| 摘要: |
| 河流CO2排放是全球碳循环的重要组成部分。以汉江上游流域低等级(Strahler等级1~3)河流月河为研究对象,采样测定2016年12月和2017年6月的关键环境因子并计算河流CO2分压(pCO2)。利用统计学模型,探讨不同等级河流水环境因子的时空变化及关键控制因素。结果表明,月河流域低等级河流CO2约有87%的采样点过饱和,pCO2变化范围是135~5960 μatm,不同等级河流环境因子和pCO2具有明显的时空差异,且河流pCO2随着河流等级的增加而增加。利用R语言“ggpair”函数分析显示,河流pCO2与建设用地占比、耕地占比和总氮(TN)、总磷(TP)、溶解性有机碳(DOC)浓度呈正相关,与森林用地占比、溶解氧(DO)浓度及坡度呈负相关。对比分析不同等级河流的关键控制因素发现,低等级河流pCO2受土地利用和环境因子共同控制,且土地利用的影响随着河流等级的增加逐渐减小。进而建立了基于土地利用和养分的不同等级河流pCO2的回归模型,旨在为区域及全球河流碳排放的估算提供参考。 |
| 关键词: 河流pCO2 土地利用 低等级河流 长江 控制因素 |
| DOI：10.18307/2023.0127 |
| 分类号: |
| 基金项目:国家自然科学基金项目(31670473)和中国科学院高层次人才计划项目(R53A362Z10)联合资助。 |
|
| Spatiotemporal variations and drivers of the low order stream pCO2 in the Yue River of the Han River Catchment |
|
Gu Shijie1,2, Li Siyue3
|
|
1.School of River and Ocean Engineering, Chongqing Jiaotong University, Chongqing 400074, P. R. China;2.Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, P. R. China;3.School of Environmental Ecology and Biological Engineering, Wuhan Institute of Technology, Wuhan 430205, P. R. China
|
| Abstract: |
| Riverine carbon dioxide (CO2) emission is an essential component of the global carbon budget. Here, environmental variables were measured in the Yue River of the upper Han River draining to the Yangtze River in the dry season (December 2016) and the rainy season (June 2017) to explore the dynamics and driving factors of the river pCO2 in the low order streams. Results reveal that around 87% of samples have pCO2 levels that are supersaturated. Riverine pCO2 ranges from 135 μatm to 5960 μatm and shows a significant seasonal difference. The pCO2 level constantly increases with the stream order increases. Correlation analysis shows that pCO2 is positively related to construction and farmland proportion and TN, TP, DOC concentrations in the low order streams, while is negatively related to the forest land proportion, DO concentration and slope. The low order stream pCO2 dynamics are driven by anthropogenic activities and environmental factors, as the influence of the former decreases with the stream order increases. We further develop multiple regression models to fit the different order streams pCO2 using environmental factors and land use. Our results will provide insight into the accurate estimation of region and global carbon budget in the headwater rivers. |
| Key words: Stream pCO2 land use low order stream Yangtze River driving factors |
