【作者】 刘丽；

【导师】 周岩梅；

【作者基本信息】 北京交通大学 ， 环境科学与工程， 2018， 硕士

【摘要】 底泥是环境污染物的源和汇。多氯联苯(polychlorinated biphenyls,PCBs)是国内外重点关注的持久性有机污染物(部分PCBs具有“三致”效应)。文献报道,中国很多河流、湖库、海湾地区底泥PCB污染严重。修复剂原位治理污染底泥技术是一种新型、高效、“绿色”治理技术,但此技术并未广泛应用于实际污染环境,其主要原因在于使用修复剂后的长期治理效果及生物效应并未明确。本研究以原炭、电厂灰、果壳活性炭和木炭为主要研究对象,以低密度聚乙烯膜(LDPE)被动采样监测技术为治理效果评估方法,以摇蚊幼虫为生物效应分析的指示生物,对比研究不同炭质修复剂对PCB污染底泥的治理效果,以及投加修复剂后对指示生物的影响,目的在于揭示不同炭质修复剂治理PCB污染底泥的机理,以及对生物的影响规律,为修复剂原位治理技术的实际应用奠定基础。主要研究结论如下:(1)4种炭质修复剂理化性质差异较大。木炭和果壳活性炭具有较发达的孔隙结构(微孔孔容贡献率分别为14.44%,13.71%),比表面积较大(BET比表面积分别为399.78m2/g,369.36m2/g);相比之下,原炭和电厂灰孔隙结构不发达(微孔孔容贡献率分别为10.88%,1.90%),比表面积较小(BET比表面积分别为 95.27m2/g,8.55m2/g)。(2)对比4种炭质修复剂总PCB的去除率,其中电厂灰最低(81.25%),原炭次之(89.18%),木炭和果壳活性炭较好(分别为97.34%,94.20%),治理效果排序基本与修复剂比表面积大小排序相匹配,说明比表面积是影响治理效果的主要因素。对于不同PCB分子,不同炭质修复剂的治理效果有所差异,电厂灰和原炭的治理效果与PCB分子直径以及辛醇-水分配系数呈显著的负相关关系(P≤0.05);木炭和果壳活性炭,这种相关关系不显著(P>0.05),说明由于具有丰富的孔隙结构,木炭和果壳活性炭治理效果不易受PCB分子差异的影响。修复剂投加量对治理效果的影响因不同修复剂而不同,对于电厂灰,修复剂投加量增大,治理效果显著提高,但对木炭和果壳活性炭影响不大。PCB污染底泥治理动力学研究表明,二级动力学方程能够很好地拟合炭质修复剂吸附PCB的动力学过程(R2>0.99),并且4种炭质修复剂对各个PCB的qe值大小排序也与修复剂比表面积大小排序相匹配,进一步说明比表面积是影响治理效果的主要因素。(3)4种炭质修复剂本身都对生物的存活、生长发育有一定的抑制作用,并且会导致SOD酶活性的降低以及CarE酶活性(即生物毒性)升高;电厂灰的抑制作用最强(治理1个月:存活率降低约10%,CarE酶活性升高约20 U/g),其次是原炭、果壳活性炭,木炭抑制作用最小(治理1个月:存活率为降低约1%,CarE酶活性升高约2U/g);随着修复剂投加量的增大,抑制作用增强(电厂灰生物全部死亡)。PCB污染底泥中投加原炭、木炭和果壳活性炭,能够缓解PCB对生物的不利影响;随着治理时间的延长,对生物的不利影响有随之降低;但是修复剂投加量增大时,对生物存活的不利影响有所增强。综合治理效果及生物影响,木炭在投加量为5%的情况下,在较短的治理时间内治理效果较好,且生物影响较小,是4种炭质修复剂中最为理想的PCB污染底泥修复剂。电厂灰的治理效果最差,且对生物的不利影响较大,不建议用于实际治理过程中。更多还原

【Abstract】 Sediment is the source and sink of environmental pollutants.Polychlorinated biphenyls(PCBs)is a kind of persistent organic pollutant that is mainly concerned whether domestic or abroad.According to the literatures,the concentration of PCB is excessive in many place of China.In situ repair agent treatment of sediment is a kind of technology,which is advanced,high efficiency and clean.However,this technology is not widely used,the reason is that the long-term governance effect and biological effect after treatment is not clear.In this research,we use power plant ash,raw carbon,charcoal and shell activated carbon as the carbon sorbents,at the same time,passive sampling with low density polyethylene film(LDPE)was used as the monitoring method,which can compare the PCB pollution treatment effect of these four kinds of carbon sorbents.At the same time,the larvae of anopheles mosquitoes were used to indicate the biological effect of these four kinds of carbon sorbents.The purpose of the study is to select an carbon sorbents with better treatment effect and less adverse effects on biology,the conclusions are as follows:(1)The physical and chemical properties of these four kinds of carbon sorbents are different.The pore structure of charcoal and fruit shell is more than raw carbon and power plant ash.The contribution rate of micropore volume of charcoal,fruit shel,raw carbon and power plant ash is 14.44%,13.71%,10.88%,1.90%respectively,the BET surface area of fruit shel,charcoal,raw carbon and power plant ash is 399.78 m2/g,369.36 m2/g,95.27 m2/g and 8.55 m2/g,respectively.(2)The total PCB removal rate in pore water of charcoal,fruit shel,raw carbon and power plant ash is 97.34%,94.20%,89.18%,81.25%respectively,and the sequence of treatment effect is similar to the sequence of BET surface area of carbon sorbents,which indicate that the treatment effect of carbon sorbents is influenced by the BET surface area of carbon sorbents.The treatment effect of these four kinds of carbon sorbents is different,the removal rate of pore water PCB of power plant ash and raw char was significantly negatively correlated with PCB molecular diameter and octanol-water partition coefficient(P<0.05);however,the removal rate of pore water PCB of charcoal and shell activated carbon was not significantly negatively correlated with PCB molecular diameter and octanol-water partition coefficient(P>0.05).The increase of dosage of remediation can significantly improve the treatment effect of power plant ash,but it has little effect on charcoal and fruit shell activated carbon.The dynamics research of PCB pollution sediment indicates that the second-order kinetic equation can well match the treatment process of carbon sorbents(R2>0.99),and the sequence of qe is similar to the sequence of BET surface area of carbon sorbents,indicating that thetreatment effect of carbon sorbents is influenced by the BET surface area of carbon sorbents.(3)The four kinds of carbon sorbents have inhibitory effect on the survival and growth of organisms,leading to a decrease in SOD enzyme activity and an increase in CarE enzyme activity.The inhibitory effect of power plant ash is the strongest,followed by is the raw carbon and shell activated carbon,and the inhibitory effect of charcoal minimum.The process of sediment treatment of raw charcoal,charcoal,and shelled activated carbon can alleviate the adverse effects of PCB contaminated sediment on the organisms,and the charcoal has the strongest relief effect.With the extension of the treatment time,the inhibitory effect on the organisms is reduce,while the treatment time is extend.However,When the dosage of carbon sorbents increases,the inhibitory effect is strengthened.Integrating the treatment effect and biological impact,charcoal under the dosage of 5%is the best carbon sorbents,which have a better treatment effect of PCB,while the biological impact is lest.The treatment effect of power plant ash is worst,meanwhile it have a serious inhibitory effect on organism,which is not recommended for the actual treatment process.更多还原