Wang Ying, Wang Genxu, Sun Xiangyang, Li Jinlong, Song Chunlin
State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource and Hydropower, Sichuan University, Chengdu, Sichuan, China.
State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource and Hydropower, Sichuan University, Chengdu, Sichuan, China.
Sci Total Environ. 2024 Jan 1;906:167370. doi: 10.1016/j.scitotenv.2023.167370. Epub 2023 Sep 25.
The earth's cryosphere is the outpost of climatic warming, which leads to rapid changes of organic carbon (OC) transport from terrestrial to aquatic ecosystems. OC in the cryosphere rivers plays vital roles in the carbon cycle and river ecosystem health. Yet, we still lack a comprehensive assessment of the spatiotemporal patterns of riverine OC across the Northern Hemisphere cryosphere. Here, we compiled OC concentration, radiocarbon (C), and the specific ultraviolet absorbance (SUVA) of dissolved OC (DOC) at 254 nm data from 1007 unique sites, extracted from 138 published literature between 1972 and 2022. Overall, the average DOC and particulate OC (POC) concentrations are 6.34 and 2.61 mg C L, respectively, with the average age of DOC and POC being ~1100 and ~4300 years BP, respectively, indicating the release of aged carbon pools. Seasonal variations in DOC and POC concentrations, ΔC-DOC and SUVA were observed, with distinct spatial variations closely linked to specific watershed characteristics. We found permafrost-impacted watersheds displayed significantly higher DOC concentrations, younger OC ages but lower POC concentrations compared to glacier-impacted watersheds. Meanwhile, in boreal forest watersheds, DOC is the most concentrated and youngest in varied ecoregions. Additionally, in permafrost regions characterized by higher permafrost extent, ground ice content, or lowlands with thick overburden cover, riverine DOC is more concentrated and aromatic. We estimated that specific OC fluxes in glacier rivers are higher than that in permafrost rivers (4.77 and 1.86 g C m yr, respectively). Our results highlight the complex and variable spatiotemporal patterns of riverine OC in the northern cryosphere, which are essential for assessing the impact of OC on the global carbon cycle and climate warming.
地球冰冻圈是气候变暖的前沿地带，这导致有机碳（OC）从陆地生态系统向水生生态系统的快速转移。冰冻圈河流中的有机碳在碳循环和河流生态系统健康方面发挥着至关重要的作用。然而，我们仍然缺乏对北半球冰冻圈河流中有机碳时空格局的全面评估。在此，我们汇总了1972年至2022年间从138篇已发表文献中提取的1007个独特站点的有机碳浓度、放射性碳（C）以及254纳米处溶解有机碳（DOC）的特定紫外吸光度（SUVA）数据。总体而言，DOC和颗粒有机碳（POC）的平均浓度分别为6.34和2.61毫克碳/升，DOC和POC的平均年龄分别约为1100年和4300年BP，表明古老碳库的释放。观察到DOC和POC浓度、ΔC-DOC和SUVA存在季节性变化，其明显的空间变化与特定流域特征密切相关。我们发现，与冰川影响的流域相比，受永久冻土影响的流域DOC浓度显著更高，有机碳年龄更年轻，但POC浓度更低。同时，在北方森林流域，DOC在不同生态区域最为集中且年龄最轻。此外，在永久冻土范围更大、地下冰含量更高或覆盖层较厚的低地等特征明显的永久冻土区域，河流DOC更为集中且具有更强的芳香性。我们估计，冰川河流中的特定有机碳通量高于永久冻土河流（分别为4.77和1.86克碳/米²·年）。我们的研究结果突出了北半球冰冻圈河流中有机碳复杂多变的时空格局，这对于评估有机碳对全球碳循环和气候变暖的影响至关重要。
