Distribution and origination of zinc contamination in newly reclaimed heterogeneous dredger fills: Field investigation and numerical simulation

Heavy metal elements, including Zn, Cd, As, Ni, Cu, Pb and Cr, were detected in soils (no deeper than 75 m) from newly reclaimed zones of Shanghai, China. The Zn concentration exceeded soil quality limits. The Zn contamination was tested in both dredger fills and sedimentary layers (①3–3, ②3, ④ and ⑤1–1). However, it was not detected in layer ⑤1–2–⑨. PCA and HCA analysis show that exogenous Zn probably was the contaminant source of dredger fills before the fills were dredged from the neighboring waters. Stochastic heterogeneity of the dredger fills affects the Zn-depollution remarkably. Numerical simulations show both acid precipitation and widespread drainage channels in the zones contributed to Zn-decrease in the dredger fills no deeper than 1.2 m. Acid rainstorms work better than acid constant precipitation in Zn-remediation for layers below 0.4 m. To remove Zn contamination in deep dredger fills, un-consolidation of the fills should be utilized. •Investigation was performed to detect heavy metal contamination in reclaimed land.•Large-scale soil Zn contamination was detected in newly reclaimed zones of Shanghai.•Potential exogenous source of Zn contamination was analyzed and simulated.•Precipitation flushing and drainage channel contributed much to Zn-depollution.•Heterogeneity of dredger fills differentiates Zn-depollution in reclaimed layers.