向家坝蓄水前后长江上游干流四川段氮磷的时空分布变化  

Variations of the Spatiotemporal Distributions of Nitrogen and Phosphorus in the Sichuan Section Mainstem in the Upper Yangtze River after the Impoundment of the Xiangjiaba Reservoir

作　　者：梁祝[1,2,3] 潘树林 郭芳成[1] LIANG Zhu;PAN Shulin;GUO Fangcheng(College of Resource&Environment,Yibin University,Yibin 644007,P.R.China;Yibin Research Base,Key Lab of Yangtze River Water Environment,Ministry of Education of the People’s Republic of China,Yibin 644007,P.R.China;Key Lab of Aromatic Plant Resources Exploitation and Utilization in Sichuan Higher Education,Yibin 644007,P.R.China)

机构地区：[1]宜宾学院资源与环境学院,四川宜宾644005 [2]宜宾学院长江水环境教育部重点实验室宜宾研究基地,四川宜宾644005 [3]香料植物资源开发与利用四川省高校重点实验室,四川宜宾644005

出　　处：《生态环境学报》2025年第4期581-592,共12页Ecology and Environmental Sciences

基　　金：四川省科技计划项目(2023JDR0277);宜宾市科技计划项目(2022NY029);香料植物资源开发与利用四川省高校重点实验室开放基金项目(21XLY01);宜宾学院高层次人才引进项目(2021QH024)。

摘　　要：长江上游干流四川段是长江上游重要的水源涵养地和三峡库区的直接水源补给区。2012年向家坝水库蓄水后,该段的水沙条件显著改变,进而对水中氮磷的迁移转化产生重大影响。系统分析了2010-2020年间四川段水沙输移特性的改变及其对氮磷通量时空分布的影响,结果表明,2012年后,四川段的含沙量大幅削减,上下游分别降低了98.7%和66.4%,同时,上下游的氮磷通量也显著降低,总磷分别减少87.1%和62.9%,氨氮分别减少44.5%和53.7%。2012年后,岷江取代金沙江成为四川段最大的氮磷贡献者,其输入的氨氮和总磷占比分别达到73.5%和53.5%,四川段的氮磷水平主要取决于岷江的输入。总磷和氨氮的通量与含沙量之间均呈现线性正相关,前者的相关性极强(r=0.995 6),而后者的相关性相对较低(r=0.520 9);总磷与粒径呈现中等正相关,而氨氮与粒径基本不相关;相比粒径,含沙量的变化对氮磷的迁移影响更大,而含沙量的变化对总磷的影响比对氨氮的强。底泥的氮磷释放是四川段氮磷的一个重要来源,2012年后,受水力条件和水沙条件改变的影响,内源释放的氮磷通量减少,但总磷的内源释放通量仍然达到0.52×10~4 t·a^(-1)(贡献率11.9%)。研究结果加深了对向家坝水库蓄水影响四川段氮磷迁移的认识,可为促进四川段流域的氮磷污染防控和保障长江上游干流水质安全提供决策参考。Nitrogen(N) and phosphorus(P) are important contaminants that cause eutrophication and the deterioration of water quality.The transportation and distribution of N and P in the water column depends directly on suspended sediment(SS),which is the key medium for N and P cycling in natural rivers.Dam interception can significantly reduce the concentration and size of SS in reservoir discharge and regulate its spatiotemporal distribution within the drainage basin,resulting in considerable changes in the transport of these two pollutants in the lower reaches of the dam.Wudongde(WDD),Baihetan(BHT),Xiluodu(XLD) and Xijiaba(XJB),the four super cascade reservoirs located in the lower Jinsha River,have been impounded successively since 2012.Sichuan section mainstem(SSM) in the upper Yangtze River(UYR),located between the downstream of XJB Reservoir(the last one of the four cascade reservoirs) and the upper reach of the Three Gorges Reservoir(TGR),plays a crucial role in protecting the aquatic environment of the UYR and ensuring a safe water supply to the Three Gorges Reservoir.Since the impoundment of the Xiangjiaba Reservoir in 2012,the sediment regime in the SSM has changed completely,causing intense influences on the spatiotemporal distributions of N and P in the SSM.However,both these influences and the potential risks to the water quality safety of SSM and its downstream reaches are not well understood.Moreover,owing to the sample pretreatment method according to the Environmental Quality Standards for Surface Water(GB 3838—2002) in China,the total P(TP) concentration in most previous reports did not reflect the P content of the initial sample;instead,it measured the P content in the sample after settling for 30 min,namely,the TSSP,resulting in an underestimation of the true TP level.Based on the monitoring data of the TSSP and SS in the SSM and its six tributaries(including the Min River,Tuo River,and four small branches:Nanguang,Changning,Yongning,and Chishui Rivers) from 2010 to 2020,we rectified the TSSP for the

关 键 词：长江上游干流 四川段 水库蓄水 泥沙 氨氮 总磷 迁移 

分 类 号：X52[环境科学与工程—环境工程] TV11[水利工程—水文学及水资源]