珠江口周丛生物功能群对农药-重金属复合污染的响应机制

Estuary can be seen as a transition type between the freshwater habitats and marine habitats, Ecotones. It has unique physical and chemical characteristics and biological characteristics, which known as “one of nature's most productive ecosystems.” Periphyton as a key fundmental structure and function of aquatic ecosystems，plays a vital role of energy flowing, material circulation and information transfer in aquatic ecosystems. Changes of the periphyton community structure will directly affect the structure and function of estuarine ecosystems, thereby affecting the function of the estuary ecosystem. Generally, the periphyton is sensitive to environmental changes, and the changes in its community is often considered environmental assessment of water quality and aquatic ecosystems is an important key health indicators. Thus, the research on monitoring and evaluation of biology science in periphyton provides the basic support for estuarine water policy formulation, water resources management and protection and aquatic conservation..The research topic is going to make the Pearl River estuary ecosystem as the research field, and set the periphyton with strong sensitivity and community - level indication was taken as the research object. First of all, the study will get hold of the pesticide residues, heavy metals compound pollution levels and trends in periphyton succession through ecological surveys. Secondly, the subject will divided periphyton community structure into different functional groups by combining used environmental metagenomic method. Afterwards, the research shall design and build Microcosm/Mesocosm simulation system of estuarine ecosystems. To carry out Microcosm/Mesocosm scale estuarine ecosystem level simulation experiments, typical of pesticides-heavy metal target contaminants of typical pesticide Eco-toxicological effects of heavy metals contamination at different levels of the estuary periphyton functional groups. At the same time, the sensitivity and tolerance of Periphyton different functional groups were studied from the population level and community level in the Microcosm/Mesocosm scale model. The response of important functional groups to pesticide-heavy metal compound pollution Variety. The mechanism of pesticide-heavy metal pollution in the tropical and subtropical estuaries of China was discussed.

河口湾是自然界生产力最高的生态系统之一，周丛生物作为水域生态系统结构和功能的关键环节，在水域生态系统的能量流动、物质循环和信息传递中起着至关重要的作用。对周丛生物科学监测与评估研究，对河口水政策制定、水资源管理与保护和水生态保育提供基础支撑。申请课题以珠江口生态系统作为研究水域，以敏感性强、具有群落级指示功能的周丛生物为研究对象，通过野外监测、结合环境宏基因组学研究方法划分周丛生物功能群。设计并建立流水-稀释型微宇宙/中宇宙尺度系统，开展模拟河口生态系统实验，以典型农药-重金属为目标污染物，研究典型农药-重金属复合污染在不同梯度对河口周丛生物功能群的生态毒理效应。同时，从种群级、群落级研究周丛生物功能群对不同污染水平的敏感性、耐受度，研究重要功能群对农药-重金属复合污染条件下的响应变化。从而揭示我国热带亚热带河口地区农药-重金属复合污染对周丛生物功能群的毒害胁迫及其受胁后的响应机制。

准确评估周丛生物群落及其受农药残留、典型重金属的影响对科学监测与评估珠江口生态系统具有重要意义，是探讨复合污染对我国热带亚热带河口周丛生物功能群与河口湾初级生产力影响的重要方式。本研究通过野外生态调查与环境宏基因组分析，评估珠江口农药残留、重金属污染水平，掌握周丛生物生态状况，为周丛生物群落评估河口生态系统提供科学依据。主要研究结论如下：（1）珠江口的DO含量水平由西向东依次递减，深圳西岸沿海的含量最低为5.7-6.0mg/L，悬浮物由西向东浓度含量依次递减，水质为弱碱性，以珠海淇澳岛为中心，北部地区和南部地区的碱性较强为8.65-8.93，其余地区相对较弱为8.35-8.6；西江河口内的水体污染程度较河口外水域严重。（2）溴氰菊酯、多氯联苯、六六六指标良好；氰菊酯整体呈北部高其余地区低的趋势，含量最高的点位位于洪奇沥水道与横门水道交汇处，为0.011μg/L；甲氰菊酯整体上呈西南高东北低的趋势，含量较高的站位位于崖门出海口和磨刀门出海口，为0.033-0.045μg/L；滴滴涕整体呈西北高东南低的趋势，含量最高的站位位于洪奇沥水道与横门水道交汇处和崖门出海口，为0.45-0.59ug/L。（3）总铬的含量为0.7-24.64μg/L，均值为5.7±7.12μg/L，未超过第二类海水水质标准50μg/L，水质情况较好；Cu的含量为0.7-20.66μg/L，均值为2.73±3.89μg/L，最大值超过第三类海水水质标准50μg/L，水质情况一般；Pb含量均值为0.7±0.92μg/L，最大值未超过第二类海水水质标准，水质情况较好；其余指标均未超Ⅰ类海水水质标准。（4）共检出浮游植物8门47属67种，丰度在34.4×104~267.6×104ind./L；检出浮游动物20种，丰度在100ind./L-380ind./L。（5）深圳湾因氮、磷等营养物质不断累积，其富营养化问题尤为突出，对生物功能群带来了严重影响，直接导致2020年12月-2021年1月珠江河口深圳湾出现罕见的大规模球形棕囊藻赤潮，球形棕囊藻胶质囊最大密度 46 ind./L。（5）周丛生物类群中，浮游生物占据优势地位。浮游植物是食物链的基础环节，浮游动物在有机物质的循环和分解环节起着重要的作用，监测结果发现珠江口浮游生物组成较为丰富，研究其与环境因子的关系是粤港澳大湾区开展水生态保护与修复的生态之基。