作者：Liu, Z., Zhou, Y., Rocher-Ros, G. et al.

Riverine dissolved organic carbon (DOC) constitutes a pivotal component in the Earth’s carbon cycle, yet little is known about the global patterns, sources, and factors governing lotic DOC. Here, we integrate a global dataset and employ machine learning to generate a global atlas of riverine DOC concentration and its radiocarbon (Δ14C) and stable-carbon (δ13C) isotopic signatures. Globally, riverine DOC has an average Δ14C value of –22.5‰ ± 144.0‰ (radiocarbon age of 221 years), with fossil carbon contributing a minor fraction (6.7% ± 3.0%). Terrestrial and autochthonous riverine production are the dominant DOC sources (>80%) at the global scale, with contemporary terrestrial DOC predominant in tropical rivers and within-river production prominent in those within temperate and semi-arid regions. Rivers draining high-latitude regions and high-elevation sites have the lowest Δ14C values (–353‰ to –78‰; ages between 3400 and 600 years). River Δ14C-DOC values correlate with soil organic carbon Δ14C values, but river DOC has much higher Δ14C values than subsurface soils indicating that riverine DOC originates from surface rather than subsurface soils. Because warming mobilizes aged organic carbon from permafrost soils, export to and processing of old carbon in recipient aquatic systems may accelerate with climate change.

河流溶解有机碳（DOC）是地球碳循环的关键组分，然而全球河流DOC的分布格局、来源及控制因子仍知之甚少。研究整合全球数据集并运用机器学习，编制了全球河流DOC浓度及其放射性碳（Δ¹⁴C）与稳定碳（δ¹³C）同位素特征图谱。全球尺度上，河流DOC的平均Δ¹⁴C值为 -22.5‰ ± 144.0‰（对应放射性碳年龄221年），化石碳贡献甚微（6.7% ± 3.0%）。在全局尺度上，陆源输入与河流内部自生源产出是DOC的主导来源（合计 > 80%）：当代陆源DOC在热带河流中占优，而河内自生产出在温带与半干旱区河流中更为突出。流经高纬度地区与高海拔站点的河流具有最低的Δ¹⁴C值（-353‰ 至 -78‰；对应年龄3400—600年）。河流DOC的Δ¹⁴C值与土壤有机碳的Δ¹⁴C值相关，但河流DOC的Δ¹⁴C值远高于地下土壤，表明河流DOC源自地表而非地下土壤。由于气候变暖正在活化永冻土中储存的古老有机碳，其向受纳水生系统的输出及在其中的加工过程可能随气候变化而加速。

（来源：National Science Review 2026 Issue 9  DOI: 10.1093/nsr/nwag237）