in reed canary grass. RDX failed to disappear with substrates. Mineralization to 14CO2 was low, but relatively higher than in the TNT experiment. Evolution into 14C-volatile organics was negligible. Important considerations for using certain aquatic and wetland plants in constructed wetlands aimed at removing explosives from water are: (1) plant persistence at the explosives level to which it is exposed, (2) specific plant-mass based explosives removal rates, (3) plant productivity, and (4) fate of parent compounds and transformation products in water, plants, and sediments.

Environmental Pollution↗
PubMed1997

Conceptual Design of a System for Selecting Appropriate Groundwater Models in Groundwater Protection Programs

/ An effective groundwater protection program requires understanding of water flow and contaminant transport processes in the subsurface. Although many mathematical models have been developed to simulate the processes, few actually are used in groundwater protection programs due to the difficulties in data collection, model selection, and model implementation. This study presents a conceptual design of a GIS-supported model selection system that evaluates available data and mathematical models to facilitate groundwater protection programs. Steady-state groundwater and contaminant transport models applied in isotropic aquifers are placed into four classes to simulate conservative or nonconservative contaminant transports in simple or complex geohydrological conditions. After analyzing specific study objectives, available data, and model requirements, the proposed system selects a class of models that can be used in simulation and recommends any need for additional data collection. This study initiates an effort to integrate GIS, mathematical models, and expert knowledge in one system to promote the application of appropriate groundwater models. The new technology of GIS and digital data-base management makes it possible to develop such a system in practice.KEY WORDS: Groundwater models; Geographic information systems

Journal Article↗
PubMed1998

The chemistry of Norwegian groundwaters: II. The chemistry of 72 groundwaters from Quaternary sedimentary aquifers.

Seventy-two samples of groundwater derived from Norwegian Quaternary (largely glaciofluvial or glacial) aquifers were analysed for a wide range of major and minor hydrochemical parameters. The waters exhibit a relatively uncomplex evolution from Na-Cl dominated, immature waters (which reflect marine salts in precipitation) to Ca-HCO3 dominated waters via calcite dissolution. The median pH of these waters is 7.37, in contrast to similar waters from crystalline bedrock aquifers with a median pH of 8.07. The water samples provide little evidence of significant acidification or sulphatisation of groundwaters by 'acid rain'. In fact, a positive correlation emerges between non-marine sulphate and alkalinity/pH, suggesting dominantly lithological sources for non-marine sulphate. No groundwaters from Quaternary deposits exceed maximum recommended concentrations for Rn, F- and Na, while 10% fall outside the required pH range. This again contrasts with bedrock aquifers where 30% of waters are non-compliant with respect to one or more of these parameters.

Acid Rain↗
PubMed2001

The chemistry of Norwegian groundwaters: IV. The pH-dependence of element concentrations in crystalline bedrock groundwaters.

A total of 1604 samples of crystalline bedrock groundwaters in Norway have been analysed for pH, major and minor elements. A subset of 476 samples were also analysed for a wide range of trace elements by ICP-MS. The pH of the samples ranges from 5.4 to 9.8, with a predominance of pH values between 8.0 and 8.2. The data-set is divided into five 20-percentile groups according to increasing pH. The concentrations of 60 elements are then displayed as box-plots for each pH group. A line through the five medians yields a visual demonstration of the relationship with, and sensitivity to, pH variations for concentrations of each element. Twelve characteristic trends are distinguishable, from which some of the main hydrogeochemical processes related to pH and groundwater evolution can be inferred.

Environmental Monitoring↗
PubMed1998

The chemistry of Norwegian groundwaters: I. The distribution of radon, major and minor elements in 1604 crystalline bedrock groundwaters.

A quality-controlled hydrogeochemical dataset of 1604 groundwater samples from Norwegian crystalline bedrock aquifers has been obtained and subject to analyses of radon (scintillation counting), major and minor elements (ion chromatography and ICP-AES), pH and alkalinity. Cumulative probability curves may be constructed to assess the risk of given parameters violating drinking water norms. Parameters such as radon and fluoride show clear lithological correlation, occurring at high concentrations in granites and low concentrations in anorthosites. Other parameters exhibit a lower degree of correlation with aquifer geochemistry (e.g. pH, major ions) and are likely to be governed by more universal thermodynamic equilibria (the calcium carbonate system) and kinetic factors. On a national basis 13.9% of the bedrock groundwaters exceed the recommended action level for radon, while 16.1% exceed the drinking water norm for fluoride. Considering pH, sodium, radon and fluoride together, 29.9% of all wells violate drinking water maximum concentrations for one or more of these parameters.

Calcium↗
PubMed2000

The chemistry of Norwegian groundwaters: III. The distribution of trace elements in 476 crystalline bedrock groundwaters, as analysed by ICP-MS techniques

Four hundred and seventy-six groundwater samples from boreholes in Norwegian crystalline bedrock have been analysed by ICP-MS techniques. The results for 53 trace elements are presented as cumulative frequency distribution diagrams and are compared with relevant international drinking water norms. A range of trace elements appear to be enriched in granitic waters and depleted in anorthositic waters which is to be expected as generally granitic rocks are enriched in trace elements above those in anorthosites. A selection of elements which may be toxic in excess when present in drinking water are further discussed (Be, Tl, Th, U, Cd, Pb, As, Ni, and Hg). For uranium, 18% of the samples exceed the American maximum admissible concentration of 20 micrograms/l; 7% of the samples fail to meet the Russian drinking water norms for beryllium of 0.2 microgram/l. For some parameters such as U, Be and Tl, no Norwegian drinking water regulations are set, while the American and the Russian norms differ significantly from each other. Between 0 and 1.5% of the wells exceed Norwegian drinking water norms for each of the other selected elements.

Journal Article↗
PubMed1994

[Pesticide pollution of groundwater and drinking water by the processes of artificial groundwater enrichment or coastal filtration: underrated sources of contamination].

The research objective of this study is to monitor the degree of pesticide pollution in public drinking waters and to characterise the pathways by which these substances get into potable waters. Public drinking waters, raw waters, ground waters, and surface waters in an area with intensive agriculture were analysed for pesticides and nitrate during the years 1987-1992. The monitoring reveals that only potable waters of water works using the process of artificial ground water recharge are polluted by pesticides. The very influence of surface water on the degree of pesticide contamination can be shown up to the wells. Wells that are influenced by bank filtration or infiltration contain significantly (P < 0.001) higher amounts and a greater number of substances than pure ground water wells. Most often triazines and phenylureas are analysed. Among the tested water works the artificial ground water recharge is the main factor for the input of pesticides into the aquifer and the drinking water. Percolation experiments, and parallel seasonal changes of pesticides and nitrate in raw and infiltration water document a high mobility during the subsoil passage and an easy vulnerability of the aquifer. There is no correlation between pesticides and nitrate. So nitrates are not suited as an indicator for pesticide pollution. Almost all tested surface waters, including channels, contain pesticides in highly varying concentrations during the whole year and are thus always a possible source for an input into the recharged ground water. In addition to agricultural runoffs a remarkable contamination of rivers with the herbicide diuron caused by municipal waste waters can be observed in the summer. Because of insufficient elimination of herbicides like triazines and phenylureas during bank filtration or infiltration and because of the high loads of surface waters with pesticides a minimisation of pesticide losses within the whole catchment area, especially of runoffs into surface waters, and the abstention from the use of slowly degradable herbicides in cities, on railways or in private gardens are inevitable. At the present time, however, a protection of ground and public drinking water from pesticide contamination can only be achieved by treating surface or ground waters with activated carbon.

Analysis of Variance↗
PubMed1996

Risks from radionuclide migration to groundwater in the Chernobyl 30-km zone.

Remediation of contaminated groundwater in the Chernobyl 30-km evacuation zone is frequently identified as a priority by technical experts and Chernobyl site officials in Ukraine. In order to evaluate the health risk basis for this groundwater remediation, we have estimated both on-site and off-site health risks caused by radionuclide migration to the groundwater and compared these risks with those from exposure to radioactive contamination on the ground surface. A simple and conservative analytical model was developed to assess radionuclide transport to the groundwater from the soil surface contaminated by radioactive fallout. 90Sr, the primary radioactive contaminant of concern for the groundwater-migration exposure pathway, was evaluated in the analysis. The estimated health risk to hypothetical, self-sufficient residents in the 30-km zone is dominated by external and internal irradiation (due primarily to ingestion of agricultural products) from 137Cs, which is present in soils of the 30-km zone in roughly equal proportion with 90Sr. The estimated risk from contaminated groundwater is approximately an order of magnitude lower. Analysis of 90Sr migration via groundwater to surface water and down-river population centers shows that, despite generally unfavorable environmental conditions in the 30-km exclusion zone, radionuclide transport via the groundwater pathway has potential to contribute only marginally to the off-site radiological risk, which is governed by wash-out of radionuclides from the contaminated river flood plain and catchment areas by surface water during spring snowmelt and rains. Health risks due to off-site radionuclide migration via groundwater are below the level requiring application of counter-measures. This analysis implies that, relative to other exposure pathways, there is little current or future health risk basis for the proposed complex and costly groundwater remediation measures in the 30-km zone. Therefore, these activities should be abandoned in favor of more pressing health issues caused by the Chernobyl accident.

Humans↗
PubMed2000

A comparison of the extent and impacts of sewage contamination on urban groundwater in developed and developing countries.

In much of the world urban groundwater is an important resource for domestic and industrial use. In many developing countries, groundwater taken directly (untreated) from individual springs and wells is the only option available to communities where comprehensive, reliable reticulated supply systems are absent. A common feature of urban groundwater in both developing and developed countries is contamination by sewage. Current and recent research is presented that shows sewer leakage impacts groundwater in developed countries whilst on-site sanitation contaminates groundwater in developing countries. In the latter case, the competing demands of sanitation and groundwater protection must be addressed. Limitations on the usefulness of accepted standard sewage indicator species in groundwater are also highlighted. As sewage contamination of groundwater is usually addressed only if an actual health risk is posed, it is vital both to developed and developing countries to understand the movement of actual pathogens in groundwater in the context of groundwater management. Further research is required on microbial survival and health risks posed by sewage contamination.

Cross-Cultural Comparison↗
PubMed2001

Hydrogeochemistry of groundwater in coastal wetlands: implications for coastal conservation in Scotland.

Groundwater in a shallow coastal aquifer in north east Scotland was monitored over the hydrological year October 1996-September 1997. Groundwater flow from inland areas sustained freshwater conditions in a dune-wetland complex of conservation importance. In particular, seasonal flooding of the coastal wetlands due to water table rise provided important roosting and breeding habitats for waterfowl. Hydrogeochemical analysis revealed that groundwater in the shallow sand aquifer was circum-neutral, and non-saline, despite being within 50 m of the sea and only 1 m above the mean high water mark. Calcium and HCO3 were the dominant cation and anion respectively, reflecting weathering processes in the aquifer. Use of the geochemical code NETPATH indicated that calcite weathering in shell fragments within the sand was the primary source of Ca and alkalinity generation. The concentrations of Na and Cl were also important, though these can be explained primarily by atmospheric inputs from precipitation. In detail, the spatial and temporal variation in groundwater chemistry was remarkably complex for what intuitively appeared a simple aquifer system. Temporal variations in groundwater chemistry mainly related to the seasonal event of groundwater recharge. Thus, the main period of rising groundwater levels resulted in a marked dilution of solutes in the aquifer, implying that water storage greatly increased in a relatively short period. A period of several weeks appeared to be required for dissolution processes to proceed to equilibrium. Spatial variation in groundwater chemistry appears to relate to the spatial distribution of geochemical processes in different hydrogeological units. Sulphate reduction, alkalinity generation and Fe precipitation appear to be locally important processes. The chemistry of groundwater maintains the wetland habitat by providing freshwater conditions that allow populations of various plant species to flourish. The potentially large recharge catchments of coastal wetlands, together with increasing pressures in the coastal zone, dictate that pollution can threaten the integrity of hydrochemical processes and requires careful monitoring if freshwater wetlands are to maintain their conservation importance.

Calcium↗
PubMed1990

What should be done to mitigate groundwater contamination?

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.

Biodegradation, Environmental↗
PubMed2001

Influence of net groundwater discharge on the chemical composition of a coastal environment: Flanders Bay, Long Island, New York.

Seasonal (October 1997 and May 1998) concentrations of dissolved (< 0.45 micron) trace metals (Ag, Al, Cd, Cu, Fe, Mn), inorganic nutrients (NO3, PO4, Si), DOC and DON were measured at seven wells during periods of low and high groundwater flow, in the aquifer around Flanders Bay in Eastern Long Island, New York. Similar measurements were made in surface waters of Flanders Bay, a shallow coastal embayment with restricted water flushing and river input. Dissolved constituents in the groundwater were classified according to their behavior under different flow conditions as follows: (1) peak during high flow (DOC, pH, Si, NO3, Al and Cu); (2) peak during low flow (salinity, DON, Ag, Cd, Mn); and (3) concentrations independent of flow conditions (PO4 and Fe). The primarily urban and agricultural land use on the North Fork of Long Island was reflected in higher concentrations of nutrients, Cu and Cd in groundwater, compared to samples from the South Fork which is mostly open parkland. Principal component analysis indicated that groundwater seepage could influence the chemical composition of Flanders Bay with respect to the major geochemical carriers (e.g. Fe and Mn). However, mass balance estimates for Cu indicated that, during low flow conditions, net groundwater Cu input was about 10% of the total input. In contrast, during high flow, net groundwater flow could account for up to 58% of all Cu inputs. Nevertheless, a large imbalance, which accounted for up to 70% of the outflux during low aquifer recharge, suggested that the Cu budget of the Bay was not adequately described by the inputs considered (river, net groundwater flow, atmospheric deposition, and tidal exchange). Important missing components of the Cu mass balance in Flanders Bay may include groundwater circulation driven by tides and waves as well as diffusive benthic fluxes.

Agriculture↗
PubMed2000

Molecular characterization of bacterial populations in petroleum-contaminated groundwater discharged from underground crude oil storage cavities.

Petroleum-contaminated groundwater discharged from underground crude oil storage cavities (cavity groundwater) harbored more than 10(6) microorganisms ml(-1), a density 100 times higher than the densities in groundwater around the cavities (control groundwater). To characterize bacterial populations growing in the cavity groundwater, 46 PCR-amplified almost full-length 16S ribosomal DNA (rDNA) fragments were cloned and sequenced, and 28 different sequences were obtained. All of the sequences were affiliated with the Proteobacteria; 25 sequences (43 clones) were affiliated with the epsilon subclass, 2 were affiliated with the beta subclass, and 1 was affiliated with the delta subclass. Two major clusters (designated clusters 1 and 2) were found for the epsilon subclass proteobacterial clones; cluster 1 (25 clones) was most closely related to Thiomicrospira denitrificans (88% identical in nucleotide sequence), while cluster 2 (11 clones) was closely related to Arcobacter spp. Denaturing gradient gel electrophoresis (DGGE) of PCR-amplified partial 16S rDNA fragments showed that one band was detected most strongly in cavity groundwater profiles independent of storage oil type and season. The sequence of this major band was identical to the sequences of most of the cluster 1 clones. Fluorescence in situ hybridization (FISH) indicated that the cluster 1 population accounted for 12 to 24% of the total bacterial population. This phylotype was not detected in the control groundwater by DGGE and FISH analyses. These results indicate that the novel members of the epsilon subclass of the Proteobacteria grow as major populations in the petroleum-contaminated cavity groundwater.

Cloning, Molecular↗
PubMed2000

Geographic variation in groundwater iodine and iodine deficiency in Israel, The West Bank and Gaza.

BACKGROUND: Iodine deficiency during pregnancy and infancy is the world's most common preventable cause of mental retardation. Previous studies have shown a high incidence of goiter and low groundwater iodine concentrations in northern Israel. OBJECTIVE: We examined the relationship between low groundwater iodine and iodine deficiency in pregnant women and schoolchildren. SUBJECTS AND METHODS: We measured the urinary iodine excretion of school-children in the West Bank and Gaza and rural and urban pregnant women in Western Galilee (an area known to have low groundwater iodine concentrations). We also measured iodine concentrations in groundwater in various locations in the West Bank and Gaza. RESULTS: Lower urinary iodine excretion was found among pregnant Arab women living in rural Western Galilee (101+/-7 microg iodine/g creatinine). 20% of them excreted <50 microg I/g creatinine. This is relatively less than found among pregnant Jewish women living in cities in the same area (154+/-13 microg I/g creatinine). Low iodine concentrations (<5 microg/l) were found in groundwater in the Nablus, Ramallah, Bethlehem highlands, as compared to normal concentrations in the lowland districts of the West Bank and Gaza. In a cohort of 728 schoolchildren aged 8-10, 10% (range 8-13%) of children from areas of low groundwater iodine had low levels of urinary iodine excretion, as compared to only <5% of those from districts with groundwater iodine concentrations >10 microg/l. CONCLUSIONS: Lower concentrations of groundwater iodine are related to low urinary iodine excretion in Israel, the West Bank and Gaza.

Child↗
PubMed1994

Assessment of the reproductive and developmental toxicity of pesticide/fertilizer mixtures based on confirmed pesticide contamination in California and Iowa groundwater.

Pesticides and fertilizers, as used in modern agriculture, contribute to the overall low-level contamination of groundwater sources. In order to determine the potential of pesticide and fertilizer mixtures to produce reproductive or developmental toxicity at concentrations up to 100 x the median level found in groundwater, we prepared and studied two mixtures of pesticides and a fertilizer (ammonium nitrate). One mixture containing aldicarb, atrazine, dibromochloropropane, 1,2-dichloropropane, ethylene dibromide, and simazine plus ammonium nitrate was considered to be a representative of groundwater contamination in California (CAL). The other, containing alachlor, atrazine, cyanazine, metolachlor, metribuzin, and ammonium nitrate, simulated groundwater contamination in Iowa (IOWA). Each mixture was administered in the drinking water of either Swiss CD-1 mice during a Reproductive Assessment by Continuous Breeding study or pregnant Sprague-Dawley rats (gd 6-20) at three dose levels (1x, 10x, and 100x) where 1x was the median concentration of each pesticide component as determined in the groundwater surveys in California or Iowa. Unlike conventional toxicology studies, the purpose of this study was to evaluate the health effects of realistic human concentrations. Thus, the testing concentrations are probably well below the maximally tolerated dose. Propylene glycol was used as the solubilizer for the pesticides in drinking water formulations in both studies. In the reproductive study, neither mixture caused any clinical signs of toxicity, changes in food or water consumption, or body weight in either F0 or F1 mice at doses up to 100x the median groundwater concentrations. There were no treatment-related effects on fertility or any measures of reproductive performance of either the F0 or the F1 generation mice exposed to either CAL or IOWA at up to 100x. Similarly, measures of spermatogenesis, epididymal sperm concentration, percentage motile sperm, percentage abnormal sperm, and testicular and epididymal histology were normal. In the developmental study, CAL- or IOWA-exposed females did not exhibit any significant treatment-related clinical signs of toxicity. No adverse effects of CAL or IOWA were observed for measures of embryo/fetal toxicity, including resorptions per litter, live litter size, or fetal body weight. CAL or IOWA did not cause an increased incidence of fetal malformations or variations. In summary, administration of these pesticide/fertilizer mixtures at levels up to 100-fold greater than the median concentrations in groundwater supplies in California or Iowa did not cause any detectable reproductive (mice), general, or developmental toxicity (rats).

Animals↗
PubMed2001

Microcosms-experiments to assess the potential for natural attenuation of contaminated groundwater.

Groundwater samples from six wells of a former gas plant site were characterised using chemical, microbial and ecotoxicological methods. Degradation studies were performed in batch-culture under aerobic conditions with the groundwater samples containing their autochthonous microflora and original contaminant mixture. The highest O2-consumption (3 mmol 100 ml-1), combined with BTEX (8.3 mg l-1) and naphthalene (171.3 mg l-1) degradation, as well as formation of organic acids was found after N- and P-supplementation with the highest contaminated groundwater sample. The other highly polluted groundwater sample showed no activity obviously because of the toxicity of some compounds. The major part of the PAHs and BTEX was eliminated in the assays with the low contaminated groundwater samples. The results indicate that the microbial degradation capacity and thereby the natural attenuation capacity in each groundwater differ and cannot be assessed simply by chemical, microbial and toxicological data. Additionally activity tests with authentic groundwater samples with and without nutrient supplementation are recommended.

Carbon Dioxide↗
PubMed2000

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

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 and the severely contaminated groundwater has to be treated in order to meet the requirement of drinking water standards. This study covers two areas of work. In the first part, polluted groundwater samples were collected from the contaminated site and analytical results indicated measurable concentrations of 12 representative chlorinated VOCs in water samples. The primary VOCs detected included trichloroethene (TCE), tetrachloroethene (PCE), 1,1,2-trichloroethane (1,1,2-TCA), and 1,1-dichloroethene (1,1-DCE). Second, to remove VOCs groundwater was treated using adsorption on activated carbon fiber (ACF). This involved pumping groundwater through vessels containing ACF. Most VOCs, including TCE, PCE, 1,1,2-TCA, and DCE, were readily adsorbed onto ACF and are removed from the water stream. Our study showed that the technology was able to significantly reduce chlorinated VOCs concentrations in groundwater.

Adsorption↗