Soil enzyme activities under the impact of long-term pollution from mining-metallurgical copper production

This study aimed to evaluate the activities of five soil hydrolases (β-glucosidase, urease, arylsulphatase, acid and alkaline phosphatase) as indicators in the area characterized with long-term pollution from one of the biggest copper smelters in Southeastern Europe. Sampling of the root zone soil of Plantago spp. was performed at five sites, at different distances from the copper smelter as the main pollution source. The results revealed serious heavy metal pollution of soil, whereby Cu, Pb and Zn were described as the primary pollutants. Concentrations of Cu, Pb and Zn were about 100, 5, and 4 times higher, respectively, than the corresponding limit values defined by the Serbian Regulation at the extremely polluted site in the proximity to the copper smelter. Among the five studied soil hydrolase activities, arylsulphatase was found to be the most sensitive to the soil heavy metal content, being significantly negatively correlated with Cu, Fe, Pb and Zn. Enzyme activity change ratio indicated inhibition of arysulphatase activity in the contaminated soils. The results denoted that arysulphatase activity could be regarded as an indicator of the soil contamination by heavy metals. The observed effects of the heavy metal concentrations on the soil enzyme activities pointed out the potential alterations of soil nutrient cycles, as well as soil quality degradation.