【作者】 王蕾；

【导师】 祁佩时；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2012， 博士

【摘要】 重金属具有生物毒性、持续性和非生物降解性，是一种危害性极强的污染物。上个世纪，由于工业化和城市化的快速发展，导致环境中、尤其是水体生态系统中的重金属含量激增，沉积物是多种污染物质，包括金属元素的天然“储蓄库”，因而沉积物对水质量的一个重要指标。本文针对北方地区城市内河沉积物重金属污染的现象，通过对沉积物中重金属的含量、分布特性、污染来源及风险评价的研究，通过对污染地区植被及根际真细菌群落的调查及检测分析，筛选适于生态修复的植物品种，同时采用盆栽试验和分子生物学方法探索了生态修复的效果及机理，以期为今后重金属污染内河沉积物的生修复提供参考，并为人类健康和生态保护提供依据。选择一条典型的环工业区北方城市内河作为研究对象，通过对河流理化性质及Pb、Zn、Cd、Ni、Cr、Cu、As和Hg的含量的分析，评价了河流重金属的污染程度，并分析了河流表层沉积物中重金属的分布规律及及来源。结果表明所有表层沉积物中重金属的浓度均高于国家沉积物Ⅰ类标准。表层沉积物重金属的污染程度依次为：Cd> Zn> Pb> Cu> Ni> Cr> Hg>As；采样点的重金属污染程度依次为采样点F>采样点D>采样点C>采样点B>采样点A>采样点E。沉积物中的重金属主要源自人类活动，包括工业排放、交通运输、市政废水和木器制造业等，而Hg则主要源于大气中Hg的沉降。通过对表层沉积物中重金属的污染及健康风险的评价，表明表层沉积物均受到了重金属的污染，受检重金属中Cd的生态风险最高，采样区域中D采样点受污染最严重，河道表层沉积物中重金属的潜在生态风险由高到低依次为：Cd>Hg>Pb>Cu>Ni>As>Zn>Cr；重金属对儿童和成人造成的健康风程度险依次为：As> Cd> Cr（Ⅵ）> Pb>Hg> Ni> Cr（Ⅲ）> Zn> Cu。根据重金属赋值形态的分析结果，重金属的迁移及生物可利用性依次为：Cd>Pb>Zn>Ni>Cr>Cu>Hg。基于河流的理化性质、重金属的沉降与释放以及重金属的分布规律构建重金属在河流中的动态模型：。水体重金属：V_w dCw/d_t=_Vs（C_s-C_s’）k_e+V_w（C_-C-w）k_h-V_w（C_w-C_j）k_j+v_h（C_h-C_w）-v_j（C_w-C_j）-V_w（C_w-C_w’）k_s沉积物重金属：V_S dC_s/dt=V_w（C_w-C_w’）k_s+V_s(C_hs-Csk_h’-V_s(C_s-C_js)k_j’-V_s（C_sC_s’）k_e+S_i通过对重金属耐性植物的调查分析，共发现了分属7个科的18种优势植物，通过CANOCO软件，采用余度分析（RDA）的方法按照重金属的耐受性可以将重金属耐性植物划分为4个类群：重度污染耐受型植物、中度污染恢复型植物、恢复型植物和As污染恢复型植物类群，并筛选得到了12种具有重金属耐性的优势植物。通过进一步检测分析了这12种优势植物对As、Cd、Cr、Cu、Pb、Ni和Zn的修复潜力，结果表明龙葵适于重金属高度复合污染环境的Cd修复；酸模和酸模叶蓼分别适于重金属高度复合污染环境下Pb和Zn污染修复潜力；酸模和苦荬菜也具有Zn的修复潜力，但是酸模适于污染水平较低沉积物Zn的修复，而大部分优势植物属于重金属规避型植物。通过盆栽试验进一步研究了酸模、龙葵和酸模叶蓼对沉积物重金属的修复潜力，结果表明这四种植物均能够有效提高沉积物中的重金属的活性及真细菌的总量；沉积物重金属污染的生物修复应采用植物联合修复及合理刈割的管理方式。分别构建了适用于受污染城市内河沉积物的重金属植物有效性的多元线性回归预测模型及重金属植物有效性总权重的离子冲量数学模型，用以预测重金属复合污染沉积物中重金属对植物的有效性，总权重的离子冲量模型为：lgwI_p=0.888lgwI_HM+0.886lgCS-0.098lgOM-1.21lgCEC-2.250lgpH+2.267（R=0.915，F=49.375，n=54，p<0.001）。采用DGGE和16S rDNA克隆文库技术深入比较分析了优势植物根际圈细菌群落结构与照沉积物的细菌群落结构的差异。过通过序列比对分析，两个根际圈文库细菌群落组成较为相似，共鉴定得到81个OTUs，其中21个为两个文库共有OTUs，而沉积物文库中没有与两个根际圈文库重叠的OTUs。两种植物根际圈文库的结构组成较为相似，通过比对分析发现根际圈文库中多为PGPRs和重金属污染土壤抗性细菌，并且优势菌多为β-变形菌；而厚壁菌和放线菌为对照沉积物样品文库的主要菌种。更多还原

【Abstract】 Pollution associated with metals is a serious problem because of their toxicity,persistence, and nondegradability in the environment. Over the past century, thelevels of metals in aquatic ecosystems have increased drastically as a result of rapidindustrialization and urbanization. The metals have accumulated in sediments. Assediment is the main sink for various pollutants, including metals, sediment qualityhas been considered as an important indicator of water contamination. Althoughthere are many researches on the sediment contamimated by heavy metals, fewapplication and study on ecological restoration of sediment has been carried out.Therefore, this paper developed the study on the distribution, sources, andecological risk assessment of heavy metals in surface sediments, screen thecandidate plant variety for bioremediation in sediment, based on the fieldinvestigation and laboratory analysis. Method of molecular biology technique wasused to evaluate the effects of ecological restoration and investigated the mechanismof plant-microorganism combined remediation. The results obtained here could notonly provide the reference for the future bioremediation in urban river sediment, butalso be used in the exploration of strategies to protect human health and theecosystem.This paper was conducted in order to determine the degree of metal pollution inthe surface sediment of an urban river across residential and industrial zones ofHarbin, China. Six sampling sites located at Xinyi river were chosen for collectingthe surface sediment samples. The sediment samples have been subjected to a totaldigestion technique and analyzed by inductive coupling plasma mass spectrometry（ICP-AES） for metals including Pb, Zn, Cd, Ni, Cr, Cu and As and AtomicFluorescence Spectrometer （AFS-2202E） for Hg. The average concentrations of As,Cu, Zn, Pb, Cr, Hg and Cd determined in the surface sediments are higher than theclassⅠstandard of Marine Sediment Quality. And the average concentration of Ni inthe surface sediments is higher than the maximum accepted level of River SedimentQuality of Hong Kong. It revealed that the surface sediments in all the samplingsites were polluted with As, Cu, Zn, Pb, Cr, Hg, Cd and Ni, especially in site D.According to the pollution assessment of heavy metal in sediment samples, thesurface sediments were contaminated with As, Cu, Zn, Pb, Cr, Hg, Cd and Ni, andthe Cd pollution was most serious. Cd poses the highest ecological risk in thesediments. While site D was the most seriously polluted among sampling sites. Thecontamination degree of heavy metals in surface sediments were in the order of Cd> Zn> Pb> Cu> Ni> Cr> Hg>As, and site F>site D> site C> site B> site A>site E. It was found that the primary inputs of heavy metals were anthropocentric disturbance, mainly including the effluent of industrial and municipal wastewater.While, Hg mainly derived from atmospheric pollution. The potential ecological riskindex （RI） and health risk assessment had been calculated. The potential ecologicalrisk of heavy metals in surface sediments were in the order of Cd> Hg> Pb> Cu>Ni> As>Zn>Cr, and1the the total health risk were in the order of As> Cd> Cr（Ⅵ）> Pb>Hg> Ni> Cr（Ⅲ）> Zn> Cu.According to the results of fractionation profile, the mobility andbioavailability of heavy metals were in the order of Cd> Pb>Zn>Ni>Cr>Cu>Hg.Based on the physicochemical properties of river, sedimentation, release anddistribution of heavy metals, dynamic models of heavy metals in polluted river wereconstructed:In water:V_w dCw/d_t=_Vs（C_s-C_s’）k_e+V_w（C_-C-w）k_h-V_w（C_w-C_j）k_j+v_h（C_h-C_w）-v_j（C_w-C_j）-V_w（C_w-C_w’）k_sAnd in sediment:V_S dC_s/dt=V_w（C_w-C_w’）k_s+V_s(C_hs-Csk_h’-V_s(C_s-C_js)k_j’-V_s（C_sC_s’）k_e+S_i18dominant species of plant, belonged to7families, were found in30plots inmud along the riverbank. RDA was introduced to analyze relationship betweenvegetation community and heavy metals in rhizospheres. As the results, the heavymetal tolerant species could be classified into4groups by the clustering analysis,such as high contamination tolerance, moderate contamination recovery, recoveryand As contamination recovery. And12metal-tolerant plants were screened. Presentresearch conducted field and pot experiments on dominant plants to find out theirphytoextraction potential. Results indicated the uptake of metals by plants showedspeaciality in different species. Solanum nigrum had a greater accumulation oncadmium （Cd） than other plants. High biomass, wide spread root system and heavymetals tolerance make S. nigrum as an attractive choice for the remediation ofsediment highly contaminated. Rumex dentatus was found a lead （Pb）-accumulatingplant. While Polygonum lapathifolium was the potential material forphytoremediating Cd in highly metals polluted condition. R. dentatus and Ixerischinensis were good Zn remediation candidates in contamination soils, but I.chinensis only suitable for moderate contamination. These other plants were themetals excluders or mainly held in the roots. The results of pot experiment showedthat R. acetosa L., S. nigrum L. and P. lapathifolium L. could increase activities ofheavy metals and bacterial number significantly. The bioremediation of heavymetals polluted sediment should adopt plant-microorganism combinated remediationand rational multi-cutting management.The statistical models of7heavy-metal phytoavailablities were constructed, taking a series of physicochemical properties of sediment samples and plants intoconsideration. The models of heavy-metal phytoavailabilties showed there wascorrelation between phytoavailabilty and physicochemical properties of sedimentsamples and other metals. phytoavailability of Cu was affected by total-Cdsignificantly. The model expressed in terms of total WI could bemathematically described bylgwI_p=0.888lgwI_HM+0.886lgCS-0.098lgOM-1.21lgCEC-2.250lgpH+2.267（R=0.915，F=49.375，n=54，p<0.001）.The difference among sediment samples and five rhizospheric samples ofdominant plant species, R. dentatus, S. nigrum, Cynodon dactylon, P. lapathifoliumand Populus canadensis, screened from field investigation were indicated andanalyzed by DGGE and16S rDNA libraries. Among the combined81OTUsidentified among S. nigrumand P. canadensis libraries, with the remaining21OTUscommon to both libraries. But there were few common OTUs among sediment andthe rhizospheric libraries. The highest relative amount of phylotypes and clones inboth rhizosphere libraries was observed for Betaproteobacteria. Results of16SrDNA sequence analysis showed metal resistant and plant growth promotingbacteria accounted for a considerable proportion in both rhizosphere libraries. Whilerepresentatives of the Actinobacteria and Firmicutes were the most numerousphylotypes in sediment clone library.更多还原