河流泥沙输移过程中矿物风化的碳汇效应初探——以长江干流为例  

A preliminary study on the inorganic carbon sink function of mineral weathering during sediment transport in the Yangtze River mainstream

作　　者：张信宝[1] 罗景城 王小国[1] 唐家良[1] 彭韬[3] 朱波[1] ZHANG Xinbao;LUO Jingcheng;WANG Xiaoguo;TANG Jialiang;PENG Tao;ZHU Bo(Key Laboratory of Mountain Environment Evolution and Regulation,Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Chengdu,Sichuan 610041,China;Faculty of Geosciences and Environmental Engineering,Southwest Jiaotong University,Chengdu,Sichuan 610031,China;Puding Karst Ecosystem Observation and Research Station,Chinese Academy of Sciences,Puding,Guizhou 550081,China)

机构地区：[1]中国科学院、水利部成都山地灾害与环境研究所,中国科学院山地表生过程与生态调控重点实验室,四川成都610041 [2]西南交通大学地球科学与环境工程学院,四川成都610031 [3]中国科学院普定喀斯特生态系统观测研究站,贵州普定550081

出　　处：《地质学报》2023年第7期2378-2385,共8页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41873025);中国科学院战略性先导科技专项(编号XDA23040202)联合资助的成果。

摘　　要：本文首先提出了河流泥沙输移过程中泥沙中的钙镁矿物溶蚀消耗水体中的CO_(2)并具有碳汇功能的观点。基于前人长江干流从源头到入海口和支流2003~2007年期间4次河流悬移质泥沙的化学元素组成和矿物组成资料,分析悬移质中CaO、MgO含量和方解石、白云石含量变化特征,定量计算了这些取样点悬移质泥沙的CO_(2)总碳汇能力和非永久性、永久性碳汇能力,分析了不同碳汇能力沿程变化规律及其原因。碳汇计算结果表明:寸滩—大通河段1956~2000年期间泥沙输移过程中钙镁矿物溶蚀产生的总碳汇量、非永久性和永久性碳汇量分别为2572万t/a、1700万t/a和872万t/a。由于输沙量减少,寸滩站—大通站河段的总碳汇量、非永久性和永久性碳汇量2006~2019年期间较1956~2000年期间相应分别减少了1852万t、1224万t和872万t。三峡水库年均淤积量1.145亿t,损失总碳汇量675.6万t,相当于三峡电站减排二氧化碳8580万t的7.9%。全球河流入海年输沙量126.1亿t,以寸滩-吴淞口河段碳汇功能0.060 t/t计,总碳汇量7.57亿t相当于全球岩石风化碳汇总量10.56亿t CO_(2)的71.6%。河流泥沙输移过程中钙镁矿物溶蚀的碳汇量具有重要的作用,其溶蚀速率大于原地风化。This study proposed that the dissolution of calcium and magnesium minerals in river sediment could sequester CO2 and function as a carbon sink.Based on the published literature,the contents of CaO,MgO,calcite and dolomite in suspended sediment collected from 25 sampling points in the mainstream and 13 sampling points in the tributaries of the Yangtze River in 4 sampling campaigns during 2003~2007 were used to calculate the total inorganic carbon sink(TCS)capacity and nonsubstantial and substantial inorganic carbon sink(NSCS and SCS)capacities of suspended sediment along the river.Results showed that the TCS,NSCS and SCS caused by weathering of Ca and Mg minerals at Cuntan-Datong section were 2.57×10^(7) tons,1.70×10^(7) tons and 0.87×10^(7) tons per year during the period of 1956~2000.Due to the reduction of sediment yield,the annual TCS,NSCS and SCS of the Cuntan-Datong section during 2006~2019 decreased by 18.52×10^(6) tons,12.24×10^(6)tons and 8.72×10^(6) tons,respectively,compared to the period before 2002.The average annual sedimentation of the Three Gorges Reservoir(TGR)was 114.5×10^(6) tons,and the related TCS loss was 6.76×10^(6) tons,which were equivalent to 7.9%of the 85.8×10^(6) tons of CO_(2) emissions reduced by the clean energy production of the Three Gorges Hydropower Station.The annual TCS of global rivers was estimated as 757×10^(6) tons(the SCS was more than one quarter of the TCS),which is equivalent to 71.6%of the TCS by global rock weathering with 1.06×10^(9) tons of sequestered CO_(2).The dissolution rate of calcium and magnesium minerals for offsite rock weathering was higher than that for in situ rock weathering.

关 键 词：岩石风化 钙镁矿物 长江 悬移质泥沙 输移 碳汇 

分 类 号：X14[环境科学与工程—环境科学] TV142[水利工程—水力学及河流动力学]