Increasing riverine export of dissolved organic carbon from China

作者：Yanzi Yan, Ronny Lauerwald, Xuhui Wang, Pierre Regnier, Philippe Ciais, Lishan Ran, Yuanyi Gao, Ling Huang, Yao Zhang, Zheng Duan, Fabrice Papa, Bing Yu, Shilong Piao · 发表于：Global Change Biology · 年份：2023 · DOI：10.1111/gcb.16819 · 被引用次数：40 · 研究领域：Marine and coastal ecosystems、Soil and Water Nutrient Dynamics、Hydrology and Watershed Management Studies

Abstract River transport of dissolved organic carbon (DOC) to the ocean is a crucial but poorly quantified regional carbon cycle component. Large uncertainties remaining on the riverine DOC export from China, as well as its trend and drivers of change, have challenged the reconciliation between atmosphere‐based and land‐based estimates of China's land carbon sink. Here, we harmonized a large database of riverine in‐situ measurements and applied a random forest model, to quantify riverine DOC fluxes (F DOC ) and DOC concentrations (C DOC ) in rivers across China. This study proposes the first DOC modeling effort capable of reproducing well the magnitude of riverine C DOC and F DOC , as well as its trends, on a monthly scale and with a much wider spatial distribution over China compared to previous studies that mainly focused on annual‐scale estimates and large rivers. Results show that over the period 2001–2015, the average C DOC was 2.25 ± 0.45 mg/L and average F DOC was 4.04 ± 1.02 Tg/year. Simultaneously, we found a significant increase in F DOC (+0.044 Tg/year 2 , p = .01), but little change in C DOC (−0.001 mg/L/year, p > .10). Although the trend in C DOC is not significant at the country scale, it is significantly increasing in the Yangtze River Basin and Huaihe River Basin (0.005 and 0.013 mg/L/year, p < .05) while significantly decreasing in the Yellow River Basin and Southwest Rivers Basin (−0.043 and −0.014 mg/L/year, p = .01). Changes in hydrology, play a stro...