SOIL MICROBIAL PROPERTIES IN COAL MINE TAILINGS UNDER REHABILITATION

Abstract

Microbial properties have been reported to be useful indicators of soil quality and could possibly serve as assessment criteria of successful rehabilitation of ecologically disturbed areas. During this study, the application value of microbial enumeration techniques and enzymatic assays as a measure of the progress of rehabilitation of coal discard sites was evaluated. Each site was analysed for physical and chemical characteristics of the topsoil; vegetation cover; potential enzymatic activities (dehydrogenase, -glucosidase, urease, acid and alkaline phosphatase) and quantification of aerobic oligotrophic and copiotrophic bacteria and fungi (selective enumeration). The relationship between soil properties, vegetation cover and microbial properties was analysed using multivariate ordination techniques. Although the discard sites had different rehabilitation ages (1 -8 years), no statistically significant difference existed between these sites based on physical and chemical characteristics or selective enumeration (p>0.05). Differentiation was possible based on enzymatic activities, where sites with relatively higher vegetation cover and organic carbon content had a positive association with enzymatic activities. Organic carbon content correlated significantly with -glucosidase (r = 0.80, p<0.05), urease (r = 0.96, p<0.05), acid phosphatase (r = 0.76, p<0.05), dehydrogenase (r = 0.69, p<0.10) and microbial biomass (r = 0.73, p<0.10). The characterisation of microbial activity holds potential as complementary criteria for evaluating rehabilitation progress on mine discard sites.