Key Laboratory of Western China's Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China.
Key Laboratory of Western China's Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China; State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; CAS Centre for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China.
Sci Total Environ. 2020 Jul 10;725:138346. doi: 10.1016/j.scitotenv.2020.138346. Epub 2020 Apr 3.
Glacier melting represents an important flux of carbon and nitrogen (N) and affects the hydrological cycle. In this study, we presented the features of dissolved organic carbon (DOC) and N concentrations, their potential sources and export from the Muz Taw glacier in Central Asia. The average DOC and total dissolved nitrogen concentrations were 1.12 ± 1.66 and 0.62 ± 0.59 mg L in surface snow and 0.21 ± 0.04 and 0.31 ± 0.10 mg L in snowpit samples, respectively. The values from snowpit of the Muz Taw glacier were comparable to data reported from glaciers in the Tibetan Plateau but were considerably higher than those from polar regions. The C/N ratios in snow ranged from 0.7 to 11.7, indicating the high bioavailability of DOC. Mass absorption cross section of DOC at 365 nm in snow indicated that during the snow melting process, light-absorbing DOC was prone to be attached to particles, especially in the ablation zone of the Muz Taw glacier. Radiative forcing caused by DOC contributed approximately 38 ± 26% and 18 ± 9.8% of that caused by black carbon for surface snow and snowpit samples, respectively. DOC and N deposition on the glacier surface were influenced by the combined sources from anthropogenic input, wild biomass burning emission, and dust input from local regions and long range transport. Export of DOC and N from the Muz Taw glacier was estimated to be 3.47-18.5 t C yr and 5.11-10.23 t N yr respectively, based on their concentrations and current glacier mass balance. These results enhanced our understanding of the sources and cycle of DOC and N released from glaciers in Central Asia, where glacier meltwater can protect the population from drought stress.
冰川融化代表了碳和氮（N）的重要通量，并且会影响水文循环。在这项研究中，我们介绍了中亚 Muz Taw 冰川中溶解有机碳（DOC）和 N 浓度的特征、它们的潜在来源以及从该冰川中的输出情况。在表面雪和雪坑样本中，DOC 和总溶解氮的平均浓度分别为 1.12±1.66 和 0.62±0.59 mg·L-1，0.21±0.04 和 0.31±0.10 mg·L-1。Muz Taw 冰川雪坑中的这些值与青藏高原冰川报告的数据相当，但明显高于极地地区的数据。雪中的 C/N 比值范围为 0.7 至 11.7，表明 DOC 具有较高的生物可利用性。雪中 DOC 在 365nm 处的质量吸收截面表明，在融雪过程中，光吸收性的 DOC 容易附着在颗粒上，尤其是在 Muz Taw 冰川的消融区。DOC 引起的辐射强迫大约占表面雪和雪坑样本中黑碳引起的辐射强迫的 38±26%和 18±9.8%。DOC 和 N 沉积在冰川表面受到来自人为输入、野生生物质燃烧排放、当地和长距离传输的灰尘输入的综合来源的影响。基于浓度和当前冰川质量平衡，估计 Muz Taw 冰川的 DOC 和 N 输出量分别为 3.47-18.5 t·C·yr-1 和 5.11-10.23 t·N·yr-1。这些结果增强了我们对中亚冰川释放的 DOC 和 N 的来源和循环的理解，冰川融水可以保护这些地区的人口免受干旱压力的影响。
