title: Meteorological and hydrological conditions driving the formation and disappearance of black blooms, an ecological disaster phenomena of eutrophication and algal blooms.
abstract: Potentially toxic black blooms can disrupt drinking water treatment plants and have fatal effects on aquatic ecosystems; therefore, lake management is required to determine whether conditions are favorable for the formation and disappearance of black blooms in water supply sources. Long-term climate background, short-term thresholds of meteorological and hydrological conditions, and the duration of harmful algal blooms (HABs) were investigated as factors affecting the formation and disappearance of black blooms in hyper-eutrophic Lake Taihu. Long-term climate warming (0.31°C/decade), decreases in wind speed (0.26m/s per decade) and air pressure (0.16hPa/decade), and the increase in the meteorological index of black blooms (3.6days/decade) in Lake Taihu over the past 51years provided climate conditions conducive to the formation and occurrence of black blooms. A total of 16 black bloom events with an area larger than 0.1km(2) were observed from 2007 to 2014. Several critical thresholds for short-term meteorological and hydrological conditions were determined for the formation of black blooms, including a five-day average air temperature above 25°C, a five-day average wind speed <2.6m/s, average precipitation of five consecutive days close to 0, and continuous HAB accumulation for >5days. Heavy precipitation events, sudden cooling, and large wind disturbances were the driving factors of black blooms' disappearance. The use of a coupling model that combines the remote sensing of HABs with environmental, meteorological, and hydrological observations could permit an adequate and timely response to black blooms in drinking water sources.
authors.affiliation: Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China. Electronic address: ylzhang@niglas.ac.cn.
authors.forename: Yunlin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Shi
authors.affiliation: Jiangsu Hydrology and Water Resources Investigation Bureau, Nanjing 210029, China.
authors.forename: Junjie
authors.initials: J
authors.lastname: Liu
authors.affiliation: Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Jianming
authors.initials: J
authors.lastname: Deng
authors.affiliation: Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Boqiang
authors.initials: B
authors.lastname: Qin
authors.affiliation: Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Guangwei
authors.initials: G
authors.lastname: Zhu
authors.affiliation: Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Zhou
mesh_terms: D002681:China; D057231:Climate Change; D004190:Disasters; D004784:Environmental Monitoring; D057097:Harmful Algal Bloom; D062070:Hydrology; D060106:Lakes / Q000737:chemistry*
keywords: Air temperature; Black blooms; Harmful algal blooms; Lake Taihu; Meteorological and hydrological conditions; Precipitation; Wind speed