Pollution induced community tolerance of microorganisms in soil polluted with different levels of lauryl benzene sulfonate

Linear alkyl benzene sulfonate is widely used in detergents. The annual amounts of the surfactant through irrigation with wastewater or the use of sewage sludge as organic fertilizer into the soil ecosystem and the continued use may result in adverse effects on health and quality of soil. To assess the risks of contamination of the soil ecosystem with surfactant there are several methods that one of these methods is pollution induced community tolerance (PICT). In this study the impact of different levels of surfactant lauryl benzene sulfonate (LBS) on microbial activity in soil were evaluated with PICT assessment.For this purpose, different levels of LBS include 0, 0.025, 0.05, 0.1, 0.5 and the 1% were added to the pots containing 2 kg of soil in 3 repeats and kept for 90 days at moisture of 65 to 75% of field capacity (equivalent to 10 kPa) and 25 ° C temperature. Dehydrogenase activity as a measure of microbial activity was measured in 3, 7, 15, 30, 60 and 90 days of incubation. The results were obtained after incubation with different levels of LBS and soil microbial population was gradually induced tolerance. Increased tolerance in soil microbial was started from day 60 and increased thereafter. In 60 and 90 days of incubation increasing PICT amount to 0.05 percent was observed gradually, after that the tolerance increased strongly. In fact this concentration is a critical level for LBS.