Niu Hewen, Kang Shichang, Gao Wanni, Sarangi Chandan, Tripathee Lekhendra, Rupakheti Dipesh, Zhang Guotao, Yan Xingguo
Yulong Snow Mountain Glacier and Environment Observation and Research Station/State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
Yulong Snow Mountain Glacier and Environment Observation and Research Station/State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China; University of Chinese Academy of Sciences (UCAS), Beijing 10049, China.
Environ Int. 2020 Nov;144:106045. doi: 10.1016/j.envint.2020.106045. Epub 2020 Sep 9.
Atmospheric aerosols are a branch of active research in recent decades. The deposition of light-absorbing substances on high-altitude glaciers causes substantial adverse impacts on the cryospheric environment, cryosphere-hydrology, and climate system. Although, the concentrations of water-soluble organic carbon (WSOC) in snow/ice on glaciers of Tibetan Plateau (TP) have been reported, their transfer processes and optical properties in the context of summer precipitation-atmosphere-snow-river water continuum are seldom studied. In this study, we have systematically examined some scientific issues associated with WSOC concentrations and light absorption properties of WSOC in various forms of samples from the Mt. Yulong region. Statistical results demonstrate that the spatial distribution of WSOC in the snow of Baishui glacier was heterogeneous. The average WSOC concentrations of each snowpit were significantly decreased, and its light-absorbing properties were significantly elevated with the time extension. Aerosol WSOC concentrations and light absorption have distinct spatial disparity and seasonal variation. Pre-monsoon and monsoon have the highest and lowest WSOC content, respectively. Whereas the light-absorbing properties present contrasting seasonal trends. Rivers of which runoff was supplied by glacier meltwater have significantly lower WSOC concentrations (e.g., 0.42 ± 0.03 mg L) compared with other forms of water bodies. Mass absorption cross-section of WSOC (MAC-) in multiple snow and meltwater samples was significantly different and type-dependent. Atmospheric aerosol has the lowest MAC- value among the four types of samples, which was likely associated with exhaust emissions from private vehicles and tour buses. Statistical results indicated that the average AAE values of various snow/ice samples are subequal. Snow of glaciers supplies a desirable platform for the deposition of gaseous materials which experienced long-range transport in high altitude zones. Biomass-burning emissions made an immense contribution to the WSOC deposition over the study area, as demonstrated by the distribution of active fire points. However, this preliminary study represents the first systematic investigation of WSOC deposition in southeastern TP. Further robust in-situ field investigations and laboratory measurements are urgently necessary to improve our understanding of the transfer process and optical property of WSOC.
大气气溶胶是近几十年来活跃的研究领域。光吸收物质在高海拔冰川上的沉积对冰冻圈环境、冰冻圈水文和气候系统造成了重大不利影响。尽管已有关于青藏高原（TP）冰川雪/冰中水溶性有机碳（WSOC）浓度的报道，但在夏季降水 - 大气 - 雪 - 河流水连续体背景下，其迁移过程和光学性质鲜有研究。在本研究中，我们系统地研究了与玉龙雪山地区各种形式样品中WSOC浓度和WSOC光吸收特性相关的一些科学问题。统计结果表明，白水冰川雪中WSOC的空间分布是不均匀的。随着时间的延长，每个雪坑的WSOC平均浓度显著降低，其光吸收特性显著升高。气溶胶WSOC浓度和光吸收具有明显的空间差异和季节变化。季风前和季风期间的WSOC含量分别最高和最低。而光吸收特性呈现出相反的季节趋势。由冰川融水补给径流的河流，其WSOC浓度（例如0.42±0.03 mg/L）明显低于其他形式的水体。多个雪和融水样品中WSOC的质量吸收截面（MAC-）显著不同且与类型有关。大气气溶胶在四种样品类型中MAC-值最低，这可能与私家车和旅游巴士的尾气排放有关。统计结果表明，各种雪/冰样品的平均吸收 Ångström 指数（AAE）值相近。冰川雪为气态物质在高海拔地区的长距离传输后的沉积提供了理想平台。正如活跃火点分布所示，生物质燃烧排放对研究区域内的WSOC沉积贡献巨大。然而，这项初步研究是对TP东南部WSOC沉积的首次系统调查。迫切需要进一步进行强有力的实地调查和实验室测量，以加深我们对WSOC迁移过程和光学性质的理解。
