State key laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Laboratory of Green Chemistry, Lappeenranta University of Technology, Mikkeli 50130, Finland.
State key laboratory of Cryospheric Science, 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, Beijing 100049, China.
Sci Total Environ. 2019 Jan 10;647:1385-1397. doi: 10.1016/j.scitotenv.2018.07.417. Epub 2018 Jul 31.
Dissolved organic carbon (DOC) in snow plays an important role in river ecosystems that are fed by snowmelt water. However, limited knowledge is available on the DOC content in snow of the Chinese Altai Mountains in Central Asia. In this study, DOC in the snow cover of the Kayiertesi river basin, southern slope of Altai Mountains, was investigated during November 2016 to April 2017. The results showed that average concentrations of DOC in the surface snow cover (1.01 ± 0.52 mg L) were only a little higher than those in glaciers of the Tibetan Plateau, European Alps, and Alaska, but much higher than in Greenland Ice Sheet. Depth variations of DOC concentrations from snowpack profiles indicated higher values in the surface layer. During the observation period, scavenging efficiency for DOC in snow cover is estimated to be 0.15 ± 0.10, suggesting that DOC in snow can be affected more by the meltwater during ablation season than during accumulation season. The average mass absorption cross section at 365 nm and the absorption Ångström exponent of DOC were 0.45 ± 0.35 m g and 2.59 ± 1.03, respectively, with higher values in March and April 2017. Fraction of radiative forcing caused by DOC relative to black carbon accounted for about 10.5%, implying DOC is a non-ignorable light-absorber of solar radiation in snow of the Altai regions. Backward trajectories analysis and aerosol vertical distribution images from satellites showed that DOC in the snow of the Altai Mountains was mainly influenced by air masses from Central Asia, Western Siberia, the Middle East, and some even from Europe. Biomass burning and organic carbon mixed with mineral dust contributed significantly to the DOC concentration. This study highlights the effects of DOC in the snow cover for radiative forcing and the need to study carbon cycling for evaluation of quality of the downstreams ecosystems.
雪水中的溶解有机碳（DOC）在以融雪水为水源的河流生态系统中起着重要作用。然而，关于中亚阿尔泰山脉的雪水中的 DOC 含量，我们的了解还很有限。本研究于 2016 年 11 月至 2017 年 4 月期间，对阿尔泰山南坡的卡伊尔特斯河流域的雪被中的 DOC 进行了调查。结果表明，表层雪被中 DOC 的平均浓度（1.01±0.52mg/L）仅略高于青藏高原、阿尔卑斯山和阿拉斯加的冰川，但远高于格陵兰冰盖。雪层剖面中 DOC 浓度的深度变化表明表层浓度更高。在观测期间，雪被中 DOC 的清除效率估计为 0.15±0.10，这表明在消融季节，DOC 更容易受到融雪的影响，而不是在积累季节。DOC 在 365nm 处的平均质量吸收截面和吸收 Ångström 指数分别为 0.45±0.35m²mg 和 2.59±1.03，2017 年 3 月和 4 月的数值更高。DOC 对太阳辐射的辐射强迫相对于黑碳的份额约为 10.5%，这表明在阿尔泰山地区的雪中，DOC 是一种不可忽视的太阳辐射吸收物质。后向轨迹分析和卫星提供的气溶胶垂直分布图像表明，阿尔泰山的雪中的 DOC 主要受来自中亚、西西伯利亚、中东和甚至来自欧洲的气团的影响。生物质燃烧和与矿物粉尘混合的有机碳对 DOC 浓度有显著贡献。本研究强调了雪被中 DOC 对辐射强迫的影响，以及为评估下游生态系统质量而研究碳循环的必要性。
