Matthew Charles Reid 
Assistant Professor, Civil and Environmental Engineering

Professor Reid is interested in the use of engineered and managed ecosystems as sustainable tools for water quality protection. His research is focused on the coupled biological, chemical, and physical processes that govern contaminant fate in soils, and on how these natural processes can be harnessed to preserve water quality and reduce greenhouse gas emissions from nutrient cycling. 

There will be a reception with food and refreshments at 4:30 pm, following the seminar in Snee 2146 for faculty, staff, and students to meet Dr. Reid.

Title: Controls on Arsenic Speciation and Bioavailability in Rice Paddy Soils 

Growing concern about arsenic contamination of rice has directed new attention to the biogeochemical processes controlling arsenic speciation and bioavailability in flooded rice paddy soils.  The first part of this talk describes complementary field and laboratory experiments exploring the effects of wetting-drying cycles on coupled manganese, iron, and arsenic mobilization into pore waters.  A specific objective of these experiments was to evaluate the role of manganese oxides as redox buffers controlling the onset of iron-reducing conditions that drive arsenic mobilization.  The second part of the talk will describe new insights into interactions between arsenic and wetland dissolved organic matter (DOM).  DOM-bound arsenic has traditionally been thought to represent a negligible fraction of the dissolved arsenic pool, but new findings with anoxically-extracted DOM and arsenic/DOM ratios representative of wetland pore waters suggest a significant contribution of DOM-bound arsenic to aqueous arsenic speciation and an important role for organic sulfur functional groups as arsenic binding sites.  The implications of arsenic-DOM binding for biological uptake of arsenic in DOM-rich environments will be evaluated using an arsenic biosensor assay.