Utilizing Eisenia andrei to assess the ecotoxicity of platinum mine tailings disposal facilities

South Africa is an important platinum mining country which results in environmental impacts due to the construction of tailing disposal facilities (TDFs). It is unclear what the effects of ageing are on the ecotoxicity of TDFs and whether it increases or decreases over time. The aim of this study was to determine the ecotoxicity of differently aged TDFs by investigating earthworm (Eisenia andrei) responses viz. growth, reproduction, neutral red retention times (NRRT) and tissue metal concentrations. Further, to evaluate the status of these in terms of a geoaccumulation index (Igeo), pollution index and integrated pollution index. Results indicated that earthworms showed reduced reproductive success (hatchlings per cocoon) and decreased NRRT in all the sites. Juveniles per cocoon between all of the different treatment groups were; control (2.83 ± 0.54)[site 2 (20 years old; 1.83 ± 0.27)[sites 1 and 3 (40 years old; 1.06 ± 0.15 and 6 years old; 0.88 ± 0.39). This might be ascribed to the elevated levels of Cr (±200 to 1,166 lg g-1) and Ni (±100 to 316 lg g-1) in all of the sites. Earthworms did not bioaccumulate metals with bioconcentration factors for all the different treatments\0.01. Studies like these could be useful when establishing a ranking of TDFs in the future to provide legislative institutions with an indication of the environmental liabilities of platinum mines.http://link.springer.com/journal/1064

Assessing the ecotoxicity of gold mine tailings utilizing earthworm and microbial assays

Problems associated with mining are the disposal of wastes on tailing disposal facilities (TDFs). The aim of this study was to determine the ecotoxicity of gold mine tailings by using earthworm bioassays, earthworm biomarkers and enzymatic analyses. End points included changes in biomass, reproduction, lysosomal membrane stability, tissue metal concentrations, and selected enzymatic activities. Results indicated high concentrations of Ni in the material as well as bioaccumulation of lead and arsenic in the earthworm body tissue after exposure. Enzymatic activity was higher in revegetated tailings than in unrehabilitated tailings. It was concluded that TDF and surrounding areas have an acidic pH which affects earthworms and metal bioavailability. Soil enzymatic activities were a sensitive indicator of metal pollution in mining areas. Growth, reproduction and lysosomal membrane stability of earthworms have also been shown to be sensitive end points to assess the ecotoxic effects of gold TD