The influence of physicochemical parameters on bioavailability and bioaccessibility of heavy metals in sediments of the intertidal zone of Asaluyeh region, Persian Gulf, Iran

In this research, we have worked on the evaluation of heavy metal contamination in the sediments taken from the intertidal zone of Asaluyeh region using Modified Community Bureau of Reference sequential extraction method (mBCR), the simplified bioaccessibility extraction test (SBET), and calculated enrichment factor (EF). Also, potential influencing factors including sediment characteristics that may affect the heavy metals bioavailability and bioaccessibility were investigated. mBCR extraction analysis indicated that among the metals, Mn, Zn, V, Cu, and Cd exhibit relatively higher mobility, while Ti, Pb, Cr, and Ni occur mainly in the residual fractions. Based on the mean values, the bioaccessibility of metals decreased in the order: Mn (50.01%) > Cd (46.26%) > Zn (14.61%) > V (13.97%) > Pb (10.88%) > Ni (9.2%) > Ti (8.43%) > Cr (6.66%) > Cu (6.23%). The obtained results from the principal component analysis (PCA), EF and mBCR extraction showed that most anthropogenic-derived metals with higher solubility are more bioaccessible compared to those of natural origin. Multiple linear regression analysis demonstrated that the main physicochemical variables of the sediment influencing the bioaccessibility of metals include cation exchange capacity (CEC), pH, and particle size fraction.