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| 2019~2023年洪湖水生态环境时空变化特征及原因解析 |
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张潇文1, 彭雪1, 邓兆林2, 葛芳杰1, 张浩坤1, 王宁俊2, 方梦婕1, 熊玙璠1, 张璐1, 李霞1, 张淑娴1, 吴振斌1, 刘碧云1
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1.中国科学院水生生物研究所;2.荆州市洪湖湿地自然保护区管理局
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| 摘要: |
| 在长江大保护和国际湿地保护背景下，为探究洪湖水生态环境变化特征及原因，本研究于2019年~2023年间对洪湖水质、沉积物参数、沉水植物盖度和浮游植物生物量开展4次野外调查研究。结果发现，（1）调查期间洪湖水体透明度（SD）逐年降低，退垸施工期间洪湖水体SD呈现从中南湖心区域向岸边递减变化特征；（2）洪湖水环境营养盐污染水平较高，水体总氮（W-TN）和氨氮（NH4+-N）浓度整体虽呈下降趋势，但水体总磷（W-TP）平均浓度从（0.06±0.04）mg/L升高至（0.19±0.06）mg/L，沉积物总磷（S-TP）含量升高32 %，S-TN、S-TP含量表现出退垸期间减少、退垸后增加变化特征。空间分布上，洪湖W-TN、W-TP浓度均呈现从西北区域四湖总干渠入湖口向东南方向递减趋势；（3）洪湖水生态系统退化趋势明显，2019年4月洪湖分布有菹草（Potamogeton crispus?L.）、穗花狐尾藻（Myriophyllum spicatum?L.）和金鱼藻（Ceratophyllum demersum?L.）等沉水植物，2020年10月调查结果显示敞水区沉水植物基本消失，叶绿素a（Chl a）平均浓度由（13.92±7.74）μg/L升高至（62.64±19.52）μg/L，并以丝状蓝藻为优势种。主成分分析显示，TN和TP始终是影响洪湖水生态环境状况的主要驱动因素，SD于2023年5月成为洪湖新增关键影响因子。上游来水污染、退垸后水动力过程导致围垸内污染物迁移以及风浪对底质扰动等是驱动洪湖水生态环境变化的重要原因。研究结果为洪湖的生态恢复提供理论和数据支撑。 |
| 关键词: 洪湖 水生态环境状态 时空分布 退垸还湖 |
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| 基金项目:国家自然科学基金项目（32171632，32101374）和湖北省生态环境厅科研项目“洪湖水生态健康现状及水华预警”（2023ZHB-001）资助。 |
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| Research on spatio-temporal Characteristics and causes of the aquatic environmental changes in Honghu Lake from 2019 to 2023 |
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Zhang Xiaowen,Peng Xue,Deng Zhaolin,Ge Fangjie,Zhang Haokun,Wang Ningjun,Fang Mengjie,Xiong Yufan,Zhang Lu,LI Xia,ZHANG Shuxian,Wu Zhenbin,Liu Biyun
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Institute of Hydrobiology, Chinese Academy of Sciences
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| Abstract: |
| In the context of the Yangtze River Conservation and international wetland protection, this study investigated the characteristics and causes of changes in the aquatic environment of Honghu Lake. Four field surveys were conducted from 2019 to 2023, focusing on water quality, sediment parameters, submerged plants coverage and phytoplankton biomass. The results showed that, (1) During the survey period, the average water secchi disk (SD) of Honghu Lake decreased year by year, and SD showed a decreasing trend from the center to the shores during the construction period of the returning embankments to lakes; (2) The level of nutrient pollution in the water environment of Honghu Lake remained high. Although the concentration of total nitrogen (W-TN) and ammonia nitrogen (NH4+-N) in the water body showed an overall decrease, the average total phosphorus concentration in the water (W-TP) increased from (0.06±0.04) mg/L to (0.19±0.06) mg/L. Total phosphorus (S-TP) in the sediment increased by 32%, while S-TN and S-TP level decreased during the embankment removal period, and increased afterward. Spatially, W-TN and W-TP levels showed a decreasing trend from the northwestern inlet of the Four Lakes Main Canal to the southeast; (3) The degradation of aquatic ecosystems of Honghu Lake was observed. Submerged plants such as Potamogeton crispus L., Myriophyllum spicatum L. and Ceratophyllum demersum?L. were present in April 2019, but had almost disappeared by Octorber 2020 in the open-water area. The average concentration of chlorophyⅡ-a (Chl a) increasd from (13.92±7.74) μg/L to (62.64±19.52) μg/L, dominated by filamentous cyanobacteria. Principal component analysis showed that TN and TP as consistent primary drivers of the aquatic environment changes, and SD emerging as a key factor in May 2023. Pollution from upstream water sources, hydrodynamic processes following embankment removal causing pollutant migration within the embanked areas, and wind and wave disturbances affecting the sediment were key factors driving changes in the aquatic environment of Honghu Lake. The results of this study will aid in developing more effective conservation and restoration measures. |
| Key words: Honghu Lake status of aquatic ecological environment spatio-temporal variation Returning embankments to lakes |
