Biosolids, mycorrhizal fungi and eucalypts for phytostabilization of arsenical sulphidic mine tailings

The effect of the addition of biosolids combined with a native arbuscular mycorrhizal inoculum on growth of a eucalypt (Eucalyptus cladocalyx), and on trace element stabilization of arsenical sulphidic gold mine tailings was tested. A glasshouse trial was established using four substrates: tailings (T); tailings with a layer of topsoil (TS); tailings amended with 100 t ha(-1) biosolids (LB), and tailings amended with 500 t ha(-1) biosolids (HB). Half of the pots were inoculated with a mixture of Glomus sp. (WUM51-9227), Scutelospora aurigloba (WUM51-53) and Acaulospora laevis (WUM46) culture mix, and others were uninoculated controls. Two seeds per pot were sown. Leaf and stem weights, leaf area and plant height were measured for each plant. Nutrients and trace element concentrations in leaves and stems were determined. Addition of biosolids significantly increased mycorrhizal colonization (both ectomycorrhizal and arbuscular mycorrhizal) in roots. Biosolids clearly increased the very early establishment and growth of the eucalypts. In general, mycorrhizal inoculum increased plant biomass production and nutrient uptake. Trace element concentrations in trees of the biosolid-amended pots were in general high, however, mycorrhizal inoculation could reduce the uptake of toxic elements by plants.