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A survey of diffuse CO2 efflux, soil temperature and soil-gas chemistry over areas of localized vegetation-kill on and around the resurgent dome of Long Valley caldera California was performed to evaluate the premise that gaseous and thermal anomalies are related to renewed intrusion of magma....

Measurements of groundwater-surface water exchange at three wetland stream sites were related to patterns in benthic productivity as part of the US Geological Survey's Northern Temperate Lakes-Water, Energy and Biogeochemical Budgets (NTL-WEBB) project. The three sites included one high groundwater discharge (HGD) site, one weak groundwater discharge (WGD) site, and...

It has been suggested, on the basis of modern hydrology and fully coupled palaeoclimate simulations, that the warm greenhouse conditions that characterized the early Palaeogene period (55-45 Myr ago) probably induced an intensified hydrological cycle with precipitation exceeding evaporation at high latitudes. Little field evidence, however, has been available to...

This study examined the influence of fall-spawning coho salmon (Oncorhynchus kisutch) on the density, growth rate, body condition, and survival to outmigration of juvenile coho salmon on the Copper River Delta, Alaska, USA. During the fall of 1999 and 2000, fish rearing in beaver ponds that received spawning salmon were...

The USGS precipitation-runoff modelling system (PRMS) hydrologic model was used to evaluate experimental, gridded, 1 km2 snow-covered area (SCA) and snow water equivalent (SWE) products for two headwater basins within the Rio Grande (i.e. upper Rio Grande River basin) and Salt River (i.e. Black River basin) drainages in the southwestern...

The Niigata Ken Chuetsu earthquake triggered a vast number of lanslides in the epicentral region. Landslide concentrations were among the highest ever measured after an earthquake, and most of the triggered landslides were relatively shallow failures parallel to the steep slope faces. The dense concentration of landslides can be attributed...

In light of recent reductions in sulphur (S) and nitrogen (N) emissions mandated by Title IV of the Clean Air Act Amendments of 1990, temporal trends and trend coherence in precipitation (1984-2001 and 1992-2001) and surface water chemistry (1992-2001) were determined in two of the most acid-sensitive regions of North...

Leachate plume emanating from an old unlined municipal landfill site near the city of Norman, Oklahoma, is discharging into the underlying alluvial aquifer. Subsurface imaging techniques, electrical resistivity tomography and electrical conductivity (EC) logging, were used on the site to detect and map the position of...

Low-permeability, non-reactive barrier walls are often used to contain contaminants in an aquifer. Rates of solute transport through such barriers are typically many orders of magnitude slower than rates through the aquifer. Nevertheless, the success of remedial actions may be sensitive to these low rates of transport. Two numerical simulation...

The USGS conducted a geophysical investigation in support of a U.S. Naval Facilities Engineering Command, Southern Division field‐scale biostimulation pilot project at Anoka County Riverfront Park (ACP), downgradient of the Naval Industrial Reserve Ordnance Plant, Fridley, Minnesota. The goal of the pilot project is to evaluate...

It has been long known that land surface topography governs both groundwater flow patterns at the regional‐to‐continental scale and on smaller scales such as in the hyporheic zone of streams. Here we show that the surface topography can be separated in a Fourier‐series...

Macro- and molecular-scale knowledge of uranyl (U(VI)) partitioning reactions with soil/sediment mineral components is important in predicting U(VI) transport processes in the vadose zone and aquifers. In this study, U(VI) reactivity and surface speciation on a poorly crystalline aluminosilicate mineral, synthetic imogolite, were...

Arsenic is a highly toxic element that supports a surprising range of biogeochemical transformations. The biochemical basis of these microbial interactions is described, with an emphasis on energy-yielding redox biotransformations that cycle between the As5+ and As3+ oxidation states. The subsequent impact of As3+-oxidising and As 5+-reducing prokaryotes on the...

Iron-hydroxysulfate minerals can be important hosts for metals such as lead, mercury, copper, zinc, silver, chromium, arsenic, and selenium and for radionuclides such as 226Ra. These mineral-bound contaminants are considered immobilized under oxic conditions. However, when anoxic conditions develop, the activities of sulfate- or iron-reducing bacteria could result in mineral...

A presumed value of shallow-habitat enhanced pelagic productivity derives from the principle that in nutrient-rich aquatic systems phytoplankton growth rate is controlled by light availability, which varies inversely with habitat depth. We measured a set of biological indicators across the gradient of habitat depth within the Sacramento–San Joaquin River...

Two practical approaches incorporating lithologic information for groundwater modeling calibration are presented to estimate distributed, cell-based hydraulic conductivity. The first approach is to estimate optimal hydraulic conductivities for geological materials by incorporating thickness distribution of materials into inverse modeling. In the second approach, residuals for the groundwater model solution are...

On its traverse to Columbia Hills, the Mars Exploration Rover Spirit investigated an outcrop designated “Wooly Patch” that exhibited morphological, mineralogical, and geochemical characteristics at the extreme ends of ranges observed among rocks studied at West Spur, a westward projecting salient near the foot of the Columbia Hills, Gusev crater....

Stratigraphic investigations of fluvio-deltaic and lacustrine sediments exposed in stream cuts, quarry walls, and deep trenches east of the Sierra Nevada in Owens Valley near Lone Pine, California have enabled the reconstruction of pluvial Owens Lake level oscillations. Age control for these sediments is from 22 radiocarbon (14C) dates and...

In 2000-2002, three rangeland and six irrigated sites were instrumented to assess the storage and transit time of chemicals in thick (15 to 50 m) unsaturated zones (UZ) in the High Plains. These processes are likely to influence relations between land use and groundwater quality, yet they have not been...

Hydraulic tests and geophysical logging performed in the Palisades sill and the underlying sedimentary rocks in the NE part of the Newark Rift Basin, New York, USA, confirm that the particular transmissive zones are localized within the dolerite-sedimentary rock contact zone and within a narrow interval below this contact...

Stream-bed sediment for the size fraction less than 150 μm, examined in 14,000 samples collected mostly from minor tributaries to the major rivers throughout the Mississippi River drainage system, is composed of 5 mineral fractions identified by factor analysis—Al-silicate minerals, quartz, calcite and dolomite, heavy minerals, and an Fe–Mn fraction....

An integrated interpretation of field experimental cross-hole radar, tracer, and hydraulic data demonstrates the value of combining time-lapse geophysical monitoring with conventional hydrologic measurements for improved characterization of a fractured-rock aquifer. Time-lapse difference-attenuation radar tomography was conducted during saline tracer experiments at the US Geological Survey Fractured Rock Hydrology...

Disposal of treated wastewater for more than 60 years onto infiltration beds on Cape Cod, Massachusetts produced a groundwater contaminant plume greater than 6 km long in a surficial sand and gravel aquifer. In December 1995 the wastewater disposal ceased. A long-term, continuous study was conducted to characterize the post-cessation...

The phosphate oxygen isotopic composition in naturally occurring particulate phosphatic compounds (δ18Op) can be used as a tracer for phosphate sources and to evaluate the cycling of phosphorus (P) in the environment. However, phosphatic compounds must be converted to silver phosphate prior to isotopic...

The stereoisomers of metolachlor and its two polar metabolites [ethane sulfonic acid (ESA) and oxanilic acid (OXA)] were separated using liquid chromatography–mass spectrometry (LC–MS) and capillary zone electrophoresis (CZE), respectively. The separation of metolachlor enantiomers was achieved using a LC–MS equipped with a...