Clean Groundwater Research Articles

Public Perceptions and Actions towards Sustainable Groundwater Management in the Pacific Northwest Region, USA

A 50-question survey was developed by the land grant universities in the Pacific Northwest to document public awareness, aptitudes, attitudes and actions toward water issues in the states of Alaska, Idaho, Oregon and Washington, USA. Demographic data were also collected about the survey respondents. The statistically designed survey was completed by over 50% of the 1800 residents who were solicited for the study. The public consider clean groundwater a high priority issue. Survey respondents currently consider groundwater quality to be good; however, most people are unaware of groundwater quantity issues. In the last 5 years, a majority of survey respondents have taken voluntary actions both to protect groundwater quality and to conserve the use of this resource. People want the government to focus more attention on groundwater issues; however, they are unwilling to pay increased taxes to achieve this end. Based on this survey, the land grant universities need to increase groundwater education programmes for the public using television, radio, newspapers and the Internet rather than by the traditional workshop delivery methods.

Analysis of Perchlorate in Water and Soil by Electrospray LC/MS/MS

A method has been developed for the determination of perchlorate in water and soil matrixes using electrospray liquid chromatography/mass spectrometry/mass spectrometry. Perchlorate is quantitated by monitoring the ion signal from mass 83, which is formed by a loss of an oxygen atom from the perchlorate molecular ion. The method was developed to be effective and economical in production laboratory analysis of perchlorate in environmental water and soil samples. Data were gathered to define method sensitivity, performance, selectivity, and robustness. Analyte stability, method susceptibility to interferences, and the reliability of the chlorine isotope ratio as an identification tool were examined. The aqueous method detection limit (MDL) is 0.05 microg/L and was determined using an actual groundwater matrix. The soil MDL is 0.5 microg/kg and was determined using Ottawa sand. The stability study was performed by spiking water samples at 0.25, 10, and 20 microg/L and analyzing them 50 days later. Acceptable recoveries were obtained for all samples. The relative standard deviation (RSD) for the replicate analyses in the stability study indicates that the method is capable of RSD values less than 5% in a relatively clean groundwater matrix. The ionization suppression study was performed by spiking water samples containing 1000 mg/L carbonate, chloride, and sulfate with 0.05 and 0.5 microg/L perchlorate and then measuring the recovery of the spike. The results indicate that the procedure does not have significant suppression effects at the high salt levels tested. Calibration, quality control sample, field sample, and suppression study data were combined to examine isotope ratio reliability. The results of that work show that chlorine isotope ratios can be used to define statistical process control limits for use as an additional analyte identification tool.

The use of natural systems to remediate groundwater: Department of energy experience at the Savannah river site

AbstractNatural remediation is moving toward the forefront as engineers clean groundwater at the Savannah River Site (SRS), a major Department of Energy (DOE) installation near Aiken, South Carolina. This article reviews two successful, innovative remediation methods currently being deployed: biosparging to treat chlorinated solvents and phytoremediation to address tritium in groundwater. The biosparging system reintroduces oxygen into the groundwater and injects nutrient compounds for in‐situ remediation. The system has greatly reduced the concentrations of trichloroethylene (TCE) and vinyl chloride in wells downgradient from a sanitary landfill (SLF). Phytoremediation is an emerging technology that promises effective and inexpensive cleanup of certain hazardous wastes. Using natural processes, plants can break down, trap and hold, or transpire contaminants. This article discusses the use of phytoremediation to reduce the discharge of tritium to an on‐site stream at SRS. © 2003 Wiley Periodicals, Inc. Reprinted from Remediation Volume 12, Number 3.

The Use of Natural Systems to Remediate Groundwater: Department of Energy Experience at the Savannah River Site

AbstractNatural remediation is moving toward the forefront as engineers clean groundwater at the Savannah River Site (SRS), a major Department of Energy (DOE) installation near Aiken, South Carolina. This article reviews two successful, innovative remediation methods currently being deployed: biosparging to treat chlorinated solvents and phytoremediation to address tritium in groundwater. The biosparging system reintroduces oxygen into the groundwater and injects nutrient compounds for in‐situ remediation. The system has greatly reduced the concentrations of trichloroethylene (TCE) and vinyl chloride in wells downgradient from a sanitary landfill (SLF). Phytoremediation is an emerging technology that promises effective and inexpensive cleanup of certain hazardous wastes. Using natural processes, plants can break down, trap and hold, or transpire contaminants. This article discusses the use of phytoremediation to reduce the discharge of tritium to an on‐site stream at SRS. © 2002 Wiley Periodicals Inc.*

Potential N-losses in three scenarios for conversion to organic farming in a local area of Denmark

Techniques are needed to investigate whether different strategies for conversion to organic farming might help to reduce N-losses. In this study, an N-balance technique was applied in a local area of Denmark; 25% of this area was designated as environmentally sensitive with special interests to protect groundwater quality. Three scenarios, where 25% of the local area was converted to organic farming, were compared to the present situation with conventional farming. The first two scenarios were conversion to organic dairy and pig production, respectively. The third scenario was conversion of the whole area with special interests in clean groundwater to organic farming, self-sufficient in fodder and fertiliser. Scenario 1 resulted in a lower N-surplus on the dairy farms, but the reduction was too small in order to significantly reduce the N-surplus in either the whole local area or within the area with special interests in clean groundwater. Scenario 2 resulted in an analogous result. In Scenario 3, the N-surplus was reduced significantly within the area with special interests in clean groundwater, but not within the whole local area. The N-surplus reduction from conversion to organic farming was divided into an extensification and a management effect. The extensification effect meant that the lower livestock density in the organic scenarios resulted in lower N-surpluses, due to an exponential relationship between livestock density and N-surplus. The management effect was primarily caused by lower net imports of fodder and fertilisers to the organic farms and the following higher self-sufficiency in fodder. In addition, the distribution of animal manure between the organic farms was more uniform than between the conventional farms and because of the exponential relationship between livestock density and N-surplus, this caused a lower average N-loss potential. We conclude that organic farming can help to reduce potential N-losses in environmentally sensitive areas, but only if the conversion is designed with respect to that aim and takes account of the spatial distribution of farm types present.

Water pricing and abatement of industrial water pollution: study of distilleries in India

This paper analyses the issue of appropriate pricing of water for effectively controlling water pollution by distilleries in India. A major focus of the study is the practice of diluting effluent streams by clean groundwater to meet environmental regulations. The analysis is undertaken using a nonlinear programming model. The results indicate that under the command and control system of environmental regulation, or if it is replaced by fiscal instruments, groundwater must be appropriately priced, reflecting its economic cost, to ensure that the distilleries undertake pollution abatement to the desired extent.

Analysis of estrogens in river water and effluents using solid-phase extraction and gas chromatography–negative chemical ionisation mass spectrometry of the pentafluorobenzoyl derivatives

A procedure was developed for the analysis of estrogens in environmental water and effluents. Samples were extracted by passing through polymer-impregnated solid-phase extraction discs or C 18 cartridges, followed by gas chromatography–negative chemical ionisation mass spectrometry of the pentafluorobenzoyl derivatives. The derivatives were stable and gave diagnostic negative molecular ions as the base peak for each of the major estrogens studied. The absolute recovery of estrogens spiked into clean groundwater using the disc procedure was 84–116% at the 10 ng l −1 level (calculation not based on use of internal standards). Using doubly deuterated estradiol as internal standard added prior to extraction, the % relative standard deviation of estrogen extraction and analysis in spiked groundwater at the 10 ng l −1 level was 2.6–9.8%. Detection limits were 0.2 ng l −1 or below for the major estrogens, based on a 2.5 litre sample. The most abundant estrogen was estrone, with concentrations over the range 6.4–29 ng l −1 in effluents, and 0.2 to 17 ng l −1 in water from the River Thames.

Numerical analysis of the transport and restoration schemes of aqueous oil in soils

On the basis of field investigations and tests, the authors developed a coupling model of water and solute movement to quantitatively analyse the effects of climate condition, irrigation mode, chemical reactions and restoration schemes on aqueous oil (effective oil) distribution using the finite difference method. It is concluded from this study that the effect of strong adsorptive forces between aqueous oil and the soil matrix is the distribution of aqueous oil in the plough layer rather than its migration to groundwater. In addition, restoration schemes involving clean-wastewater mixing irrigation and crop-type adjustment may greatly reduce the aqueous oil concentrations, but clean surface water or groundwater irrigation must be used for complete restoration of the contaminated soils.

N-losses and energy use in a scenario for conversion to organic farming.

The aims of organic farming include the recycling of nutrients and organic matter and the minimisa-tion of the environmental impact of agriculture. Reduced nitrogen (N)-losses and energy (E)-use are therefore fundamental objectives of conversion to organic farming. However, the case is not straightforward, and different scenarios for conversion to organic farming might lead to reduced or increased N-losses and E-use. This paper presents a scenario tool that uses a Geographical Information System in association with models for crop rotations, fertilisation practices, N-losses, and E-uses. The scenario tool has been developed within the multidisciplinary research project Land Use and Landscape Development Illustrated with Scenarios (ARLAS). A pilot scenario was carried out, where predicted changes in N-losses and E-uses following conversion to organic farming in areas with special interests in clean groundwater were compared. The N-surplus and E-use were on average reduced by 10 and 54%, respectively. However, these reductions following the predicted changes in crop rotations, livestock densities, and fertilisation practices were not large enough to ensure a statistically significant reduction at the 95% level. We therefore recommend further research in how conversion to organic farming or other changes in the agricultural practice might help to reduce N-surpluses and E-uses. In that context, the presented scenario tool would be useful.

Relating lithofacies to hydrofacies: outcrop-based hydrogeological characterisation of Quaternary gravel deposits

Abstract A considerable part of today's drinking water supplies in Europe and North America rely on clean groundwater from gravelly valley aquifers of Quaternary age. The sedimentary architecture, the distribution of lithofacies and of architectural elements in such heterogeneous deposits are of fundamental importance for the analysis of groundwater flow and contaminant transport. As the aquifers are not directly accessible for observation, representative outcrop analogues were used to study the sedimentology on a local scale. Conventional sedimentological classification schemes were adapted for the purpose of hydrogeological evaluations. Measurements of hydraulic properties were then used to define a set of 5 hydrofacies from 23 possible sediment lithofacies. A digital-photographic mapping procedure was developed to allow fast data acquisition in the field. The sedimentologically interpreted outcrops were stored in a GIS style database and thus allow the output for further sedimentological or hydrogeological analysis.

Determination of arsenic in ambient water at sub-part-per-trillion levels by hydride generation Pd coated platform collection and GFAAS detection

A method for trace determination of total arsenic in ambient waters is described. Arsenic is separated on-line from a large volume water sample by hydride generation and purging, pre-collected on a Pd coated pyrolytic platform cuvette using a simple and inexpensive system, and finally detected by GFAAS. Instrument parameters, hydride generation, transportation, and collection were optimized. The analytical behavior for major species including As 3+, As 5+, monomethyl As (MMA), and dimethyl As (DMA) were investigated individually. Problems arising from use of the system were discussed and eliminated. The necessity of sample digestion and an efficient digestion method were studied. Sample digestion for water with low organic content such as tap water and clean ground water and some clean surface water can be omitted. The method detection limit (MDL) is 0.3 ng l −1 for a 25 ml water sample. Recoveries close to 100% with R.S.D.<5% can be easily achieved. Typical aqueous samples including tap, ground, lake, river, rain, sewage effluent, and saline water from different origins in the US, China, and Canada were collected and analyzed using ultra clean sampling and analysis techniques. The background levels of As in most water analyzed were established for the first time, and found to be far above the EPA's health effect criteria, 18 ng l −1.

Subsurface Injection of Dissolved Ferric Chloride to Form a Chemical Barrier: Laboratory Investigations

AbstractA chemical barrier is a permeable zone of reactive materials emplaced in the subsurface to remove ground‐water contaminants while allowing clean ground water to pass through. Because dissolved ferric chloride hydrolyzes to amorphous ferric oxyhydroxide when it contacts calcite (CaCO3), it may be viable to emplace a zone of amorphous ferric oxyhydroxide (an absorbent for U, Mo, and other inorganic contaminants) into calcite‐bearing geologic units by injecting ferric chloride through wells. For a chemical barrier to be successful, it must remain permeable and must be immobile.This investigation monitored chemical compositions, hydraulic conductivity, and iron mobility in laboratory columns and in a two‐dimensional tank to determine the viability of injecting ferric chloride to form an amorphous ferric oxyhydroxide chemical barrier. We introduced a ferric chloride solution (1,345 mg/l [0.024 m] Fe) to calcite‐bearing alluvial gravel to form a chemical barrier of amorphous ferric oxyhydroxide, followed by solutions contaminated with U and Mo. The simulated chemical barriers decreased U and Mo concentrations to less than 0.05 mg/1 (2.1×10‐7 m) and 0.01 (1.0×10‐7 m), respectively; however, the breakthrough front is spread out with concentrations increasing to more than regulatory guideline values sooner than predicted. The hydraulic conductivity of calcite‐bearing alluvial gravel decreased substantially during ferric chloride introduction because of the formation of carbon dioxide but increased to within factors of 1 to 5 of the original value as synthetic ground water flowed through the system. Amorphous ferric oxyhydroxide that formed in these experiments remained immobile at flow rates exceeding those typical of ground water. These laboratory results, in conjunction with site‐specific characterization data, can be used to design chemical barriers emplaced by injection of ferric chloride.

Use of a mathematical model for prediction of optimum feeding strategies forin situ bioremediation

Liquid wastes containing radioactive, hazardous, and regulated chemicals have been generated throughout the 40 + years of operations at the US Department of Energy (DOE) Hanford site. Some of these wastes were discharged to the soil column, and many of the waste components, including nitrate, carbon tetrachloride (CCl4), and several radionuclides, have been detected in the Hanford ground water. Current DOE policy prohibits the disposal of the contaminated liquids directly to the environment, and remediation of the existing contaminated ground waters may be required.In situ bioremediation is one technology currently being developed at the Hanford to meet the need for cost-effective technologies to clean ground water contaminated with CCl4, nitrate, and other organic and inorganic contaminants. This article focuses on the latest results of an ongoing effort to develop effectivein situ remediation strategies through the use of predictive simulations. In particular, strategies for nutrient injection are developed that minimize biomass accumulation within the flow field and thus extend the life of injection wells.

IN SITU MEASUREMENT OF ADSORPTION AND BIOTRANSFORMATION AT A HAZARDOUS WASTE SITE1

ABSTRACT: A three well injection‐production test was performed at the United Creosoting Company (UCC) site in Conroe, Texas, to estimate the effective in situ retardation factors for adsorption and to evaluate the significance of biotransformation in limiting the transport of polycydic aromatics present in the shallow aquifer. The field test was also used as a model to determine if this type of testing would be feasible at other hazardous waste sites. During the test, chloride, a non‐reactive tracer and two organic compounds, naphthalene and paradichlorobenzene (pDCB), were injected into a center well for 24 hours followed by clean ground water for six days. Ground water was continuously produced from two adjoining wells and monitored to observe the breakthrough of these compounds. Data from the test were analyzed by comparing the statistical moments of the chloride and organics distributions. Retardation factors for naphthalene and pDCB were estimated to be 1.03 and 0.97 by comparison of the statistical moments. A significant loss of naphthalene and pDCB was also observed during the three well test, apparently due to biotransformation. These results suggest that biotransformation is the major process limiting the transport of naphthalene and similar compounds at the UCC site.

Agricultural Chemicals in Ground Water: Suggestions for The Environmental Protection Agency Strategy

Ground water, a hidden resource whose volume is over 50 times that of the nation's surface water, was once thought to remain forever pure. People had little reason not to believe that the soil would naturally purify water returning to an aquifer. It was not until the late 1970s when the Love Canal and Times Beach incidences redirected public opinion and touched off a nationwide concern for the protection of ground water. In August 1984, the Environmental Protection Agency (EPA) issued a Ground Water Protection Strategy to "provide a common reference for responsible institutions as they work toward the shared goal of preserving, for current and future generations, clean ground water for drinking and other uses, while protecting the public health of citizens who may be exposed to the effects of past contamination."1 More specifically, "EPA will increase efforts to protect ground water from pesticide and nitrate contamination." In response, the EPA's Office of Pesticide Protection reviewed existing information on the extent and causes of pesticide contamination, its potential health hazards, existing statutory authorities, and programs available to aid state policy makers. An increased interest in solving problems associated with pesticides in ground water has resulted in the EPA's current development of a national strategy on Agricultural Chemicals in Ground Water. This strategy will outline the EPA's general course of action in addressing the problem of pesticides in ground water during the next 5 to 10 yr. The purpose of this report is to provide EPA with suggestions to be considered in the formulation of the strategy.

Borehole sampling techniques and field analysis of groundwater in landfill pollution studies

Abstract A borehole drilled at a landfill for site investigation and/or monitoring purposes will generally intercept a vertical interval within an aquifer which may have a wide range of permeabilities and so the entry of a pollutant into a borehole column will not be uniform. Drilling methods and the need to avoid the introduction of contaminants to groundwater mean that hydraulic testing may be restricted, particularly in unconsolidated formations. Techniques that do not add water should be used in preference to injection or tracer tests. Sampling and testing during borehole drilling are necessary to define the groundwater flow system within the borehole, to enable an effective completion to be made. In unconsolidated formations, silt and clay horizons may restrict vertical groundwater movement with the result that pollutants become stratified and move in discrete zones within the aquifer. Therefore taking a bulk or average water sample from a borehole completed to monitor full aquifer thickness will usually result in dilution and mixing of the contaminant with cleaner groundwater. Formation disturbance caused by percussion drilling can also cause vertical groundwater flow and mixing outside the borehole casing making the isolation of discrete zones difficult. Groundwater samples obtained during site investigation drilling or from routine sampling visits will be subject to temperature and pressure change. As a sample is depressurised, variables such as pH, Eh, dissolved gas content and the speciation of certain constituents can be altered. Quantification of these changes and their minimisation means that strict procedures should be adhered to in sample handling and analysis on site. This paper, covering landfill research work funded mainly by the Department of the Environment and carried out by the Fluid Processes Research Group of the British Geological Survey describes techniques and equipment used to overcome some of the problems cited, to obtain representative groundwater samples.

Microbial degradation of the water-soluble fraction of gas oil—I

The microbial degradation of the water-soluble components of gas oil was measured both qualitatively and quantitatively. The mixed autochthonous flora in clean ground water served as the inoculum in continuous percolation experiments. Concentration gradients of individual compounds as well as of DOC were measured as a function of the percolation time. A lag period of ∼5 days at 10°C and of ∼1 day at 25°C respectively preceded measurable attack of the dissolved hydrocarbons. At the experimental infiltration rates, complete hydrocarbon elimination within a few decimeters of percolation depth occurred when steady state conditions of the microbial settlement of the sand were established.

Microbial degradation of the water-soluble fraction of gas oil—II bioassays with pure strains

The rate of degradation of 47 water-soluble components of gas oil by the mixed autochthonous microflora of clean ground water as well as by 4 isolates was measured in batch experiments. Identification of some intermediate degradation products gave insight into the primary reactions of the oxidative breakdown of some of the aromatic components of gas oil. Available nitrogen and disolved oxygen are limiting factors in the microbial purification of hydrocarbon-contaminated ground water.