You Yanbin, Jia Binghao, Xie Zhenghui, Wang Yan, Wang Longhuan, Li Ruichao, Wu Ruixueer, Yan Heng, Wang Runyu, Tian Yuhang
State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
Sci Total Environ. 2024 Dec 1;954:176642. doi: 10.1016/j.scitotenv.2024.176642. Epub 2024 Oct 1.
The lateral transport of dissolved organic carbon (DOC) from land to rivers and oceans is a significant but overlooked component of the global carbon cycle. However, there are still large uncertainties in the magnitude and trend of global DOC export fluxes, as well as their response to environmental change. In this study, several simulations were conducted using a developed land surface model that considered riverine DOC transport and anthropogenic disturbance to investigate the terrestrial DOC loading and riverine DOC export, and to quantify the relative contributions of natural and anthropogenic factors over the past four decades (1981-2016). These factors include climate change, nitrogen deposition, land use change, atmospheric CO concentration, anthropogenic water regulation, and fertilizer and manure application. Results showed that the average global annual terrestrial DOC loading was about 432.30 ± 53.59 Tg C yr, and rivers exported about 209.73 ± 36.58 Tg C yr to oceans over the past four decades. Simultaneously, a significant increase in terrestrial DOC loading and riverine DOC export fluxes (3.36 Tg C yr and 2.99 Tg Cyr, p < 0.01) was found, which increased by 26.88 % and 47.02 %, respectively. According to our factorial analysis, the interannual variability in DOC fluxes in most regions was mainly attributed to climate change and contributed more than 60 % of the long-term increase. In addition, rising atmospheric CO and land use change amplified the increase in terrestrial DOC loading, with the area dominated by the two factors expanding from 7.94 % in the 1980s to 23.84 % in the 2010s, and riverine DOC export showed a similar pattern, which may be related to the increased soil DOC sources. Anthropogenic water regulation and nitrogen addition have led to a slight increase in DOC fluxes, which should not be ignored, otherwise carbon fluxes may be underestimated.
溶解有机碳（DOC）从陆地向河流和海洋的侧向输送是全球碳循环中一个重要但被忽视的组成部分。然而，全球DOC输出通量的大小、趋势及其对环境变化的响应仍存在很大的不确定性。在本研究中，使用一个考虑河流DOC输送和人为干扰的改进陆地表面模型进行了多次模拟，以研究陆地DOC负荷和河流DOC输出，并量化过去四十年（1981 - 2016年）自然和人为因素的相对贡献。这些因素包括气候变化、氮沉降、土地利用变化、大气CO浓度、人为水资源调控以及化肥和粪肥施用。结果表明，过去四十年全球陆地年均DOC负荷约为432.30±53.59 Tg C/年，河流向海洋输出约209.73±36.58 Tg C/年。同时，发现陆地DOC负荷和河流DOC输出通量显著增加（分别为3.36 Tg C/年和2.99 Tg C/年，p < 0.01），分别增加了26.88%和47.02%。根据我们的因子分析，大多数地区DOC通量的年际变化主要归因于气候变化，其贡献超过长期增加量的60%。此外，大气CO浓度上升和土地利用变化加剧了陆地DOC负荷的增加，受这两个因素主导的区域面积从20世纪80年代的7.94%扩大到2010年代的23.84%，河流DOC输出也呈现类似模式，这可能与土壤DOC来源增加有关。人为水资源调控和氮添加导致DOC通量略有增加，这一点不容忽视，否则碳通量可能被低估。
