The construction of heavy metal environmental background values of the intertidal sediments in Dongzhai port

As a source and sink of heavy metal pollutants, intertidal sediments have a crucial impact on the ecological environment of coastal zones. In this paper, the spatial distribution characteristics of 12 elements in sediments, including SiO₂, Al₂O₃, Fe₂O_3, CaO, Li, Ba, Cu, Pb, Zn, Cd, Cr and Ni, were analyzed by using two columnar sediment samples data of heavy metals in Dongzhai port of Hainan province, combined with mathematical statistical methods, and the environmental background lines of heavy metals in the intertidal zone sediments of Dongzhai port were established by selecting normalized heavy metal elements. The results showed that the average content sequence of all elements in the sediment was Si(base on SiO₂)>Al(base on Al₂O₃)>Fe(base on Fe₂O₃)>Ca(base on CaO)>Ba>Zn>Cr>Li>Pb>Ni>Cu>Cd, among them, the variation coefficient of SiO₂, CaO, Cu and Pb is less than 10%, showing weak variability, while the other 8 elements show moderate variation intensity. The vertical distribution of each element is obviously different, of which the content of SiO₂ in sediment is the highest, and gradually decreases with the increase of depth, and the variation of heavy metal elements in sediments below 30cm is similar to that of Al, Fe, Ba and Li. Al was selected as the normalized element, and univariate linear regression equation of Al element and heavy metal elements were established, whose absolute coefficients R² were mostly above 0.85. Based on the equation, the regional environmental background lines of heavy metals were established. In this paper, Dongzhai port is taken as a representative of the specific types of sediments in southern China. The background values of heavy metals in sediments provide a powerful complement to the national background construction of intertidal sediment environment, and provide basic data support for the ecological and environmental security of intertidal zone.