太湖蓝藻水华“暴发”的动态特征及其机制  

Dynamics of variability and mechanism of harmful cyanobacteria bloom in Lake Taihu, China

作　　者：秦伯强[1] 杨桂军[2] 马健荣[1,3] 邓建明[1] 李未[1] 吴挺峰[1] 刘丽贞[1,4] 高光[1] 朱广伟[1] 张运林[1] 

机构地区：[1]中国科学院南京地理与湖泊研究所,南京210008 [2]江南大学环境与土木工程学院,无锡214122 [3]中国科学院重庆绿色智能技术研究院三峡生态环境研究所,重庆400714 [4]江西省科学院鄱阳湖研究中心,南昌330096

出　　处：《科学通报》2016年第7期759-770,共12页Chinese Science Bulletin

基　　金：国家自然科学基金(41230744;41471021);国家重大科技专项(2012ZX07101-010);中国科学院重大交叉项目(KZCX2-YW-419)资助

摘　　要：湖泊富营养化和有害藻类水华是目前全世界普遍面临的水域生态环境问题.太湖是典型的大型浅水富营养化湖泊,其富营养化导致的蓝藻水华"暴发"常常呈现时间和空间上的高度变异与不稳定性.以往的研究,无论是国际上流行的光合作用调节的藻类细胞上浮与下沉,还是国内流行的蓝藻水华"暴发"四阶段理论,都无法很好地解释太湖蓝藻水华"暴发"的时空动态变化特性.本文基于对太湖多次的野外观测与模拟实验,提出了关于太湖蓝藻水华"暴发"的全新概念性解释.在蓝藻细胞生长阶段,营养盐、温度、光照等环境因素影响较为显著,决定了蓝藻生物量的多少,为蓝藻水华"暴发"蓄积物质基础;在蓝藻水华暴发阶段,则主要受蓝藻细胞(团)浮力作用与水动力湍流作用的共同影响,决定了蓝藻水华出现后的规模、范围及位置.野外调查显示,在太湖这样的大型浅水湖泊,风浪作用条件下蓝藻细胞(团)在水柱中呈均匀分布;而当风浪消失后,蓝藻细胞(团)即迅速上浮形成水体表面可见的水华.蓝藻颗粒的上浮速度随着细胞团的增大而加快,适度的扰动促使蓝藻细胞团碰撞而形成更大的细胞团,更容易在水动力消失后快速上浮形成水华.湖流的辐合辐散是蓝藻水华上浮后形成可见的斑块形状、位置、漂移和聚集的决定因素.正是太湖地区风场高度多变与不稳定,才导致太湖蓝藻水华"暴发"的时空分布呈现多变的动态特征.上述研究结果澄清了长期以来一直困扰人们的太湖蓝藻水华难以监测、无法防控的问题,为蓝藻水华监测、预测预警、防控及应对措施的制定提供了科学的理论依据.Eutrophication of lakes and harmful algae blooms are recently widespread water ecological environmental issues all over the world. Lake Taihu is a typical large shallow and eutrophic lake, and the cyanobacteria blooms induced by eutrophication have always been presenting high spatial-temporal variability and instability that made it very difficult to monitor and predict. Many previous publications have related to the eutrophication and cyanobacteria bloom with the most attention paid to phytoplankton growth, biomass increase and dominant species, while a few works addressed the appearance/disappearance of cyanobacteria bloom; however, none of them could explain the swift shift of cyanobacteria bloom in time and space in Lake Taihu. Based on the long-term field observation data and simulation experiments in Lake Taihu, here we presented a physical process controlled cyanobacteria bloom formation mechanism. In Lake Taihu, the visible cyanobacteria bloom occurrence was mainly controlled by the hydrodynamic intensity. When the cyanobacteria biomass accumulated in the water column, the large size colonies would increase during the process of cell division and proliferation, cells and colonies collisions, colonies aggregation （due to the stick extracellular polysaccharides） and disaggregation （due to the intensive turbulence）. The bloom would occur if the wind influence decline and the colonies suspended at water column were able to float to the water surface to form bloom and scum. These colonies floating at the surface couldnot migrate downward because of the large size and great buoyancy; furthermore, they would drift to the downwind zone. But even the hydrodynamic process played the key role in the cyanobacteria bloom formation in this large shallow lake; it couldnot exclude the existence of other dynamics determining the cyanobacteria bloom formation. During the calm weather periods, the light controlled colonies diurnal migration, the zooplankton predation induced colony formation, and toxic materials ind

关 键 词：太湖 蓝藻生长 微囊藻细胞团 水华暴发 水动力 概念性模式 

分 类 号：X524[环境科学与工程—环境工程]