Chemical weathering in Manas River Basin:Driven by sulfuric acid or carbonic acid?  

作　　者：Jiaxin Zhang Bingqi Zhu 

机构地区：[1]Key Laboratory of Water Cycle and Related Land Surface Processes,Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing,China [2]University of Chinese Academy of Sciences,Beijing,China

出　　处：《Acta Geochimica》2025年第1期59-85,共27页地球化学学报(英文)

基　　金：support from the Third Xinjiang Scientific Expedition Program(2021XJKK0803);the National Natural Science Foundation of China(No.41930640);the Project of the Second Comprehensive Scientific Investigation on the Qinghai-Tibetan Plateau(2019QZKK1003)。

摘　　要：Carbonic acid produced by the dissolution of atmospheric and soil CO_(2)in water is usually the most dominant catalyst for chemical weathering,but a sulfuric aciddriven phenomenon,different from usual,was found in the orogenic belt watersheds dominated by silicate bedrock.This study,rooted in comprehensive field investigations in the Manas River Basin(MRB)north of the Tianshan Mountains,delves into the mechanisms and impacts of sulfuric and carbonic acid as catalysts driving diff erent types of chemical weathering in the Central Asian Orogenic Belt.Quantitative analyses elucidate that carbonate weathering constitutes 52.4%of the total chemical weathering,while silicate and evaporite account for 18.6%and 25.3%,respectively,with anthropogenic activities and atmospheric precipitation having little eff ect.The estimated total chemical weathering rate in MRB is approximately 0.075×10^(6)mol/km^(2)/year.Quantitative findings further suggest that,preceding carbonate precipitation(<10^(4)year),chemical weathering can absorb CO_(2).Subsequently,and following carbonate precipitation(10^(4)-10^(7)year),it will release CO_(2).The release significantly surpasses the global average CO_(2)consumption,contributing to a noteworthy climate impact.This study underscores the distinctive weathering mechanisms,wherein sulfuric acid emerges as the predominant catalyst.The quantity of sulfuric acid as a catalyst is approximately three times that of carbonic acid.Sulfuric acid-driven carbonate rock weathering(SCW)is identified as the sole chemical weathering type with a net CO_(2)release eff ect.SCW CO_(2)release flux(5176 mol/km^(2)/year)is roughly 2.5 times the CO_(2)absorption by Ca-Mg silicate weathering,highlighting the pivotal role of chemical weathering in sourcing atmospheric CO_(2)over the timescales of carbonate precipitation and sulfate reduction.Lastly,this study posits that catalyst and transport limitations are the most plausible critical factors in MRB.The interplay between sulfuric acid and dissolved CO_(2)competitively

关 键 词：Catchment chemical weathering Mid-latitude orogenic belt Sulfide oxidation Manas River Basin 

分 类 号：P512.12[天文地球—地质学]