【作者】 郭观林；

【导师】 周启星；

【作者基本信息】 中国科学院研究生院（沈阳应用生态研究所） ， 生态学， 2006， 博士

【摘要】 东北黑土高有机质含量和巨大而连续的耕作带使它成为中国重要的粮食生产基地。随着人类开发和利用程度的加剧,其直接后果是导致黑土健康质量逐渐下降。土壤重金属污染是导致黑土健康质量下降的重要因素之一。本研究通过对东北黑土重金属污染初步调查,确定黑土分布地区重金属污染的主要类型、来源、污染趋势和分布状况,分析污染黑土中重金属形态、迁移和生物有效性等特点。结果表明:黑土环境中,镉、铅、锌的含量呈明显上升趋势,镉是对土壤健康危害最大的重金属;污染较为严重的区域主要分布在城区和城乡结合部,重金属在这些区域中生物有效性高,工业排放和污水灌溉是其重要来源;而在农区耕作土壤中磷肥的长期施用是造成土壤中镉含量上升的主要原因。根据调查结果,选择黑土中主要重金属污染类型—镉,对其在土壤中导致污染发生的主要机理进行了深入研究。从形态、生物有效性和吸附-解吸过程等方面阐述了镉在土壤环境中的主要化学行为,以及这些行为对有机农药交互作用的响应。研究表明,外源镉离子进入土壤后能很快被吸附,由于这种吸附作用,使交换态镉容易向结合态和残渣态转化,被土壤吸附的镉离子有一部分被解吸下来,这也使形态转化呈一个互为可逆的过程。由于黑土特殊的土壤理化性质,镉离子在黑土中的吸附和转化趋势明显强于棕壤。乙草胺的加入能加强这种吸附作用和转化趋势,而敌敌畏的作用则增加了吸附态镉离子释放的风险。镉和乙草胺复合污染条件下对生物的毒性呈拮抗作用。最后,采用化学固定修复的方法,对镉污染黑土进行健康调控研究。通过重金属溶出、形态转化、生物毒性和微观构像等实验评估的结果表明,一种富含H2PO4-、HCO3-和CO32-等配位体的人工合成固定剂对镉污染黑土具有一定的修复潜力。对污染程度较低的重金属面源污染耕作土壤的调控,化学固定化修复在时间和成本等方面显示其修复的优越性。更多还原

【Abstract】 High organic matter contents and large continuous farmland distribution make Phaeozem as an important base for food production in China. The soil health of Phaeozem is being deteriorated with increasing exploitation and utilization, of which heavy metal contamination was one of the reasons for the quality declining of soil health. This work was focused on investigating contaminative mechanisms of heavy metals in Phaeozem in northeast China in order to identify the pollution sources, types, trends and distribution, and making clear about the speciation, mobilization and bioavailability of heavy metals in contaminated Phaeozem. The results showed that cadmium pollution was at the most serious extent in Phaeozem. The contents of cadmium, lead and zinc were increasing in this area, which resulted in the soil contamination mainly distributed in urban area and boundary of the city for their high bioavailability. Industrial emission and wastewater irrigation were the main sources of the contamination in these areas, while the utilization of phosphoric fertilizers for long time was the main reason for cadmium increasing in farmland.According to the previous investigation, cadmium was selected as main element for the further study of contaminative mechanisms. The main behaviors including sorption-desorption and transferring of speciation and bioavailability with or without the interaction of organic chemicals in soils were stated. The results indicated that the Cd2+ was quickly absorbed after having introduced into soil. And these make the possibility of transforming from exchangeable cadmium into bounded forms. Some parts of the sorbed cadmium on soil can be desorbed into equilibrium, which make the speciation transformation into a reversible process. The sorption and transformation forces of Cd2+ in Phaeozem were higher than that in burozem for the physicochemical soil properties. The interaction of acetochlor could enhance cadmium sorption and transformation, while the dichlorvos addition could increase cadmium release in soils. The interaction between cadmium and acetochlor was an antagonism, which could lower the biological toxicity.Chemical immobilization was selected as a remediation method to adjust soil health of Phaeozem contaminated with heavy metals. A synthetic amendment riched in the ligands of H2PO4-、HCO3- and CO32- was confirmed as a potential additive for chemical fixation after the experiments of toxic characteristic leaching process (TCLP), speciation, biological toxicity and microstructure. Although the bioavailability is the key factor for the remediation strategy, the in situ fixation with exterior amendments in low content of metal may offer a promising option, especially for the non-point and light pollution derived from agricultural sources.更多还原