ORIGINAL ARTICLE A study on soil physico-chemical, microbial and metal content in Sukinda chromite mine of Odisha, India S. Das • S. S. Ram • H. K. Sahu • D. S. Rao • A. Chakraborty • M. Sudarshan • H. N. Thatoi Received: 23 March 2012 / Accepted: 19 October 2012 / Published online: 24 November 2012 Ó Springer-Verlag Berlin Heidelberg 2012 Abstract Soil samples from chromite mining site and its adjacent overburden dumps and fallow land of Sukinda, Odisha, were analysed for their physico-chemical, micro- bial and metal contents. Chromite mine soils were heter- ogenous mixture of clay, mud, minerals and rocks. The pH of the soils ranges between 5.87 and 7.36. The nutrient contents of the mine soils (N, P, K and organic C) were found to be extremely low. Analysis of chromite mine soils revealed accumulation of a number of metals in high concentrations (Fe [ Cr [ Mn [ Ni [ Zn [ Pb [ Sr) which exceeded ecotoxicological limits in soil. Correlation and cluster analysis of metals revealed a strong relation between Cr, Ni, Fe, Mn among the different attributes studied. Assessment of different microbial groups such as fungi, actinomycetes and bacteria (heterotrophic, spore forming, free-living nitrogen fixing, phosphate solubilising and cellulose degrading) from mine soils were found to be either extremely low or absent in some soil samples. Fur- ther chromium tolerant bacteria (CTB) were isolated using 100 mg/L Cr(VI) enriched nutrient agar medium and were screened for their tolerance towards increasing concentra- tions of hexavalent chromium and other toxic metals. Out of 23 CTB isolates, three bacteria tolerated up to 900 mg/L, 6 up to 500 mg/L, 20 up to 200 mg/L of Cr(VI). These bacteria were also found to be sensitive towards Cu [ Co [ Cd and very few CTB strains could show multiple metal tolerance. These strains have great scope for their application in bioremediation of toxic chromium ions in presence of other metals ions, which needs to be explored for their biotechnological applications. Keywords Hexavalent chromium  Metals tolerance  Soil physico-chemical characteristics  Microbial population  Mine environment Introduction Mining operations such as excavation of ore and minerals and tailings disposal provide sources of metal contamina- tion in the environment (Vidali 2001). Fate of heavy metals in soils is of great environmental concern. Heavy metals can persist for long periods in aquatic as well as terrestrial environments (Nouri et al. 2008) thereby they affect these environments adversely. Since metals are non-degradable and tend to accumulate in soil and sediment, they pose a serious ecological risk due to their contamination and leaching problems (Sevgi et al. 2009). Sukinda valley of Jajpur district, Odisha (India) spreading over 420 km 2 , is the richest chromiferous field mass accounting 97 % of India’s chromite ore deposits. Extensive open cast mining for last several years has resulted in soil contamination with chromite and other metals with generation of million tones of overburdens. The hexavalent chromium is the S. Das  H. N. Thatoi (&) Department of Biotechnology, College of Engineering and Technology, Biju Patnaik University of Technology, Bhubaneswar 751003, Odisha, India e-mail: hn_thatoi@rediffmail.com S. S. Ram  A. Chakraborty  M. Sudarshan UGC-DAE-Consortium for Scientific Research, Kolkata Center, Bidhan Nagar, Kolkata 700098, West Bengal, India H. K. Sahu Department of Zoology, North Orissa University, Takatpur, Baripada 757003, Odisha, India D. S. Rao CSIR-Institute of Minerals and Materials Technology, Bhubaneswar 751013, Odisha, India 123 Environ Earth Sci (2013) 69:2487–2497 DOI 10.1007/s12665-012-2074-4