鄱阳湖蓝藻毒素与重金属污染的复合效应及其诱发的水产品风险研究

Eutrophication and heavy metal pollution in water bodies are mainly caused by sustained anthropic activities and also common in many waters in China. Heavy metals discharged into the water can react with MCs released from cyanobacteria blooms in eutrophic waters through complexation adsorption, photochemical reaction, and other indirect interactions. These reactions may change the chemical or physiological properties of MC, together with its transportation and fate in natural environment. It may also mitigate the environmental and health risks of MCs, and cause harm to aquatic ecosystem and humans. In this study, water solubility, molecular polarity and cytotoxicity of MC-metal complex would be evaluated. Dose effect of different heavy metals on the physiological feature change of different hydrophytes and aquatic products(including Zizania latifolia,Artemisia selengensis Turcz and Procambarus clarkii), together with MC uptake by them will be studied through ecological simulation. The underlying mechanism for these processes would also be elucidated by monitoring the changes of enzyme activities in these hydrophytes and aquatic products, such as SOD, POD, CAT and GSH-Px. Finally, field investigation in Poyang Lake polluted by both heavy metals and microcystins would be conducted to study the MC accumulation in sediments, water, hydrophytes and aquatic products, to compare with results and conclusions from ecological simulation. Then the overall effect and risk of heavy metal pollution on microcystin characteristic change and its uptake or bioaccumulation by hydrophytes and aquatic products will be evaluated. This study will benefit the human health and aquatic ecosystem security protection and provide guidance for water pollution control and aquatic environment risk warning.

湖泊沉积物重金属污染问题与水体蓝藻水华毒素污染问题在我国均较为突出。重金属可以与水华蓝藻产生的蓝藻毒素发生多种作用，包括络合亲和作用、光反应作用及各种间接的吸收降解作用等。上述作用或将部分改变蓝藻毒素的理化/生理特性，影响蓝藻毒素在环境和生物体中的迁移归趋，对水生态环境及人类健康构成潜在威胁。本研究以鄱阳湖为例，通过研究蓝藻毒素与重金属污染物反应前后毒素水溶性、分子极性及人体细胞毒性的转变，探讨重金属在不同环境剂量下对典型可食用水生动植物茭白、藜蒿和克氏原螯虾吸收积累微囊藻毒素影响的潜在机理机制，并调查重金属污染程度差异时不同湖泊/湖泊不同区域蓝藻毒素在环境和生物体中的存量及富集系数差异，从而综合评价重金属污染物对蓝藻毒素性质转变及毒素在环境生物体中的累积吸收行为变化的影响，为科学评估重金属-蓝藻毒素复合污染对湖泊水生态系统的风险提供依据，同时为水环境的预警和污染控制提供科学指导。

湖泊沉积物重金属污染问题与水体蓝藻水华毒素污染问题在我国均较为突出。野外调查结果表明，鄱阳湖周边的水产品受到了明显的微囊藻毒素污染。通过分析水产品毒素与多种水质环境因子之间的关系，发现典型水产品（虾，蟹等）毒素富集系数与水体金属铁含量具有非常明显的正相关，与其它金属无明显关系。蓝藻细胞数量和水体蓝藻毒素的含量也与Fe存在正相关关系。表明水体铁的含量高，蓝藻生长较好，产生的藻毒素总量也高，将促进水产品吸收积累更多毒素。室内研究显示毒素与典型金属如Fe结合后分子极性、水溶解性/水相分配能力大为增强，可能不利于动物组织积累MC，但生物细胞毒性并没有明显变化。生态模拟实验实验组结果表明，Cu和Pb离子作用下泥鳅肌肉中微囊藻毒素累积较慢但总体以促进作用为主。高浓度Fe可以阻碍水产品如泥鳅肌肉累积微囊藻毒素，该结果与野外调查结果不太一致，可能与选择的调查对象不同有关。Cu对水生植物如粉绿狐尾藻组织累积微囊藻毒素无显著影响，但Fe和Pb可以显著抑制粉绿狐尾藻组织累积微囊藻毒素.因此，重金属对各类生物体吸收积累MC有较大影响，但不同物种的表现略有差异。