【作者】 刘尧；

【导师】 周启星；

【作者基本信息】 南开大学 ， 环境科学， 2011， 硕士

【摘要】 本论文选择土壤环境中的BTEX物质为研究对象,对我国污染土壤修复基准展开了尝试性研究。选择蚯蚓、小麦和土壤微生物为生态受体,结合传统毒理实验方法和分子生物学技术,对其开展群落、个体、亚分子及分子水平上的生态毒理学试验研究。急性毒性试验研究发现,3种污染物对赤子爱胜蚓和小麦毒性影响呈明显的剂量-效应关系,甲苯、乙苯和二甲苯对蚯蚓的48h LC50分别为454.3、167.1和127.2mg/kg,对小麦根长的50%抑制率(IC50)分别为978.6、343.8和197.2mg/kg。实验还通过检测蚯蚓和小麦体内抗氧化酶(SOD、POD和CAT)活性的变化情况,探讨了甲苯、乙苯和二甲苯对其的氧化胁迫效应。研究发现,蚯蚓和小麦体内三种酶对三种污染物的敏感性各不相同,但大体呈现一个钟型趋势(酶活性暴露于低浓度污染物时被诱导,高浓度时被抑制),实验得到甲苯、乙苯和二甲苯对蚯蚓的中毒阈值分别为：5、10和5mg/kg;对小麦的中毒阈值分别为：50、17.5和2mg/kg。蚯蚓彗星实验结果表明,甲苯、乙苯和二甲苯能够极显著(P<0.01)的增加蚯蚓体腔细胞的DNA损伤程度,而且DNA损伤程度与污染物浓度之间有明显的剂量-效应关系,表明甲苯、乙苯和二甲苯可能对蚯蚓存在潜在的基因毒性效应。能够导致蚯蚓体腔细胞DNA损伤程度增加10%(EC10)的甲苯、乙苯和二甲苯浓度分别为：2.43、1.23和1.37mg/kg。上述结果表明,蚯蚓彗星实验能够简便、快捷的诊断出土壤中污染物的潜在基因毒性。土壤微生物变性梯度凝胶电泳实验(DGGE)结果表明,甲苯、乙苯和二甲苯对土壤微生物产生了一定的影响,随着培养时间的不同,土壤微生物群落多样性存在一定的差异。选用污染物暴露7d时的微生物多样性指数(H)进行进一步分析,发现能够导致H降低50%(EC50)的甲苯、乙苯和二甲苯浓度分别为：3638、3263和5844mg/kg。根据以上实验结果,最终确定甲苯、乙苯和二甲苯基于生态毒理数据的污染土壤修复基准推荐值为：2.43、1.23和1.27mg/kg。更多还原

【Abstract】 In this paper, we made an initial attempt to enact the remediation criteria for TEX (toluene, ethylbenzene and xylene) contaminated soils. Earthworm(Eisenia fetida), wheat (Triticum aestivum L.) and bacterial were selected as ecological receptors in our research, and ecotoxicological experiments were made at community, individual, sub-molecular and molecular levels on these terrestrial organisms with the conventional methods and molecular biology technologies. Acute results indicated that there were significantly positive correlations between the lethal or inhibitory effects on Eisenia fetida and Triticum aestivum L. and the tested concentration of the three pollutants. The 48h LC50 values of TEX toxic to Eisenia fetida were 454.3. 167.1 and 127.2mg/kg, respectively. The IC50 values based on the toxicity of TEX to root elongation of Triticum aestivum L.were 978.6,343.8 and 197.2mg/kg, respectively. Also, antioxidant defense system (SOD, POD and CAT) influences of toluene, ethylbenzene and xylene to Eisenia fetida and Triticum aestivum L. were studied. The results showed that the exposure of the three pollutants caused a stress response of the three enzymes, an approximate bell-shaped change (a tendency of inducement firstly and then inhibition with increasing concentrations of the pollutants) was mostly found. The three enzymes tested differed in their sensitivity to different pollutants. According to the test date, the threshold concentrations of TEX on Eisenia fetida were 5.10 and 5mg/kg, respectively; the threshold concentrations of TEX on Triticum aestivum L. were 50,17.5 and 2mg/kg, respectively.The SCGE assay results showed that these three pollutants could significantly (P < 0.01) induce DNA damage in earthworms and the clear dose-dependent relationships were displayed, indicating potential genotoxic effects of toluene, ethylbenzene. and xylene on Eisenia fetida. The EC10 values based on the inducement of DNA damage of TEX on Eisenia fetida were 2.43,1.23 and 1.37mg/kg, respectively. The results suggest that the SCGE assay of earthworms is simple and efficient for diagnosing the genotoxicity of pollutants in terrestrial environment. The DGGE method results indicated that there were a certain differences in bacterial communities diversity in soil treated with different concentrations of TEX. The communities diversity indexes (H) of 7d exposure were chosen for further analysis. The EC50 values of TEX based on the reduction of H were 3638,3263 and 5844mg/kg, respectively.Based on all the ecotoxicological date, the final recommended values of remediation criteria for TEX (toluene, ethylbenzene and xylene) contaminated soils were 2.43,1.23 and 1.27mg/kg.更多还原