| 摘要: |
| 滆湖作为新型通江湖泊，是太湖流域湖西地区重要的行蓄洪湖泊和新孟河引江济太的重要通道，滆湖治理是新一轮太湖治理的重要内容。为探究滆湖水体和沉积物中氮、磷污染状况，及沉积物内源污染释放风险，在全湖设置13个采样点位进行调查，并通过静态释放培养法模拟实验分析沉积物氮、磷的释放规律和释放效应。结果表明：（1）滆湖水体的总氮（1.43±0.27 mg/L）和总磷（0.12±0.06 mg/L）含量处于Ⅳ类水范围内，开发利用较大的北部湖区污染程度较重，空间上由北向南污染降低；（2）现阶段沉积物总氮（1.38±0.44 mg/g）和总磷（0.34±0.07 mg/g）的综合评价指标显示全湖沉积物氮磷整体处于轻度污染水平，污染区域主要集中在北部滆湖旅游点附近、湖心区，以及靠近太滆运河、漕桥河和殷村港的出湖河口的区域，泥沙在该区域可能有淤积，表层沉积物更疏松、偏软，抗剪切能力小，泥沙输移和内源释放潜力较大；（3）沉积物存在内源氮磷释放的风险，释放效应集中在前48h，沉积物中的氮主要影响上覆水中硝态氮的含量，磷存在正磷酸盐的释放和颗粒态有机磷的解吸附，湖心处和南部湖区是内源污染的重要区域。因此，在滆湖未来生态治理和引水工程中，应着重关注湖心及出湖河口处表层沉积物的迁移输运和淤积，这些区域也应是阶段性生态清淤工作的重点。研究结果为深入了解滆湖、改善滆湖生态环境和长三角太湖流域环境保护，以及优化新孟河调水工程实施提供参考。 |
| 关键词: 滆湖 沉积物性质 内源污染 氮磷释放 |
| DOI： |
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| 基金项目:国家自然科学基金长江水科学研究联合项目（U2240208）、江苏省碳达峰碳中和科技创新专项（BK20220043）、中科院科研仪器设备研制项目（YJKYYQ20190050） |
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| Study on the distribution and release characteristics of endogenous pollutants in sediments of Lake Gehu, a new river-connected lake |
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Zhao zheng1, Qian Shuyu2, Bai leilei1, Wang chunliu1, Jiang He-long1
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1.State Key Laboratory of Lake Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Science,Nanjing ,PRChina;2.State Key Laboratory of Lake Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Science,Nanjing ,P.R.China/School of Environment Science and Engineering, Naniing University of Information Science and Technology, Naniing, P.R.China
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| Abstract: |
| As an emerging river-lake connection, Lake Gehu serves as an important flood detention reservoir and a vital conduit for the Xinmeng River diversion project in the western region of the Lake Taihu basin. The management of Lake Gehu constitutes an essential component of the latest round of Lake Taihu governance. 13 sampling were set up to investigate the nitrogen (N) and phosphorus (P) pollution status of water and sediment in Lake Gehu, as well as the risk of internal pollutant release from sediment. Cultivation experiments were employed to analyse nitrogen and phosphorus release patterns and effects. The findings indicate the following: (1) At present, the concentrations of TN (1.43±0.27 mg/L) and TP (0.12±0.06 mg/L) in the water are within the Class Ⅳ range. The pollution intensity is higher in the heavily developed northern lake region, with pollution decreasing spatially from north to south. (2) Currently, the comprehensive evaluation indices of TN (1.38±0.44 mg/g) and TP (0.34±0.07 mg/g) in sediment indicate that the entire lake is mildly polluted. Pollution is mainly concentrated in the northern tourist areas of Lake Gehu, the central region, and the areas near the outlets of Taige Canal, Caoqiao River, and Yincun Port. Sediments in these areas may be prone to siltation, with surface sediments being loose, soft, and having low shear strength. This suggests a higher potential for sediment transport and endogenous release. (3) There is a risk of endogenous nitrogen and phosphorus release from sediments, with the release effects concentrated in the first 48 hours. N in the sediments primarily affects the NO3- content in the overlying water, while P is released as PO43- and through the desorption of particulate organic P. The central and southern regions of the lake are critical areas for endogenous pollution. Therefore, in future ecological management and water diversion projects of Lake Gehu, special attention should be paid to the migration, transport, and deposition of surface sediments in the lake center and outlet area. These areas should also be the focus of phased ecological dredging efforts. Those findings provide a reference for an in-depth understanding of Gehu Lake, improving its ecological environment, protecting the environment of the Lake Taihu Basin in the Yangtze River Delta, and optimizing the implementation of the Xinmeng River water diversion project. |
| Key words: Lake Gehu Sediment characteristic Internal pollution Nitrogen, phosphorus static release |
