Our understanding of subsurface microbiology is hindered by the inaccessibility of this environment, particularly when the hydrogeologic medium is contaminated with toxic substances. In this study, surrogate geological media contained in a porous receptacle were incubated in a well within the saturated zone of a pristine region of an aquifer to capture populations from the extant communities. A...

Vulnerability assessment to delineate areas that are more susceptible to contamination from anthropogenic sources has become an important element for sensible resource management and land use planning. This contribution aims at estimating aquifer vulnerability by applying the DRASTIC model as well as utilizing sensitivity analyses to evaluate the relative importance of the model parameters for ...

A hydrogeologic characterization was performed to evaluate the nature of groundwater flow in an alluvial and underlying fractured bedrock aquifer in the area between an unlined, inactive landfill and a river in southern California. The hydrogeologic characterization was used to enhance the site conceptual model for the site, and to design a bioaugmentation pilot test to evaluate the use of enha...

A USGS investigation into the transport of contaminants to public-supply wells (PSWs) in four distinctly different aquifers demonstrates how differences in the chemistry of water produced by PSWs and nearby monitoring wells can reveal where and how contamination-susceptible water enters PSWs. This knowledge can be translated into improved monitoring strategies and protection plans. Samples were...

[1] The generalized radial flow approach to hydraulic test interpretation uses the flow dimension to describe the change in flow area versus radial distance from the borehole. The flow dimension of a hydraulic test may reflect several characteristics of the hydrogeologic system, including heterogeneity, boundaries, and leakage. We show that a radial flow system with a linear, constant-head boun...

Nitrate-N (NO3 N) is one of the most pervasive contaminants in groundwater. Nitrate in groundwater exhibits long-term behavior due to complex interactions at multiple scales among various geophysical factors, such as sources of nitrate-N, characteristics of the vadose zone and aquifer attributes. To minimize contamination of nitrate-N in groundwater, it is important to estimate hot spots (>10 m...

[1] In 2003–2005, systematic studies in four contrasting hydrogeologic settings were undertaken to improve understanding of source and transport controls on nitrate movement to public supply wells (PSW) in principal aquifers of the United States. Chemical, isotopic, and age tracer data show that agricultural fertilizers and urban septic leachate were the primary sources of large nitrate concent...

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report. iii Figures 1-4. Maps showing: 1. Study area, regions within the study area, and all well...

First posted July 28, 2023 For additional information, contact: Director, Lower Mississippi-Gulf Water Science Center U.S. Geological Survey 640 Grassmere Park, Suite 100 Nashville, TN 37211 https://www.usgs.gov/centers/lmg-water/Contact Pubs Warehouse A hydrogeologic framework was constructed for the Coastal Lowlands aquifer system in southwestern Louisiana. Data from previous and geologic stu...

Despite its purported importance, previous studies of the influence of sea-level rise on coastal aquifers have focused on specific sites, and a generalized systematic analysis of the general case of the sea water intrusion response to sea-level rise has not been reported. In this study, a simple conceptual framework is used to provide a first-order assessment of sea water intrusion changes in c...