Remediation of chromium contaminated soils: Potential for phyto and bioremediation

Abstract

Long term disposal of tannery wastes has resulted in extensive contamination of agricultural land and water sources in many parts of India. Chromium (Cr), a toxic heavy metal, is a major contaminant in tannery wastes and its accumulation in soil and water is an environmental issue of increasing public concern in India, particularly in Tamil Nadu. Remediation of Cr-contaminated soils is a challenging task which may not only help in sustaining agriculture, but also in minimizing adverse environmental impacts. We examined the potential of phytoremediation and bioremediation techniques suitable for Cr-contaminated soils. Non-edible flower crops were found suitable in remediation as they grow well under Cr-rich effluent irrigation. Amongst the plants examined, Jasminum species showed a high degree of tolerance towards soil Cr. While a mustard crop did not establish, a sunflower crop established very well and exhibited higher tolerance towards soil Cr. However, the accumulation of Cr in seeds is likely to diminish its potential for phytoremediation. Application of biological wastes namely, coir pith and poultry manure, to Cr-contaminated soil was found effective in reducing the bioavailable fractions of Cr mainly by forming organic complexes and demonstrated their potential in bioremediating the Cr-contaminated soil.