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Full-Text Articles in Chemistry

The Influence Of Hydrogeomorphology, Soil Redox Conditions, And Salinity On The Spatial Zoning Of Saltgrass, Salt Rush, And Cattails In Scotts Creek Marsh, Swanton Pacific Ranch, Ca, Mark D. Gormley Dec 2013

The Influence Of Hydrogeomorphology, Soil Redox Conditions, And Salinity On The Spatial Zoning Of Saltgrass, Salt Rush, And Cattails In Scotts Creek Marsh, Swanton Pacific Ranch, Ca, Mark D. Gormley

Master's Theses

Scotts Creek Marsh (SCM) is a small coastal wetland ecosystem in Davenport, CA. The vegetation of SCM is dominated by three halophytic zones comprised of saltgrass, salt rush, cattails. The objectives of the study were (i) to investigate the variables that influence the zoning of the three dominant halophyte communities in SCM and (ii) to the test the effectiveness of Indicator of Reduction in Soil (IRIS) tubes to indicate the reduction of S. The study examined the following parameters from April 6 to July 21, 2013: (i) the HGM of Scotts Creek Marsh, (ii) soil oxidation and reduction (redox) conditions, …


The Influence Of Soil Organic Matter Stabilization Mechanisms On Carbon Mean Residence Time Within Various Ecosystems In The United States, Vicky Lynn Giese, Kate Heckman Phd Aug 2013

The Influence Of Soil Organic Matter Stabilization Mechanisms On Carbon Mean Residence Time Within Various Ecosystems In The United States, Vicky Lynn Giese, Kate Heckman Phd

STAR Program Research Presentations

Some terrestrial ecosystems and soils serve as carbon sinks, partially offsetting rising atmospheric CO2 levels. Physiochemical mechanisms of soil organic matter (SOM) stabilization affect how carbon stocks respond to global warming. In order to clarify the variance in SOM stabilization mechanisms across different soil types, SOM abundance, distribution and mean residence time (MRT) were compared for thirty-two soil samples from six ecosystems across the United States. Soils were previously described, collected and archived by the United States Geological Survey. Samples were processed by LLNL at the Center for Accelerator Mass Spectrometry (CAMS) using density fractionation to separate particulate organics …


Investigation Of Ozone In Urban And Rural Areas Of California, Mia J. Hiles, David Parrish Aug 2013

Investigation Of Ozone In Urban And Rural Areas Of California, Mia J. Hiles, David Parrish

STAR Program Research Presentations

Ozone is the air pollutant about which we have probably heard the most. Two types of ozone exist: stratospheric and tropospheric. Stratospheric ozone absorbs most of the damaging ultra-violet sunlight and tropospheric ozone comes into direct contact with life-forms and is toxic at high levels. Ozone concentration in California has been studied for over five decades, and there is a long history of control efforts. During 2010, California Air Resources Board (CARB) and National Oceanic and Atmospheric Administration (NOAA) conducted a major climate and air quality study in California called CalNex 2010 (California Research at the Nexus of Air Quality …


Spectroscopic Study Of Uranium (Vi) Reduction By Plant Biomass, Margaret C. Murphy, John Bargar, Noémie Janot Aug 2013

Spectroscopic Study Of Uranium (Vi) Reduction By Plant Biomass, Margaret C. Murphy, John Bargar, Noémie Janot

STAR Program Research Presentations

Uranium is a common and problematic groundwater contaminant at Department of Energy legacy sites. At the former uranium ore processing plant at Rifle, Colorado, sediments rich in decayed plant biomass contain large concentrations of uranium that are slowly being released back to the aquifer. To simulate the reaction that occurs in organic rich sediments of the Rifle aquifer, biomass was incubated in U (VI) bearing groundwater. Carbon X-ray absorption spectroscopy (XAS) was then used to measure if uranium was bound to the biomass. When uranium binds to biomass the peaks in the C XAS spectra will change shape. Uranium L …


Using Stable Isotope Analysis Of Zooplankton To Document Trophic And Biogeochemical Changes In The San Francisco Estuary, Steven C. Westbrook, Julien Moderan Jan 2013

Using Stable Isotope Analysis Of Zooplankton To Document Trophic And Biogeochemical Changes In The San Francisco Estuary, Steven C. Westbrook, Julien Moderan

STAR Program Research Presentations

Zooplankton represent a vital link between phytoplankton and fish, like the endangered Delta Smelt. Human interferences (nitrates from waste water, flow alteration, invasive species introduction…) have altered the structure of the San Francisco Estuary (SFE) ecosystem. We use stable isotope analysis to improve our knowledge of the planktonic food web in the SFE and gain insights into its evolution over the past decades. We use the ratios of certain isotopes (Nitrogen, Carbon, Sulfur, etc.) in different species of zooplankton to tell us what it is feeding on as well as the trophic level it feeds in. My research focused on …