Spatiotemporal variability of organic carbon in streams and rivers of the Northern Hemisphere cryosphere

Ying Wang; Genxu Wang; Xiangyang Sun; Jinlong Li; Chunlin Song

doi:10.1016/j.scitotenv.2023.167370

Spatiotemporal variability of organic carbon in streams and rivers of the Northern Hemisphere cryosphere

Sci Total Environ. 2024 Jan 1:906:167370. doi: 10.1016/j.scitotenv.2023.167370. Epub 2023 Sep 25.

Authors

Ying Wang¹, Genxu Wang¹, Xiangyang Sun¹, Jinlong Li¹, Chunlin Song²

Affiliations

¹ State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource and Hydropower, Sichuan University, Chengdu, Sichuan, China.
² State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource and Hydropower, Sichuan University, Chengdu, Sichuan, China. Electronic address: songchunlin@scu.edu.cn.

PMID: 37758149
DOI: 10.1016/j.scitotenv.2023.167370

Abstract

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 (¹⁴C), 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^-1, 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, Δ¹⁴C-DOC and SUVA₂₅₄ 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^-2 yr^-1, 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.

Keywords: Climate change; Cryosphere rivers; Dissolved organic carbon; Particulate organic carbon; Radiocarbon; Specific organic carbon flux.