Publications

Questions of major importance for subsurface contaminant transport at the Idaho National Engineering and Environmental Laboratory (INEEL) include (i) travel times to the aquifer, both average or typical values and the range of values to be expected, and (ii) modes of contaminant transport, especially sorption processes. The hydraulic and geochemical framework within which these questions...

The U.S. Geological Survey Reconstructed Trends National Synthesis study collected sediment cores from 56 lakes and reservoirs between 1992 and 2001 across the United States. Most of the sampling was conducted as part of the National Water-Quality Assessment (NAWQA) Program. The primary objective of the study was to determine trends in particle-associated contaminants in response to...

1,1,2,2-Tetrachloroethane (TeCA) contaminated groundwater at the Aberdeen Proving Ground discharges through an anaerobic wetland in West Branch Canal Creek (MD), where dechlorination occurs. Two microbially mediated pathways, dichloroelimination and hydrogenolysis, account for most of the TeCA degradation at this site. The dichloroelimination pathways lead to the formation of vinyl...

The influences of spiked Zn concentrations (1–40 μmol/g) and equilibration time (˜ 95 d) on the partitioning of Zn between pore water (PW) and sediment were evaluated with estuarine sediments containing two levels (5 and 15 μmol/g) of acid volatile sulfides (AVS). Their influence on Zn bioavailability was also evaluated by a parallel, 10‐d amphipod (Leptocheirus plumulosus) mortality...

Imaging with acoustic and optical televiewers results in continuous and oriented 360° views of the borehole wall from which the character, relation, and orientation of lithologic and structural planar features can be defined for studies of fractured-rock aquifers. Fractures are more clearly defined under a wider range of conditions on acoustic images than on optical images including dark...

California's primary hydrologic system, the San Francisco Estuary and its upstream watershed, is vulnerable to the regional hydrologic consequences of projected global climate change. Previous work has shown that a projected warming would result in a reduction of snowpack storage leading to higher winter and lower spring-summer streamflows and increased spring-summer salinities in the...

In a contaminated water‐table aquifer, we related microbial community structure on aquifer sediments to gradients in 24 geochemical and contaminant variables at five depths, under three recharge conditions. Community amplified ribsosomal DNA restriction analysis (ARDRA) using universal 16S rDNA primers and denaturing gradient gel electrophoresis (DGGE) using bacterial 16S rDNA primers...

In the late 1800s, mills in the Washoe Lake area, Nevada, used elemental mercury to remove gold and silver from the ores of the Comstock deposit. Since that time, mercury contaminated waste has been distributed from Washoe Lake, down Steamboat Creek, and to the Truckee River. The creek has high mercury concentrations in both water and sediments, and continues to be a constant source of...

Well water temperatures are often collected simultaneously with water levels; however, temperature data are generally considered only as a water quality parameter and are not utilized as an environmental tracer. In this paper, water levels and seasonal temperatures are used to estimate hydraulic conductivities in a stream-aquifer system. To demonstrate this method, temperatures and water...

Periphyton (Cladophora sp.) samples from a suburban stream lacking detectable dissolved As were able to reduce added As(V) to As(III) when incubated under anoxic conditions and, conversely, oxidized added As(III) to As(V) with aerobic incubation. Both types of activity were abolished in autoclaved controls, thereby demonstrating its biological nature. The reduction of As(V) was inhibited...

A multi-offset ground penetrating radar (GPR) dataset was acquired by the U.S. Geological Survey (USGS) at a crude oil spill site near Bemidji, Minnesota, USA. The dataset consists of two, parallel profiles, each with 17 transmitter-receiver offsets ranging from 0.60 to 5.15m. One profile was acquired over a known oil pool floating on the water table, and the other profile was acquired...

The San Francisco Estuary is critical habitat for delta smelt Hypomesus transpacificus, a fish whose abundance has declined greatly since 1983 and is now listed as threatened. In addition, the estuary receives drainage from the Central Valley, an urban and agricultural region with intense and diverse pesticide usage. One possible factor of the delta smelt population decline is pesticide...