[Biological toxicity effect of petroleum contaminated soil before and after physicochemical remediation]

Toxicity analysis was studied from using seed germination as an ecological indicator, and the earthworm was considered as a suitable biomonitor animal to determine the ecological hazard of polluted soil. The main results are as follows: These crop seeds have significantly different responses to petroleum pollution. Compared with those plants in clean soil, the germination of most crop seeds planted in contaminated soils is obviously inhabited. Soybean, horse bean and maize are the crop affected most adversely. Fortunately, strong endurance is observed for green soybean under 4 different levels of petroleum pollution, and the seed germination rate are all above 90%. When exposed to pollutants, earthworms could be changed obviously on the level of physiology. That might affect the survival and growth capacity of earthworms, and changed population finally. In high petroleum contaminated soil (concentration of petroleum > 30 000 mg/kg) earthworms can only survive about 5 days. The results suggest that petroleum pollution has great poison to earthworms and can kill earthworms finally. Because pollutants make them dehydrate. Even on the low pollution level, the survival time of earthworm is still very short (3 d or so) in the treated petroleum-contaminated soil. Because after a petroleum ether-treated, the nutrients of soil are disposed with the oil, and the organic matter and other nutrients of the soil have a great impact on the survival of earthworms.