Publications

Unlike conventional flood control systems that frequently isolate rivers from ecologically-essential floodplain habitat, California's Yolo Bypass has been engineered to allow Sacramento Valley floodwaters to inundate a broad floodplain. From a flood control standpoint, the 24,000 ha leveed floodplain has been exceptionally successful based on its ability to convey up to 80% of the flow...

The water quality, habitats, and biota of streams in the upper Animas River watershed of Colorado, USA, are affected by metal contamination associated with acid drainage. We determined metal concentrations in components of the food web of the Animas River and its tributaries - periphyton (aufwuchs), benthic invertebrates, and livers of brook trout (Salvelinus fontinalis) - and evaluated...

A series of column experiments was conducted using manganese oxide coated sediments collected from the hyporheic zone in Pinal Creek (AZ), a metal-contaminated stream, to study the uptake and retention of Mn, Ni, and Co. Experimental variables included the absence (abiotic) and presence (biotic) of active Mn-oxidizing bacteria, the absence and presence of dissolved Mn, and sediment...

The inter-annual variation in the structure of the benthic community of riffles and pools was evaluated in contrasting geomorphic settings. The community structure of riffles and pools was a function of habitat, reach gradient, and discharge and was taxon specific. In years of below average peak discharge, riffles had higher taxon richness than pools (66 versus 47) but richness was...

Use of open wells to conduct aquifer tests in fractured crystalline rock aquifers is potentially problematic, because open wells can hydraulically connect highly permeable fracture zones at different depths within the rock. Because of this effect, it is questionable whether estimates of the hydraulic properties of the rock obtained from analysis of an open-well aquifer test in fractured

Molecular weight distributions of fulvic acid from the Suwannee River, Georgia, were investigated by electrospray ionization/quadrupole mass spectrometry (ESI/QMS), and fragmentation pathways of specific fulvic acid masses were investigated by electrospray ionization/ion trap multistage tandem mass spectrometry (ESI/MST/MS). ESI/QMS studies of the free acid form of low molecular weight...

Trace metal clean sampling and analysis techniques were used to examine the temporal patterns of Hg, Cu, and Zn concentrations in shallow ground water, and the relationships between metal concentrations in ground water and in a hydrologically connected river. Hg, Cu, and Zn concentrations in ground water ranged from 0.07 to 4.6 ng L−1, 0.07 to 3.10 μg L−1, and 0.17 to 2.18 μg L−1...

Microorganisms indigenous to stream and lake bed sediments, collected from 11 sites throughout the United States, demonstrated significant mineralization of the fuel oxygenate, methyl-tert-butyl ether (MTBE). Mineralization of [U-14C]MTBE to 14CO2 ranged from 15 to 66% over 50 days and did not differ significantly between sediments collected from MTBE contaminated sites and from sites...

A multidisciplinary study of a crude-oil contaminated aquifer shows that the distribution of microbial physiologic types is strongly controlled by the aquifer properties and crude oil location. The microbial populations of four physiologic types were analyzed together with permeability, pore-water chemistry, nonaqueous oil content, and extractable sediment iron. Microbial data from three...

No abstract available.

The accurate determination of an organic contaminant’s physico-chemical properties is essential for predicting its environmental impact and fate. Approximately 700 publications (1944–2001) were reviewed and all known aqueous solubilities (Sw) and octanol-water partition coefficients (Kow) for the organochlorine pesticide, DDT, and its persistent metabolite, DDE were compiled and examined...

Metals enter Little Cottonwood Creek in Salt Lake County, Utah, in drainage water that discharges from inactive mines in the watershed (fig. 1). As part of a study to evaluate the effects of this mine drainage on water quality, a sodium chloride tracer was injected into Little Cottonwood Creek during September 17-18, 1998. The purpose of the injection was to quantify stream discharge; to...