Speciation of chromium in 12 agricultural soils from Turkey

The objective of the study was to speciate and to evaluate various soil Cr species in relation to soil properties. Surface soil samples were taken from outskirts of the Cr factory and applied a sequential extraction procedure. Extracts analyzed in atomic absorption spectrophotometry (AAS). Chromium was partitioned into exchangeable Cr, Cr bound to carbonate, Fe-Mn oxide, and organic matter, and residual Cr. The most common form of chromium was in the residual form, followed by the organic form. Very low concentrations of Cr were found in the exchangeable and carbonate forms. Mean values of the extractable forms of Cr, expressed in percentages of total soil contents were: 0.94% exchangeable, 0.80% carbonates, 2.13% oxides, 7.08% organics and 89.81% residual. Multiple regression analysis of analytical data revealed that soil pH, contents of organic matter and calcium carbonate were the most important factor controlling the distribution of Cr forms determined.