Influence of Chromium Contamination on Carbon Mineralization and Enzymatic Activities in Vertisol

Chromium (Cr) contamination may affect different biochemical process in the soil. In a laboratory experiment, graded doses of hexavalent chromium were applied to a clay loam soil to investigate the impact on carbon (C) mineralization rate and the enzymatic activities at various time intervals. The maximum reduction in C mineralization was noticed at 100 mg/kg Cr at 45 days after incubation. Initially, the C mineralization rate was high but decreased at faster rate with lapse of time. It was observed that increasing the Cr concentration from 0 to 100 mg/kg resulted in reduction in dehydrogenase, alkaline phosphatase and fluorescein diacetate activities to the extent of 70, 63 and 41%, respectively. Among the enzymes, dehydrogenase activity was more sensitive to Cr toxicity. In conclusion, Cr toxicity negatively affected the microbial mediated C mineralization and enzymatic activities, which may adversely affect nutrient transformation in the soil and deterioration of soil health.