英国牛津大学Robert G. Hilton团队揭示了旧碳通过全球河流系统从陆地输送到大气中。相关论文于2025年6月4日发表在《自然》杂志上。

河流和溪流是全球碳循环的重要途径，从其水面向大气释放二氧化碳（CO₂）和甲烷（CH₄）。到目前为止，人们认为河流排放的二氧化碳和甲烷主要来自最近（亚十年）的生物质生产，因此是生态系统呼吸的一部分。 

研究组结合新的和已发表的测量结果，创建了一个河流溶解无机碳（DIC）、二氧化碳和甲烷放射性碳含量的全球数据库。该数据库的同位素质量平衡表明，59 ± 17% 全球河流二氧化碳排放量的一半来自旧碳（千禧年或更早），其释放与河流流域岩性和生物群落有关。

这种以前未被认识的通过横向水文路线从长期土壤、沉积物和地质碳库向大气释放的旧的、工业化前的碳相当于1.2 ± 0.3 Pg C 1年，其规模与陆地净生态系统交换相似。这种通量的结果是，陆地上老化有机物储存的碳净损失大于预期。这需要重新评估人为碳在陆地系统和全球碳循环预算和模型中的命运。

附：英文原文

Title: Old carbon routed from land to the atmosphere by global river systems

Author: Dean, Joshua F., Coxon, Gemma, Zheng, Yanchen, Bishop, Jack, Garnett, Mark H., Bastviken, David, Galy, Valier, Spencer, Robert G. M., Tank, Suzanne E., Tipper, Edward T., Vonk, Jorien E., Wallin, Marcus B., Zhang, Liwei, Evans, Chris D., Hilton, Robert G.

Issue&Volume: 2025-06-04

Abstract: Rivers and streams are an important pathway in the global carbon cycle, releasing carbon dioxide (CO2) and methane (CH4) from their water surfaces to the atmosphere1,2. Until now, CO2 and CH4 emitted from rivers were thought to be predominantly derived from recent (sub-decadal) biomass production and, thus, part of ecosystem respiration3,4,5,6. Here we combine new and published measurements to create a global database of the radiocarbon content of river dissolved inorganic carbon (DIC), CO2 and CH4. Isotopic mass balance of our database suggests that 59±17% of global river CO2 emissions are derived from old carbon (millennial or older), the release of which is linked to river catchment lithology and biome. This previously unrecognized release of old, pre-industrial-aged carbon to the atmosphere from long-term soil, sediment and geologic carbon stores through lateral hydrological routing equates to 1.2±0.3PgCyear1, similar in magnitude to terrestrial net ecosystem exchange. A consequence of this flux is a greater than expected net loss of carbon from aged organic matter stores on land. This requires a reassessment of the fate of anthropogenic carbon in terrestrial systems and in global carbon cycle budgets and models.

DOI: 10.1038/s41586-025-09023-w

Source: https://www.nature.com/articles/s41586-025-09023-w