环境水化学 络合与金属形态.ppt

The environmental repercussions of the discharge of disinfected effluents are still poorly understood. This study assessed the impact of ozonation and UV oxidative treatment processes on metal forms – particulate, colloidal and permeable fractions – and bioavailability in disinfected wastewaters. In addition to wastewater analyses, mussels were placed in continuous flow-through aquaria and exposed for 4?wk to wastewater, then metals in their tissues were analysed in parallel with exposure biomarkers. Metal size distribution was affected by oxidative processes; results showed that ozonation treatment generally increases the permeable fraction of some metals, particularly Cd and Cu, in treated waters, whereas UV treatment fosters the formation of permeable Zn. Ozone treatment of wastewater generally increased the bioavailability of specific metals. Metal bioaccumulation was in most cases significantly higher in mussels exposed to ozone-treated effluent compared to the UV treatment: 58%, 32%, 42% and 47% higher, respectively, for Ag, Cd, Cr and Cu. Physical metal speciation in these wastewaters comparatively measured the permeable fraction of metals to relate them to the bioaccumulation results for the exposed mussels. The levels of lipid peroxidation were significantly increased in gills but not in the digestive gland. The levels of metallothionein in the digestive gland were also significantly reduced suggest decreased input of particulate metals. Results of bioaccumulation in mussels suggested that metal bioavailability can be modified by the different oxidative processes. Despite this disadvantage, ozonation still represents a great choice of treatment considering the overall environmental benefits. * BLM模型：第一个原则，金属生物可利用性与水化学条件有关，自由离子浓度用于预测金属累积，影响络合的因素如阴离子和DOC不再影响金属累积。这时需要考虑的是与金属在配体上竞争的因素。第二个原则，在生物配体上的金属浓度直接与金属的负效应相关，存在临界金属配体浓度，与水化学或生物体生理条件无关。 * * VMINEQL计算 与有机配体作用 Cu、Zn的优势形态 柠檬酸量对形态的影响。钙的竞争 * 腐殖质络合 腐殖酸humic acid、富里酸fulvic acid 官能团密度10-20 meq/g C。 * * * 分泌强的络合剂 有