| 摘要: |
| 白洋淀是华北地区最大的淡水湿地，府河是白洋淀上游主要的入淀河流之一。近年来极端降雨的频率和强度增大，府河水体氮、磷浓度及通量的时空变化规律复杂，极大影响了白洋淀的水环境质量。本研究以府河至白洋淀水体为研究对象，结合野外在线监测、野外采样、室内测定分析等方法，研究极端降雨影响条件下府河至白洋淀沿线水体总氮（TN）、总磷（TP）浓度的年内时空变化特征，并解析水体氮、磷浓度与负荷对极端降雨事件的响应规律。结果表明：TN浓度春冬高，夏季低；TP浓度春冬低，夏季高；且从府河上游至下游TN和TP浓度呈降低的趋势。2023年“7.29”极端降雨后至结冰期前，水体TN浓度呈现升高-降低-再升高的变化趋势，TP浓度呈现升高-降低的变化趋势。农业面源污染的外源输入和底泥的内源释放均导致水体TN浓度升高，稀释、反硝化和沉积作用导致极端降雨后TN降低，而后期底泥内源释放和生物吸收利用减弱导致TN浓度持续升高；极端降雨后面源污染物输入增加使TP浓度升高，而磷向底泥的沉积和生物吸收利用导致TP浓度逐渐降低。极端降雨前沿线水体氮、磷负荷逐渐降低；极端降雨后由于面源污染物的输入沿线氮、磷负荷显著升高，升高10.5~47.4倍，极端降雨期控制污染物入淀是保证白洋淀水质安全的必要条件。该研究可为变化环境下白洋淀及入淀河流的水环境管理提供科学依据。 |
| 关键词: 氮 磷 极端降雨 时空动态 白洋淀 |
| DOI： |
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| 基金项目:国家重点研发计划项目（ 2021YFD1700500）；河北省创新能力提升计划项目（225A3902D） |
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| The spatial and temporal variation characteristics of nitrogen and phosphorus in the water from Fu River to Baiyangdian Lake and their response to extreme rainfall |
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Tang Yushuo1, Wang Shiqin1, Lü Jiali2, Gu Congke1
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1.Center for Agricultural Resources Research,Institute of Genetics and Developmental Biology,Chinese Academy of Sciences,Key Laboratory of Agricultural Water Resources,Chinese Academy of Sciences,Hebei Key Laboratory of Water-Saving Agriculture;2.Sino-Danish College,University of Chinese Academy of Sciences
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| Abstract: |
| Baiyangdian Lake is the largest freshwater wetland in North China. Fu River is one of the main rivers that flow into Baiyangdian Lake. In recent years, increasing frequency and intensity of extreme rainfall events have introduced new challenges, driving complex spatiotemporal variations in nitrogen and phosphorus concentrations and fluxes. This study systematically investigated the Fu River-Baiyangdian Lake system through field monitoring, water sampling, laboratory measurements and statistical analysis to reveal the dynamics of total nitrogen (TN) and total phosphorus (TP) concentrations and their response to extreme rainfall. Results revealed distinct seasonal trends: TN concentration was highest in spring and winter and lowest in summer, whereas the TP concentration peaked in summer and declined in spring and winter. Spatially, TN and TP concentrations decreased from upstream to downstream along the Fu River. After the "7.29" extreme rainfall event, TN concentration showed a complex increase-decrease-increase trajectory influenced by agricultural runoff, sedimentary nutrient release, and biogeochemical processes such as dilution and denitrification. TP concentration showed a simpler increase-decrease pattern driven by sediment resuspension and subsequent attenuation. Before the extreme rainfall event, nitrogen and phosphorus loads along the river gradually decreased. After the extreme rainfall event, nitrogen and phosphorus loads along the river significantly increased due to the input of non-point source pollutants. Nutrient loads surged significantly after the extreme rainfall event, increasing by factors of 10.5 to 47.4 due to the input of non-point source pollutants. These findings underscore the vulnerability of Baiyangdian Lake to extreme hydrological events and highlight the urgent need for targeted interventions to reduce pollutant loads during such events. This research provides critical insights into nutrient cycling dynamics under changing climatic and hydrological conditions, offering a scientific basis for sustainable water quality management in lake-watershed systems. |
| Key words: Nitrogen Phosphorus Extreme rainfall Temporal and spatial changes Baiyangdian Lake |
