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| 太湖水质达III类背景下藻情与水质变化特征分析 |
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朱广伟1, 国超旋1, 康丽娟2, 陶陶1, 杨芷萱3, 李娜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;2.巢湖学院;3.西华师范大学
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| 摘要: |
| 根据生态环境部设在太湖的17个国考断面周年监测， 2024年太湖水体总磷浓度年均值低于0.05 mg/L，是自2007年太湖大规模治理以来首次达到III类。为揭示太湖总磷浓度下降的生态环境背景与机制，基于太湖湖泊生态系统研究站2005~2024年的长期监测数据，分析了太湖水体总磷浓度与藻情、气象水文条件及其他营养盐之间的协同变化特征。分析发现，2024年太湖总磷浓度低值的出现与2022年以来蓝藻水华强度下降、外源氮磷入湖负荷下降密切相关，特别是2023年蓝藻水华强度显著偏低，惯性延续导致2024年上半年藻情极轻，对全年水体磷浓度低值的出现具有重要的影响；2024年下半年太湖藻情有明显反弹，8月时水体蓝藻生物量明显增加，与2024年度降雨量大、外源氮、磷负荷增高有关。此外，2024年10~12月蓝藻水华面积大幅增加，但同期水体藻类生物量、叶绿素a浓度的反弹幅度明显较小，表明2024年秋冬季气温偏暖、入湖水量较大引起的藻颗粒表层聚积条件良好等气候背景放大了蓝藻水华的表观强度。研究表明，外源氮磷负荷下降对太湖蓝藻水华强度有重要的遏制作用，但气温、降雨、风浪等气候条件对蓝藻水华表观强度仍然有重要的影响；在蓝藻水华控制策略上，应进一步加强外源氮、磷入湖负荷削减，以稳定太湖水质改善成果，并加强对局部湖区草型生态系统恢复的工程引导湖体生态恢复，以推动太湖水环境的进一步改善。 |
| 关键词: 磷，氮磷双控，外源削减，蓝藻水华，气候变化 |
| DOI： |
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| 基金项目:江苏省自然科学基金（BK20220041）、国家自然科学基金国际合作项目（42220104010）、中国科学院南京地理与湖泊研究所自主部署项目（NIGLAS2022GS03） |
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| Dynamics of cyanobacterial bloom and water quality in Lake Taihu under class III water quality achieved in 2024 |
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Zhu Guangwei,Guo Chaoxuan,Kang Lijuan,Tao Tao,Yang Zhixuan,Li Na,Qin Boqiang
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| Abstract: |
| According to the whole year total phosphorus (TP) monitor data from 17 national water quality monitor sites in Lake Taihu, class III level of TP, or TP concentration was lower than 0.05 mg/L, was achieved since 2007. To clarify the simultaneous environmental and ecological variation with the decrease of TP, long-term variation of observatory data were analyzed using ecological monitoring data of Taihu Laboratory for Lake Ecosystem Research (TLLER) during 2005 to 2024. It was found that the low external loadings of TP and total nitrogen (TN) and low intensity of Microcystis bloom during 2022 to 2023 provided an important foundation for the low TP in 2024. The inertia of low bloom intensity of 2023 result in extreme low bloom intensity in first half year of 2024, further caused relatively low yearly average of TP in 2024. In the other hand, the increase of bloom intensity during the second half year of 2024 was also owing to the increasing of external loading of TP and TN, as well as the extreme high autumn rainfall and air temperature. Moreover, the abnormal large area of bloom area during November and December in 2024 was inconsistent to Chlorophyll a concentration and cyanobacterial biomass indicators. It suggested that the higher rainfall and warmer air-temperature amplified the apparent bloom intensity. This research indicated that external TP and TN loading reduction could significantly suppressed the bloom intensity in Lake Taihu. While the climatic conditions, such as temperature, rainfall, wind wave still can significantly affect the bloom intensity. To keep the good condition of water quality, further external loading reduction of TN and TP was still need. Furthermore, ecological restoration of macrophytes in certain lake zone were necessary to improve water quality under the golden opportunity of low nutrient concentration. |
| Key words: phosphorus dual-control of nitrogen and phosphorus external loading reduction cyanobacterial bloom ecological restoration. |
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