摘要
对湖北宜昌境内典型喀斯特溪流下牢溪的干支流开展了持续1年的两周1次的采样监测,分析了水化学时空变化特征,并利用正演模型和水化学径流法估算了流域内岩石风化速率、碳汇通量和碳汇量.结果表明:水体中Mg^(2+)、Ca^(2+)和HCO_(3)^(-)主要来源于白云石等碳酸盐岩风化溶解作用,其浓度与流量的稀释效应密切相关,表现为丰水期浓度低于枯水期,并在主河道上沿程降低;Na^(+)、K^(+)、Cl^(-)、NO_(3)^(-)、SO_(4)^(2-)源于人为输入,浓度在人口密集的下游和人类活动强度大的季节显著增加.流域内岩石风化速率、碳汇通量和碳汇量分别为71.83t/(km^(2)·a)、5.31×10^(5)mol/(km^(2)·a)、6.96×10^(7)mol/a.下牢溪碳汇通量与中、大型喀斯特河流处于同一量级,高于非喀斯特河流和世界均值,这与流域内碳酸盐岩的高覆盖率和其相对温暖湿润的气候条件密不可分,说明亚热带季风气候下的喀斯特小溪流是一个重要“遗失碳汇”.
This study investigates the temporal and spatial variabilities of hydro-chemistry in Xialaoxi,a typical karst river in Yichang,Hubei Province,via biweekly sampling and monitoring at multiple sites in the main stream and tributaries throughout one year.The rock weathering rate,carbon sink flux,and carbon sink in the watershed were estimated using the forward model and the chemical runoff method.The results show that Mg^(2+),Ca^(2+),and HCO_(3)^(-)mainly came from the weathering and dissolution of carbonate rocks,and their concentrations were closely related to the dilution effect of the flow and decreased along the main channel,with lower concentrations in the wet season comparing to the dry season.Na^(+),K^(+),Cl^(-),NO_(3)^(-),SO_(4)^(2-)in water were from anthropogenic input,thus their concentrations increased dramatically in the densely populated downstream and in the seasons with intense human activities.The estimated rock weathering rate,carbon sink flux,and carbon sink amount in the catchment were 71.83t/(km^(2)·a),5.31×10^(5)mol/(km^(2)·a),and 6.96×10^(7)mol/a,respectively.The carbon sink flux of Xialaoxi is as the same magnitude order as that of medium and large karst rivers,and higher than that of non-karst rivers and the world average,which can be attributed to the high coverage of carbonate rocks within the watershed and relatively warm and humid climatic conditions.Therefore,it indicates that karst streams under subtropical monsoon climate are an important“missing carbon sink”.
作者
张小薇
虞之锋
陈敏
肖尚斌
梁爽
康满春
ZHANG Xiao-wei;YU Zhi-feng;CHEN Min;XIAO Shang-bin;LIANG Shuang;KANG Man-chun(Engineering Research Center of Eco-environment in Three Gorges Reservoir Region,Yichang 443002,China;Collge of Hydraulic and Environmental Engineering,China Three Gorges University,Yichang 443002,China;Jiaxing Water Resources&Hydroelectric Prospecting&Design Research Institute Co,Ltd,Jiaxing 314001,China;Three Gorges Base Development Co,Ltd,Wuhan 430074,China)
出处
《中国环境科学》
EI
CAS
CSCD
北大核心
2023年第2期648-657,共10页
China Environmental Science
基金
国家自然科学基金资助项目(41807513,51979148,51809149)
湖北省自然科学基金创新群体项目(2019CFA032)。
关键词
喀斯特河流
水化学特征
岩石风化
碳汇通量
karst river
hydro-chemical characteristics
rock weathering
carbon sink flux
