Distribution feature of heavy metals in the system of sediment-submerged plant-water in Xuanwu Lake

Abstract

In view of the distribution of heavy metal pollutants in Xuanwu Lake after the comprehensive dredging, contents of Cr, Mn, Ni, Cu, Zn, Cd and Pb in 4 dominant submerged plants and their corresponding sediments in the lake and in surface water were determined, so as to reveal the pollution and distribution of the heavy metals in the system of sediments-submerged plants-water in Xuanwu Lake. Results showed that the average mass concentration of Cr and Ni in the surface water of Xuanwu Lake exceeded the national standard Grade II of the quality of surface water which were 1.79 and 1.56 times, respectively; The contents of Cd and Pd in sediments was respectively 3.31 and 1.17 times of the background value of Nanjing soil, and the North Lake, the contents of Mn, Ni, Zn, Cd and Pd in surface water and Cr, Ni, Zn, Cd and Pd in sediments were higher than other lake areas. The average value Igeo of each element was ranked by size as Cd > Pb > Zn > Cr > Cu > Mn > Ni, except that Cd was the slight pollution (Igeo value is 0.20–0.47), the other heavy metal elements were at a clean level. In the four submerged plants, Mn was significantly positively correlated with Ni, Cu, Zn and Cd (p < 0.01). Ni was significantly positively correlated with Cu, Zn and Cd. Cr in the submerged plants was significantly positively correlated with Cr and Ni in the surface water; The contents of Cd and Pd were significantly positively correlated with Pd and Cu in the surface water (p < 0.05).