[Effect Factors and Model Prediction of Soil Heavy Metal Bioaccessibility]

The soil environmental pollution situation has been severe in recent years, but studies on evaluating with bioavailability testing and prediction models are lacking, which makes it difficult to accurately assess the ecological risks of contaminated soil. As an important indicator of bioavailability, the bioaccessibility of cadmium (Cd), arsenic (As), copper (Cu), zinc (Zn), and lead (Pb) in the soil was analyzed in this study. The bioaccessibility content and their corresponding soil property data were screened and systematically analyzed to explore the relationship between bioaccessibility content and soil properties. Furthermore, some testing methods for bioaccessibility were summarized to analyze the relationship between bioaccessibility content, test methods, and bioavailability content. Additionally, the bioaccessibility content prediction models were established. The results showed that there was a strong correlation between the bioaccessibility content and the total content of heavy metals (P<0.01) and a significant (P<0.05) correlation with the soil pH. Different test methods had obvious effects on bioavailability. The proportion of bioaccessibility content determined via various test methods was as follows:in vitro gastrointestinal tract simulation>chemical reagent extraction. The proportions of bioaccessibility content of Cd and Pb in natural soil were relatively high, with mean values of 42.12% and 37.33%, respectively, indicating that Cd and Pb had higher risks of being absorbed by soil organisms. Moreover, 30 bioaccessibility prediction models for five heavy metals were constructed, which involved the soil properties and test methods. The results of this study can provide scientific information and bioaccessibility prediction models that can help in accurately assessing the ecological risks of contaminated soil.