Paper Title
Natural Attenuation Of Hydrocarbon Contaminated Soil

Abstract
Biodegradation of petroleum hydrocarbons was investigated in contaminated soil surrounding Tehran Oil refining Co. Tehran, Iran. During the experiment which took 10 weeks, nitrogen and phosphorus amounts, total hydrocarbon utilizing bacteria (THUB), total heterotrophic bacteria (THB) and total petroleum hydrocarbons (TPHs) were specified. Also trend in TPHs removal and microbial population were studied. Results indicated that, after 10 weeks TPH level reduced from 25073.3 mg kg-1 to 7173.10 mg kg-1. The nitrogen and phosphorus concentrations also decreased during degradation. But the total hydrocarbon utilizing bacteria increased from 4.1104 to 11. 9104 cfu g-1 at the end of 6th week and finally reduced to 6.5104 cfu g-1 at the end of experiment, while the THB reduced from 2.7108 to 0.001108 cfu g-1. In studied soils TPHs significantly has positive correlation with N and P and THB count and negative correlation with THUB. Keywords- Petroleum Hydrocarbon; bioremediation; natural attenuation; hydrocarbon utilizing bacteria; total heterotrophic bacteria.