The Research For Mutual Effects Between Ryegrass And Soil Contaminated With Crude Petroleum

The petroleum were unavoidably leaved out to the operation area during the process of petroleum exploration in the land, and the appearance of this kind of creamy liquid arised the focus of environment science researchers. When the focus ranged from marine to soil to the petroleum contamination, the most interested thing of all was how to abolish them, then, the disappearance of petroleum from the leaved-out-place experienced earlier physical carrying and burring, chemical extraction and oxidation, and microbial and (or) special plant degradation now. The leavings out of petroleum on the land should be first studied was the internal effects between petroleum and its surroundings, and only having known these changing characteristics, we could imply an effective method for the accelerating degradation of petroleum on the land. The uncontaminated soil of MoMoGe natural wetland reserve was selected to adopt in the experiment, and studied the effects of them. The followings were the main results:(1) During every sampling period(including 20days, 60days, 40days and 80days ), there was a significant difference between soil without petroleum and any added petroleum(5000mg/kg,8000mg/kg and 10000mg/kg) for the plant height, it indicated that petroleum showed a significant inhibition for the ryegrass; as far as the period of plant growth was concerned, inhibition in early time was lower than later, demonstrating that it need time accumulation for the observed inhibition.(2) The conclusion also can be got for the petroleum's inhibition on the fresh weight of plant according to the significant analysis, so petroleum showed a significant inhibition for the ryegrass mass. Meanwhile, the changes of plant fresh weight also illustrated that ryegrass had a stronger resistance for the petroleum during the time from 0-40 days.(3) For total petroleum hydrocarbons, the higher the concentration was at the beginning of the experiment, the lower the degradation ratio was at last, on the controversy, the degradation content was higher.(4) After analyzing the saturated hydrocarbons of C₁₄-C₃₀ by using GC-MS, we concluded that its distribution was normal, and the content of C₂₂-C₂₃ was highest. During the process of degradation, the hydrocarbons with less carbon and the ones with more carbon didn't have synchronism and unity, the degradation of lower carbon hydrocarbons was faster than the higher ones, while the higher carbon hydrocarbons degraded through the lower ones.(5) We measured the diversity of bacteria population through Shannon-Weaver diversity index H and similarity coefficient S_D. The results showed that H index changing lesser from beginning to the end of the experiment; S_D was less in the early time, and remained steady after return to the normal.(6) The soil pH showed a slow tendency for ascending, but never across the critical pH=7.