Publications

The Grand Canyon region in northern Arizona is a home or sacred place of origin for many Native Americans and is visited by over 6 million tourists each year. Most communities in the area depend upon groundwater for all water uses. Some of the highest-grade uranium ore in the United States also is found in the Grand Canyon region. A withdrawal of over 1 million acres of Federal land in...

The U.S. Geological Survey (USGS), in cooperation with the City of Grandview, Missouri, assessed flooding of the Little Blue River at Grandview resulting from varying precipitation magnitudes and durations and expected land-cover changes. The precipitation scenarios were used to develop a library of flood-inundation maps that included a 3.5-mile reach of the Little Blue River and...

Trace element contamination is known to be widely present in sediment of Lake Roosevelt and the riverine reach of the Columbia River in Washington State, USA due to discharges from several smelters and numerous mines dating back to the mid-1800's. In this study, the concentrations of aqueous elements in contact with bed sediment from the lake and river were examined under varying degrees...

Wetland soil stocks are important global repositories of carbon (C) but are difficult to quantify and model due to varying sampling protocols, and geomorphic/spatio-temporal discontinuity. Merging scales of soil-survey spatial extents with wetland-specific point-based data offers an explicit, empirical and updatable improvement for regional and continental scale soil C stock assessments...

Statistical modeling of water-quality data collected at the Sacramento River at Freeport and San Joaquin River near Vernalis, California, USA, was used to examine trends in concentrations and loads of various forms of dissolved and particulate nitrogen and phosphorus that entered the Sacramento–San Joaquin River Delta (Delta) from upstream sources between 1970 and 2019. Ammonium...

No abstract available.

A pesticide is a substance, or mixture of substances, used to kill or control insects, weeds, plant diseases, and other pest organisms. Commercial pesticide applicators, farmers, and homeowners apply about 1.1 billion pounds of pesticides annually to agricultural land, non-crop land, and urban areas throughout the United States. Although intended for beneficial uses, there are also risks

Acidic deposition is the result of upwind sulfur (S) and nitrogen (N) emissions into the atmosphere from human activities. Environmental impacts from acidic deposition across forested landscapes include acidification of soil and drainage water, depletion of available soil nutrient bases, and impacts to and changes in forest and aquatic species composition and biodiversity. Acidic...

No abstract available.

We report He-CO2-N2 isotopic and relative abundances in free gases and dissolved gas phase of geothermal fluids from the Ethiopian Rift. Fluid samples were collected from ~30 geothermal localities from three key regions throughout rifted and non-rifted areas of Ethiopia. The majority of samples, including off-rift samples, indicate a strong contribution of mantle-derived He-C-N to the...

White Sturgeon (Acipenser transmontanus), a species of concern in the San Francisco Estuary, is in relatively low abundance due to a variety of factors. The purpose of our study was to identify the estuarine habitat used by White Sturgeon to aid in the conservation and management of the species locally and across its range. We seasonally sampled sub-adult and adult White Sturgeon in the...

Repeated sampling to detect changes in forest soils was rarely used before 1990, but the value of soil monitoring in understanding environmental change is becoming well established. The growing number of resampling studies has shown that sampling designs and procedures must be adapted to the objectives of the monitoring program and the soils being monitored. In the Adirondack region...