Response of six Australian plant species to heavy metal contamination at an abandoned mine site

This investigation was carried out to assess the potential suitability of certain Australian plants for use in the phytoremediation of derelict mine sites. The plant species studied were native to the area surrounding a silver mine at Yerranderie in NSW, Australia, which has been derelict now for over 70 years. The contamination on this site is typical of that caused by acid mine drainage, with very low soil and water pH, and large areas devoid of topsoil and vegetation. Soil metal concentrations exceeded the Australian and New Zealand Environment and Conservation Council (ANZECC) 1992 guidelines for soil quality in several locations. Corresponding topsoil and upper plant samples were collected along three transects crossing the path of drainage from the mine wastes. Six plant species were dominant on the site, including Juncus usitatus (common rush), Lomandra longifolia (spiny-headed mat rush), Cynodon dactylon (couch), Pteridium esculentum (bracken fern), Acacia decurrens (black wattle) and Melaleuca alternifolia (teatree). Of these species, C. dactylon, J. usitatus and L. longifolia were identified as of potential use in phytostabilisation programs, due to tolerance of acid soils and tolerance and/or accumulation of significantly higher concentrations of Pb and Cd than other plant species present on the site.