SELENIUM MOBILIZATION IN SMALL WATERSHEDS OF KANSAS AND UTAH: A HYDRO-GEOCHEMICAL STUDY

Public concerns about the quality of waterfowl habitat and high levels of Se in cattle milk in areas of Utah and Kansas is a growing environmental concern. While selenium is known to be an important nutrient to sustain life, it is toxic a high concentration for many aquatic organisms in their developmental stages. In this work we will be addressing the Se toxicity examples and relation to Se budgeting in the sediments in the American west. Selenium concentrates in sediments where it bio-accumulates in riparian and wetland vegetation, becoming available for water fowl and other aquatic reasons. To date no studies have traced contaminant pathways for selenium from source areas in various soils (under contrasting land use and climatic conditions) through the mouths of American west watersheds. In order to determine the factors that influence the mobility and speciation of selenium in western watersheds two small watersheds (a 300 mi2 area of Pariette Draw in Utah and Solomon River subwatershed-North Central parts of Kansas) are being studied. Preliminary surface water and sediment samples were taken from upper, middle, and downstream locations in Pariette Draw, UT, last November. X-Ray Diffraction is being employed for detailed mineralogical analysis and clay analyses of the sediment samples after they have been analysed for particle size. Handheld XRF is being employed to find the bulk sediment chemistry. In situ measurements of water parameters will be used to geochemically model the mineral-water interaction that in turn can shed light on ways/pathways of mobilization of Se from the sediments. A sequential extraction procedure is being used to gain an understanding of the relative concentrations of selenium in different soil and sediment compartments/fractionations. Selenium and other oxyanion concentrations in the surface waters are being determined via ICP-MS. Upon merging the above lines of analyses insights into the geochemical parameters that lead to the mobilization of selenium with be gained and then compared between the two sites.