891 Journal of Environmental Biology uSeptember 2012u Phytoremediation of crude oil contaminated soil using nut grass, Cyperus rotundus Author Details Budhadev Basumatary Resource Management and Environment Division, Institute of Advanced Study in Science and (Corresponding author) Technology, Guwahati-781 035, India e-mail: budhabasumatary@yahoo.com Rubul Saikia Resource Management and Environment Division, Institute of Advanced Study in Science and Technology, Guwahati-781 035, India Sabitry Bordoloi Resource Management and Environment Division, Institute of Advanced Study in Science and Technology, Guwahati-781 035, India ' Triveni Enterprises Vikas Nagar, Lucknow, INDIA editor@jeb.co.in Full paper available on: www.jeb.co.in J. Environ. Biol. 33, 891-896 (2012) ISSN: 0254 - 8704 CODEN: JEBIDP Abstract The aim of this study was to evaluate the efficacy of Cyperus rotundus (nut grass), that could be effective in phytoremediation of crude oil contaminated soil. A net house experiment was conducted with different concentrations (2.05, 4.08, 6.1, 8.15 and 10.2%) of crude oil-contaminated soil for 180 days. Plant growth, biomass, total oil and grease (TOG) degradation and microbial numbers were analyzed at different intervals i.e. 60, 120 and 180 days in different percentages of crude oil contaminated soil. In presence of crude oil, plant biomass and heights reduced up to 26 and 21.9% respectively. Concerning TOG content in soil, C. rotundus could decrease up to 50.01, 46.1, 42.6, 38.8 and 32.6% in treatment I, II, III, IV and V respectively in vegetated pots during 180 days. In case of unvegetated pots, the reductions of TOG were 4.4, 5.6, 6.6, 7.6 and 9.6% in treatment A, B, C, D and E respectively. However, there was significant degradation (P=0.05) of TOG in vegetated pots in comparison to unvegetated pots thereby proving the efficacy of this plant species for use in phytoremediation. Key words Crude oil, Phytoremediation, Cyperus rotundus Publication Data Paper received: 11 November 2010 Revised received: 20 September 2011 Re-revised received: 29 October 2011 Re-re-revised received: 29 November 2011 Accepted: 22 December 2011 Introduction As raw material for production of petroleum and other chemicals, crude oil has become one of the most important energy sources in the world. However, contamination of water and soil by crude oil as a result of exploration, production, maintenance, transportation, storage and accidental release, add hazardous chemicals to the ecosystem. Apart from bioaugmentation with oil- degrading microorganisms, phytoremediation is applied to provide long-term rehabilitation of the residual oil-contamination (Panchenko et al., 2002). The successful application of plant species to the bioremediation of oil-contaminated soil has been shown in a number of studies (Gunther et al., 1996; Carmen et al., 1998; Pichtel et al., 2001; Banks et al., 2003; Jones et al., 2004; White et al., 2006; Kaimi et al., 2006; Brandt et al., 2006; Muratova et al., 2008. Searching for the most effective remediation species for a particular compound is a critical step in phytoremediation trials. Mathematical modeling has been used to determine the appropriate plant species (Thoma et al., 2003) but, in general, the selection of phytoremediation for specific sites is empirical and based on preliminary results from pot experiments (Kirkpatrick et al., 2006; Liste et al., 2006; Euliss et al., 2007). Most studies on the phytoremediation of petroleum hydrocarbon (PHC) contaminated soil reported the use of grasses (Poaceae) and legumes (Leguminosae) (Aprill et al.,1990; Qiu et