天山科其喀尔冰川末端降水化学特征及控制因素  

Chemical characteristics and their influencing factors of precipitation at the end of the Koxkar Glacier,Tianshan Mountains

作　　者：王建[1] 韩海东 许君利[1] 颜伟 WANG Jian;HAN Haidong;XU Junli;YAN Wei(North Jiangsu Research Institute of Agricultural and Rural Modernization,Yancheng Teachers University,Yancheng 224007,Jiangsu,China;State Key Laboratory of Cryospheric Science,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,Gansu,China;School of Geographic Sciences,Xinyang Normal University,Xinyang 464000,Henan,China)

机构地区：[1]盐城师范学院苏北农业农村现代化研究院,江苏盐城224007 [2]中国科学院西北生态环境资源研究院冰冻圈科学国家重点实验室,甘肃兰州730000 [3]信阳师范学院地理科学学院,河南信阳464000

出　　处：《干旱区研究》2022年第2期347-358,共12页Arid Zone Research

基　　金：国家自然科学基金项目(41871055,41471060);中国科学院西北生态环境资源研究院冰冻圈科学国家重点实验室开放基金(SKLCS-OP-2020-7);江苏省自然科学基金项目(BK20181059)。

摘　　要：对内陆高寒山区的天山南坡科其喀尔冰川末端夏季降水进行采样,在分析各离子浓度、电导率和pH值的基础上,利用因子分析、富集因子及后向轨迹法,探讨区域降水的溶质来源及控制因素。结果表明:(1)科其喀尔冰川末端大气降水的pH值介于7.15~8.52,整体偏弱碱性,阴、阳离子分别受HCO_(3)^(-)和Ca^(2+)支配,属于典型HCO_(3)-Ca型。白天降水的电导率和总离子浓度较夜间分别偏高11.56%和9.40%,这可能是在山谷风或冰川风作用下,塔里木盆地内气溶胶物质随近地层风从山麓地带与平原区迁移到研究区后湿沉降所致。(2)降水离子主要来自地壳源物质补给,占总离子量的85.54%。其中HCO_(3)^(-)、Ca^(2+)和Mg^(2+)主要受侏罗系沉积层和第四系黄土沉积层中碳酸盐岩(Ca_(x)Mg_(1-x)CO_(3))风化补给,Cl^(-)、SO_(4)^(2-)、Na^(+)和K^(+)主要受中亚与塔里木盆地因干旱而发育的盐湖(咸水湖)蒸发或冲积/洪积作用形成的盐土风化补给。降水中仅有41.52%的Na^(+)和96.22%的Cl^(-)源自海洋源,且二者浓度之比为2.13:1,表明海洋源气团在长距离输送过程中明显地受到降水再蒸发作用和地表物质风蚀等因素的影响,导致海洋源补给量仅占降水总离子的4.87%。源自人类活动补给的溶质约是海洋源的2倍,以NH_(4)^(+)、NO_(3)^(-)和SO_(4)^(2-)为主,可为高寒山区土壤形成和植被生长提供必要的氮、硫元素。(3)气团后向轨迹追踪表明,西风环流对天山南坡降水及化学组成影响非常显著,形成降水的频次和降水量平均分别占64.35%和53.04%,其降水的离子总浓度虽然仅为局地环流的69.91%,但NO_(3)^(-)浓度平均为局地环流降水的1.42倍,间接表明塔里木盆地空气与水源质量可能受到中亚人类活动的影响。Atmospheric precipitation was sampled in the summer at the end of the Koxkar Glacier,Tianshan Mountains,China.Based on analyses of the ion concentration,conductivity,and pH characteristics,we explored the solute sources and control factors for regional precipitation using factor analysis,enrichment factors,and backward trajectory tracking.Atmospheric precipitation was slightly alkaline,with a pH between 7.15 and 8.52,and their anions and cations were dominated by HCO_(3)^(-)and Ca^(2+),respectively,which belong to the typical HCO_(3)^(-)Ca type.The conductivity and total ion concentration of precipitation during the daytime were 11.56%and 9.40%higher,respectively,than those of the nighttime;this may be caused by the wet deposition of aerosol materials from the piedmont and plain areas with the near-surface wind under the action of valley wind or glacial wind during the daytime.Precipitation ions mainly originated from the supply of crustal source materials,accounting for 85.54%of the total ion content;among them,HCO_(3)^(-),Ca^(2+),and Mg^(2+)were mainly supplied by carbonate rock weathering(Ca_(x)Mg_(1−x)CO_(3)) in the Jurassic sedimentary layer and Quaternary loess sedimentary layer,whereas Cl^(-),SO_(4)^(2-),Na^(+),and K^(+) were mainly supplied by the evaporation of salt lakes caused by drought or the weathering of saline soil formed by alluvial/proluvial processes in Central Asia and the Tarim Basin.Only 41.52%of Na^(+) and 96.22%of Cl^(-)in precipitation originated from ocean sources and salt lakes,and their concentration ratio was 2.13:1,indicating that ocean source air masses were affected by the precipitation reevaporation and wind erosion of surface materials during long-distance transportation;this resulted in ocean source recharge only accounting for 4.87%of the total precipitation ions.The solute supplied by human activities was approximately twice that of ocean sources,mainly NH_(4)^(+),NO_(3)^(-),and SO_(4)^(2-),which could provide the necessary nitrogen and sulfur for soil formation and alpine v

关 键 词：大气降水 溶质来源 人类活动 水汽输送 高寒山区 

分 类 号：P343.6[天文地球—水文科学]