In the mid-1990s, a groundwater plume of uranium (U) was detected in monitoring wells in the B-BX-BY Waste Management Area at the Hanford Site in Washington. This area has been used since the late 1940s to store high-level radioactive waste and other products of U fuel-rod processing. Using multiple-collector ICP source magnetic sector mass spectrometry, high-precision uranium isotopic analyses...

To investigate the role of the seepage zone in transport, chemical speciation, and attenuation of nitrogen loads carried by submarine groundwater discharge, we collected nearshore groundwater samples (n 5 328) and examined the distribution and isotopic signature (d15N) of nitrate and ammonium. In addition, we estimated nutrient fluxes from terrestrial and marine groundwater sources. We discuss ...

Regional surveys of groundwater quality in Central Canterbury, from 1977 to the present, show widespread occurrence of nitrate contamination primarily from agricultural land use. Two reported analyses of these surveys, in 1984 and 2002, describe a general decrease of nitrate concentration with depth from the groundwater table to uncontaminated water at about 50-80 m. This high quality water is ...

Coastal waters are severely threatened by nitrogen (N) loading from direct groundwater discharge. The subterranean estuary, the mixing zone of fresh groundwater and sea water in a coastal aquifer, has a high potential to remove substantial N. A network of piezometers was used to characterize the denitrification capacity and groundwater flow paths in the subterranean estuary below a Rhode Island...

An isotopic study was performed to assess the movement of groundwater for a site located in Miami-Dade County, Florida. The site encompasses portions of a protected wetland environment (northeast Everglades National Park) and suburban residential Miami, incorporating municipal pumping wells and lakes formed by rock mining. Samples of ground, surface, and rainwater were analyzed for their isotop...

At the “Pašino vrelo” source, groundwater is exploited by means of wells which tap a carbonate aquifer of Badenian age. The natural quality of groundwater complies with the provisions of the Regulation on health and safety of drinking water. However, anthropogenic impacts in the form of microbiological pollution have been observed. Extensive hydrogeological investigations have been conducted in...

freshwater lens on small islands may easily be overexploited or polluted due to overdrafts of fresh water by pumping which causes drawdown of the water table a rise or up-coning of the saltwater interface. present study is concerned with using a three-dimensional finite-difference numerical model to simulate the groundwater flow and transport model to predict the behavior of groundwater system ...

The Gafsa mining basin district in Southwestern Tunisia is one of the most important producers of phosphate in the world. The exploitation of this district started at the beginning of the twentieth century a few years after the first discovery of this valuable resource. The over-exploitation of groundwater to wash the phosphate caused water-level decline in the main aquifers and the corollaries...

Topological groundwater hydrodynamics is an emerging subdiscipline in the mechanics of ¯uids in porous media whose objective is to investigate the invariant geometric properties of subsurface ¯ow and transport processes. In this paper, the topological characteristics of groundwater ¯ows governed by the Darcy law are studied. It is demonstrated that: (i) the topological constraint of zero helici...

Groundwater quality degradation is a major threat to sustainable development in Texas. The aim of this study was to elucidate spatiotemporal patterns of groundwater fluoride (F) contamination in different water use classes in 16 groundwater management areas in Texas between 1960 and 2010. Groundwater F concentration data were obtained from the Texas Water Development Board and aggregated over a...