Regionalization of sorption capacities for arsenic and cadmium

Abstract

To fulfill the purpose as a sink for trace elements, soils must not be overloaded with As and Cd. Therefore, it is necessary to get knowledge of the sorption capacities of soils on a regional scale. The determination of these sorption capacities for large areas is, however, impeded by the great expenditure of laboratory work involved. With data presented here retention capacities for cadmium and arsenic from routinely determined soil parameters are estimated. In batch experiments the sorption behaviour of 40 soils from the area of Freiberg/Saxony in Germany was examined. The obtained sorption isotherms from the laboratory were fitted to the Freundlich equation (S = k^*C^m). The two constants (k, m) of this equation were used for multiple linear regression to correlate the sorption capacity and the soil parameters, namely clay content, pH value, total organic carbon, and dithionite extractable Fe contents. Due to long lasting ore mining of Freiberg there exist high background levels in that area for the two surveyed elements As and Cd. Therefore, this study offers two different mathematical procedures to take these contaminations into account. Thus the experimental data were corrected before they were fitted to Freundlich and pedotransfer equations were determined. Using the transfer equation, parameter k and m for cadmium sorption could be estimated with statistical certainties of 91% and 61% (adjusted R²), respectively, whereas the predictability for the arsenic sorption is not practicable because achieved R₂ values are very low (17% and 7%).