沙颍河流域人为输入对水体水化学组成的影响

人类活动输入影响河流水体化学组成,增加经河流体系向海洋输出物质的通量,影响全球物质循环过程。有效识别人为输入的影响途径和范围对于量化人类活动对全球物质循环的影响具有重要作用。沙颍河是淮河上游最大支流,流域水体受人为输入影响严重,通过研究沙颍河流域强人为输入对河水水化学组成的影响过程,有利于弄清楚强烈人为活动干扰下河流输出物质通量的变化。本文通过平水期(2019年12月)采集河水(n=41)以及地下水样品(n=12),分析其水化学及氢氧同位素组成,阐明人为输入影响方式和途径以及在空间上的分布规律,辨别控制水体化学组成的主要因素。结果表明:沙颍河支流河水和地下水阴离子以HCO₃^-为主,阳离子以Ca2⁺为主,干流河水逐渐转变为阴离子以Cl^-为主,阳离子以Na⁺为主的水体水化学类型;碳酸盐岩和硅酸盐岩化学风化、城市工业和生活污水以及农业面源是控制流域水体化学组成的主要因素。多数沙河河水以及上游颍河河水水化学组成主要受岩石化学风化为主,少受工业废水及生活污水影响,贾鲁河和沙颍河干流河水受城市工业及生活污水影响,流域地下水普遍受到农业面源的影响;研究区地下水氯碱指数小于0,与硅酸盐岩矿物中K⁺和Na⁺与水体中Ca2⁺和Mg2⁺发生阳离子交换有关。沙颍河干流河水水体K⁺和Na⁺含量高于地下水,除地下水补给河水部分K⁺和Na^(⁺)外,工业废水和生活污水输入的K⁺和Na⁺是沙颍河干流河水K⁺和Na⁺含量升高的主要原因;沙颍河干流河水Cl^-等行为保守元素含量往下游逐渐降低,与地下水补给和下游闸坝畜水稀释有关,而水体氘盈余值持续升高,显示下游河水经历强烈蒸发过程。本研究阐明了强人为输入对河水的影响,为沙颍河流域水污染治理提供了科学依据。

Effects of anthropogenic inputs on hydrochemical compositions of water in the Shaying River Basin

Hydrochemical compositions of river water have been profoundly altered by anthropogenic inputs,resulting in increased ion fluxes to the ocean and affecting the global material cycling.Identifying the pathways and ranges of anthropogenic contributions to river water is important for quantifying the influences of anthropogenic activities on global material cycling.Shaying River is the largest tributary in the upstream of Huai River,which has been seriously disturbed by anthropogenic inputs for a long time.Hence,it was a suitable place to examine the variations of riverine material fluxes caused by anthropogenic activities.The results would shed light on the related processes and impacts of anthropogenic input on hydrochemical compositions of river water.A total of 41 samples of river water and 12 samples of groundwater were collected in December 2019(a normal period of water level).Hydrochemical compositions and water isotope values were analyzed,with the aim to elucidate the pathways,ranges and spatial distributions of anthropogenic inputs,and to constrain the controlling factors in the Shaying River Basin.The results showed that major anion and cation in most river water and groundwater was bicarbonate(HCO₃^-)and calcium(Ca2⁺),respectively,and that chloride(Cl^-)and sodium(Na⁺)was dominated anion and cation in the downstream of Shaying River,respectively.The chemical weathering of carbonate and silicate,industrial wastewater and sewage,and agricultural nonpoint pollution sources were identified as the main factors controlling hydrochemical compositions of water.Most of Sha River water and the upstream water of the Ying River were primarily controlled by rock chemical weathering,and less affected by industrial wastewater and sewage.However,the whole Jialu River and the mainstream of Shaying River were heavily affected by industrial wastewater and sewage.Most groundwater was also influenced by agricultural no-point pollution sources.The chloride-alkali index was less than zero because of the exchange between adsorbed sodium,potassium cations in silicate and dissolved calcium,magnesium cations in the local groundwater,rendering more released Na⁺and K⁺in the groundwater.However,the higher Na⁺and K⁺concentrations in river water than those in groundwater,which were mainly sourced from industrial wastewater and sewage inputs rather than from groundwater inputs.Decreased concentrations of conservative Cl^-along the Shaying River mainstream was resulted from the discharge of groundwater with low Cl^-concentrations and dilution by downstream damed river water.The d-excess values became more positive,indicating extensive water evaporation of downstream river water.Our results confirmed the effects of anthropogenic input on river water and provided a profound theoretical footstone for further water pollution treatment.