1. Biogeochemical Cycling of Arsenic in Rice Paddies
Growing awareness of the global problem of arsenic (As) contamination of rice has directed substantial research into the biogeochemical cycling and fate of As in rice paddy soils. Our group investigates how As biotransformations in rice paddy soils affect the mobility and availability of As for uptake into rice plants. This work combines techniques in analytical environmental chemistry and molecular microbiology, and makes use of soil-plant microcosm experiments to test theories and hypotheses in more realistic conditions. We also work on the characterization of arsenic geochemistry and functional genes involved in arsenic biotransformations in soils of rice-producing regions of the U.S. through a collaboration with the Dale Bumpers National Rice Research Center in Stuttgart, Arkansas.
2. Coupled Physical and Biological Dynamics of Gases in Engineered Soils
Low-impact design and green engineering infrastructure incorporate natural landscape features within the built environment to intercept polluted water before it is released into aquatic environments. These landscape features include constructed treatment wetlands, denitrifying bioreactors, and riparian buffer strips. From a wastewater perspective, both septic system leach fields (used by approximately 20% of the U.S. population) and pit latrines (used by approximately 25% of the global population) are examples of soil environments engineered to intercept and transform nutrients in polluted waters before they are released into aquatic systems.
Our laboratory’s work in this area is concerned with how coupled biological and abiotic processes influence the cycling and fate of nitrogen and carbon within these complex systems. A special focus is on the role of physical gas transfer/transport processes in controlling the behavior of carbon and nitrogen gases, as well as oxygen, and how gas dynamics impact the performance of these ecological engineering technologies.