三峡库区悬沙颗粒磷的粒径变化和滞留特征

陈晴空; 陈治君; 王殿常; 兰峰; 高千红; 李姗泽

doi:10.13928/j.cnki.wrahe.2025.01.015

水利水电技术（中英文） ›› 2025, Vol. 56 ›› Issue (1) : 181 -192. DOI: 10.13928/j.cnki.wrahe.2025.01.015

泥沙研究

三峡库区悬沙颗粒磷的粒径变化和滞留特征

陈晴空 ¹^,²^,³ ,
陈治君 ¹^,² ,
王殿常 ³^,⁴ ,
兰峰 ⁵ ,
高千红 ⁶ ,
李姗泽 ⁷

作者信息 +

Particle size variation and retention characteristics of phosphorus in suspended sediments in Three Gorges Reservoir Area

Qingkong CHEN ¹^,²^,³ ,
Zhijun CHEN ¹^,² ,
Dianchang WANG ³^,⁴ ,
Feng LAN ⁵ ,
Qianhong GAO ⁶ ,
Shanze LI ⁷

Author information +

文章历史 +

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摘要

【目的】磷是长江的主要污染物和生源要素，三峡大坝的建成导致大量携带磷的悬沙(颗粒磷)被拦截而影响长江流域的生态环境。粒径(D)是悬沙的重要物理特性，但目前对长江颗粒磷的研究缺乏粒径方面的信息。【方法】2021年在三峡库区长江干流和支流嘉陵江、乌江的8个水文断面逐月开展了悬沙粒径级配分析和各粒径段悬沙含磷量(PP′)的监测，获得了各断面不同时间、不同粒径段悬沙的PP′值，输沙率和流量、流速等水文参数以及总磷(TP)、溶解态磷(DP)、颗粒磷(PP)的浓度，总结了库区悬沙粒度特征和含磷量的时空变化规律并分析了库区中主导颗粒磷输移的主要悬沙成分，估算了库区对不同悬沙成分的拦截作用。【结果】结果显示：(1)库区悬沙以D≤0.062 mm的细颗粒为主，从上游到下游有细化趋势；粉砂通量最大可占全年D≤0.062 mm悬沙通量的77%,粉砂颗粒磷通量最大可占全年D≤0.062 mm悬沙颗粒磷通量的82%,粉砂是库区颗粒磷的主要载体。(2)非汛期库区长江干流各粒径段的悬沙平均含磷量大于汛期，且粒径越小PP′值越大，但汛期却是0.002<d80%,黏粒颗粒磷的滞留率>60%。【结论】结果表明：悬沙粒径级配与土壤测磷相结合的监测方法能明确库区不同粒径悬沙的含磷量，为库区磷监测提供新的技术参考；库区悬沙成分占比对颗粒磷输移的影响大于悬沙粒径，悬沙成分占比越大，对颗粒磷输移的影响越大，因此长江上游控磷更应侧重对悬沙成分占比方面。

Abstract

[Objective] Phosphorus is the main pollutant and biogenic element in the Yangtze River, and the completion of the Three Gorges Dam has led to the interception of a large number of suspended sediment(particulate phosphorus) carrying phosphorus, which has affected the ecological environment of the Yangtze River Basin.Particle size(D) is an important physical property of suspended sediment, but there is a lack of information on particle size(D) in the study of particulate phosphorus in the Yangtze River.[Methods] Suspended sediment particle size gradation analysis and suspended sediment phosphorus content(PP′) monitoring were carried out monthly in eight hydrological sections of the Yangtze River mainstream and its tributaries Jialing River and Wujiang River in the reservoir area in 2021, and the PP′ values of suspended sediment at different time and different particle size sections were obtained.Sediment transport rate, flow velocity and other hydrological parameters, as well as total phosphorus(TP), dissolved phosphorus(DP) and particulate phosphorus(PP) concentrations, the temporal and spatial variation of suspended sediment particle size characteristics and phosphorus content in the reservoir area were summarized, the main suspended sediment components dominating the transport of particulate phosphorus in the reservoir area were analyzed, and the interception effect of the reservoir area on different suspended sediment components was estimated.[Results] The results show that:(1) The suspended sediment in the reservoir area was dominated by fine particles with D≤0.062 mm, and there was a trend of refinement from upstream to downstream. Silt is the main carrier of particulate phosphorus in the reservoir area, accounting for 77% of the annual suspended sediment flux(D≤0.062 mm) and 82% of the annual suspended sediment flux(D≤0.062 mm).(2) The average phosphorus content of suspended sediment in each section of the Yangtze River mainstream in the non-flood season is greater than that in the flood season, and the smaller the particle size is, the greater the PP′value is, but in the flood season, the clay with 0.002<D <0. 004 mm contains the most phosphorus, and the sediment transport rate determines the amount of suspended sediment flux, which is the main factor affecting the transport of particulate phosphorus. (3) The phosphorus in the reservoir water is mainly DP in the non-flood season and PP in the flood season, and the suspended sediment and PP are retained throughout the year, especially in the flood season, and the suspended sediment and particulate phosphorus retention in the flood period account for about 94.5% and 97.1% of the annual retention, respectively. The retention rate of silt particulate phosphorus in the reservoir area is more than 80%, and that of clay particulate phosphorus is more than 60%. [Conclusion] The results show that the combined monitoring method of particle size distribution of suspended sediment and soil phosphorus measurement could determine the phosphorus content of suspended sediment with different particle sizes in the reservoir area, which provided a new technical reference for phosphorus monitoring in the reservoir area. The ratio of suspended sediment composition has greater influence on the transport of particulate phosphorus than the particle size of suspended sediment in the reservoir area, and the greater the ratio of suspended sediment composition is, the greater the influence on the transport of particulate phosphorus is. Therefore, phosphorus control in the upper reaches of the Yangtze River should focus more on the ratio of suspension sediment composition.