Effect of salinity on the bioremediation of petroleum hydrocarbons in a saline-alkaline soil

AIMS: The aim of this paper is to check the effect of salinity on the bioremediation process of petroleum hydrocarbons in the saline-alkaline soil. METHODS AND RESULTS: In this study, soil salinity was adjusted to different levels by water leaching method and the bioremediation process was conducted for 28 days. Soil pH increased after leaching and decreased during bioremediation process. At initial time, moderate salinity enhanced the biodegradation and addition of microbial consortium was not effective in enhancing degradation rate of petroleum hydrocarbons. At day of 28 days, higher degradation rate was found in treatments with more leaching times with a maximum value of 42·36%. Dehydrogenase activity increased with the progress of bioremediation and positive correlation was found between dehydrogenase activity and degradation rate of petroleum hydrocarbons. Denaturing gradient gel electrophoresis analysis result showed decreased microbial community diversity with increased salt content. CONCLUSIONS: The result suggested that salinity had great impact on bioremediation, and leaching and addition of inoculated consortium were effective in enhancing biodegradation of petroleum hydrocarbons in the saline-alkaline soil. SIGNIFICANCE AND IMPACT OF THE STUDY: The result of this study is important for understanding the bioremediation process of petroleum in contaminated soil. New remediation method of petroleum contaminated soil can be developed based on this study.