Development of site specific guidelines for future land use at the Woodcutters lead zinc mine

The National Environment Protection Measures (NEPMs) guidelines for soil contamination in Australia require further assessment if the Health Investigation Levels (HIL) are exceeded. It was identified that the current NEPM’s do not provide accurate close out criteria for mined land as the bioavailability of contaminated soil is usually a fraction of 100%. Absolute bioavailability is measured via animal uptake but is expensive and time consuming. A more practical approach uses in-vitro PBET (physiologically based extraction test) to determine the bio-accessibility of individual soils. A risk assessment conducted on a metal and metalloid survey of surface soils representing different categories of mine wastes employed as risk assessment tools: (i) in-vivo bioavailability measurement of composite wastes using rats; and (ii) the in-vitro PBET (physiologically based extraction test) determination of bio-accessibility of individual soils. All mine waste samples were tested for bioaccessibility (PBET) under various pHs in a synthetic gastric fluid system. pH values were 1.3, 2.5 and 4.0 simulating fasting, partially fed and fed stomach conditions respectively, and at pH 7.0 simulating the small intestinal pH condition. The bioavailability of arsenic was 1.6 – 8.9% but arsenic bioavailability is dependent on its oxidation states. Arsenate (AsV), the oxidized form of arsenic, is more likely to be found in mine waste materials. Arsenate bioavailability from these mining wastes was found to b