【作者】 叶华香；

【导师】 臧淑英；

【作者基本信息】 哈尔滨师范大学 ， 自然地理学， 2014， 博士

【摘要】 湿地是地球上水陆相互作用形成的独特生境，随着人们对湿地资源的不合理利用以及湿地保护手段的缺乏，湿地生态破坏及污染越来越严重，湿地生态系统保护及污染防控的研究已成为当前湿地研究的重点和热点之一。沉积物是湿地生态系统主要环境要素之一，是营养物质的中心环节，也是营养盐和重金属等污染物的主要蓄积库；当环境条件变化时，营养盐和重金属等污染物从沉积物中释放出来，沉积物转成水体污染的“源”。因此，对湿地沉积物污染的研究具有重要的科学意义。本论文以扎龙湿地为研究对象，通过科学的野外采样和实验室测定，利用GIS技术和多种统计分析方法，系统研究了沉积物营养盐及重金属的分布规律、来源、控制因素及污染状况，从一个全新的视角反映扎龙湿地的污染情况。并在此基础上分析了沉积物重金属的生物有效性，筛选出吸附重金属性能良好的植物，探讨了重金属在沉积物——芦苇中的迁移模型。主要研究结果如下：研究区表层沉积物有机质(OM)、总氮(TN)和总磷(TP)的平均值分别为34554、1371和404mg·kg-1，均高于其在深层中的含量，存在明显的累积性，累积程度顺序为TN> OM> TP，并由生态毒性效应评价得出，沉积物已经受营养盐的污染，尤其是OM和TN污染明显，其内源负荷不容忽视。氮和磷的形态研究表明，总氮主要以有机氮(Org-N)的形态存在；总磷中无机磷(IP)含量稍高于有机磷(OP)，但基本上各占一半，而无机磷以钙磷(Ca-P)为主。从空间分布格局整体上看，研究区表层沉积物中营养盐含量北部高于南部，西部高于东部，OM和TN高值区位于西南，TP的高值区位于东北。有机氮、有机磷与有机质存在显著相关性，其空间分布规律基本相同，高值区位于西南部，而无机磷不同于有机磷，其高值区位于研究区的东北部。碳-氮-磷耦合研究表明，沉积物中有机质和氮具有同源性，来源于湿地水生生物和陆源输入，而磷和有机质的来源不完全相同；在研究区西南部及部分核心区，N/P值大于10，且氮、磷的含量均较高，此区域发生富营养化的风险大，要控制此区域富营养化的发生或加剧，在削减沉积物氮含量的同时，关键是控制磷的含量；对于研究区的北部，要控制富营养化的发生或加剧，关键是控制氮的含量；研究区南部，目前，富营养化发生几率较低。研究区表层沉积物Hg、Cd、As、Cu、Pb、Zn和Cr的平均值分别0.065、0.198、10.26、18.20、21.35、52.08和46.47mg·kg-1，均超过松嫩平原土壤背景值。重金属含量分布因其来源的不同，分布规律存在明显的差异性。除Pb和Hg之外，Cd、As、Cu、Cr和Zn主要来源于工农业废水和生活污水，其空间分布规律基本相同。但从总体上看，整个研究区中，重金属含量北部高于南部，东部高于西部，核心区含量低，且东部含量最高，将作为今后重金属污染防治的重点区域。沉积物中重金属赋存形态表明，沉积物中Pb、Zn、Cr、Cu和As主要以残渣态形态存在，均具有较好的环境稳定性；而Cd和Hg的非残渣态含量较高，生物有效性强，潜在生态风险大。重金属各形态的含量除与其总量有关，还与沉积物理化性质（pH、有机质和粒度）有关，尤其是有机质，除As外，重金属可氧化态含量与有机质均呈极显著正相关。但目前扎龙湿地盐碱化加剧，沉积物中重金属释放风险加大，应该引起当地政府及有关部门的高度重视。基于重金属总量和形态学两种体系的评价方法得出扎龙湿地表层沉积物中7种重金属的污染程度不同，Cd属于中——重度污染，Hg属于轻——中度污染，As、Cu、Pb、Zn、Cr均属于无——轻度污染。从研究区的角度来看，沉积物重金属生态危害程度为实验区>缓冲区>核心区。研究区被采集的植物中芦苇、香蒲、光头野稗和苋菜对重金属吸附性能较好，且根部富集能力强于茎叶，尤其是苋菜，根部Cd的富集能力最强。利用多元回归分析方法拟合了重金属的迁移累积和植物有效性与沉积物重金属形态分布和土壤理化性质等环境因子的定量关系，结果表明芦苇重金属的迁移模型为对数线性模型，其中模型对Cd、Hg、Cu、Pb和Zn的拟合效果较好，对As模拟效果相对较差。说明本研究的对数线性迁移模型能够较好预测实际环境中沉积物——芦苇系统重金属的迁移累积，但也存在一些缺陷，有待进一步改进。更多还原

【Abstract】 Wetland, formed by the interaction between water and land, is the specialecological environment in the earth. These years, pollution and destruction of thewetland ecological system has become more and more serious due to misuse thewetland resources and lack of protection. As a result, wetland ecological systemprotection and pollution prevention has become the core and hotspot of current wetlandresearch. Sediments are the major environmental elements of the wetland ecologicalsystem, the main accumulation reservoir of nutrients and heavy metals. When theenvironmental condition changed, nutrients and heavy metals will release from thesediments. The sediments become the source of water pollution. Therefore, research onthe pollution of wetland sediments has important scientific significance.Taking the Zhalong Wetland as the research object, and using GIS technique andmany statistic methods, this dissertation systematically analyzes the spatial distribution,sources, controlling factors, and pollution features of nutrients and heavy metals. Inaddition, this dissertation analyzes the biological availability of heavy metals in thesediments, selects plants which are good at absorbing heavy metals, and explores thetransferring model of heavy metals in the sediments and reed. The results can besummarized as followings:The average values of OM，TN and TP were34554,1371, and404mg·kg-1respectively, all above their values in the deep part of the sediments. It indicates thatthere is obvious accumulation by the order of TN> OM> TP. The evaluation ofbiological toxic effect indicates that the sediments have been polluted by nutrients,especially by OM and TN which should be paid attention to.The analysis of speciation of N and P indicates that TN mainly exists as Org-N.The concentration of IP is relatively higher than OP, both has almost the equal share ofTP. Their spatial distributions were distinctly different. The concentration of nutritivesalt in the north was higher than that in the south and the west was higher than the east.The high value zone of OM and TN is in the southeast and the high value zone of TP isin the northeast. Org-N, OP and OM have significant correlations. They have similarspatial distribution. The high value zone is in the southwest. While IP is different fromOP, the high value zone of IP is in the northeast. The coupling analysis of C, N and P shows that OM and N have the same sourcewhich is from aquatic biology and land input. N and OM have different source. In thesouthwest area and partial core zone, N/P is bigger than10. And the concentration of Nand P are high. These areas have big potential of eutrophication. In order to controleutrophication, it should cut the concentration of N, and put the concentration of P in areasonable scale. In the north part, it should pay attention to the concentration of N. Inthe other hand, the risk of entrophication in the south part is still relatively low.The concentrations of Hg, Cd, As, Cu, Pb, Zn and Cr were0.065,0.198,10.26,18.20,21.35,52.08and46.47mg·kg-1respectively, which were all above the soilbackground values of Songnen Plain. Their spatial distributions were distinctly different.Except Pb and Hg, Cd、As、Cu、Cr and Zn are mainly from industrial and agriculturalwaste water. The concentration of heavy metals in the north was higher than that in thesouth, and the east was higher than the west. And in the core zone, the concentrationwas relatively low. Particularly in the eastern region, the concentrations of Hg and Cdwere extremely high which should be treated as the major heavy metal pollutionprevention sites.The dominant proportion of Pb, Zn and Cr were in the residual fraction, suggestingthat they were environmental stable. The concentrations of Cu and Hg in the reduciblefraction were relatively high, indicating they had greater environmental effects. Thespeciation of heavy metals is related with not only the total quantity, but also thephysical and chemical features of the sediments such as pH and OM. Except for As, theconcentration of oxidizable fraction of heavy metals has significant correlation with OM.Currently the trend of salinization (of soil) in the wetland is becoming serious, meaningthat the risk of heavy metal release becomes bigger, which should be gain enoughattention by the local authority.The level of pollution of the7heavy metals in the sediments is different based ontwo different evaluation methods. Cd belongs to middle-serious pollution. Hg belongsto light-middle pollution. And As、Cu、Pb、Zn、Cr belong to none-light pollution. Ingeneral, the ecological risk of the heavy metals and metalloid by zone wereexperimental zone> buffering zone> ecological tourism zone> core zone.Among all the plants, reed, bulrush, bald weeds and edible amaranth haverelatively better ability of absorbing heavy metals. Their root is better than their leaf to absorb heavy metals. Especially for edible amaranth, its root has best absorbing ability. Iuse the multiple regression analysis to simulate the quantitative relations betweentransferring accumulation, biological availability, and speciation distribution and thesoil physical and chemical features. The result indicates that the transferring model ofreed heavy metal is log-linear model. The model has a better simulation result to Cd、Hg、Cu、Pb and Zn. However, it is weak to simulate As. The log-linear transferring model ofthis research can predict the accumulation of heavy metals in sediments-reed system. Inthe meanwhile, the model still has disadvantages, which should be put into futureresearch agenda.更多还原