| 引用本文: | 朱广伟,邹伟,国超旋,秦伯强,张运林,许海,朱梦圆.太湖水体磷浓度与赋存量长期变化(2005-2018年)及其对未来磷控制目标管理的启示.湖泊科学,2020,32(1):21-35. DOI:10.18307/2020.0103 |
| ZHU Guangwei,ZOU Wei,GUO Chaoxuan,QIN Boqiang,ZHANG Yunlin,XU Hai,ZHU Mengyuan.Long-term variations of phosphorus concentration and capacity in Lake Taihu,2005-2018: Implications for future phosphorus reduction target management. J. Lake Sci.2020,32(1):21-35. DOI:10.18307/2020.0103 |
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| 太湖水体磷浓度与赋存量长期变化(2005-2018年)及其对未来磷控制目标管理的启示 |
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朱广伟, 邹伟, 国超旋, 秦伯强, 张运林, 许海, 朱梦圆
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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, 太湖湖泊生态系统研究站, 南京 210008
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| 摘要: |
| 为揭示大型浅水湖泊水体磷浓度对湖泊外源负荷削减和生态系统变化的响应规律，指导富营养化湖泊水生态修复和管理实践，利用太湖湖泊生态系统研究站2005-2018年连续14年的太湖水体各形态磷浓度的月、季度调查数据，估算了太湖湖体各形态磷赋存量的季度变化，分析了太湖水体磷浓度受湖泊水位、水量、蓝藻水华态势（蓝藻总生物量及水华出现面积）等环境条件变化的影响特征.结果表明，在连续10年的全流域高投入污染治理背景下，太湖水体总磷浓度仍未发生显著下降，水体各形态磷浓度在年际、月际及空间上的变幅大，不同季节和不同湖区总磷浓度的时空差异性大于14年来总磷浓度年均值的差异性；全湖32个监测点上、中、下3层混合样水体总磷平均值为0.113 mg/L（n=1788），其中颗粒态磷浓度平均值为0.077 mg/L，是水体总磷的主要赋存形式，溶解性总磷浓度平均值为0.036 mg/L，其中反应性活性磷浓度平均值为0.015 mg/L，占总磷浓度的13%；太湖水体总磷的赋存量介于410~1098 t之间，56个季度的平均值为688 t，其中冬季（12-2月）、春季（3-5月）、夏季（6-8月）、秋季（9-11月）平均值分别为683、604、792和673 t，夏季湖体磷赋存量明显高于其他季节.统计分析表明，蓝藻水华态势和水情要素（水位）对水相总磷、颗粒态磷等主要形态磷的赋存量影响显著，蓝藻水华态势的影响可能大于水量变化的影响.本研究表明，在水体营养盐浓度仍然充分满足蓝藻水华发生的背景下，气象水文波动所造成的湖泊水华面积及生物量的变化及大型水生植被消长带来的内源交换变化能引起水体总磷浓度剧烈变化，太湖水体磷浓度的稳定控制也依赖于蓝藻水华态势的稳定控制，由于太湖当前的蓝藻水华态势受气象水文条件变化影响甚大，短期内太湖水相总磷浓度稳定控制到0.05 mg/L的水质治理目标较难实现.治理策略上，若要实现太湖水体磷浓度的进一步明显下降，一方面需要大幅度削减外源磷负荷，另一方面需要大面积恢复沉水植被等.管理策略上，由于湖体磷浓度变化包括了较大的非人为因素影响，应将太湖总磷治理目标考核重点放在流域磷减排强度、入湖负荷等方面，科学看待气候波动等非人为因素影响下的水相磷浓度波动. |
| 关键词: 磷 大型浅水湖泊 蓝藻水华 富营养化 气候变化 太湖 |
| DOI：10.18307/2020.0103 |
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| 基金项目:中国科学院A类战略性先导科技专项（XDA23040201）、国家自然科学基金项目（41671494）、国家水体污染控制与治理科技重大专项（2017ZX07203001）、中国科学院前沿科学重点研究项目（QYZDJ-SSW-DQC008）、中国科学院南京地理与湖泊研究所“一三五”自主部署项目（NIGLAS2017GH04）和山东省重大科技创新工程项目（2018YFJH0902）联合资助. |
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| Long-term variations of phosphorus concentration and capacity in Lake Taihu,2005-2018: Implications for future phosphorus reduction target management |
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ZHU Guangwei, ZOU Wei, GUO Chaoxuan, QIN Boqiang, ZHANG Yunlin, XU Hai, ZHU Mengyuan
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Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, P. R. China
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| Abstract: |
| To understand the responding mechanism of phosphorus concentration to external nutrient reduction in large shallow lakes, phosphorus concentrations, capacity in water column, and seasonal variations in Lake Taihu were calculated, based on 14 years (2005-2018) monthly monitoring data undertaken by Taihu Laboratory for Lake Ecosystem Research, Chinese Academy of Sciences. The responses of phosphorus capacity to water level, water volume and cyanobacterial bloom condition had been discussed. The result showed that total phosphorus concentration in Lake Taihu has not decreased significantly after the tremendous catchment restoration activities in the past 14 years. Fluctuations of total phosphorus concentration among seasonal timescale were spatially larger than inter-annual differences. The average total phosphorus concentration was 0.113 mg/L (n=1788), based on statistics of 32 sites in the lake and 3 layers in water column monitoring in the past 14 years. The average particulate phosphorus concentration was 0.077 mg/L, which was the main fraction of total phosphorus in the water column of Lake Taihu. Dissolved total phosphorus concentration was 0.036 mg/L in average, and the soluble reactive phosphorus concentration was 0.015 mg/L, which occupied only 13% of total phosphorus in water. The capacity of total phosphorus in Lake Taihu ranged between 410 t and 1098 t, with an average value of 688 t. The average capacities in spring, summer, autumn and winter were 604, 792, 673 and 683 t, respectively. Total phosphorus capacity in summer was much higher than that in other seasons. Conditions of algal blooms and hydrology, such as chlorophyll-a concentrations, suspended solid contents and water level, significantly influenced the spatial and temporal dynamics of phosphorus capacities in Lake Taihu. Influence of algal biomass dynamics on phosphorus capacity was even greater than hydrological conditions. The results suggested that the fluctuation of phosphorus concentrations in Lake Taihu was influenced by algal bloom and macrophyte dynamics under changing climate change scenarios. The restoration target of total phosphorus concentrations of 0.05 mg/L in the end of 2020 was difficult to achieve shortly. To further decrease the total phosphorus concentration in Lake Taihu, drastic decrease of external phosphorus loading and large-scale restoration of macrophyte vegetation are needed. For the phosphorus target management, more attention should be paid on the discharge reduction and inflow phosphorus loading, and the fluctuation of phosphorus concentration impacted by the future uncertainty of climate change favorably considered. |
| Key words: Phosphorus large shallow lake cyanobacterial bloom eutrophication climate change Lake Taihu |
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