| 引用本文: | 康丽娟,朱广伟,邹伟,朱梦圆,国超旋,许海,肖曼,李娜,张运林,秦伯强.高温干旱背景下太湖藻情变化特征及机制.湖泊科学,2023,35(6):1866-1880. DOI:10.18307/2023.0611 |
| Kang Lijuan,Zhu Guangwei,Zou Wei,Zhu Mengyuan,Guo Chaoxuan,Xu Hai,Xiao Man,Li Na,Zhang Yunlin,Qin Boqiang.Dynamics and mechanism of cyanobacterial blooms in Lake Taihu reacted extreme drought and warming. J. Lake Sci.2023,35(6):1866-1880. DOI:10.18307/2023.0611 |
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| 高温干旱背景下太湖藻情变化特征及机制 |
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康丽娟1,2, 朱广伟1,2, 邹伟1, 朱梦圆1, 国超旋1, 许海1, 肖曼1, 李娜1, 张运林1, 秦伯强1
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1.中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008;2.中国科学院大学, 北京 100049
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| 摘要: |
| 2022年我国长江流域经历了长期的高温干旱,对湖泊水生态环境和湖内藻情态势产生了深远影响。但目前关于干旱环境下湖泊水华的响应特征研究较少。以太湖为例,基于2005—2022年湖体营养盐与叶绿素a浓度的长期监测数据,结合卫星遥感影像反演的蓝藻水华面积变化,探讨了2022年高温干旱对太湖蓝藻的影响特征及驱动机制。结果表明,2022年蓝藻水华高发季节(5—9月),太湖蓝藻水华的平均面积和最大面积均明显下降,其中5月的水华面积仅为近5年同期平均面积的20%;水样采集分析获得的水体叶绿素a浓度和微囊藻生物量在春季也明显下降。营养盐方面,2022年太湖的总氮和总磷均值分别为1.41和0.084 mg/L,较近5年均值分别下降了30.6%和27.3%,均为2005年以来的最低值。氮磷浓度空间分布的克里金插值显示,除西北湖区(竺山湾)受河流入湖影响外,大部分湖区的溶解态氮磷也都处于较低状态,冬季溶解性总磷浓度小于0.02 mg/L 的水域面积占全湖面积的79%。随机森林分析表明,总磷、水温和风速是影响春季微囊藻和藻类生物量的关键因子。冬季湖体磷水平低,加上春季外源负荷较少,致使2022年春季太湖大范围湖区磷浓度较低,对微囊藻的生物量产生了限制作用。此外,在随后夏季连续高温的背景下,太湖蓝藻水华面积虽然发生了反弹,但并未明显高于往年,这与极端干旱导致外源磷补给低、湖体仍能维持大范围低氮低磷条件有关。综上表明,目前太湖部分湖区的藻类生物量对氮磷浓度变化敏感,外源营养盐负荷开始对蓝藻水华情势产生调控作用。坚持外源负荷削减,关注湖泊氮磷内源效应,调控湖体的生态系统结构,是有效降低太湖蓝藻水华强度,应对未来多变气候带来生态风险的重要途径。 |
| 关键词: 干旱 太湖 蓝藻水华 营养盐限制 外源负荷 |
| DOI：10.18307/2023.0611 |
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| 基金项目:中国科学院战略性先导科技专项(A类)(XDA23040201)、江苏省水利科技项目(2020004)、国家自然科学基金青年项目(42107078)和中国科学院南京地理与湖泊研究所自主部署项目(NIGLAS2022GS03)联合资助。 |
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| Dynamics and mechanism of cyanobacterial blooms in Lake Taihu reacted extreme drought and warming |
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Kang Lijuan1,2, Zhu Guangwei1,2, Zou Wei1, Zhu Mengyuan1, Guo Chaoxuan1, Xu Hai1, Xiao Man1, Li Na1, Zhang Yunlin1, Qin Boqiang1
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1.State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, P.R. China;2.University of Chinese Academy of Sciences, Beijing 100049, P.R. China
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| Abstract: |
| The Yangtze River Basin experienced long-term drought and extreme warming in 2022, which substantially affected the water quality, aquatic ecosystem in lakes, and altered the dynamics of algae. By now, little research has focused on the impact of drought events on cyanobacterial blooms. This study analyzed the characteristics of cyanobacterial blooms and the key drivers in Lake Taihu in 2022, based on the long-term monitoring data (2005-2022) of nutrient and chlorophyll-a (Chl.a) concentrations in the lake, combined with the cyanobacteria bloom area interpreted from remote sensing images. The results showed that the average area and maximum area of cyanobacteria bloom in Lake Taihu decreased significantly in 2022 during the bloom season (May to September), with the bloom area in May only occupying 20% of the average of the past five years. The concentration of Chl.a and Microcystis biomass obtained by water sample collection also showed a downward trend in May. For nutrients, the average total nitrogen and total phosphorus were 1.41 mg/L and 0.084 mg/L, respectively, in Lake Taihu in 2022, which decreased by 30.6% and 27.3% compared with the average of the past five years, and the lowest values since 2005. The results of kriging interpolation revealed that in February, the majority of lake areas exhibited low concentrations of dissolved nitrogen and phosphorus, except for the estuarine region of Zhushan Bay. Specifically, in 79% of the lake area, the total dissolved phosphorus concentration was less than 0.02 mg/L. The random forest analysis showed that total phosphorus, water temperature, and wind speed were the key factors that influenced the biomass of Microcystis and algae in May. The decline of phosphorus levels and inadequate external loading during the spring season resulted in low concentrations of phosphorus spread widely across the lake, which restricted the growth of Microcystis in 2022 spring. Additionally, in the context of extremely high temperatures in summer, the cyanobacterial blooms had not expanded significantly, which was attributed to the reduction of external loading due to the extreme drought maintained the low nutrients in most regions of the lake. The results showed that the sensitivity of algal biomass to nutrient dynamics had emerged in a large area of Lake Taihu and highlighted the regulating role of external loading. It is crucial for controlling the bloom intensity under the changeable climates in the future through persistently reducing the external input, paying attention to the internal loading, and regulating the ecosystem structure in the lake. |
| Key words: Drought Lake Taihu cyanobacterial blooms nutrient restriction external loading |
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