地理学报 ›› 2023, Vol. 78 ›› Issue (7): 1792-1808.doi: 10.11821/dlxb202307017

• 植被地理与地表过程 • 上一篇    下一篇

青藏高原北部典型冰川流域化学风化研究

李铮1(), 钟君1(), 李思亮1,3, 秦翔2, 徐森1, 陈率1,4   

  1. 1.天津大学地球系统科学学院,天津 300072
    2.中国科学院西北生态环境资源研究院 祁连山冰冻圈与生态环境综合观测研究站,兰州 730000
    3.天津市环渤海关键带科学与可持续发展重点实验室,天津 300072
    4.香港大学地理系,香港 999077
  • 收稿日期:2023-03-15 修回日期:2023-07-12 出版日期:2023-07-25 发布日期:2023-08-01
  • 通讯作者: 钟君(1987-), 男, 山东潍坊人, 副研究员, 研究方向为地表地球化学。E-mail: jun.zhong@tju.edu.cn
  • 作者简介:李铮(1996-), 男, 河北承德人, 博士生, 研究方向为同位素地球化学。E-mail: lizheng_sess@tju.edu.cn
  • 基金资助:
    国家自然科学基金项目(42173013);国家自然科学基金项目(41925002);冰冻圈科学国家重点实验室自主课题(SKLCS-ZZ-2020-15)

Chemical weathering in a typical glacier catchment in the northern Qinghai-Tibet Plateau

LI Zheng1(), ZHONG Jun1(), LI Siliang1,3, QIN Xiang2, XU Sen1, CHEN Shuai1,4   

  1. 1. Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
    2. Qilianshan Station of Cryosphere and Ecologic Environment, Northwest Institute of Eco-Environment and Resources, CAS, Lanzhou 730000, China
    3. Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China
    4. Department of Geography, The University of Hong Kong, Hong Kong 999077, China
  • Received:2023-03-15 Revised:2023-07-12 Published:2023-07-25 Online:2023-08-01
  • Supported by:
    National Natural Science Foundation of China(42173013);National Natural Science Foundation of China(41925002);State Key Laboratory of Cryospheric Science(SKLCS-ZZ-2020-15)

摘要:

青藏高原生态环境对气候变化的响应是全球变化研究关注的重点问题。地表风化与气候变化之间具有紧密的联系,因此对冰川流域硅酸盐岩风化以及黄铁矿氧化进行定量研究可为理解高原气候变化提供关键性认识。本文以青藏高原北部祁连山典型冰川流域—老虎沟流域为研究对象,通过分析流域河水及降水的水化学和氢氧同位素,研究了冰川径流来源,河流溶质来源以及水文条件对溶质的影响,流域化学风化速率以及黄铁矿氧化对化学风化碳汇效应的影响。利用同位素径流分割得到地下水、冰川融水以及大气降水对冰川径流的贡献分别为18.2%、58.3%和23.5%,并进一步通过溶质产生模型讨论了冰川河流量对溶质的影响。通过反演模型计算得到碳酸盐岩、硅酸盐岩、蒸发岩和降水对河水阳离子的贡献分别为59.1%、20.1%、8.3%和12.5%,蒸发岩、降水和融雪、黄铁矿对$SO_{4}^{2-}$的贡献分别为14.4%、8.0%、77.6%。最终估算得到碳酸盐岩和硅酸盐岩的风化通量分别为50.8 g/s和7.8 g/s,相应的CO2吸收速率分别为24.4 t/(km2 a)和5.9 t/(km2 a)。考虑黄铁矿氧化的影响后,短时间尺度(<106 a)老虎沟流域总CO2吸收速率为8.3 t/(km2 a),在长时间尺度(>106 a)则会释放CO2,总CO2释放速率为16.2 t/(km2 a)。总体来说,本文对老虎沟冰川流域的硅酸盐岩风化以及黄铁矿氧化对气候变化的响应进行了评估,明确了黄铁矿氧化对碳循环的影响,丰富了青藏高原流域风化和碳循环理论研究。

关键词: 老虎沟冰川, 水化学, 氢氧同位素, 径流分割, 化学风化

Abstract:

The response of the ecological environment on the Qinghai-Tibet Plateau to global climate change is a crucial topic in global change research. Given the close relationship between surface weathering and climate change, conducting quantitative research on silicate weathering and pyrite oxidation in glacial catchments can provide valuable insights into understanding climate change on the plateau. In this study, we focused on a typical glacial catchment, the Laohugou glacier catchment, located in the Qilian Mountains, north of the Qinghai-Tibet Plateau. Through the analysis of hydrochemistry, water isotopes of the river and precipitation, we explored the sources of glacier runoff, the origin of river solutes, the influence of hydrological conditions on solutes, the rate of chemical weathering in the catchment, and the impact of pyrite oxidation on the carbon sink effect of chemical weathering. Using isotopic hydrograph separation, we found that groundwater, glacial meltwater, and atmospheric precipitation contributed 18.2%, 58.3%, and 23.5%, respectively to glacial runoff. By employing a solute production modeling framework, we further examined the influence of discharge changes on the solutes. Additionally, utilizing an inverse model, we estimated the average mass contributions of carbonate, silicate, evaporite, and precipitation to the cations as 59.1%, 20.1%, 8.3%, and 12.5%, respectively. For $SO_{4}^{2-}$, the contributions of evaporite, precipitation and meltwater, and pyrite were 14.4%, 8.0%, and 77.6%, respectively. Finally, we estimated that the weathering fluxes of carbonate rock and silicate rock were 50.8 g/s and 7.8 g/s, respectively, with relative CO2 consumption rates of 24.4 t/(km2 a) and 5.9 t/(km2 a), respectively. As for the impact of pyrite oxidation, the total CO2 consumption rate of the Laohugou basin was estimated at 8.3 t/(km2 a) in the short term (<106 a), while the total CO2 release rate was 16.2 t/(km2 a) in the long term (>106 a). Overall, this study provides an evaluation of silicate weathering and pyrite oxidation in the Laohugou glacier catchment under the influence of current climate change. It also sheds light on the impact of pyrite oxidation on the carbon cycle, thereby enhancing our understanding of the weathering and carbon cycle processes on the Qinghai-Tibet Plateau.

Key words: Laohugou glacier, river chemistry, water isotopes, hydrograph separation, chemical weathering