Publications

The Richmond Mine of the Iron Mountain copper deposit contains some of the most acid mine waters ever reported. Values of pH have been measured as low as -3.6, combined metal concentrations as high as 200 g/liter, and sulfate concentrations as high as 760 g/liter. Copious quantities of soluble metal sulfate salts such as melanterite, chalcanthite, coquimbite, rhomboclase, voltaite, copiapite, and

ABSTRACT: Most of the application of the organophosphate insecticide diazinon in the San Joaquin River Basin occurs in winter to control wood-boring insects in dormant almond orchards. A federalstate collaborative study found that diazinon accounted for most of the observed toxicity of San Joaquin River water in February 1993. Previous studies focused mainly on west-side inputs to the San Joaquin

Normally, slug test measurements are limited to the well in which the water level is perturbed. Consequently, it is often difficult to obtain reliable estimates of hydraulic properties, particularly if the aquifer is anisotropic or if there is a wellbore skin. In this investigation, we use partially penetrating stress and observation wells to evaluate specific storage, radial hydraulic conductivit

Soil water collected from suction lysimeters and wick samplers buried in the unsaturated zone of a sand and gravel aquifer and extracted from soil cores were analyzed for stable oxygen and hydrogen isotope values. Soil water isotopic values differed among the three sampling methods in most cases. However, because each sampling method collected different fractions of the total soil-water reservoir,

The formation and spatial distribution of phytoplankton blooms in estuaries are controlled by (1) local mechanisms, which determine the production-loss balance for a water column at a particular spatial location (i.e. control if a bloom is possible), and (2) transport-related mechanisms, which govern biomass distribution (i.e. control if and where a bloom actually occurs). In this study, the first

The hydraulic and geochemical performance of a 366 m long permeable reactive barrier (PRB) at the Denver Federal Center, Denver, Colorado, was evaluated. The funnel and gate system, which was installed in 1996 to intercept and remediate ground water contaminated with chlorinated aliphatic hydrocarbons (CAHs), contained four 12.2 m wide gates filled with zero‐valent iron. Ground water mounding on t

A band of seismicity transects the southern Sierra Nevada range between the northeastern end of the site of the 1952 MW (moment magnitude) 7.3 Kern County earthquake and the site of the 1946 MW 6.1 Walker Pass earthquake. Relocated earthquakes in this band, which lacks a surface expression, better delineate the northeast-trending seismic lineament and resolve complex structure near the Walker Pass

A regional-scale, steady-state, saturated-zone ground-water flow model was constructed to evaluate potential regional ground-water flow in the vicinity of Yucca Mountain, Nevada. The model was limited to three layers in an effort to evaluate the characteristics governing large-scale subsurface flow. Geoscientific information systems (GSIS) were used to characterize the complex surface and subsurfa

An analytical method useful for the quantification of a range of pesticides and pesticide degradation products associated with suspended sediments was developed by testing a variety of extraction and cleanup schemes. The final extraction and cleanup methods chosen for use are suitable for the quantification of the listed pesticides using gas chromatography-ion trap mass spectrometry and the remova

The results of two studies of the effect of agricultural land use on shallow ground water quality indicate that monitoring wells may be a better choice than domestic wells for studies of pesticide occurrence or transport, or for use as early-warning indicators of potential drinking water contamination. Because domestic wells represent the used resource, and because domestic well water may be affec

ABSTRACT: Suspended sediment samples were collected in west-side tributaries and the main stem of the San Joaquin River, California, in June 1994 during the irrigation season and in January 1995 during a winter storm. These samples were analyzed for 15 organochiorine pesticides to determine their occurrence and their concentrations on suspended sediment and to compare transport during the irrigati