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Contact: 151 Hilgard Hall
Email: mkausch-at-berkeley.edu
Matteo studies the effects of chemical gradients arising from diffusion limited transport within soil aggregates on biogeochemical processes driving the fate and mobility of environmentally relevant elements. He uses a combination of modeling and experimental techniques including multi-dimensional reactive transport models and flow-through experiments with aggregate systems of various complexities. He has worked on modeling the spatially resolved biotransformation of Fe(hydr)oxides within artificial soil aggregates and is focusing on microbial Se-reduction for his thesis work.
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Contact: 151 Hilgard Hall
Email: cmr5064-at-berkeley.edu
Chandra studies the environmental and biogeochemical controls that drive the kinetics of iron and sulfate reduction in littoral aquatic wetland sediments. This research will elucidate the fate, transport, and transformative processes that factor into Fe cycling, investigate the effects of increased S loadings on the Fe cycle, and illuminate the role that Fe-oxides play in mobilizing or immobilizing toxic metals, such as arsenic, selenium, uranium, and chromium. Her work focuses on three sites in the western United States: Baylands Nature Preserve (Palo Alto, CA), Pescadero Marsh Preserve (Pescadero, CA), and Fraser Experimental Forest (Fraser, CO). These sites represent a range of surficial wetland environments with large concentrations of sulfides and toxic heavy metals in the sediment. She will be measuring the rates of Fe and S reduction using novel flow-through experiments that mimic in-situ conditions. She joined the Pallud Lab in 2011 and was awarded the Bay Area Water Quality Fellowship in 2012 to continue studying wetlands in the San Francisco estuarine system.
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Contact: 151 Hilgard Hall
Email: villaromero-at-berkeley.edu
Juan Fernando is interested in the interplay between biodiversity, ecosystem functioning, and environmental change. His work focuses on microbial diversity, microbially-driven rates of selenium transformation, as affected by salinity. His research focuses on the Salton Sea, a hypersaline lake located in Southern California characterized by accumulation of selenium in its sediments. Water diversion is expected to result in a reduction of the volume of the Salton Sea in the next 25 years. As a consequence, currently submerged sediments would become gradually exposed to increasing water salinities and, in the case of the Salton Sea littoral, to more oxidizing conditions when exposed to atmospheric oxygen as the waterline recedes.
Salinity has been proposed as one of the primary drivers of phylogenetic differentiation in microbes. At the same time, a transition from reducing to oxidizing conditions is expected to result in a remobilization of currently sequestered selenium. This means microbial communities currently driving selenium transformation in littoral sediments of the Salton Sea will be gradually exposed to increasing water salinities and to atmospheric oxygen as the volume of the Salton Sea decreases. It is important to know the effect of these environmental changes on the rates at which microbes process selenium at the water-sediment interface. Reduced forms of selenium are biologically inert, while oxidized forms are water soluble and readily available for biological uptake.
Juan Fernando uses traditional methods to characterize the physico-chemical properties of sediments, slurry incubations and flow-through reactors to characterize the kinetics of selenate reduction and selenium oxidation, and DNA microarrays and sequencing for the characterization of microbial functional and phylogenetic diversity. He joined the Pallud lab in 2009 and was awarded an EPA-STAR Fellowship to continue his work in the Salton Sea in 2011.
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