Redistribution index and relative binding intensity of heavy metals in salt-amended soils

Redistribution processes of heavy metals and their binding intensity in sal t-amended arid-zone soils were analyzed under saturated, field capacity and wetting-drying cycle moisture regimes. Two newly developed parameters, red istribution index and reduced partitioning parameter, were used to depict t he removal/attainment of metal-amended soils from/to the fractional distrib ution pattern in the native soils and the relative binding intensity of met als in the amended soils, respectively. Metal-amended soils, in forms of sa lts approached the fractional distribution pattern in the non-amended soils with time. The rates at which the metal-amended arid-zone soils approached the fractional distribution pattern characteristic of the native soil were affected by the nature and loading levels of the metals, soil properties a nd time. Metals in amended soils at low loading levels approach the fractio nal distribution pattern characteristic of non-amended soil more rapidly th an at high loading levels. The sequences of approach by various metals to t he fractional distribution pattern in the native soil are as follows: Cd > Cu > Ni, Zn > Cr. Moisture regime, however, did not considerably affect the metal-amended soils' overall rates of approach to the fractional distribut ion pattern prevailing in the non-amended soils. The binding intensity of m etals in soils was affected by the nature of metal, loading level, soil pro perties and time. In both non-amended and amended soils, Cr had highest bin ding intensity, Cd lowest and Cu, Ni and Zn intermediate. The binding inten sity decreased with the loading level of the metals and increased with time . The redistribution index and reduced partitioning index can quantitativel y and effectively depict the kinetics of redistribution processes of metals and their relatively binding intensity in waste-amended soils.