Probing the impact of metal impurities on the structure, reactivity, and transformation of biogenic manganese oxides

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

This project is funded by the Environmental Chemical Sciences (ECS) Program of the Chemistry Division. Professor Yuanzhi Tang of the Georgia Institute of Technology investigates the impact of metal impurities on the structure and reactivity of manganese (Mn) oxides. Manganese oxides exist in nearly all environmental settings. They have significant influence on the biogeochemical cycling of metals, nutrients, and organic compounds in these cycles manganese is transferred between living systems and the environment. It also studies the transformation pathways of Mn oxides produced by living organisms under environmentally-relevant conditions. The project includes developing high school curriculum materials that integrate earth and environmental sciences, chemistry, and biology. It promotes the next generation of scientists from underrepresented groups and with different cultural backgrounds and research experiences. Professor Tang and her students develop community outreach activities to showcase mineral and mineral properties to the general public. This task is conducted annually in March during the Atlanta Science Festival, Georgia?s biggest science fair that showcases science and technology to the general public. Specifically, the research group puts on a ?rock show? where the general public, students, and science educators have the opportunities to learn mineral properties with hands-on demonstrations of parameters such as color, hardness, texture, and chemical alteration. They also develop a kit for the demonstration of biomineralization and mineral-facilitated environmental remediation such as microscope and visual observation of microbial Mn oxidation and color changes during chemical reactions. Manganese oxides play an important role in the biogeochemical cycling of many important nutrients and contaminants. Still, much remains unknown about the influence of ubiquitous metal impurities on the structure, reactivity, and transformation pathways of biogenic Mn oxides. This knowledge is needed to develop accurate predictive models for understanding the fate of contaminants and nutrients in the natural environment. This project systematically examines the changes in biogenic Mn oxide reactivities when they are formed in the presence of common metal ions. The processes of geological and environmental interest include sorption of cations and anions, and abiotic reductive transformation induced by Mn(II). Controlled laboratory studies lead to predictive insight into the relative importance of different metal ions in controlling Mn oxide reactivity.