长江流域河流CO₂分压的控制因素识别与空间模拟

Identification of Controlling Factors and Spatial Modeling of Riverine CO₂ Partial Pressure in the Yangtze River Basin

摘要: 河流的二氧化碳(CO₂)排放是全球碳循环的重要组成部分。然而，各种不同的环境因子将以某种复杂的方式影响着河流的CO₂排放，长江流域河流二氧化碳分压(pCO₂)的主要控制因子尚不明确。本文计算了长江流域河流的pCO₂并通过随机森林方法对长江流域的pCO₂进行建模，识别出了与人为活动相关的因素(国民生产总值，区域人口密度，城镇和耕地覆盖率)在长江流域pCO₂空间变化中发挥着重要作用。最后，使用训练好的随机森林模型模拟了0.05˚ × 0.05˚的空间范围下长江流域年尺度的河流pCO₂空间分布，结果表明长江流域河流pCO₂从上游至下游呈增加趋势，同时在2010~2018这一研究期间，河流pCO₂呈下降趋势。我们认为高强度的人类活动在改变陆地碳循环的同时，也会改变河流碳循环，这将是未来实现“碳中和”目标的一个重要考虑因素。

Abstract: The emission of carbon dioxide (CO₂) from rivers is a critical component of the global carbon cycle. However, the environmental factors influencing riverine CO₂ emissions interact in complex ways, and the key drivers of partial pressure of CO₂ (pCO₂) in rivers across the Yangtze River Basin remain unclear. This paper calculated riverine pCO₂ in the Yangtze River Basin and modeled it using a Random Forest method. The analysis revealed that anthropogenic factors, such as gross domestic product, population density, and urban and cropland coverage, significantly contribute to the spatial variability of pCO₂. Applying the trained random forest model to simulate the annual spatial distribution of riverine pCO₂ at a 0.05˚ × 0.05˚ grid resolution across the basin, the results indicate an increasing trend in riverine pCO₂ from upstream to downstream, while pCO₂ exhibited a declining trend during the 2010~2018 study period. It concludes that intensive human activities, while altering the terrestrial carbon cycle, also modify the riverine carbon cycle, which will be a critical consideration for achieving future “carbon neutrality” goals.