Physicochemical properties and microbial community dynamics of remediated Cu-Pb-Zn mine tailings

Abstract

Mine activities generate large amounts of wastes, known as tailings, with low pH and high concentrations of heavy metals, which are stored in tailings dams. Mine owners have a legal obligation to restore tailings dams to a safe, stable and sustainable final land use. Woodlawn Mine has elected to restore their tailings dams to a native shrubland, however the various physicochemical constraints of the tailings and the mine's lack of access to traditional tailings rehabilitation materials has resulted in the establishment of trial rehabilitation plots to determine which combinations of amendments can ameliorate the tailings constraints most effectively. 38 samples were collected across Woodlawn Mine, including from the bare tailings and native woodland, and freshly produced Woodlawn Organic Output (WOO). Samples were tested for pH, electrical conductivity, moisture content, carbon and nitrogen content, and levels of arsenic, cadmium, copper, lead, and zinc. The environmental DNA in each sample was also sequenced using 16S and ITS primers to determine the bacterial and fungal community composition in each sample. The WOO samples were distinct from the stockpiled topsoils both physicochemically and biologically, and the native soils were also distinct. Results indicate acute ecotoxicity of the WOO likely induced by salt and heavy metal contamination. Show more