Molecular Environmental Soil Science

Critical environmental processes are often driven by micro- to molecular scale phenomena. The Molecular Environmental Soil Science (MESS) research program seeks to understand the fundamental biological and chemical processes that control the speciation, transformation, bioavailability, fate, and transport of nutrients and contaminants in the environment. To approach these complex problems, investigations hinge on blending cutting-edge spectroscopic, microscopic, and molecular techniques with traditional chemical and microbiological approaches in both field and laboratory studies. These studies develop the basic scientific understanding that underpins the development of sound management strategies.

Fundamental features of X-ray absorbtion spectra.

The solid and aqueous phase speciation of chemicals in soils determines their mobility and bioavailability. For example, precisely managing phosphorus as both a plant nutrient and an environmental contaminant will be best accomplished from a fundamental understanding of the chemical species present in a soil and the reactivity of these species. Dean Hesterberg (Soil Physical Chemistry) uses advanced X-ray spectroscopic techniques to determine solid-phase chemical species of phosphorus and trace elements in soils, and to study their reactivity. Research ranges from molecular-scale characterization to direct observation of contaminant dissolution in soil materials.

molecular descriptionThe distributions of contaminant trace elements in soils, sediments, and natural waters are controlled by a host of physical, chemical, and biological processes. Matt Polizzotto (Soil and Environmental Hydrogeochemistry) supplements field and laboratory experiments with spectroscopic analyses in order to determine how contaminant speciation changes spatially and temporally within the environment. Integrated efforts are designed to better understand how soil processes – from molecular to field scales – effect surface and groundwater quality.

biogeochemistryThe biogeochemistry of many nutrients and contaminants in the environment is mediated by microbes and mineral surfaces. Owen Duckworth (Soil Biogeochemistry) focuses primarily on the thermodynamics and kinetics of aqueous and interfacial reactions that control the biogeochemical cycling of natural and anthropogenic species. Specific interests include the effects of biogenic exudates, including small organic acids, biopolymers, and siderophores, on the speciation and solublization of trace metals in the environment, and the biomineraization and bioweathering of minerals. A wide array of spectroscopic and microscopic techniques are used to support macroscopic observations derived from traditional chemical and microbiological approaches.

Microorganisms play fundamental roles in many soil processes including but not limited to soil carbon sequestration, nitrogen and phosphorus cycling, and detoxification of inorganic and organic pollutants. Soil microbes regulate these processes through their survival strategies at the organismal level, competitive and synergistic interactions at the community level, and feedback control mechanisms at the ecosystem level. Wei Shi (Soil Microbiology and Ecology) uses molecular biology, biochemical and ecological approaches to address questions regarding soil microbial ecophysiology, community diversity and composition, and the cycling of carbon, nitrogen, and phosphorus in managed and natural ecosystems. Soil Microbiology and Ecology Laboratory is equipped with tools for conducting organismal, community, and process-level studies.

Microorganisms

Terrence Gardner (Soil Microbial Ecology and Biogeochemistry) focuses on enhancing our understanding of the linkages between microbial diversity and microbially mediated processes providing ecosystem services related to metabolic functioning, in agronomic and environmental systems. Specific interests involve utilizing a combination of microscopic, spectroscopic, molecular biology, Metagenomic, and bioinformatics techniques to elucidate microbial contributions to nutrient cycling and the transformations of pollutants in soils, sediments and water. Goals of developing novel strategies related to important emerging issues in soil microbial ecology (e.g. climate change, contaminated waste remediation and soil erosion), will lead to the development of sustainable management practices essential for increased crop production and improving water, soil, and air quality.

Soil Microbial ecologist and biogeochemist

Alexandria Graves (Soil and Environmental Microbiology) uses nucleic acid-based methods for the identification of enteric bacteria (E. coli, Enterococcus, Salmonella, etc.) recovered from soil and water matrices. The use of PCR provides the capability to detect the presence of enteric bacteria without relying on the need to culture the target microorganisms. This tool also provides the ability to track several different genes concomitantly, thus allowing for a greater level of confidence in microbial source tracking and pathogen detection.

Students trained in the MESS program will develop diverse technical skills and a multidisciplinary perspective on soils and the environment. Prospective students interested in any of these topics, or applying these techniques and approaches to other problems, should feel free to contact any of the faculty listed above for more information.