| 摘要: |
| 基于1990—2018年于桥水库流域入库河流与水库的逐月总氮(TN)和总磷(TP)监测数据,整理并分析了1990—2002、2003—2014和2015—2018年3个时段TN、TP浓度和氮磷比(TN/TP)的时空变化特征,探究流域内点面源污染削减、调水、氮磷滞留等对营养盐浓度变化的影响。结果表明,1990—2018年于桥水库TN浓度年均值在1.14~3.74 mg/L之间,水库TP浓度年均值在0.025~0.131 mg/L之间,多年TN/TP平均值为45,远高于淡水磷限氮磷比,是磷限水库。于桥水库流域5个测点中,沙河TN浓度最高,黎河TP浓度最高,入库TN、TP浓度大于库区,水库TP滞留率略大于TN。水库TN、TP浓度在2000s中后期下降,之后出现反弹。原因是2003年水源保护工程实施后,入库营养物浓度降低;2014年底南水北调中线一期工程通水后,于桥水库的引滦水量减少,TN的稀释效应弱化,上游来水TP浓度上升与水库内夏秋两季浮游植物的增殖,导致第三时段水库内TP浓度上升。基于月尺度水质分析,夏季水库TN浓度最低,TP浓度达到峰值,主成分分析表明,历年6—10月的水库Chl.a浓度与TP浓度呈显著正相关。后续富营养化治理应当控制沙河及库周面源的TN输入,同步削减流域内TP负荷,并通过建设和完善前置库、截污沟等工程措施降低入库氮磷浓度。 |
| 关键词: 营养盐 氮磷比 调水 于桥水库 氮磷滞留 |
| DOI：10.18307/2023.0622 |
| 分类号: |
| 基金项目:国家自然科学基金项目(52079089)资助。 |
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| Variation trend and impact factors of total nitrogen and total phosphorus concentrations in Yuqiao Reservoir Basin during 1990-2018 |
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Zhang Chen, Zhou Yadi, Song Didi
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State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300350, P.R. China
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| Abstract: |
| To explore the variations in nutrients concentrations of the Yuqiao Reservoir Basin, we analyzed the spatial and temporal variations of total nitrogen and total phosphorus concentrations and TN/TP (mass ratio of total nitrogen to total phosphorus) in three periods from 1990-2002, 2003-2014 and 2015-2018. Simultaneously, the effect of pollution reduction, water transfer, and retention on nutrient concentrations were elucidated based on the monthly observed data of inlet rivers and reservoirs in the basin from 1990 to 2018. The results showed that the annual average TN concentration of Yuqiao Reservoir from 1990 to 2018 ranged from 1.14-3.74 mg/L and the annual average TP concentration ranged from 0.025-0.131 mg/L. The multi-year average TN/TP of Yuqiao Reservoir from 1990 to 2018 was 45, which was a phosphorus-limited reservoir. Both TN and TP concentrations were higher in the inflow than that were in the reservoir. Additionally, the TP retention rate in the reservoir was slightly higher than that of TN. The TN and TP concentrations in the reservoir decreased in the mid-to-late 2000s, but rebounded thereafter. The water protection project implemented in 2003 effectively reduced the incoming nutrient concentrations, especially the TP concentration. At the end of 2014, when the first-stage of the Middle Route South-to-North Water Diversion Project delivered water, the amount of diversion from Luanhe River was decreased and TP concentration increased. Excessive growth of phytoplankton in summer and autumn led to an increase in TP concentration during the third period in the reservoir. Based on the monthly water quality dataset, TN concentration in the reservoir was the lowest and TP concentration reached its peak in summer. The principal component analysis showed that a significantly positive correlation between Chl.a concentrations and TP concentrations in the reservoir from June to October. In the future, the TN from the Shahe River and the surrounding non-point sources should be controlled, and it should reduce the TP loadings of the whole basin simultaneously. In addition, engineering measures, such as front storage, sewage intercepting ditch, can be used to reduce the incoming nutrient concentrations. |
| Key words: Nutrients nitrogen to phosphorus ratio water transfer Yuqiao Reservoir nitrogen and phosphorus retention |
