青藏高原冰川表层雪中低分子有机酸的化学特征及来源分析  

Chemical characteristics and potential sources of low molecular weight organic acids in glacial surface snow on the Qinghai-Xizang Plateau

作　　者：张波 王宁练 张愉萱[1,2] 姚秀南 方玲 ZHANG Bo;WANG Ninglian;ZHANG Yuxuan;YAO Xiunan;FANG Ling(Shaanxi Key Laboratory of Surface System and Environmental Carrying Capacity,Xi’an 710127,China;Institute of Surface Systems and Hazards,College of Urban and Environmental Sciences,Northwest University,Xi’an 710127,China;Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China)

机构地区：[1]陕西省地表系统与环境承载力重点实验室,陕西西安710127 [2]西北大学城市与环境学院地表系统与灾害研究院,陕西西安710127 [3]中国科学院青藏高原研究所,北京100101

出　　处：《冰川冻土》2023年第5期1437-1450,共14页Journal of Glaciology and Geocryology

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK020102)资助。

摘　　要：偏远地区雪冰中的化学组成在一定程度上可以反映当地的大气环境状况。为揭示青藏高原冰川表层雪中低分子有机酸的特征、探讨其可能来源及对降水酸度的贡献,进一步理解偏远地区酸沉降的形成机制,本研究基于2021年5至6月在青藏高原的五条冰川:阿尔金、扎子沟、七一、煤矿和玉珠峰采集的28个表层新雪样,分析了雪样中低分子有机酸的含量和组成特征。结果表明:研究区表层雪中的甲酸、乙酸和草酸的浓度范围分别为90.2~225.2 ng·mL^(-1)、54.6~277.8 ng·mL^(-1)和46.1~474.0 ng·mL^(-1),除煤矿冰川外,雪样中有机酸总浓度相对较高。根据亨利定律和理想气体方程对有机酸的来源进行分析,表明阿尔金、扎子沟和煤矿冰川地区表层雪中的有机酸均主要来源于大气中不饱和碳氢化物的氧化反应等间接来源,而玉珠峰和七一冰川地区表层雪中的有机酸则主要来源于植物、土壤、生物质和化石燃料燃烧以及人类活动直接排放。在本研究中,甲酸、乙酸和草酸之间高度相关(相关系数介于0.73~0.97之间),表明它们可能均来自生物质燃烧。在有机酸的降水酸度贡献分析中,发现无机阴离子对降水的总自由酸度有较强的影响,是导致该地区降水酸化的主要原因。但有机酸对总自由酸度的贡献为13.4%~33.3%,说明有机酸对这些地区降水的酸化也起了一定的作用,其对降水酸度的贡献不容忽视。本研究旨在更好地了解研究区酸沉降形成机制,为青藏高原地区表层雪中有机酸的后续研究提供基础资料。The chemical composition of snow and ice in remote regions can reflects the local atmospheric envi⁃ronmental conditions.To reveal the characteristics of low molecular weight organic acids in glacial surface snow on the Tibetan Plateau,explore their potential sources,and assess their contribution to precipitation acidity,thereby enhancing our understanding of the formation mechanism of acid deposition in remote areas,this study collected 28 surface snow samples from five glaciers(A-erh-chin,Zazigou,Qiyi,Meikuang,and Yuzhufeng)on the Tibetan Plateau during May to June 2021.The samples were analyzed to determine the content and com⁃position of low molecular weight organic acids.The results showed that the concentrations of formic acid,acetic acid,and oxalic acid in the surface snow of the study area ranged from 90.2 to 225.2 ng·mL^(-1),54.6 to 277.8 ng·mL^(-1),and 46.1 to 474.0 ng·mL^(-1),respectively.The overall concentration of organic acids in the study ar⁃ea,except for the Meikuang region,was relatively high.Based on Henry’s law and the ideal gas equation,the sources of organic acids were analyzed.It was found that the organic acids in the surface snow of the A-erhchin,Zazigou,and Meikuang glacier areas primarily originated from the oxidation of unsaturated hydrocarbons in the atmosphere,while those in the Yuzhufeng and Qiyi glacier areas primarily originated from direct emis⁃sions from plants,soil,biomass,fossil fuel combustion,and human activities.In this study,a strong correla⁃tion was observed among formic acid,acetic acid,and oxalic acid(with correlation coefficients ranging from 0.73 to 0.97),suggesting a common origin,possibly from biomass burning.Regarding the contribution of or⁃ganic acids to precipitation acidity,it was found that inorganic anions strongly influenced the total free acidity of precipitation,constituting the primary cause of acidification in the region.However,the contribution of organic acids to the total free acidity ranged from 13.4%to 33.3%,indicating their significa

关 键 词：青藏高原 表层雪 有机酸 总自由酸度 

分 类 号：P343.6[天文地球—水文科学] P426.635[天文地球—地球物理学]