Benzylsuccinate (BSA), methylbenzylsuccinate (methylBSA), and ethylbenzylsuccinate (ethylBSA) are unambiguous anaerobic biotransformation products from toluene, xylenes, and ethylbenzene decay, respectively, and may be used to indicate intrinsic bioremediation is occurring at hydrocarbon-contaminated sites. In order to improve upon current methods that detect and quantify anaerobic hydrocarbon metabolites in field samples, solid-phase-extraction...
This study investigated complete reductive dechlorination of chlorinated aliphatic hydrocarbons (CAHs) over a broad range of concentrations. Tetrabutoxysilane (TBOS), as a slow-release anaerobic substrate, was studied for enhanced reductive dechlorination of tetrachioroethylene (PCE) present as a dense non-aqueous liquid (DNAPL). Four different site-mixed cultures were used in the study: Site-300...
The procedure described in this publication helps
you assess the potential for any specific pesticide
to travel through any specific soil to reach
groundwater.
Increases in food demand, favorable commodity markets and drive towards increasing productivity at a greater economic efficiency have accelerated negative agricultural
externalities, particularly erosion and water quality. The potential impact of these externalities on environmental quality and human health prompted an examination of current and potential production strategies on four...
Assessment of the environmental impacts of an agricultural production system
requires information on both soil water quality and solute flux. Passive Capillary Samplers
(PCAPS), which sample water from the vadose zone using fiber glass wicks, have shown
potential to provide both flux and solute concentration in unsaturated zone sampling but...
Radon-222 gas has unique properties allowing it to be used as an indicator for the
presence of organic phase liquids in the saturated zone. It naturally occurs in soils. It is
radioactive, making quantitative detection straight forward. A noble gas, it is chemically
inert and does not react with aquifer...
Chlorinated aliphatic hydrocarbons (CAHs) such as vinyl chloride (VC) and 1,-2 dichioroethane (DCA), are wide-spread groundwater pollutants found at many contaminated field sites around the world. Quantitative tools are needed to determine the in situ rates of VC and DCA transformation to ethene in contaminated groundwater. The objective of this...
The agricultural production of peppermint has been shown to contribute significant quantities of nitrate-nitrogen to groundwater recharge. In an effort to provide new tools for increasing nitrogen efficiency within peppermint production, three research questions were proposed: i) How should plant tissue samples be collected to achieve the greatest precision when...
The unifying purpose of this dissertation was to describe, model, and map
relationships between epiphvtic macrolichen communities and air quality in Ibrests of
northern and central California. First, multivariate analyses were used to subdivide the
large study area into three model areas with similar climate, topography, and lichen
communities: the...
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Chapter 3. Bioindication of Air Pollution in the Greater Central Valley of
California. U.S.A
Groundwater nitrate contamination is a well-documented issue in the Southern Willamette Valley (SWV) of Oregon, as a Groundwater Management Area (GWMA) has recently been declared. As a GWMA, groundwater nitrate monitoring must occur until regional concentrations are below 7 mg/L NO3-N. However, the presence of temporal variability can make it...