Bioavailabilty Of Heavy Metals
The bioavailability of heavy metals is carried out in line with Environment Agency guidelines using modified SBET (for lead) and PBET (other heavy metals) methods. A portion of the soil is extracted in a way to simulate digestion of the soil by the human body and the concentration of the heavy metal of interest is measured (ICP-OES). Heavy metals can be bound within fractions of the soil which are less available and therefore the total concentration of the heavy metal may be high but the risk to human health lower than otherwise indicated.
Fractionation of Heavy Metals
Added value regarding heavy metal availability may be obtained by identifying how much of the total and bioavailable metal is bound within chemical fractions of the soil. This can be achieved by using a modified sequential extraction technique and determining the major chemical components (Ca, Mg, Fe, S, Si etc) and the corresponding heavy metal concentration within that extract. This can be used to model the binding of the heavy metal within the soil and aid the interpretation of total and bioavailability measurements.