太湖蓝藻水华对多环芳烃赋存、生物富集及食物链传递的影响及其机制研究

Algal bloom and persitent organic pollutants (POPs) are two environmental issues in lakes. Although great efforts have been put on these two issues individually, to date little is known about the correlation between these two issues. In this study, Lake Taihu, a large shallow eutrophic lake with frequent cyanobacterial blooms,and the widely distributed PAHs will be chosen to investigate the effects of algal blooms on the distribution, bioaccumulation and trophic transfer of PAHs in Lake Taihu. Effects of the stages of algal blooms (pre algal bloom, algal bloom and post algal bloom) on the distribution, bioaccumulation and trophic transfer of PAHs in Lake Taihu will be explored. The magnitude of algal blooms on the distribution, bioaccumulation and trophic transfer of PAHs in Lake Taihu will also be investigated. Effects of algal bloom on the distribution, bioaccumulation and trophic transfer of PAHs in different bays with various ecosystems of Lake Taihu will be explored as well. Major water parameters, communities of phytoplankton, zooplankton and fish, trophic position of the organisms, and bioconcentration factor (BCF), bioaccumulation factor (BAF) and trophic magnification factor of PAHs will be analyzed. Principal component analysis and multivariate stepwise regression analysis will be used to elucidate the major factors on the distribution, bioaccumulation and trophic transfer of PAHs during the different stages of algal blooms. The related mechanisms will be investigated as well. This study will elucidate the correlation between algal bloom and POPs. It will help understand the side effects of algal blooms. It will also provide new knowledge to manage large shallow eutrophic lakes such as Lake Taihu.

藻类水华与POPs污染是国内外众多湖泊正面临的两大环境问题，目前关于二者之间的耦合关系认识极少。本项目拟选取蓝藻水华频发的大型浅水富营养化湖泊太湖为研究对象，以在太湖中分布广泛、来源稳定、风险较大的多环芳烃（PAHs）为目标污染物，通过重要水质参数的监测、水体不同介质中PAHs分布剖析、生物群落结构分析、生物营养级测定、生物富集因子及食物链放大因子等的计算，结合主成分分析及多元逐步回归分析等统计手段，探索蓝藻水华形成、暴发及衰退不同时期以及蓝藻水华暴发强度对太湖藻华频发湖区PAHs的赋存、生物富集及其在浮游食物链传递的影响，揭示蓝藻水华暴发对太湖不同生态系统湖区PAHs主要生物地球化学过程的影响差异，阐明太湖蓝藻水华对PAHs主要生物地球化学过程的影响机制，揭示藻类水华与POPs主要生物地球化学过程之间的耦合关系，补充对藻类水华次生危害的认识，为太湖等富营养化湖泊的综合治理提供理论依据。

藻类水华与POPs污染是国内外众多湖泊正面临的两大环境问题，关于二者之间的耦合关系认识极少。本项目选取了蓝藻水华频发的大型浅水富营养化湖泊太湖为研究对象，以在太湖中分布广泛、来源稳定、风险较大的多环芳烃（PAHs）为目标污染物，通过对春季、夏季及冬季全湖大气、水体、浮游生物及表层沉积物中多环境指标的同步监测，揭示了富营养化对水体POPs的大气-水界面交换通量、沉降通量及其在表层沉积物和水体中赋存的间接影响机制；长期富营养化显著增加了水体pH值，降低了沉积物有机质和溶解有机质的芳香性以及藻类细胞表面的疏水性，因而降低了沉积物、溶解有机质及藻类对PAHs的富集，降低了PAHs的沉降通量及在表层沉积物中的富集，但增加了整个水体PAHs的总浓度和自由溶解态浓度，进而促进了各季节大气-水界面PAHs的挥发；因藻类水华漂浮于水体表面，沉降的有机质比例随藻类生物量增大而降低，因此PAHs沉降通量及每日沉降量随藻类生物量增大而降低；水柱中PAHs年均浓度随湖泊年均营养状态指数及年均藻类生物量增加；PAHs在浮游生物中的富集随其疏水性增加，PAHs从藻类向浮游动物的传递因子随营养状态指数降低，生物放大效应仅出现在藻类水华期间。本项目首次研究了富营养化对POPs地球化学过程的间接影响，率先发现蓝藻水华间接影响超越了生物泵效应，为生物泵理论提供重要补充。增加了对富营养化与POPs耦合关系的认识以及富营养化间接危害的认识。