9629276 O'Day The proposed research program of this Faculty Early Career Development proposal involves: (1) Spectroscopic and microscopic characterization of field samples from Pinal Creek, AZ. and (2) model studies of Zn sorption and precipitation and the characterization of reaction products by X-ray absorption spectroscopy. During the first phase, the PI would like to directly verify the chemical state and distribution of Co, Ni, CU and Zn associated with solid phases in the stream bed and alluvial sediments, and determine the nature and amount of amorphous and crystalline phases. Part 2 will focus on two aspects of the Zn (II) sorption system: (I) The influence of mineral substrate on uptake and release of Zn and the identification of coordination change with sorption with XAS, and (ii) the local molecular structure and kinetics of Zn(OH)2 homogenous precipitation and surface precipitation. Sample characterization will be done by SIMS and probe. Analytical methods to be used include TEM, PEELS, and XAS.
