My research objectives include characterization of dissolved and particulate natural organic acid influence on the reactivity, bioavailability, and mobility of metal ions and inorganic surfaces in aquatic environments. An important research objective of my project is examination of formation and dissolution rates of carbonate minerals. Biocalcification is a significant carbon sink in the world carbon budget and requires further investigation. I study aspects of biocalcification processes that proceed through a highly unstable calcium carbonate polymorph – amorphous calcium carbonate (ACC) stabilized by organic acids. I use chemical thermodynamics and kinetics to better describe and predict the fate and distribution of contaminant metal ions (for example, uranium and strontium-90) in the aquatic environment. I combine onsite field measurements and sampling, laboratory analysis and simulation, and geochemical computer modeling to support fundamental studies in geochemical kinetic processes and metal ion-natural organic acid interactions research. I study carbonate mineral formation and dissolution reaction rates and characterize the influence of natural organic acid on carbonate mineral reaction mechanisms in aqueous systems. I also examine DOA mediation of the transport and accumulation of mercury and calcium ions in aquatic systems. US Geological Survey study sites I use include: the Florida Everglades; the Sleepers River Basin, Vermont; Rocky Mountain National Park, Colorado; the Yukon River Basin, Alaska; Pyramid and Big Soda Lakes, Nevada; the Amargosa Desert Research Site, near Beatty, Nevada and the Shingobee River Headwaters Area, north central Minnesota.
