ABSTRACT
The environmental behaviour of trace elements depends critically on the form in which they occur (Bacon & Davidson 2008), which governs the mobility and retention of the element in the natural environmental matrix and determines bioavailability and toxicity of the element to organisms. Sequential operational speciation approaches gives a comprehensive understanding of the chemical and physical process of deposition, mobilization and transport of metals, non-metals and metalloids (Ure 1991). The objective of this research was: i) to quantify the levels of As in cultivated soils; and ii) to determine the distribution of As in different soil fractions using Sequential Extraction Procedures (SEP) as a basis for risk assessment. The study areas are located in a transect which is one of the major productive agriculture areas in the mining
a soil:solution (1:2), soil texture was determined using soil hydrometer (ASTM-152H). Cation Exchange Capacity (CEC) was determined with the ammonium oxalate (NH4C2O4) method, available phosphorus (P) was determined by the BrayKurtz method, Organic Matter (OM) using the Walkley-Black modified method.
