【作者】 孙晓菲；

【导师】 韩宝平；

【作者基本信息】 中国矿业大学 ， 环境科学， 2013， 博士

【摘要】 京杭大运河苏北段作为南水北调东线工程的输水通道，其水质质量将直接影响到调水效果。调水之后，大运河的环境化学条件、水力条件都会发生变化，将打破原有水相和沉积物相中污染物的平衡状态，沉积物相中的污染物，尤其是持久性有机物将会重新进入水相，从而影响调水水质。多氯联苯（PCBs）是持久性有机污染物之一，可在环境和生物体内长期残留，具有“三致”作用，因此作为受控的污染物之一被首批列入了《斯德哥尔摩公约》。研究京杭大运河沉积物中的PCBs污染特征及释放规律将为预测及防治其內源性污染，及营造南水北调东线的清水廊道工程提供理论依据。本文在江苏省自然科学基金、江苏省普通高校研究生科研创新计划和中央高校基本科研业务费专项资助项目的联合资助下，在系统分析了国内外沉积物中PCBs研究现状的基础上，通过现场环境调查，采集表层沉积物样品测试和室内模拟实验开展了对京杭大运河苏北段表层沉积物中PCBs污染特征及释放规律的研究，主要取得了以下成果：1.京杭大运河苏北段主航道采集的37个表层沉积物样品中PCBs的检出率为94.6%，含量在nd²6.819ng/g（干重，下同）之间，平均值为9.316ng/g。在37个监测点中出现PCBs含量峰值的两个监测点均位于徐州段。在空间分布上，呈现出了明显的由南至北，由下游至上游浓度逐渐升高的趋势，徐州段的平均含量高于扬州段和淮安—宿迁段，并且是以低氯代的PCBs为主。京杭大运河苏北段有三个重要的过水湖泊，分别是洪泽湖、骆马湖和微山湖，三个湖泊共采集29个表层沉积物样品，均检出了PCBs，其中洪泽湖表层沉积物中的PCBs平均含量最高，为9.451ng/g，微山湖次之，平均含量为4.240ng/g，骆马湖的PCBs含量最低，平均值为3.542ng/g。2.利用特征化合物比值法和主成分分析法对京杭大运河苏北段主航道和过水湖泊表层沉积物中的PCBs进行源解析后发现，主航道中的PCBs主要来自于五氯联苯和六氯联苯的商业产品，其次是燃煤、市政垃圾焚烧等高温过程产生的废气。洪泽湖中的PCBs主要来自于六氯联苯的商业产品，其次是高温过程；而骆马湖的PCBs则主要是来自于高温过程，其次是低氯代的PCBs商业产品；微山湖中的PCBs主要来自于Aroclor1242等五氯联苯的商业产品，高温过程的副产物对于微山湖的影响较小。3.利用潜在生态危害指数法和毒性效应评价法对京杭大运河苏北段主航道和过水湖泊中的PCBs进行生态风险评价后发现，潜在生态危害指数法虽然简单快捷，但是结果对于真实毒性的反映不够全面，结合毒性效应评价法则可以更好的反映对生态的真实潜在风险。评价结果显示，京杭大运河的扬州段潜在生态危害虽然较为轻微，但由于PCBs同系物中毒性较大的PCB126和PCB169的贡献率较大，反而使得该河段相比淮安—宿迁段和徐州段具有更严重的生态风险。三个过水湖泊中骆马湖和微山湖表层沉积物中PCBs的潜在生态风险较小，对生物的影响较小，而洪泽湖表层沉积物中PCBs的生态毒性在三个湖泊中则是最高的。但总体来讲，三个湖泊的生态风险远低于主航道的生态风险。4.利用模拟释放实验装置，研究了大运河河道中沉积物粒径、水流流速和表面活性剂等影响因素控制下的沉积物中PCBs的释放规律。实验结果显示，在释放初期的5-9天是快速释放阶段，在这一阶段PCBs释放量在总释放量中占相当大的比例；之后进入慢速释放阶段。在快速释放阶段，释放速率和释放量与上覆水的水流流速大小正相关，但在慢速释放阶段则无明显相关性。实验选用的两种表面活性剂SDS和OP-10均对PCBs有增溶促释放的作用，其中OP-10效果显著。OP-10的增溶促释作用在投加浓度（500mg/L和700mg/L）高于其临界胶束浓度时效果更为显著；而当投加浓度（100mg/L）低于临界胶束浓度时反而会抑制沉积物中PCBs的释放。不同粒径沉积物的释放实验表明小粒径（<0.45mm）的沉积物中PCBs释放量要明显高于粗粒径（0.45-1.25mm）的沉积物。5. PCBs的释放动力学实验表明，沉积物中的PCBs向水相的释放过程符合一级动力学模型，并建立了释放动力学模型：Cw（0）=Cs（0）·Ms/V-Cs（0）·Ms/V·Frap·e^-krap^t-Cs（0）·Ms/V·（1-Frap）·e^-kstow^t其中PCB118、114和126的快速释放速率常数（krap）为0.1154d-1、0.1850d-1、0.1403d-1；慢速释放速率常数（kslow）分别为0.0057d-1、0.0057d-1、0.0031d-1；快速释放部分所占份额（Frap）分别为67.81%、71.59%和73.97%。6.根据实验结果，对京杭大运河苏北段沉积物中PCBs未来可能释放进入所调水中影响南水北调水质问题，提出了防治措施与建议。更多还原

【Abstract】 As the main water transport passage of the South-to-North Water DiversionProject, the Grand Canal （North Section of Jiang Su） would directly influence theeffects of the quality of water transport. After the water transport, the environmentalconditions and water power conditions would change and break the equivalent state ofpollutants of sediments and previous aqueous phase, especially the persistentorganisms would re-enter the previous aqueous phase and thus influence the waterquality of water transport. PCBs is one of the persistent organic pollutants, which canretain in the environment and organism as residuals for a long time and function as theteratogenic, carcinogenic and mutagenic causes; therefore, PCBs is classified into thefirst batch of “The Stockholm Convention” as one of the controlled pollutants. Thestudy on the distribution features and release rules of PCBs in surface sediments ofthe Grand Canal （North Section of Jiang Su） is of vital importance and provides dataand references for prevention and control of organism pollution of the Grand Canal.Sponsored by the Innovation Fund of Jiang Su Province, the paper hassystematically introduced the current studies of PCBs of sediments at home andabroad, collected the specimens of sediments on spot, and carried out the research ofPCBs in surface sediments of the Grand Canal （North Section of Jiang Su） with thefollowing research findings:1. By analyzing37samples of surface sediments collected from the main channel ofthe Grand Canal （North Section of Jiang Su）, the relevance ratio of PCBs is94.6%,the content is between nd²6.819ng/g（dry weight） and average value is9.316ng/g.Two monitoring spots containing the peak value of PCBs content out of37monitoringspots are both located in Xu Zhou Section. As for the space distribution, it is obviousthat the concentration is gradually rising from south to north and from downstream toupstream. The average content of Xu Zhou Section is higher than that of Yang ZhouSection and Su Qian to Huai An Section, and the pollutants are mainly lowchlorinated PCBs. There are three water-passing lakes of the Grand Canal （NorthSection of Jiang Su）, Hong Ze Lake, Luo Ma Lake and Wei Shan Lake respectively, inall which PCBs are detected. The average concentration of PCBs in the sediments ofHong Ze Lake comes first as9.451ng/g, second comes as4.240ng/g in Wei Shan Lake, and the concentration of Luo Ma Lake is lowest, which is only3.542ng/g.2. By adopting the Characteristics of Compound Ratio Method and the PrincipalComponent Analysis, the PCBs in the Grand Canal （North Section of Jiang Su） andthree water-passing lakes are examined to check the source apportionment with thefollowing findings: the PCBs in the main channel mainly stem from the commercialproducts of pentachlorobiphenyl and hexachlorobiphenyl and then from the waste gasout of the high temperature process of coal burning and combustion of urban garbage;the PCBs in Hong Ze Lake mainly come from the commercial products of PCB1andPCB6, and then from the high temperature process; the PCBs in the Luo Ma Lakemainly come from the high temperature process and then the lower chlorinated PCBscommercial products; the PCBs in Wei Shan Lake mainly come from thepentachlorobiphenyl commercial products, such as Aroclor1242, while theby-products of the high temperature process have relatively less impact on Wei ShanLake.3. By adopting the Potential Ecological Harm Index Method and the Toxic EffectEvaluation Method, the author has conducted an ecological risk evaluation of thePCBs in both the main channel of the Grand Canal and the water-passing lakes. Itindicates that the Potential Ecological Harm Index Method is simple and fast butcovers less comprehensive reaction of authentic toxicity; it is better to adopt the ToxicEffect Evaluation Method to reflect the authentic potential risk of ecology. Thepotential ecological risks in Yang Zhou Section are relatively slight, but the moretoxic homologues of PCB126and PCB169cause the more serious ecological risk ofYang Zhou Section than those in Huai An-Su Qian Section and Xu Zhou Section. Thepotential ecological risks in two water-passing lakes （Luo Ma Lake and Wei ShanLake） are relatively low, which has little influence upon biology; while the ecologicaltoxicity of PCBs in surface sediments of Hong Ze Lake is the highest. Totallyspeaking, the ecological risks of these three lakes are far below the ecological risk ofthe main channel of the Grand Cannel.4. By utilizing home-made release simulation device, the PCBs in the sediments areconducted with a simulation release experiment. The results indicate that the first5to9days are the fast-release stage, during which the emission amount of PCBs accountsfor a large proportion of the total emission amount, and then follows the slow-releasestage. During the fast-release stage, the emission ratio and the total emission amountare positively related to speed of stirring device in the water while it is not obvious in the slow-release stage. Two surfactant （SDS and OP-10） in the experiment havefunctions of solubilization and promotion of release, among which OP-10has asignificant effect, especially when it is above the critical micelle concentration （500mg/L and700mg/L）; while the concentration is below the critical micelleconcentration （100mg/L）, it will suppress the release of PCBs in the sediments. Thereleases of sediments with different particle size indicate that the amount of PCBs insediments with small particles（<0.45mm） are obviously higher than those in thelarge particles（0.45-1.25mm）.5. By adopting the PCBs pollutants release dynamics experiment of static shakingflask, the emission process of PCBs in the sediments match with the model offirst-order two compartments and an emission dynamics model is set up as follows:Cw（0）=Cs（0）·Ms/V-Cs（0）·Ms/V·Frap·e^-krap^t-Cs（0）·Ms/V·（1-Frap）·e^-kstow^tThe constants （krap）of the fast release ratio of PCB118,114and126are0.1154d-1、0.1850d-1、0.1403d-1; the constants （krap）of the slow release ratio are0.0057d-1，0.0057d-1and0.0031d-1; the amount of the fast release（Frap） accountsfor67.81%,71.59%and73.97%.6. According to testing and release experimental results, the author puts forwordsuggestions for pollution preventions concerning the future release effect of PCBs insediments of the Grand Canal （North Section of Jiang Su） upon the water quality ofthe South-to-North Water Diversion Project.更多还原