摘要
为明确三峡水库沉积物氮污染及内源释放潜力,以常年回水区为对象,布设9个采样点采集0—30 cm柱状沉积物,测定多形态氮含量及氮素转化速率,并分析关键影响因子。结果显示:(1)沉积物总氮(TN)均值792.13 mg/kg,远低于重污染阈值及长江中下游主要湖泊,污染总体处于低水平;(2)氮素以总有机氮(TON)为主,且其中残渣态氮(RN)占比超96%,氮素矿化速率低,稳定性高;(3)活性氮形态含量偏低,短期大量释放风险可能较低;(4)空间上,上游深层沉积物TN高于表层,下游表层TN高于深层,存在局部累积风险;(5)pH值(8.03~8.95)是关键影响因子,与多数氮形态及氨化速率呈显著负相关,过高pH值抑制氮素转化。综上,当前三峡水库沉积物氮污染程度低、释放风险低,但需重点关注坝前段表层TN累积,pH值可作为氮素循环调控切入点。研究内容可为三峡水库氮污染防控提供科学依据。
To clarify the nitrogen pollution status and endogenous release potential of sediments in the Three Gorges Reservoir,this study focused on the perennial backwater area,where nine typical sampling sites were set up to collect 0–30 cm sediment cores.The contents of nitrogen in various forms and nitrogen transformation rates were determined,and the key influencing factors were analyzed.The results show that:①The average total nitrogen(TN)content in the sediments is 792.13 mg/kg,which is much lower than the heavy pollution threshold and the levels in major lakes in the middle and lower reaches of the Yangtze River,indicating an overall low level of nitrogen pollution.②Nitrogen is mainly in the form of total organic nitrogen(TON),and the proportion of residual nitrogen(RN)in TON exceeds 96%.The nitrogen mineralization rate is low,suggesting high nitrogen stability.③The content of active nitrogen is relatively low,implying a low risk of large-scale nitrogen release in the short term.④Spatially,the TN content in the deep sediments of the upper reservoir area is higher than that in the surface sediments,while in the lower reservoir area,the TN content in the surface sediments is higher than that in the deep sediments,indicating a potential risk of local TN accumulation.⑤pH(ranging from 8.03 to 8.95)is a key influencing factor,showing a significant negative correlation with most nitrogen forms and ammonification rate.Excessively high pH will inhibit nitrogen transformation.In conclusion,the current level of nitrogen pollution in the reservoir sediments is low,and the risk of endogenous nitrogen release is low.However,the accumulation of TN in the surface sediments of the pre-dam section requires more attention.Additionally,pH can be used as a key entry point for regulating nitrogen cycling.This study can provide a scientific basis for the prevention and control of nitrogen pollution in the Three Gorges Reservoir.
作者
韩畅
杨文俊
毕胜
胡曼
滕素芬
胡煜
曹慧群
HAN Chang;YANG Wenjun;BI Sheng;HU Man;TENG Sufen;HU Yu;CAO Huiqun(Changjiang River Scientific Research Institute,Changjiang Water Resources Commission of the Ministry of Water Resources,Wuhan 430010,China;College of Water Conservancy&Hydropower Engineering,Hohai University,Nanjing 210098,China)
出处
《中国水利》
2026年第2期36-46,共11页
China Water Resources
基金
国家自然科学基金重点项目(52130903)
中央级公益性科研院所基本科研业务费项目(CKSF2025172/SL)。
关键词
三峡水库
常年回水区
沉积物
氮形态
空间分布
矿化速率
内源释放风险
Three Gorges Reservoir
perennial backwater area
sediment
nitrogen form
spatial distribution
mineralization rate
endogenous release risk
