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Reuse of oilfield‐produced water (OPW) for crop irrigation has the potential to make a critical difference in the water budgets of highly productive but drought‐stressed agricultural watersheds. This is the first peer‐reviewed study to evaluate how trace metals in OPW used to irrigate California crops may affect human health. We modeled and quantified risks associated with consuming foods irrigated with OPW using available concentration data. The probabilistic risk assessment simulated OPW metal concentrations, crop uptake, human exposures, and potential noncancer and carcinogenic health effects. Overall, our findings indicate that there is a low risk of ingesting toxic amounts of metals from the consumption of tree nuts, citrus, grapes, and root vegetables irrigated with low‐saline OPW. Results show increased arsenic cancer risk (at 10−6) for adult vegetarians, assuming higher consumption of multiple foods irrigated with OPW that contain high arsenic concentrations. All other cancer risks are below levels of concern and all noncancer hazards are far below levels of concern. Arsenic risk concerns could be mitigated by practices such as blending high‐arsenic OPW. Future risk assessment research should model the risks of organic compounds in OPW, as our study focused on inorganic compounds. Nevertheless, our findings indicate that low‐saline OPW may provide a safe and sustainable alternative irrigation water source if water quality is adequately monitored and blended as needed prior to irrigation.

Environmental concerns regarding the potential for drinking water contamination in shallow aquifers have accompanied unconventional energy development in the northern Appalachian Basin. These activities have also raised several critical questions about the hydrogeological parameters that control the naturally occurring presence and migration of hydrocarbon gases in shallow aquifers within petroliferous basins. To interrogate these factors, we analyzed the noble gas, dissolved ion, and hydrocarbon gas (molecular and isotopic composition) geochemistry of 98 groundwater samples from south-central New York. All samples were collected ≫1km from unconventional drilling activities and sample locations were intentionally targeted based on their proximity to various types of documented fault systems. In agreement with studies from other petroliferous basins, our results show significant correlations between elevated levels of radiogenic [4 He], thermogenic [CH4 ], and dissolved ions (e.g., Cl, Br, Sr, Ba). In combination, our data suggest that faults have facilitated the transport of exogenous hydrocarbon-rich brines from Devonian source rocks into overlying Upper Devonian aquifer lithologies over geologic time. These data conflict with previous reports, which conclude that hydrodynamic focusing regulates the occurrence of methane and salt in shallow aquifers and leads to elevated levels of these species in restricted flow zones within valley bottoms. Instead, our data suggest that faults in Paleozoic rocks play a fundamental role in gas and brine transport from depth, regulate the distribution of their occurrence in shallow aquifers, and influence the geochemistry of shallow groundwater in this petroliferous basin.

Enhanced production of unconventional hydrocarbons in the United States has driven interest in natural gas development globally, but simultaneously raised concerns regarding water quantity and quality impacts associated with hydrocarbon extraction. We conducted a pre-development assessment of groundwater geochemistry in the critically water-restricted Karoo Basin, South Africa. Twenty-two springs and groundwater samples were analyzed for major dissolved ions, trace elements, water stable isotopes, strontium and boron isotopes, hydrocarbons and helium composition. The data revealed three end-members: a deep, saline groundwater with a sodium-chloride composition, an old, deep freshwater with a sodium-bicarbonate-chloride composition and a shallow, calcium-bicarbonate freshwater. In a few cases, we identified direct mixing of the deep saline water and shallow groundwater. Stable water isotopes indicate that the shallow groundwater was controlled by evaporation in arid conditions, while the saline waters were diluted by apparently fossil meteoric water originated under wetter climatic conditions. These geochemical and isotopic data, in combination with elevated helium levels, suggest that exogenous fluids are the source of the saline groundwater and originated from remnant seawater prior to dilution by old meteoric water combined with further modification by water-rock interactions. Samples with elevated methane concentrations (>14 ccSTP/kg) were strongly associated with the sodium-chloride water located near dolerite intrusions, which likely provide a preferential pathway for vertical migration of deeply sourced hydrocarbon-rich saline waters to the surface. This pre-drill evaluation indicates that the natural migration of methane- and salt-rich waters provides a source of geogenic contamination to shallow aquifers prior to shale gas development in the Karoo Basin.

Private wells are the source of drinking water for approximately 15% of households in the United States, but these wells are not regulated or monitored by government agencies. The well waters can contain arsenic, a known carcinogen that occurs in groundwater throughout the nation at concentrations that can exceed the Maximum Contaminant Level defined by the U.S. Environmental Protection Agency (10 ppb). In order to reduce arsenic exposure, homeowners can either rely on bottled water for drinking or install in-house water treatment systems for arsenic removal. Here, we document the arsenic levels associated with these options. We examined 24 different major bottled water brands and found that all have arsenic levels

Israel and the Palestinian Authority share the southern Mediterranean coastal aquifer. Long-term overexploitation in the Gaza Strip has resulted in a decreasing water table, accompanied by the degradation of its water quality. Due to high levels of salinity and nitrate and boron pollution, most of the ground water is inadequate for both domestic and agricultural consumption. The rapid rate of population growth in the Gaza Strip and dependence upon ground water as a single water source present a serious challenge for future political stability and economic development. Here, we integrate the results of geochemical studies and numerical modeling to postulate different management scenarios for joint management between Israel and the Palestinian Authority. The chemical and isotopic data show that most of the salinity phenomena in the Gaza Strip are derived from the natural flow of saline ground water from Israel toward the Gaza Strip. As a result, the southern coastal aquifer does not resemble a classic "upstream-downstream" dispute because Israel's pumping of the saline ground water reduces the salinization rates of ground water in the Gaza Strip. Simulation of different pumping scenarios using a monolayer, hydrodynamic, two-dimensional model (MARTHE) confirms the hypothesis that increasing pumping along the Gaza Strip border combined with a moderate reduction of pumping within the Gaza Strip would improve ground water quality within the Gaza Strip. We find that pumping the saline ground water for a source of reverse-osmosis desalination and then supplying the desalinated water to the Gaza Strip should be an essential component of a future joint management strategy between Israel and the Palestinian Authority.

In 1998 the European Union (EU) revised its Drinking Water Directive, which is responsible for regulating the quality of water in the EU intended for human consumption. Specifically, the EU added a new standard for the element boron in drinking water (1 mg/l). Yet, because of scientific uncertainty concerning the causes and magnitude of the boron problem in Europe during the regulatory standard-setting process, we find that full compliance with the new drinking water standard for boron has been hampered. Prior to the standard’s enactment, it was unclear whether boron was derived from natural or anthropogenic sources. A new geochemical study reveals that a significant part of the boron contamination is derived from natural sources. Countries such as Italy and Cyprus with high natural boron concentrations in their drinking water are, thus, finding that compliance with the new EU boron regulation is more difficult and expensive than originally anticipated. Copyright © 2005 John Wiley & Sons, Ltd and ERP Environment.

tions from small springs and rare flood events. Currently, the only two water sources at the starting point The Lower Jordan River is located in the semiarid area of the of the Lower Jordan River are the effluent of the Bitania Jordan Valley, along the border between Israel and Jordan. The implementation of the water sections of the peace treaty between wastewater treatment plant and the Saline Water CarIsrael and Jordan and the countries’ commitment to improve the rier (Sites 1 and 2 in Fig. 1). The Bitania source includes ecological sustainability of the river system require a better under- poorly treated human and animal waste effluents. The standing of the riverine environment. This paper investigates the Saline Water Carrier contains a mixture of saline spring sources and transformations of nitrogen compounds in the Lower water diverted from the Sea of Galilee and urban sewage Jordan River by applying a combination of physical, chemical, isoto- effluent. As a result of the degradation of water quantity pic, and mathematical techniques. The source waters of the Lower and quality, the Lower Jordan River has become brackJordan River contain sewage, which contributes high ammonium loads

One of the major problems in the lower Jordan Valley is the increasing salinization (i.e., chloride content) of local ground water. The high levels of salinity limit the utilization of ground water for both domestic and agriculture applications. This joint collaborative study evaluates the sources and mechanisms for salinization in the Jericho area. We employ diagnostic geochemical fingerprinting methods to trace the potential sources of the salinity in (1) the deep confined subaquifer system (K2) of Lower Cenomanian age; (2) the upper subaquifer system (K1) of Upper Cenomanian and Turonian ages; and (3) the shallow aquifer system (Q) of Plio-Pleistocene ages. The chemical composition of the saline ground water from the two Cenomanian subaquifers (K1 and K2) point to a single saline source with Na/Cl approximately 0.5 and Br/Cl approximately 7 x 10(-3). This composition is similar to that of thermal hypersaline spring that are found along the western shore of the Dead Sea (e.g., En Gedi thermal spring). We suggest that the increasing salinity in both K1 and K2 subaquifers is derived from mixing with deep-seated brines that flow through the Rift fault system. The salinization rate depends on the discharge volume of the fresh meteoric water in the Cenomanian Aquifer. In contrast, the chemical composition of ground water from the Plio-Pleistocene Aquifer shows a wide range of Cl- (100-2000 mg/L), Na/Cl (0.4-1.0), Br/Cl (2-6 x 10(-3)), and SO4/Cl (0.01-0.4) ratios. These variations, together with the high SO4(2-), K+, and NO3- concentrations, suggest that the salinity in the shallow aquifer is derived from the combination of (1) upconing of deep brines as reflected by low Na/Cl and high Br/Cl ratios; (2) leaching of salts from the Lisan Formation within the Plio-Pleistocene Aquifer, as suggested by the high SO4(2-) concentrations; and (3) anthropogenic contamination of agriculture return flow and sewage effluents with distinctive high K+ (80 mg/L) and NO3- (80 mg/l) contents and low Br/Cl ratios (2 x 10(-3)). Our data demonstrates that the chemical composition of salinized ground water can be used to delineate the sources of salinity and hence to establish the conceptual model for explaining salinization processes.

The boron isotopic compositions of common synthetic boron products, municipal wastewaters from Switzerland, and three Swiss freshwater lakes were investigated. The δ11B values (δ11B values are normalized to the standard NIST SRM-951) of synthetic Na-borates (–0.4 to 7.6‰) and Ca-Na-borates (–13.4 to –4.9‰) overlap with those of natural borate minerals and hence suggest that the isotopic signal of anthropogenic boron is not modified during the manufacturing process. As a result it is possible to predict the isotopic composition of synthetic boron products and their potential impact upon contamination of water resources. The δ11B values of municipal wastewaters from two locations in northern Switzerland (–7.7 to –4.5‰) reflect utilization of Na/Ca- and/or Ca-borates depleted in 11B. Freshwater lakes from Switzerland (Lake Zurich, Greifensee, Lake Lugano) yielded a δ11B range of –1.7 to 7.1‰ and boron concentrations of 17 to 102 mg L–1. The boron isotopic ratios decrease with increasing boron concentrations, indicating mixing between anthropogenic boron with a low δ11B signature and meteoric boron with a heavier isotopic signal. We suggest that the isotopic composition of meteoric boron over central Europe has δ11B values in the range of ca. 10 to 20‰, whereas in coastal areas the marine component is larger with a higher 11B/10B ratio (δ11B ∼ 30‰). Isotopenzusammensetzung des Bors in einigen zentraleuropaischen Suswasserseen und mogliche Kontaminationsquellen Untersucht wurde die Isotopenzusammensetzung von verbreiteten synthetischen Borprodukten, von kommunalen Abwassern in der Schweiz und von drei Schweizer Suswasserseen. Die δ11B-Werte (bezogen auf den Standard NIST SRM-951) synthetischer Natriumborate (–0.4 bis 7.6‰) und Calciumborate (–13.4 bis –4.9‰) uberlappen mit denen naturlicher Boratminerale, was den Schlus nahelegt, das sich die Isotopensignatur bei der Verarbeitung zu kunstlichen Borprodukten beim Herstellungsprozes nicht verandert. Folglich ist es moglich, die Isotopenzusammensetzung synthetischer Borprodukte vorherzusagen bzw. aus der Isotopenzusammensetzung Bor-kontaminierter Gewasser auf den Eintragspfad zu schliesen. Die δ11BB-Werte des kommunalen Abwassers von zwei Orten in der Nordschweiz (–7.7 bis –4.5) spiegeln den Einsatz von δ11B-abgereicherten Natrium-Calcium- oder Calcium-Boraten wider. Die in dieser Arbeit untersuchten Schweizer Seen (Zurichsee, Greifensee, Luganer See) wiesen einen δ11B-Wert-Bereich von –1.7 bis 7.1‰ und Borkonzentrationen von 17 bis 102 μg L–1 auf. Das Isotopenverhaltnis des Bors sinkt mit steigender Borkonzentration, was auf einen Mischungsvorgang zwischen anthropogenem Bor mit niedriger δ11B-Signatur und Bor atmospharischen Ursprungs – meteorisches Bor τ mit einem groseren Anteil des schwereren Borisotops hinweist. Fur die isotopische Zusammensetzung des meteorischen Bors wird fur Zentraleuropa ein Bereich von 10 bis 20‰ zu Grunde gelegt, wahrend in Kustenbereichen die marine Komponente des Boreintrags mit ihrem hoheren 11B/10B-Verhaltnis (ca. 30‰) einen groseren Anteil hat.

To establish geochemical tools for tracing the origin of ground water contamination, we examined the variations of Cl/Br and Cl/F (weight) ratios in (1) domestic waste water from the Dan Region Sewage Reclamation Project and from reservoirs in the central coast of Israel; (2) associated contaminated ground water; and (3) pristine ground water from the Mediterranean coastal aquifer of Israel. Our data show that supply water, anthropogenic NaCl and fluoridation control the Cl/Br (410 to 873) and Cl/F (468 to 1070) ratios of domestic waste water, and conventional sewage treatment does not affect the anthropogenic inorganic signals. The Cl/Br ratios of ground water contaminated with sewage effluent reflect conservative mixing proportions of sewage and regional ground water components. Sensitivity tests demonstrate that it is possible to detect and distinguish sewage contamination from marine ratios after a sewage contribution of 5 to 15% is mixed with regional ground water. Mixing with Br-enriched fresh water (e.g., Sea of Galilee; Cl/Br=145), however, would reduce this sensitivity. Since the high Cl/Br signal of sewage effluents is distinguishable from other anthropogenic sources with low Cl/Br ratios (e.g., street runoff, agriculture return flows) and from natural contamination sources (e.g., salt water intrusion; Cl/Br=293), Cl/Br ratios can therefore be a useful inorganic tracer for identification of the origin of contaminated ground water. The Cl/F ratios of sewage-contaminated ground water (284 to 5186) were higher than those in the original sewage effluent, which suggests retention of fluoride into the aquifer solid phase.