Analysis of the Spatially Heterogeneous Distribution of Copper in Contaminated Soils Using Electron Microscopy and X-Ray-Microfluorescence Spectroscopy.
Astrid Jacobson1, Sylvie Dousset2, Philippe Baveye1, and Francis Andreux3. (1) Cornell Univ, 1002 Bradfield Hall, Ithaca, NY 14853, (2) Université de Bourgogne - CST - Géosol, 6 Boulevard Gabriel, Dijon, 2100, France, (3) Microbiologie et Géochimie des Sols - INRA Université de Bourgogne, 6, Boulevard Gabriel, Dijon, 21000, France
Many vineyard and orchard soils are contaminated with high concentrations of copper due to repeated applications of copper sulfate containing Bordeaux mixture that is applied as a fungicide. Up to now most studies of metal contaminated soils have been limited to assessments of bulk concentrations with little regard for the spatial distribution of the metals except at the landscape scale. Although spatial distribution has important consequences for the mobility and bioavailability of the metals microscale distribution has not been possible due to a lack of suitably sensitive techniques. Recent work using micro x-ray fluorescence to study soil aggregates or geologic nodules shows that this technique could work. Unlike previous studies that have been conducted on soil particles or single aggregates, we determined the microspatial distribution of Cu and associated elements (As, Ca, Fe, Mn, and Zn) on thin sections of the surface 4 cm of soil (intact structure) by scanning electron microscopy and x-ray microfluorescence microscopy. The soils were also characterized by traditional bulk physico/chemical analyses of Cu, pH, organic matter, etc. texture and mineralogy. The results indicate that the copper is heterogeneously distributed and largely associated with fresh organic matter.