A microbial approach in soils from contaminated mine areas: The Jales mine (Portugal) case study

Abstract

Microorganisms play a crucial role in decomposition processes and nutrient cycling and, therefore, in soil quality. Soil enzymes have shown sensitivity to contaminants, such as heavy metals, due to their interaction with the specific reaction sites, thereby reducing the formation of the reaction products. In this study, several enzymatic bioassays were applied (dehydrogenase, acid phosphatase, arylsulfatase, urease and B-glucosidase) to soils with different heavy metal contents, from the abandoned Jales mine (Portugal), before, during and after a rehabilitation process (years 2002, 2003 and 2004, respectively). Additionally, the mineralization of N and the microbial biomass of C and N were measured. The results obtained in this study indicated that dehydrogenase, arylsulfatase and N-mineralization activities demonstrated that there had been a recovery in soil microbial numbers, but provided no information on the influence of contaminants in soils. Microbial biomass C and N also presented an increase from 2002 to 2004, and soil organic matter and pH influenced the enzymatic activities, mainly dehydrogenase, acid phosphatase and arylsulfatase. An increase of microbial activities was observed in 2003, with several soil enzymes showing recoveries in their activities. Therefore, nutrient cycles have probably benefited from this, improving soil quality.