Thomas M Young - US grants

9733621 Young The objective of this research is to (i) establish the mechanisms of desorption resistance for organic chemicals in soils and sediments, (ii) develop predictive models and improved experimental techniques for assessing desorption rate limitations and (iii) quantify the potential risk variation resulting from desorption resistance by incorporating these predictive models into contaminant transport and risk assessment models. The presumptive mechanism underlying this research is that desorption resistance arises when organic compounds migrate to remote locations within rigid, condensed natural organic matter networks (NOMs) that significantly impede diffusion out of the matrix. This hypothesis will be tested by examining organic chemical desorption equilibria, rates, enthalpies and activation energies from natural materials containing diverse NOM types and quantities into both aqueous and supercritical carbon dioxide solvents. Predictive models of the desorption process will be developed by correlating NOM structural characteristics with model parameters. Desorption rate limitations will be incorporated into existing transport models, forming the basis for revised risk assessment models that can be used to estimate the impacts of the phenomenon on soil cleanup standards. The educational plan seeks to illustrate the importance of fundamental physical-chemical process models by linking them with chemical transport and risk assessment models. Chemical equilibrium and rate models will be linked to transport models for groundwater and surface water and, subsequently, to risk assessment models. Training on how policy-makers and managers analyze engineering design options, using tools such as risk and cost-benefit analysis, is being integrated into courses. Case studies will be prepared using the soil risk assessment model developed in this research.

9977873
Patrick Brown
UC Davis



Abstract


This project involves the acquisition of instrumentation in support of the establishment of a Center for Elemental mass spectrometry at the University of California, Davis. The instrumentation to be purchased will be capable of isotope ratio and quantitative determination of elements. The proposed center, in combination with the recently NSF-funded facility for H, C, N and O isotope determination will provide a world-class facility for inorganic mass spectrometry. The instruments to be purchased include a normal resolution, inductively coupled plasma mass spectrometer (ICP-MS); an ICP-MS equipped with magnetic sector MS and multi-collector detection system (MC-ICP-MS); and an ICP optical emission spectrometer (ICP-OES). These instruments will have a broad user base that will make optimal use of their varied capabilities.

Many disciplines in the fields of biological, environmental , geological and engineering sciences require detailed knowledge of the chemical and isotopic compositions of naturally occurring and laboratory-synthesized materials. Of special interest to the biological and environmental sciences are, for example, the pathways of trace constituents in the food web, biological complexation and transformations of trace elements in plants, animals and aquatic organisms; the fate of contaminants in surface and sub-surface environments, and modeling of watershed dynamics. In the geological and engineering sciences knowledge of element abundance and isotopic composition are used to establish evolutionary trends from rock successions/suites; to constrain paleoenvironmental parameters and paleoclimates and characterize material properties. What is common among these diverse applications of trace elements and isotope systems is the requirement of analytical instrumentation capable of measuring elements and individual isotopes in samples with high precision and accuracy.

The requested instruments and sample introduction systems will provide analytical capabilities to characterize the chemical composition of high solute-containing samples and solute concentrations at extreme dilutions with high precision and accuracy.

Sixteen PIs and senior personnel associated with 9 campus departments, 15 graduate programs and three colleges directly support this proposal and a significant number of additional faculty will benefit directly. A large number of graduate and undergraduate students will also benefit from the proposed center through course work and individual research projects.

ABSTRACT

CBET- 0756074
Young, Thomas
University of California at Davis

Antimicrobial chemicals in biosolid amended soils: persistence and effects


If TCS and TCC accumulate in biosolids-amended soils to the point where soil fertility or groundwater quality is adversely impacted, the agricultural market for these materials could disappear very quickly. This would require other outlets for biosolids disposal, all of which would likely be more costly and less environmentally friendly than land application. This fact, combined with the potential threats to human health posed by TCS/TCC, justifies further study regarding the fate and impact of these compounds in soils where biosolids are land applied.

The proposed work is to investigate the impact of triclosan (TCS) and triclocarban (TCC) on soil microbial community structure, biomass, and diversity. It would also investigate the role that these communities play in degrading TCS/TCC and cycling of nitrogen in soil. Lastly, it would also elucidate environmental conditions that favor biotransformation of the compounds in soils, determine process rates, and identify types of microorganisms involved in the transformation. The hypotheses to be tested are well defined, and the experimental approaches to test the hypotheses are well-designed. Preliminary data collected by the research team suggests that this approach will be successful and yield valuable information.

The experimental plan includes the use of a variety of complimentary techniques for characterizing the community structure in combination with techniques to determine function and potential activity of the microbial populations. Three soil types will be tested in order to include soils representative of those that have had long-term exposure to TCS/TCC, those that have not had long term exposure, those that are primarily aerobic, and those that are anaerobic.

ABSTRACT: PROJECT 1 This project will develop and evaluate a comprehensive and integrated suite of analytical, computational, and bioassay based approaches for assessing overall reductions in toxicity resulting from bioremediation of Superfund (SF) sites. These tools will then be applied to optimize biodegradation of two contaminant mixtures, triazine herbicides and polycyclic aromatic hydrocarbons representative of environmental exposures faced by our community partners the Yurok Tribe, through systematic investigation of carbon sources, electron acceptors, and reactor detention times. Although both of these contaminant mixtures are known to biodegrade, transformation products (TPs) accumulate and are widely found in groundwater (triazines) and/or have increased toxicity compared to parent compounds (PAHs). Bioreactor performance will be characterized by measuring shifts in microbial community composition, bioassay activity, and both target and nontarget chemical concentrations measured with GC and LC high resolution mass spectrometry (HRMS). This combination of measurements will provide unique insights into interactions among contaminant transformations, microbial populations and overall reductions in human and ecosystem risks. Novel enzyme engineering approaches will be used to identify rate limiting steps in triazine mineralization and to isolate or design improved enzymes to carry out these steps. Microorganisms with improved ability to degrade triazines will be prepared and tested in the bioreactors to assess ability to remove target compounds and to reduce overall bioactivity compared to standard enrichment approaches. Our central hypothesis is that chemical hazard reduction during SF site remediation can be best characterized through broad consideration of both contaminant destruction and byproduct formation. We further hypothesize that a minimum suite of high- throughput assays can be defined to effectively capture the overall risk reduction during remediation and that this suite of assays can guide optimization of bioreactor design and operation. This project will support a paradigm shift in the SRP away from reducing concentrations of specific constituents and toward the overall reduction of deleterious biological effects. The project is strongly integrated with the overall program, drawing on HRMS, metabolomics, and statistical expertise in the Analytical Core, the full range of bioassays available in the Bioanalytical Core, immunoassays from Project 3 especially for triazines and TPs, as well as integrative bioassays for ER and oxidative stress being developed by Projects 4 and 5. The bioassay suite developed here will be used to analyze environmental samples collected through the Community Engagement Core and the overall workflow will be transferred to a broader user community with the assistance of the Research Translation Core.