Publications

No abstract available.

Since 1984, hydrologic data have been collected as part of a U.S. Geological Survey study of the occurrence and movement of acidic contamination in the aquifer and streams of the Pinal Creek drainage basin near Globe, Arizona. Ground-water data from that study are presented for water years 1994, 1995, and 1996 and include location, construction information, site plans, water levels...

As part of the Clean Water Act of 1972 (Public Law 92-500), all States are required to establish water-quality standards for every river basin in the State. During 1994, the Colorado Department of Public Health and Environment proposed to the Colorado Water Quality Control Commission (CWQCC) an aquatic-life standard of 225 µg/L (micrograms per liter) for the dissolved-zinc concentration...

The kinetics of anaerobic mineralization of DCE and VC under methanogenic and Fe(III)-reducing conditions as a function of dissolved contaminant concentration were evaluated. Microorganisms indigenous to creek bed sedi ments, where groundwater contaminated with chlorinated ethenes continuously discharges, demonstrated significant mineralization of DCE and VC under methanogenic and Fe(III...

Herbicides were detected in rainfall throughout the midwestern and northeastern United States during late spring and summer of 1990 and 1991. Herbicide concentrations exhibited distinct geographic and seasonal patterns. The highest concentrations occurred in midwestern cornbelt states following herbicide application to cropland. Volume-weighted concentrations of 0.2−0.4 μg/L for atrazine...

Natural surficial accumulations of nitrate-rich salts in the Atacama Desert, northern Chile, and in the Death Valley region of the Mojave Desert, southern California, are well known, but despite many geologic and geochemical studies, the origins of the nitrates have remained controversial. N and O isotopes in nitrate, and S isotopes in coexisting soluble sulfate, were measured to...

The purpose of this paper is to illustrate the significantly increased resolution of determining macropore recharge by combining physical, chemical, and isotopic methods of analysis. Techniques for quantifying macropore recharge were developed for both small-scale (1 to 10 km2) and regional-scale areas in and semi-arid areas. The Southern High Plains region of Texas and New Mexico was...

No abstract available.

In a column experiment, acidic groundwater from Pinal Creek Arizona, a Cu mining area, was eluted through a composited alluvial sample obtained from a core that had been removed from a well downgradient of the acidic groundwater. The minerals present in typical grains and flakes in the alluvium before and after the elution were determined by X-ray diffraction (XRD), scanning electron...

Tracer experiments are valuable tools for analyzing the transport characteristics of streams and their interactions with shallow groundwater. The focus of this work is the design of tracer studies in high-gradient stream systems subject to advection, dispersion, groundwater inflow, and exchange between the active channel and zones in surface or subsurface water where flow is stagnant or...

The micropore volumes of 2 montmorillonites (SAz-1 and SWy-1), each exchanged with Ca, Na, K, Cs and tetramethylammonium (TMA) ions, were calculated from the measured vapor adsorption data of N2 and neo-hexane by use of t- and αs-plots. The corresponding surface areas of the exchanged clays were determined from Brunauer-Emmett-Teller (BET) plots of N2 adsorption data. Micropore volumes...

The different oxidation species of iodine have markedly different sorption properties. Hence, changes in iodine redox states can greatly affect the mobility of iodine in the environment. Although a major microbial role has been suggested in the past to account for these redox changes, little has been done to elucidate the responsible microorganisms or the mechanisms involved. In the work...