| 引用本文: | 李一凡,谷孝鸿,曾庆飞,贾冰婵,訾鑫源,陈辉辉,毛志刚,葛优.1990—2021年东太湖网围养殖规模变化下的水质变化特征及成因分析.湖泊科学,2023,35(1):155-167. DOI:10.18307/2023.0110 |
| Li Yifan,Gu Xiaohong,Zeng Qingfei,Jia Bingchan,Zi Xinyuan,Chen Huihui,Mao Zhigang,Ge You.Fluctuations of nutrient concentrations and their influencing factors under various net-pen aquaculture scales in East Lake Taihu from 1990 to 2021. J. Lake Sci.2023,35(1):155-167. DOI:10.18307/2023.0110 |
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| 1990—2021年东太湖网围养殖规模变化下的水质变化特征及成因分析 |
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李一凡1,2, 谷孝鸿1, 曾庆飞1, 贾冰婵1, 訾鑫源1,2, 陈辉辉1, 毛志刚1, 葛优1,2
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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: |
| 2019年,东太湖30 km2养殖网围实现清零,结束了长达34年的太湖网围养殖历史。系统整理东太湖30年来(1990—2021年)水体氮、磷等营养盐浓度监测资料,对比分析14个监测点位水质在不同网围利用和整治时期的时空差异性及影响因素,判识网围拆除后水体营养盐变化趋势及存在问题对东太湖生态修复与保护具有重要意义。结果表明,东太湖30年来水体营养盐浓度年际变化随养殖结构(主养鱼到主养蟹)和养殖规模(过度利用到网围整治和拆除)的变化而变化,网围养蟹因其有效的水生植物管控和生态混养相对于主养鱼类水质较优,但水质均随着养殖强度的增大而变差,网围规模缩减对改善水质有正面效应。总氮(TN)、总磷(TP)、高锰酸盐指数(CODMn)和叶绿素a(Chl.a)浓度分别由1990年的0.53 mg/L、0.014 mg/L、3.58 mg/L和2.90 μg/L上升到2021年的1.87 mg/L、0.128 mg/L、5.72 mg/L和28.09 μg/L,TN是主要的污染因子。原网围区和湖心区因较高的水生植被覆盖度,TN、TP、磷酸盐、悬浮颗粒物(SS)30年来变化不大,原网围区透明度维持在0.8 m左右;太浦河口和东茭咀水域TN、TP、Chl.a、CODMn和SS浓度上升明显,透明度显著下降,该水域的Chl.a浓度与太浦河口出水量呈显著正相关。网围拆除、出湖水量增加和水生植被消失造成的水动力作用增强,加上原网围区底泥营养盐释放,是引起东太湖南部区域营养盐浓度大幅上升的主要原因。网围拆除后东太湖营养盐浓度和Chl.a浓度存在夏、秋季较低和冬、春季较高的季节波动,冬季水草腐败坏水的风险增大。30年来东太湖水体营养盐变化对网围拆除湖泊生态修复与保护具有启示意义:应及早开展水生植物资源调控,强化水质净化,加强对湖泊生态环境进行监测并建立生态档案,创建渔业新模式,确保恢复健康自然的草型生态系统格局。 |
| 关键词: 东太湖 网围养殖 退围还湖 出湖流量 水生植被 |
| DOI：10.18307/2023.0110 |
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| 基金项目:国家重点研发计划项目(2020YFD0900500)、江苏省农业科技自主创新项目(CX(20)2026)、中国科学院科研仪器设备研制项目(YJKYYQ20200048)和国家自然科学基金项目(31972813)联合资助。 |
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| Fluctuations of nutrient concentrations and their influencing factors under various net-pen aquaculture scales in East Lake Taihu from 1990 to 2021 |
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Li Yifan1,2, Gu Xiaohong1, Zeng Qingfei1, Jia Bingchan1, Zi Xinyuan1,2, Chen Huihui1, Mao Zhigang1, Ge You1,2
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1.State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Acadamy 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 30 km2 net-pen aquaculture in East Lake Taihu was cleared in 2019, ending its 34 years history of net-pen aquaculture breeding. The temporal-spatial differences and influencing factors of water quality at 14 monitoring sites during the period of 30 years' (1990-2021) net-pen aquaculture were analyzed. The results showed that the variations of nutrient concentrations in East Lake Taihu in the past 30 years varied with the changes of aquaculture structures (from fish to crab) and aquaculture scales (from excessive utilization to net-pen aquaculture rectification and demolition). The water quality of breeding crabs in net is better than that of breeding fish, owing to the effective management of aquatic plants and mixed breeding pattern. However, as the increase in the intensity of net-pen aquaculture, the water quality degraded. The reduction of the scales of net-pen aquaculture could help improve water quality. The concentrations of total nitrogen (TN), total phosphorus (TP), the permanganate index (CODMn) and chlorophyll-a (Chl.a) increased from 0.53 mg/L, 0.014 mg/L, 3.58 mg/L and 2.90 μg/L in 1990 to 1.87 mg/L, 0.128 mg/L, 5.72 mg/L and 28.09 μg/L in 2021, respectively. TN was the main pollution factor. The concentrations of TN, TP, phosphate and suspended solid (SS) in the former net-pen areas and lake center area maintained and unchanged in the past three decades owing to higher aquatic vegetation coverage. The transparency (SD) in the former net-pen areas maintained at 0.8 m. The concentrations of TN, TP, Chl.a, CODMn and SS at the sites of Taipu River Estuary and Dongjiaozui showed an increasing trend, while the SD at these sites decreased significantly. The average concentrations of Chl.a at the sites of Taipu River Estuary and Dongjiaozui were significantly positively correlated with the water discharges of the Taipu River. The removal of net-pen, the increase of water discharges and the disappearance of aquatic vegetations increased the hydrodynamic effect. The hydrodynamic effect and the release of nutrients from the sediments in the former net-pen areas resulted in the significant increase of nutrient concentrations in the southern parts of East Lake Taihu. The nutrient concentrations in East Lake Taihu were high in summer and autumn and low in winter and spring since all the net-pen aquaculture was closed down. The implications of this study to other lakes are, in order to ensure the restoration of healthy and natural macrophytic ecosystem patterns, the regulations of aquatic plant resources to be carried out as early as possible so as to strengthen water purification, monitoring of the ecological lake environment, establishing ecological archives, and creating new fishery models. |
| Key words: East Lake Taihu net-pen aquaculture returning net-pen to lake flux of lake outflow aquatic plants |
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