台灣土壤中銅和鋅的生物有效性

Cu and Zn were the main heavy metal pollutants of farmland soils in Changhua, Dading, and Chisanyan sites in Taiwan. High exposure to this potentially toxic elements will induce some adverse effects to plants and environment, and end up in the human body. Physiologically based extraction test (PBET) and Simplified bioaccessibility extraction test (SBET) were used to evaluate the fraction of these heavy metals that is soluble in gastrointestinal and is available for absorption. Sequential extraction procedure (SEP) optimized BCR (Bureau Communautaire de Référence-France:) was used to understand the mobilisation of Cu and Zn in specific chemical solution. Chemical equilibrium model software (visual minteq) was used to attempt simulation of intestinal phase PBET. The results showed that bioaccessible concentrations of Cu and Zn in some soils were above the permissible limit of monitoring standards of farmland soil in Taiwan. There was a significant difference between high concentration sites and normal concentration sites in terms of bioaccessible concentration in both Cu and Zn (p-value < 0.05). PBET intestinal phase was found to have more conservative result in assessing Cu and Zn bioaccessibility, followed by PBET gastric phase, and SBET. The factors that significantly associated with Cu and Zn bioaccessible in both sites were: total concentration, phase 1 and phase 2 SEP, and soil pH. Visual minteq results showed that the two elements dissolved in gastric phase did not precipitate in intestinal phases. For Cu, the experiment result was almost similar with the simulation result. However, the same phenomenon did not happen with Zn. Appropriate soil remediation strategies are needed to reduce its total concentration, and thus reduce its bioaccessibility.