大气沉降对太湖浮游植物初级生产力及群落结构的影响研究

Atmospheric deposition is an important nutrient input in the process of lake eutrophication. Atmospheric deposition of nitrogen in Lake Taihu has been exceeded the theory allowed level. Long-term and high-level load of Atmospheric deposition of nitrogen would lead to changes in phytoplankton community structure and function, thus affecting the ecosystem structure of Lake Taihu. Moreover, atmospheric deposition of total nitrogen concentration has exceeded the 2.0mg/L, and this uncontrollable factor has become a scientific challenge of water quality protection Lake Taihu.Study on the influence of atmospheric deposition on Lake Taihu ecosystem will help the comprehensive understand of Lake Taihu eutrophication.Based on field monitoring surround the lake, we will evaluate the influence of atmospheric deposition on ecosystem of Lake Taihu, which will help to understand the mechanism of form of algae bloom in Lake Taihu and its impacts on lake primary productivity; mutual effects of atmospheric deposition on water of physical, chemical and the biotic process will also be studied by using in situ enclosure experiments to reveals the key factors of planktonic communities succession and bloom forming. The current research will provide theoretical basis for early-warning of cyanobacteria bloom and comprehensive management in Lake Taihu.

大气沉降是湖泊富营养化过程中重要的外源输入途径之一。太湖大气氮沉降量已经远超过太湖湖泊生态系统理论允许值。长期的高负荷大气氮沉降将导致水体浮游植物的群落结构和功能发生改变，从而影响太湖湖泊生态系统的结构。此外大气沉降总氮背景值已超过2.0mg/L的限值，这一不可控因素也成为科学确定太湖水质保护目标的难题。探讨大气氮、磷沉降输入对太湖生态系统的影响，对于全方位把握太湖富营养化影响机制有重要意义。本研究以太湖为研究区域，在蓝藻水华暴发期，通过太湖湖体原位现场围隔试验，捕捉典型降雨事件，研究整个沉降过程对水体的物理、化学及生物诸过程的相互影响，揭示大气沉降过程对太湖浮游植物种群演替的影响机制；通过环太湖定点野外调查，把握大气沉降输入对太湖富营养化的贡献，解析其对太湖浮游植物初级生产力水平的影响。为太湖富营养化综合管理研究提供理论依据。

大气沉降是湖泊富营养化过程中重要的外源输入途径之一。太湖大气氮沉降量已经远超过太湖湖泊生态系统理论允许值。长期的高负荷大气氮沉降将导致水体浮游植物的群落结构和功能发生改变，从而影响太湖湖泊生态系统的结构。本文针对太湖大气湿沉降氮、磷营养盐特征及其对浮游植物的影响这一核心问题展开研究。分析了环太湖大气湿沉降氮、磷营养盐的组成、时空分布特征，计算了氮、磷营养盐的湿沉降率和入湖负荷贡献等。其次，在太湖蓝藻水华暴发早期，于太湖西部沿岸进行了密集的原位调查实验，跟踪调查了几次降雨的前、中、后过程中湖体水质的变化，分析了短期湿沉降对太湖水体浮游植物造成的综合影响，并利用GAM模型拟合了湿沉降前后水体叶绿素a含量变化与环境因子的关系，明确了影响叶绿素a含量的变化的关键环境因子。最后，在太湖西部沿岸设置了围隔装置，进行了原位围隔实验。在当地蓝藻水华暴发期，捕捉典型规模的降雨，监测并对比了降雨前后湖泊围隔内水体温度、营养盐浓度及浮游藻类群落的变化，分析了湿沉降对湖泊水质及藻类群落的影响。相关结论为太湖富营养化综合管理研究提供理论依据。