导　　师： 马焕成;肖唐付

学科专业： 090702

授予学位： 博士

作　　者： ;

机构地区： 四川农业大学

摘　　要： 黔西北土法炼锌具有300多a的冶炼历史，由于冶炼工艺简单，重金属回收率低，大量重金属累积废渣中，造成冶炼区环境严重污染。冶炼过程中产生了大量的烟尘，没有采取任何环境保护措施，烟尘中含有大量的重金属和二氧化硫等有毒有害物质，破坏了冶炼区附近植被，大量的重金属随烟尘向四周扩散，导致大面积大气、土壤、植物、水体的重金属污染。虽然土法炼锌目前已基本上取缔，但留下了2000万t废渣和1200hm<'2>的废弃地。因而对废弃地的植被重建与生态恢复、对污染环境的修复具有重要科学价值和实际意义。本研究充分调查了重金属在生态系统中的分布与扩散规律，分析了土壤和植被退化的过程。通过苗圃的模拟实验和田间植被重建实验，探讨了废弃地植被重建的主要限制因子，基质改良的有效手段及耐性植物的筛选。对废弃地自然形成的优势植物进行调查，筛选重金属的超富集植物，并研究其富集特性与机理。主要的研究结果如下： 土法炼锌导致了pb、zn、cd在土壤、水体和植物中大量积累，对整个生态系统构成了严重的威胁。在冶炼废渣中，pb、zn、cd的含量分别为4632 mg/kg、8968 mg/kg、58 mg/kg；冶炼区周围的土壤pb、zn、cd含量分别达到234 mg/kg、400 mg/kg、9.6mg/kg。废弃地的基质的地球化学形态分析表明，废渣中pb、zn、cd具有很低的生物有效性和迁移性，交换态含量低于0.2％，但其交换态与碳酸盐态含量相当高，构成了潜在的环境风险。相对而言，冶炼区附近污染土壤的pb、zn、cd可交换态含量较高，具有较大迁移性和生物有效性。冶炼区的小河受到严重的pb、zn、cd污染，地下水受到轻微污染，未超出三类水体的质量标准。在小河水体中，可溶态的pb、zn、cd含量少，大部分的pb、zn、cd以悬浮态的形式存在，表明了河流重金 The widely spread indigenous zinc smelting sites in western Guizhou, China, with a history of 300 years, have caused serious pollution of heavy metals of lead /(Pb/), zinc /(Zn/) and cadmium /(Cd/) in slags due to low recovery rate. A large amount of fumes rich in heavy metals and sulfur dioxide, have destroyed vegetation around the smelting areas and have released heavy metals into soil, plant and water body. Although indigenous zinc smelting activities have been abolished due to heavy environmental pollution in 2004, 20 millions tons of open dumped slags and 1200 hectares of polluted land were environmental concerns at present with high risk to the local ecosystem. It is of importance to understand revegtation on smelting wasteland and remediation on heavy metals in the smelting areas. This study is conducted to: 1/) analyze distribution and transfer of heavy metals and degradation of soil and vegetation in the polluted environments; 2/) explore limited factors on revegetation, substrate amendment methods and strongly-tolerant plant; 3/) screen hyperaccumulators for heavy metals and study their accumulation properties and mechanism. The main research results were as follows. Concentrations of Pb, Zn and Cd in slags averaged at 4632 mg//kg, 8968 mg//kg, and 58 mg//kg, respectively, whereas 234 mg//kg Pb, 400 mg//kg Zn and 9.6 mg//kg Cd occurred in soil around the smelting areas. The geochemical leaching test showed that Pb, Zn and Cd in slags have low mobility and bioavailability because their concentrations presented small percentages /(all less than 2 /%/) in the exchangeable fraction, whereas the contaminated soils had higher mobility and bioavailability for the metals. The Pb, Zn and Cd concentrations in exchangeable and carbonate fractions in slags were high and posed potential environmental risks. Concentrations of Pb, Zn and Cd were high in the local stream water but low in groundwater. In the stream water, Pb, Zn and Cd were significantly concentrated in the suspended sediments, and indicated tha

关 键 词： 重金属污染 冶炼废弃地 植被重建 基质改良 超富集植物 生态恢复

领　　域： [环境科学与工程] [环境科学与工程]