Paul F. Hudak

Alternatives for Ground Water Cleanup

Aquifer remediation is one of our most difficult environmental challenges; technological limitations and problems arising from the physical and chemical complexities of contaminated subsurface environments thwart our best efforts. A 19-member committee of leaders in environmental engineering, hydrogeology, epidemiology, environmental economics, and environmental policy has written an ambitious book that broadly addresses the groundwater remediation problem. Topics include site characterization, capabilities and limitations of pump-and-treat and alternative technologies, alternative goals for ground water cleanup, and policy implications. One of the books strengths is its information base, which includes various public and private groups, data from 80 pump-and-treat sites, and an extensive literature review. The text is clearly written and well organized. Specific conclusions are stated at the end of each major chapter, and sound policy recommendations are offered at the end of the final chapter. An appendix summarizes pump-andtreat systems reviewed during the study. Several case studies, diagrams, and photographs effectively illustrate concepts and ideas conveyed in the text.

Use of geographic information systems for assessing groundwater pollution potential by pesticides in Central Thailand

This study employed geographic information systems (GIS) technology to evaluate the vulnerability of groundwater to pesticide pollution in Thailand. The study area included three provinces, Kanchana Buri, Ratcha Buri, and Suphan Buri, located in west-central Thailand. Factors used for the vulnerability assessment included soil texture, slope, land use, well depth, and rainfall. These vulnerability factors were reclassified to a common scale, and a weighted average was computed to yield a vulnerability score. Vulnerability factors and weights were assigned considering pesticide concentrations in 90 wells throughout the study area. Well depth was the most significant vulnerability factor. Groundwater vulnerability maps were generated for several pesticides. The eastern, agricultural part of the study area has relatively deep wells and fine soils. Shallow wells are present in the mountainous west; however, fewer pesticides are applied in that region. Consequently, much of the study area had a medium groundwater vulnerability rating, although there were pockets of high vulnerability, for example, in agricultural areas with shallow wells. The groundwater vulnerability maps are effective for identifying locations warranting more detailed groundwater pollution and vulnerability investigations.

Evaluation of ecological and in vitro effects of boron on prostate cancer risk (United States)

To determine: (1) the correlation of prostate cancer incidence and mortality with groundwater boron and selenium concentrations; and (2) the impact of boron on prostate cancer cell proliferation during co-treatment with alternative chemo-preventative agents, along with boron pre-treatment effects on cell sensitivity to ionizing radiation. For regression analysis, data on prostate cancer incidence and mortality were obtained from the Texas Cancer Registry, while groundwater boron and selenium concentrations were derived from the Texas Water Development Board. Cultured DU-145 prostate cancer cells were used to assess the impact of boric acid on cell proliferation when applied in combination with selenomethionine and genistein, or preceding radiation exposure. Groundwater boron levels correlated with a decrease in prostate cancer incidence (R = 0.6) and mortality (R = 0.6) in state planning regions, whereas selenium did not (R = 0.1; R = 0.2). Growth inhibition was greater during combined treatments of boric acid and selenomethionine, or boric acid and genistein, versus singular treatments. 8-day boric acid pre-exposure enhanced the toxicity of ionizing radiation treatment, while dose-dependently decreasing the expression of anti-apoptotic protein Bcl-2. Increased groundwater boron concentrations, across the state of Texas, correlate with reduced risk of prostate cancer incidence and mortality. Also, boric acid improves the anti-proliferative effectiveness of chemo-preventative agents, selenomethionine and genistein, while enhancing ionizing radiation cell kill.

Pesticide Use and Residual Occurrence in Thailand

This paper addresses pesticide use, environmental problems, and regulations in Thailand. Annually, Thailand imports several thousand metric tons of herbicides, fungicides, and insecticides. Agricultural goods are among the countrys primary exports. Over the past decade, Thailands agricultural sector has shifted from labor- to machine-intensive farming practices. Pressures to sustain high crop yields have led to heavy usage of pesticides. Residues, especially organochlorine and organophosphate compounds, have been found in soil, water, and agricultural products throughout the country. Occupational exposure and suicide are the main causes of pesticide poisoning to Thailands residents. Recognizing the growing problem, Thailands government has enacted environmental laws and education programs aimed at minimizing adverse effects of pesticides.

A location modeling approach for groundwater monitoring network augmentation

A heuristic approach based on facility location theory effectively augments groundwater quality monitoring configurations through the strategic siting of additional wells. The approach is an alternative to variance-based schemes previously established for the augmentation problem. The method developed herein is practical in that it (1) is relatively easily understood, (2) is not difficult to implement and solve, and (3) does not require a large number of preexisting observation points. The approach has been applied to a case study involving a landfill-contaminated buried valley aquifer in southwest Ohio. Configurations derived by the heuristic approach exhibit two key characteristics: (1) location of wells near areas of high estimated contaminant concentration and (2) interwell separation distances that facilitate areal plume coverage.

An optimization method for monitoring network design in multilayered groundwater flow systems

Multiple migration pathways and the need to consider several potential siting horizons render the problem of groundwater monitoring network design a difficult task for three-dimensional systems. While the application of quantitative simulation-based approaches for this problem is often impractical due to computational requirements, qualitative approaches can be ineffective because they are highly subjective and typically lack a set of well-defined criteria for locating sampling sites. An analytically based methodology developed in this paper integrates the practical implementation aspects of a qualitative approach with a quantitative analysis in deriving groundwater monitoring networks geared toward early detection of migrating contaminant. Monitoring wells are located among sets of candidate nodes in each of several hydrostratigraphic intervals on the basis of contamination susceptibility. Susceptibility is defined by nodal weights, which are derived on the basis of the locations of sites relative to contaminant source boundaries and potential contaminant plumes. As is illustrated from the results of a case study application, derived monitoring network configurations exhibit two key characteristics: (1) clustering of wells around outlets at contaminant source boundaries and (2) coverage of vacant areas in multiple siting horizons that are susceptible to contamination.

A Comprehensive Analysis of Groundwater Quality in The Barnett Shale Region

The exploration of unconventional shale energy reserves and the extensive use of hydraulic fracturing during well stimulation have raised concerns about the potential effects of unconventional oil and gas extraction (UOG) on the environment. Most accounts of groundwater contamination have focused primarily on the compositional analysis of dissolved gases to address whether UOG activities have had deleterious effects on overlying aquifers. Here, we present an analysis of 550 groundwater samples collected from private and public supply water wells drawing from aquifers overlying the Barnett shale formation of Texas. We detected multiple volatile organic carbon compounds throughout the region, including various alcohols, the BTEX family of compounds, and several chlorinated compounds. These data do not necessarily identify UOG activities as the source of contamination; however, they do provide a strong impetus for further monitoring and analysis of groundwater quality in this region as many of the compounds we detected are known to be associated with UOG techniques.

Spatial Patterns of Nitrate, Chloride, Sulfate, and Fluoride Concentrations in the Woodbine Aquifer of North-Central Texas

A geographic information system was used to map and analyze nitrate, chloride, sulfate, and fluoride concentrations in 110 wells tapping the Woodbine Aquifer. The study area, covering ninecounties in north-central Texas, includes large percentages of both urban and agricultural land uses. Land use maps were compared with solute concentration data, and statistics were applied to detect associations between solutes, well depth, andland use. Anthropogenic sources such as fertilizer applications and natural sources such as gypsum, lignite, and clay deposits controlled nitrate, chloride, and sulfate concentrations, each inversely correlated with well depth. However, only one nitrate observation – from a shallow well in the aquifers outcrop zone – surpassed the maximum contaminant level (MCL) of 44.3 mg L-1. By comparison, nearly half of the sulfate and several of the chloride observations surpassed the MCL of 250 mg L-1for each of those ions. Volcanic ash deposits influenced fluorideconcentrations, which directly correlated with well depth. There were no statistically significant associations between solute concentrations and land use. Low recharge rates and confining layers have mitigated anthropogenic impacts on solute levels in the aquifer.

Mapping landslide susceptibility in Travis County, Texas, USA

A geographic information system (GIS) was used to construct a landslide hazard map for Travis County, Texas. The County is experiencing rapid growth, and development has encroached into unstable terrain that is vulnerable to landslides. Four layers of data were superimposed to create the landslide hazard map. Slope was given the most emphasis, followed by geology, vegetation, and proximity to faults. The final map shows areas of low, medium, and high landslide susceptibility. Areas of high susceptibility occupy stream and reservoir banks, rock escarpments, and agricultural land. The landslide hazard map can be a useful geologic criterion for land use planning. Planners can use the map to allocate appropriate land uses to unstable terrain, and to identify existing structures at risk from landslide activity. The methods presented in this paper can be adapted to other counties in the U.S. and elsewhere. Results of this study suggest that geographic information systems can effectively compile and overlay several data layers relevant to landslide hazards.

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.