基于水体溯源的澜沧江梯级水库水体总磷来源及滞留效应分析

An Analysis of the Water Body Traceability of the Total Phosphorus Sources and Retention Effects of Cascade Reservoirs in the Lancang River

梯级水库建设对澜沧江流域生源物质迁移过程的影响受到国内外学者广泛关注。研究利用稳定同位素技术,于枯水期(2017年2月)、丰水期(2017年6月)分别测定了小湾、漫湾、糯扎渡、景洪四个水库不同来源水体(上一级水库下泄水量、支流汇入、坡面径流、人工水循环)总磷(TP)浓度及水库水体氢氧同位素值(18O、D),基于多元线性混合模型,分析了不同来源水体水量的贡献率,并计算了澜沧江流域梯级水库TP滞留量。结果表明:上一级水库下泄水量对水库TP来源及滞留效应的贡献率在丰水期及枯水期均占主要部分,贡献率分别为54.8%~79.3%、39.1%~82.8%,从上游到下游呈沿程增加趋势;人工水循环水量在枯水期呈沿程增加趋势;坡面径流水量在丰水期呈沿程增加趋势。TP滞留率在枯水期和丰水期分别为-49.34%~66.72%、-88.79%~88.40%,丰水期滞留率受水量增加影响较大,枯水期则受人类活动及沿程输入影响较大。研究为对有针对性地控制流域TP滞留量及为下游水生态环境质量评价提供数据支撑。

The effect of cascade reservoirs constructions on the migration process of biogenic materials in the Lancang River has attracted extensive attention of scholars around the world.Stable isotope technology is implemented in the current study:total phosphorus(TP)concentrations and hydrogen and oxygen stable isotope concentrations(D,18O)of different sources of water in the XW,MW,NZD,JH reservoirs(discharge of upper reservoir,inflow of tributaries,slope runoff and artificial water cycle)were measured from the dry season(February 2017)to the wet season(June 2017).According to the multivariate linear mixed model,contribution rates of water volume from different sources are analyzed,and TP retention of cascade reservoirs in the Lancang River is simulated and calculated.Modeling and analysis results indicate that the contribution rates of discharges in the upper reservoir to the retention effect of TP in reservoirs accounts for the main part in both wet seasons and dry seasons,with contribution rates of 54.8%~79.3%and 39.1%~82.8%,respectively.Contribution rates increase from the upstream to the downstream.The amount of artificial water circulation increases along the way in the dry season.The runoff on the slope increases along the way during the wet season.The retention rates of TP in the dry season and the wet season is-49.34%~66.72%and-88.79%~88.40%respectively.The retention rate of TP in the wet season is greatly affected by increasing water volume,while in the dry season,it is greatly affected by human activities and excessive inputs from the upstream.This study can provide data support for the targeted controlling of TP retention in the Lancang Basin and the evaluation of downstream water ecological environment quality.