青藏高原流域岩石风化机制及其CO_(2)消耗通量:以拉萨河为例  被引量:7

Chemical weathering and its associated CO_(2) consumption on the Tibetan Plateau:A case of the Lhasa River Basin

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作  者:谢银财 于奭[1,2] 缪雄谊[1,2] 李军 何师意 孙平安[1,2] XIE Yincai;YU Shi;MIAO Xiongyi;LI Jun;HE Shiyi;SUN Ping’an(Ministry of Natureal and Resources&Guangxi Key Laboratory of Karst Dynamics,Institute of Karst Geology,Chinese Academy of Geological Sciences,Guilin 541004,China;International Research Centre on Karst under the Auspices of UNESCO/National Center for International Research on Karst Dynamic System and Global Change,Guilin 541004,China;Hebei Key Laboratory of Water Quality Engineering and Comprehensive Utilization of Water Resources,Hebei University of Architecture,Zhangjiakou 075000,China)

机构地区:[1]中国地质科学院岩溶地质研究所自然资源部、广西岩溶动力学重点实验室,广西桂林541004 [2]联合国教科文组织国际岩溶研究中心/岩溶动力系统与全球变化国际联合研究中心,广西桂林541004 [3]河北建筑工程学院河北省水质工程与水资源综合利用重点实验室,河北张家口075000

出  处:《地学前缘》2023年第5期510-525,共16页Earth Science Frontiers

基  金:广西自然科学基金项目(2021GXNSFBA220065);广西重点研发专项(桂科AB21196050);国家自然科学基金项目(42177075);中国地质调查局地质调查项目(DD20221808,DD20230547)。

摘  要:为研究青藏高原流域岩石风化机制及其对CO_(2)消耗通量和气候变化的影响,于2019年11月至2020年10月对拉萨河流域控制断面进行一个完整水文年每月2次的监测和采样,结合水化学及δ^(13)C_(DIC)和δ^(34)S_(SO_4),探讨了流域水化学特征及其主要影响因素,基于化学计量平衡与正演模型方法定量计算了河流水体主要物质来源,并对流域岩石风化速率与大气CO_(2)消耗通量进行了估算。结果表明:拉萨河流域水体中Ca^(2+)和HCO_(3)~-为主要的阳离子和阴离子,水化学类型为HCO_(3)-Ca型,大气输入、人为输入、硅酸盐岩和碳酸盐岩风化端员对河水阳离子的年平均贡献率分别为6%、4%、21%和70%;河水化学计量学、δ^(13)C_(DIC)(-8.78‰~-1.35‰)和δ^(34)S_(SO_4)(-2.26‰~-1.10‰)变化均证明由煤系地层硫化物及矿床硫化物的氧化形成的硫酸(各占约50%)广泛参与了流域的化学侵蚀,硫酸对碳酸盐岩的风化作用旱季显著强于雨季。流域硅酸盐岩风化速率与大气CO_(2)消耗通量的年平均值分别为5.20 t·km^(-2)·a^(-1)和118×10^(3) mol·km^(-2)·a^(-1);仅考虑碳酸风化作用时,流域碳酸盐岩风化速率与大气CO_(2)消耗通量分别为22.5 t·km^(-2)·a^(-1)和202×10^(3) mol·km^(-2)·a^(-1);硫酸参与作用下,流域碳酸盐岩风化速率估算结果提高了31%(升至29.4 t·km^(-2)·a^(-1)),岩石(碳酸盐岩和硅酸盐岩)风化消耗大气CO_(2)通量则降低了35%(降至207×10^(3) mol·km^(-2)·a^(-1))。硫酸参与流域碳酸盐岩的风化改变了区域碳循环,这是全球碳循环模型应该考虑的一个重要环节。In order to study chemical weathering and its effects on CO_(2) consumption and climate change on the Tibetan Plateau,hydrochemical data were collected bi-monthly,over a hydrological year between November 2019 to October 2020,at selected hydrological monitoring stations across the Lhasa River Basin.Combined withδ^(13) C_(DIC) andδ^(34) S_(SO_(4)) data,the hydrochemistry of the river basin and its major influencing factors were investigated.Mass-balance and forward-model approaches were applied to calculate the end-member contribution,chemical weathering rate,and atmospheric CO_(2) consumption flux in the river basin.The main ionic species in river water were Ca^(2+) and HCO^(-)_(3),and the hydrochemical type was HCO_(3)-Ca.The cation contribution percentages from atmospheric input,human activities,silicate weathering,and carbonate weathering were 6%,4%,21%and 70%,respectively.Chemical weathering is largely caused by sulfuric acid corrosion,where coal strata and sulfide deposits each contributed 50%sulfides,as evidenced by the chemical composition of river water,andδ^(13)C(-8.78‰-1.35‰)of dissolved inorganic carbon andδ^(34)S(-2.26‰-1.10‰)of sulfate in river water;and the sulfuric acid involvement in carbonate weathering was significantly stronger in dry season than in rainy season.By estimation,the annualized weathering rate and CO_(2) consumption flux were 5.20 t·km^(-2)·a^(-1) and 118×10^(3) mol·km^(-2)·a^(-1) respectively for silicate,and 22.5 t·km^(-2)·a^(-1) and 202×10^(3) mol·km^(-2)·a^(-1) respectively for carbonate,excluding the impact of sulfuric acid.With sulfuric acid involvement,the annualized weathering rate for car bonate increased by 31%to 29.4 t·km^(-2)·a^(-1),and CO_(2) consumption flux for carbonate and silicate combined reduced by 35%to 207×10^(3) mol·km^(-2)·a^(-1).This work revealed that sulfuric acid-mediated weathering can change the regional carbon cycle and should be taken into consideration in carbon cycling modeling.

关 键 词:岩石风化 CO_(2)消耗 碳循环 硫酸 碳和硫同位素 拉萨河 

分 类 号:X143[环境科学与工程—环境科学] P641.134[天文地球—地质矿产勘探] P597.2[天文地球—地质学]

 

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