2026-10-12T12:32:33Z https://api.figshare.com/v2/oai

oai:figshare.com:article/34003145 2026-09-26T14:17:56Z category_15 category_21 category_272 category_873 category_39 category_45 category_734 category_61 category_64 category_135 portal_63 item_type_3 month_year_09_2026

Photodegradation Unlocks Permafrost Carbon in Qinghai-Tibetan Plateau Rivers Ting Wang (16292) Wenjie Hong (6057260) Leyan Feng (20315742) Yueting Meng (22943463) Dongfeng Li (192917) Jinren Ni (1534255) Neuroscience Biotechnology Environmental Sciences not elsewhere classified Chemical Sciences not elsewhere classified Ecology Sociology Biological Sciences not elsewhere classified Developmental Biology Cancer Computational Biology yarlung tsangpo river warming alpine regions tibetan plateau serve study identifies high potentially promoting ch positive climate feedback distinctive photochemical reactors dissolved organic matter critical photochemical hubs ancient carbon reservoirs strong sunlight drives molecular analyses show 3 </ sup 2 </ sup 18 </ sup 14 </ sup 13 </ sup 2 </ sub old carbon derived carbon carbon source terrestrial lignin synergistic control photodegradation products molecular formulas mercury accumulation mainly composed like compounds level characterization labile fraction isotopic tracers highly photoreactive fundamentally reshape dominant source dom cycling dom ). derived dom aromatic dom altitude rivers High-altitude rivers on the Qinghai-Tibetan Plateau serve as distinctive photochemical reactors, where intense solar radiation interacts with ancient carbon reservoirs to fundamentally reshape the fate of dissolved organic matter (DOM). Based on isotopic tracers (δ²H, δ¹⁸O, δ³H, Δ¹⁴C, and δ¹³C) and molecular-level characterization with 7979 unique formulas identified along the Yarlung Tsangpo River, we reveal a synergistic control of sunlight and carbon source on DOM cycling. Isotopic signatures indicate considerable inputs of “old water” (i.e., glacial meltwater) and confirm permafrost-derived carbon as a dominant source of aged sedimentary organic matter. Molecular analyses show that aromatic DOM, mainly composed of terrestrial lignin- and tannin-like compounds, is highly photoreactive, and strong sunlight drives its dearomatization and oxidation. Photodegradation products of aromatic DOM share 26.8% of their molecular formulas with F_pre1953-related DOM and 44.8% with permafrost-derived DOM. This process unlocks previously stable and old carbon into labile fraction, enhancing fluvial carbon mineralization. The liberated ancient DOM shows higher bioavailability, potentially promoting CH₄/CO₂ emissions and mercury accumulation. Our study identifies high-altitude rivers as critical photochemical hubs that mobilize cryospheric organic carbon and imply a positive climate feedback in warming alpine regions. 2026-09-26T00:00:00Z Dataset Dataset 10.1021/acs.est.6c04255.s002 https://figshare.com/articles/dataset/Photodegradation_Unlocks_Permafrost_Carbon_in_Qinghai-Tibetan_Plateau_Rivers/34003145 CC BY-NC 4.0