Groundwater Quality Protection Research Articles

Modeling vulnerability of groundwater to pollution under future scenarios of climate change and biofuels-related land use change: A case study in North Dakota, USA

Modeling groundwater vulnerability to pollution is critical for implementing programs to protect groundwater quality. Most groundwater vulnerability modeling has been based on current hydrogeology and land use conditions. However, groundwater vulnerability is strongly dependent on factors such as depth-to-water, recharge and land use conditions that may change in response to future changes in climate and/or socio-economic conditions. In this research, a modeling framework, which employs three sets of models linked within a geographic information system (GIS) environment, was used to evaluate groundwater pollution risks under future climate and land use changes in North Dakota. The results showed that areas with high vulnerability will expand northward and/or northwestward in Eastern North Dakota under different scenarios. GIS-based models that account for future changes in climate and land use can help decision-makers identify potential future threats to groundwater quality and take early steps to protect this critical resource.

Hydrogeochemical and Isotopic Investigations on Groundwater Salinization in the Datong Basin, Northern China1

Abstract: Analyses of major elements, environmental isotope ratios (δ18O, δ2H), and PHREEQC inverse modeling investigations were conducted to understand the processes controlling the salinization of groundwater within the Datong Basin. The hydrochemical results showed that groundwater with high total dissolved solid (TDS) concentrations was dominated by sodium bicarbonate (Na‐HCO3), sodium chlorite (Na‐Cl), and sodium sulfate (Na‐SO4) type waters, whereas low‐TDS groundwater from near mountain areas was dominated by calcium bicarbonate (Ca‐HCO3) and magnesium bicarbonate (Mg‐HCO3) type waters. The characterization of the major components of groundwater and PHREEQC inverse modeling indicated that the aluminosilicate hydrolysis, cation exchange, and dissolution of evaporites (halite, mirabilite, and gypsum) governed the salinization of groundwater within the Datong Basin. The environmental isotope (δ18O, δ2H) and Cl−/Br− ratios revealed the impact of fast vertical recharge by irrigation returns and salt‐flushing water on the groundwater salinization. According to the analyses of major hydrochemical components and PHREEQC inverse modeling, evaporite dissolution associated with irrigation and salt‐flushing practice was probably the dominant controlling factor for the groundwater salinization, especially in the central part of the basin. Therefore, groundwater pumping for irrigation and salt‐flushing should be controlled to protect groundwater quality in this area.

Use of Nested Flow Models and Interpolation Techniques for Science‐Based Management of the Sheyenne National Grassland, North Dakota, USA

Noxious weeds threaten the Sheyenne National Grassland (SNG) ecosystem and therefore herbicides have been used for control. To protect groundwater quality, the herbicide application is restricted to areas where the water table is less than 10 feet (3.05 m) below the ground surface in highly permeable soils, or less than 6 feet (1.83 m) below the ground surface in low permeable soils. A local MODFLOW model was extracted from a regional GFLOW analytic element model and used to develop depth-to-groundwater maps in the SNG that are representative for the particular time frame of herbicide applications. These maps are based on a modeled groundwater table and a digital elevation model (DEM). The accuracy of these depth-to-groundwater maps is enhanced by an artificial neural networks (ANNs) interpolation scheme that reduces residuals at 48 monitoring wells. The combination of groundwater modeling and ANN improved depth-to-groundwater maps, which in turn provided more informed decisions about where herbicides can or cannot be safely applied.

Assessment of microbial contamination of groundwater in upper Limphasa River catchment, located in a rural area of northern Malawi

In rural Africa, scientific evidence is often lacking to guide the scaling-up of groundwater as the safest source of potable water. An investigation was conducted in the Upper Limphasa Catchment in northern Malawi to determine the safety of groundwater sources and to explore factors influencing water quality. Water samples from 17 boreholes, 6 hand-dug wells and 90 households were analysed for selected parameters. Portable incubators, multi-parameter probe and colorimetric standard methods were used for field measurements, and standard methods were used for laboratory water analysis. Results were compared to specified guidelines of the World Health Organization and Malawi Bureau of Standards to establish the potability of water. Statistical results using non-parametric t-tests indicated that the wells were more contaminated with E. coli bacteria than boreholes (p=6.2x10-6), suggesting non-consideration of local hydrogeologic factors in groundwater development. Water from boreholes that tested negative for pathogens at source tested positive at some households (total coliform: p=0.0042 and E. coli p=7.8x10-7) suggesting the effect of handling practices. Water from wells that was not treated with chlorine showed higher levels of E. coli than treated water from the same sources, confirming the effectiveness of chlorine in reducing pathogenic bacteria in households’ stored drinking-water, reinforcing the scientific basis for scaling up chlorine as effective disinfectant. However, this study demonstrated that chlorine failed to effectively eliminate all pathogens in drinking water. As a case study in tropical rural environments in Africa, these findings on the suitability of using chlorine as disinfectant and on factors explaining groundwater contamination, though provisional, provide a scientific basis for assessing cost-effectiveness and sustainability of scaling-up the use of chlorine as a curative remedy and of systematically investigating local hydrogeologic factors in order to implement measures to protect groundwater quality in poverty-prone rural communities.

Groundwater quality protection at biosolids land application sites

Using the United States (US) Environmental Protection Agency's (EPA) Multimedia, Multi-pathway, Multi-receptor Exposure and Risk Assessment (3MRA) technology, a computer-based biosolids groundwater risk characterization screening tool (RCST) was developed. The RCST, which generates a non-carcinogenic human health risk estimate (i.e., hazard quotient or HQ value), has the ability to conduct screening-level risk-based characterization of potential human risks associated with pollutants released from biosolids land application sites. The HQ is a human health indicator that is equal to the ratio of the pollutant dose (mass of pollutant per unit body weight per time) to the specific pollutant reference dose (Rfd) which, in turn, is a human health benchmark defined by the EPA as a scientific estimate of the daily exposure level. A HQ value equal to or greater than one (1) suggests that the resulting conditions pose an unacceptable risk to human health.The focus of the current study was to evaluate whether the present regulatory limits established for biosolids pollutants (e.g., heavy metals) were sufficiently protective of human health associated with potential groundwater consumption using a new EPA risk assessment tool. Application of the RCST to two biosolids land application sites located near Columbus, Georgia predicted that, when the depth to groundwater was maintained at a distance of at least 2 m, regulated pollutant concentrations as large as ten (10) times the current regulatory limit (i.e., Title 40 of the US Code of Federal Regulations Part 503 – Ceiling Concentration Limit) could be safely land applied at rates as high as ninety (90) Megagrams per hectare (Mg ha−1) with no apparent non-carcinogenic human health effects associated with groundwater consumption. At these pollutant concentrations, the HQ ranged from 1.79 × 10−9 for cadmium to 3.03 × 10−3 for selenium.Only under unrealistically high biosolids application rates were the public health risks associated with groundwater impairment characterized as significant (HQ ≥ 1.0). For example, when the biosolids application rate was increased to 450 Megagrams per hectare (Mg ha−1) and the pollutant concentrations were increased to ten times the 40 CFR Part 503 Ceiling Concentration Limit, a HQ value of 2.23 was estimated (selenium). Similarly, when the biosolids application rate was increased to 900 Mg ha−1 and the pollutant concentrations were increased to ten times the regulatory limit, the HQ ranged varied from 1.4 (for zinc) to 324.0 (for selenium).

Picking Apples: Can Multi-Attribute Ecolabels Compete?

Abstract Global food markets in Europe, the U.S. and elsewhere, are experiencing a rapid growth in the number of private party and government environmental labeling programs. Most current ecolabels are defined by standards related to multiple environmental practices. This study presents an analysis of consumers’ choice of food products, in this case apples with or without ecolabels, where the ecolabels present varying combinations of farm practices with implications for environmental quality. These practices include: whether or not standards are met specific to on-farm pest management; presence of stream or groundwater quality protection; presence of on-farm wildlife habitat provision; and which certifier provides the guarantee. Factors influencing consumer preferences for ecolabel attributes are evaluated as a choice-based conjoint analysis. To empirically test the effect of heterogeneity of consumers on preferences for ecolabel attributes, surveys were conducted in a stratified sample in three regions (Portland, Oregon; Minneapolis, Minnesota; Rhode Island) with a focus on sampling across shoppers at different types of markets including conventional supermarkets, farmers markets, natural food stores and food co-ops. Results show that preferences for ecolabels are most strongly driven by type of pesticide usage, in particular for non-synthetic pesticides which were identified with organic production. With an appropriate price premium, ecolabels with an alternative pest management practice and other environmental practices were preferred to conventionally produced apples. These results varied according to age and gender of respondents, and type of store at which respondents shopped.

Aquifer Vulnerability Assessment and Wellhead Protection Areas to Prevent Groundwater Contamination in Agricultural Areas: An Integrated Approach

To implement successful policies for the protection of groundwater and curtail the possibility of water supply contamination, an early evaluation of aquifer vulnerability is needed. Rather than implementing broad restrictions to land use and effluent discharge, it is more cost-effective and economically favourable to approach protection in a stepwise manner by first assessing the intrinsic vulnerability of the aquifer when defining the level of land use control that is needed to protect groundwater quality. Following aquifer vulnerability evaluation, specific land uses and restrictions should be defined locally for each water supply within the wellhead protection areas (WHPAs), which are identified by means of the groundwater time of travel (TOT). The WHPA should be established for each individual situation, considering the level of vulnerability of the exploited aquifer. We applied our findings to a specific test site in the Piemonte region of NW Italy, following the current local procedure for individuating the WHPAs. Using data gathered from this site-specific exercise, we identified that the procedure allows methods that consider only aquifer parameters to evaluate vulnerability and discourages the use of techniques that already compartmentalize soil parameters in the vulnerability assessment.

Influence of irrigation practices on arsenic mobilization: Evidence from isotope composition and Cl/Br ratios in groundwater from Datong Basin, northern China

Summary Environment isotopes (δ18O and δ2H) and Cl/Br ratios in groundwater have been used to trace groundwater recharge and geochemical processes for arsenic contamination in Datong Basin. The arsenic concentrations of groundwater samples ranged from 0.4 to 434.9 μg/L with the average of 51.2 μg/L, which exceeded China’s drinking water standard (10 μg/L). All the groundwater samples are plotted on or close to the meteoric water line of the δ18O vs. δ2H plot, indicating their meteoric origin. The relationship between δ18O values and Cl/Br ratios and Cl concentrations demonstrate that leaching and mixing are the dominant processes affecting the distribution of high arsenic groundwater in this area. The observed non-linearity in the trend between δ18O and arsenic concentration is due to combined effects of mixing and leaching. The similarity of the trend in Cl/Br ratios and δ18O values for high arsenic groundwater demonstrate that extensive leaching of irrigation return and salt flushing water flow could be the dominant process driving arsenic mobilization in the groundwater system. Moreover, the long term irrigation practice can cause the drastic change of the biogeochemical and redox condition of in the aquifer system, which in turn promotes the mobilization of arsenic. Therefore, groundwater pumping for irrigation in this area of waterborne endemic arsenic poisoning should be under strict control to protect groundwater quality in this area.

The changes of groundwater chemistry of semi-confined buried valley aquifer during one decade of water exploitation

This article presents the analysis of the temporal changes in water chemistry in a semi-confined aquifer (Wielkopolska Buried Valley aquifer, Poland) during one decade of water exploitation. It is shown that the groundwater contamination, as documented in a previous work, still persists and has lead to steady groundwater quality deterioration. The most intensive changes in water chemistry due to contamination are observed in the regions recognized earlier as the most vulnerable parts of the aquifer. The influence of contamination is effective despite implementation of groundwater protection activities. The travails of groundwater quality protection of the confined or semi-confined aquifers were accented.

Does the Coase theorem hold in real markets? An application to the negotiations between waterworks and farmers in Denmark

The Coase theorem depends on a number of assumptions, among others, perfect information about each other's payoff function, maximising behaviour and zero transaction costs. An important question is whether the Coase theorem holds for real market transactions when these assumptions are violated. This is the question examined in this paper. We consider the results of Danish waterworks' attempts to establish voluntary cultivation agreements with Danish farmers. A survey of these negotiations shows that the Coase theorem is not robust in the presence of imperfect information, non-maximising behaviour and transaction costs. Thus, negotiations between Danish waterworks and farmers may not be a suitable mechanism to achieve efficiency in the protection of groundwater quality due to violations of the assumptions of the Coase theorem. The use of standard schemes or government intervention (e.g. expropriation) may, under some conditions, be a more effective and cost efficient approach for the protection of vulnerable groundwater resources in Denmark.

Sustainable yield of a karst aquifer system: a case study of Jinan springs in northern China

Based on the long-term monitoring data of rainfall, groundwater levels, groundwater abstraction, spring flow rates and groundwater quality, an assessment has been undertaken of the sustainable yield of a karst aquifer system in Shandong Province, northern China, to maintain perennial outflow of the karst springs while meeting water demands. One of the fundamental indicators for sustainable yield of groundwater is identified as maximum allowable water-level drawdown. A regional three-dimensional finite-difference numerical model has been developed to optimize the schemes associated with well fields and their locations and sustainable yields, in the Jinan spring catchment and its adjacent karst groundwater catchments, with the aim of maintaining the water level higher than the allowable lowest water level of 27.5 m above sea level. Furthermore, measures necessary to move towards sustainable use of the karst groundwater are outlined, drawing on contingency plans of water-source replacement and artificial recharge, dual water supply (based in water quality), use of the spring waters themselves, and groundwater quality protection.

Conceptual Framework for Protecting Groundwater Quality

A conceptual framework is defined to establish safeguard zones in groundwater bodies intended for drinking water according to the requirements of the Water Framework Directive. For this, the foundations of a three-phase methodology within a dynamic process are proposed. The results of the first two phases are presented, which contemplate the distribution of groundwater body abstraction points as well as hydrogeological criteria, evaluation of pressures and aquifer vulnerability, in addition to the defined wellhead protection areas of abstraction points. As a final proposal, it will be necessary for competent authorities to create a recommendations and restrictions guideline, which should be integrated into the rest of the policies related to land-use planning in order to protect groundwater adequately.

Assessing the flow regime in a contaminated fractured and karstic dolostone aquifer supplying municipal water

► Flow regime in a south Ontario dolostone aquifer is investigated using a range of field methods. ► Two main levels of karst-enhanced permeability could be identified in the dolostone. ► The karst flow system became non-functional after the aquifer confinement by glacial sediments. ► Groundwater flow and transport are mainly controlled by the fractured network. The Silurian dolostone bedrock in Ontario, Canada, is a broad 400 km long swath northward from Niagara Falls through the Bruce Peninsula that represents an important water source for municipal, industrial, and agricultural uses. Where the Quaternary overburden is thin or absent, karst is common. This study concerns an urban area where the dolostone aquifer is 100 m thick beneath up to 50 m thick Quaternary deposits and where karst features identified by borehole information are common. Hydraulic tests show moderate to large bulk rock hydraulic conductivity and rock core tests indicate much smaller matrix hydraulic conductivity than the bulk rock values. Therefore, the aquifer is essentially a dual permeability, fully saturated system in which conduits occur within a network of ubiquitous extensive, horizontally- and vertically-interconnected fractures. Karst features are concentrated in a thin zone at the top-of-rock, likely representing former epikarst, and also in a thicker zone in the middle of the aquifer. Some pumping test results and large yields of some municipal wells are consistent with conduit occurrences. However, atmospheric tritium, distributed-source contamination (Cl − , NO 3 - ), and a point-source pesticide plume (metolachlor) show detailed concentration distributions lacking influence of flow in conduits. Detailed hydraulic head profiles also show no influence of conduit flow. This study shows that when designing monitoring networks for groundwater quality and source water protection in similar contexts, locating conduits is not necessary because contaminant distributions are governed by the combined influences of the rock matrix, fractures and conduits, the hydraulic boundary conditions, and the interconnected fracture network with only minimal conduit effects. Prior to glaciations, an integrated karstic aquifer could develop with flow controlled by conduits; however, this original, converging flow system became non-functional when the Quaternary sediments drastically modified the boundary hydrologic conditions and the head distribution.

A Land Surface Zoning Approach Based on Three-Component Risk Criteria for Groundwater Quality Protection

Protecting the quality of groundwater is a necessity that requires significant restrictions on land use. Because such restrictions are of complex socio-economic consequences, they should be carefully adjusted to the spatially varied protection needs. This paper describes the development of a series of maps designed to facilitate groundwater protection decisions according to land surface zoning. The zoning was based on attributes descriptive of the basic elements of risk (hazard, exposure and consequences) to groundwater quality in Kuwait to provide basis for adjusting the protective regulations to the needs. Standardized maps of the major categories of potentially hazardous activities were prepared using ArcGIS. A country scale map combining and ranking all the hazardous activities was prepared using the USEPA’s hazard ranking system (HRS). The intrinsic vulnerability of the groundwater was mapped using the DRASTIC model. The relative value of the groundwater was mapped according to the three-component criteria of current and future dependence on groundwater, as well as interaction with environmental resources, which were adapted from USEPA criteria for prioritizing the protection/remediation funds. Agricultural activities and oil-related industries were ranked the most hazardous activities in Kuwait. The patterns of the intrinsic vulnerability seemed to be dictated by the depth to the groundwater and the material of the unsaturated zone. Decision making tools were produced by combining the above maps as follows: (1) vulnerability and hazard maps to produce the risk map, (2) risk and value maps to produce the value weighted risk map, and (3) vulnerability and value maps to produce release consequences map. The produced maps should serve the purposes of identifying all potential monitoring targets, prioritizing of funds allocation for monitoring or other corrective actions, and adjusting the land use restrictions to the needs as well as allocating future potentially hazardous land use, respectively. Benefits of including the groundwater value in the criteria for protecting the resource were illustrated by comparing the decisions that would be logically made based on schemes with and without groundwater value as part of the criteria.

Measures to protect groundwater quality from Nitrate and Nitrite Nitrogen pollution

硝酸性窒素及び亜硝酸性窒素については，地下水中で高濃度に検出されたこと等を踏まえ，平成11年2月に地下水の人の健康の保護に関する水質環境基準に追加された。それ以降地下水質の調査が全国の都道府県・政令市において実施されているが，高い環境基準超過率で推移しており，その対策が喫緊の課題となっている。 硝酸性窒素及び亜硝酸性窒素による地下水汚染の汚染原因は，施肥，家畜排せつ物，生活排水等と多岐にわたり，有効な対策が地域毎に異なることから，地域の自然的・社会的特性，汚染実態，発生源等の状況に応じた有効な対策を講ずることが必要である。対策を推進するため，対象地域の関係者で構成する連絡組織を設置し，この連絡組織において汚染範囲，汚染原因，対象地域等の共通認識を持ち，窒素負荷発生源毎の窒素負荷低減の目標の設定，目標達成のための対策について検討することが重要である。また，都道府県等により対策推進計画等を策定し，それに基づいて対策を実施することも効果的である。 そこで，環境省としては引き続き硝酸性窒素及び亜硝酸性窒素による地下水汚染の特性に応じた対策の促進を図っていくこととし，そのために流域の水量，流動との関連性等の汚染機構の解明を進めるとともに，農業関係者の取組へのインセンティブを高めて硝酸性窒素削減につながるような制度を含め，モデル地域の設定による具体的な取組への支援を通して，実効性のある対策の検討を進めている。

Hydrogeochemical assessment of groundwater in Kaltungo and Environs, northeastern Nigeria.

Analytical results indicate that groundwater samples from kaltungo and environs are polluted due to high concentrations of iron, fluoride, nitrate, and coliform bacteria. Iron concentrations range from 1.9 mg/l to 4.8 mg/l, fluoride values range from 0.6 mg/l to 1.9 mg/l, and nitrate concentrations range from 46.8 mg/l to 164 mg/l while coliform number counts range from nil to 80 number counts. The results further reveal that the water is generally good for agricultural uses. The SAR values range from 0.003 meq/l to 0.38 meq/l, RSC values range from -6.20 meq/l to 4.97 meq/l, EC values vary from 160 1S/cm to 790 1S/cm, and TDS ranges from 80 mg/l to 400.5 mg/l. However, the water may not be suitable for some industries due to high concentrations of iron, bicarbonate, and total hardness. Bicarbonate values range from 206 mg/l to 612 mg/l, and total hardness range from 73.4 mg/l to 163.7 mg/l. Piper trilinear plots classified the water into Ca-(Mg)-HCO3 which belongs to the normal alkaline fresh water type. Based on Mg2+/Ca2+ ratio, about 39% of water samples reveal water from silicate aquifer. Plots of logTDS against Na+/(Na+ + Ca2+) reveal that the groundwater chemistry is influenced by evaporation, weathering induced dissolution, and dilution effects. The water would require treatment for human consumption and for industrial applications. It is recommended that regular groundwater quality monitoring will ensure groundwater quality protection and conservation.KEY WORDS: Groundwater chemistry, silicate aquifer, alkaline fresh water, kaltungo area, polluted.

Nitrogen and phosphorus budgets for the Yucatán littoral: An approach for groundwater management

Human activities have altered the balance of ecosystems to the detriment of natural environments. Eutrophication is a serious risk in Yucatán, a state in the eastern peninsula of México where groundwater supplies the only freshwater to a karst shelf environment. While economic development in Yucatán is increasing, environmental awareness is lagging, and efficient waste treatment systems are lacking. To assess potential nitrogen and phosphorus inputs into the coastal zone of Yucatán, we analyzed government reports and the chemical composition of groundwater and aquaculture wastewater. Swine, poultry, and tourism are revealed as the main continental nutrient sources, while groundwater with high nitrate concentrations is the principal coastal nutrient source, a pattern similar to other river discharges around the world. This study demonstrates that environmental risk management practices must be implemented in the Yucatán region to protect groundwater quality.

Protecting Groundwater Quality at Biosolids Land Application Sites Using EPA's Multimedia, Multi-Pathway, Multi-Receptor Exposure and Risk Assessment (3MRA) Technology

Protecting Groundwater Quality at Biosolids Land Application Sites Using EPA's Multimedia, Multi-Pathway, Multi-Receptor Exposure and Risk Assessment (3MRA) Technology

Protecting Groundwater Quality at Biosolids Land Application Sites Using EPA's Multimedia, Multi-Pathway, Multi-Receptor Exposure and Risk Assessment (3MRA) Technology

Protecting Groundwater Quality at Biosolids Land Application Sites Using EPA's Multimedia, Multi-Pathway, Multi-Receptor Exposure and Risk Assessment (3MRA) Technology

A Receding Horizon Control algorithm for adaptive management of soil moisture and chemical levels during irrigation

The capacity to adaptively manage irrigation and associated contaminant transport is desirable from the perspectives of water conservation, groundwater quality protection, and other concerns. This paper introduces the application of a feedback-control strategy known as Receding Horizon Control (RHC) to the problem of irrigation management. The RHC method incorporates sensor measurements, predictive models, and optimization algorithms to maintain soil moisture at certain levels or prevent contaminant propagation beyond desirable thresholds. Theoretical test cases are first presented to examine the RHC scheme performance for the control of soil moisture and nitrate levels in a soil irrigation problem. Then, soil moisture control is successfully demonstrated for a center-pivot system in Palmdale, CA where reclaimed water is used for agricultural irrigation. Real-time soil moisture, temperature, and meteorological data were streamed wirelessly to a field computer to enable autonomous execution of the RHC algorithm. The RHC scheme is demonstrated to be a viable strategy for achieving water reuse and agricultural objectives while minimizing negative impacts on environmental quality.