重庆师范大学王晓锋团队报道了中国内陆水域CO₂排放特征及影响因素。相关论文于2024年5月8日发表于国际顶尖学术期刊《中国科学：地球科学》杂志上。

据研究人员介绍，陆地水体作为最活跃的生物地球化学循环反应器，在全球碳循环和二氧化碳收支中起着举足轻重的作用。本研究整合了中国河流、湖泊和水库现有的CO₂通量观测数据，阐明其时空格局和关键影响因素，并重新评价其对区域碳平衡的意义。

研究结果表明，中国河流、湖泊和水库中fCO₂变率显著，变化范围分别为-379.3至-4947.6、-160.1至785.0和-74.0至-1603.1mg CO₂ m^-2 h ^-1。河流中fCO₂的中位数为228.5mg CO₂ m^-2 h ^-1，明显高于湖泊和水库(分别为26.0和28.3mg CO₂ m^-2 h ^-1)。由于普遍的气候抑制作用，河流和水库中fCO₂从南到北呈下降趋势，珠江流域和长江流域的平均fCO₂明显高于东北地区的河流。蒙新湖区和东北湖区平均fCO₂高于其他湖区，青藏湖区次之，东部湖区和云贵湖区总体较低，与气候限制相矛盾。人类活动导致的水初级生产增强是湖泊fCO₂空间变化的主要驱动力。河流中fCO₂含量呈现雨季高于旱季的季节性特征，而湖泊和水库中fCO₂含量则相反。

季节温度、降水和水分初产是主要影响因素。此外，它还表明pH值是指示河流、湖泊或水库中fCO₂水平变化的关键因子。湖泊中fCO₂与叶绿素a (Chl-a)和溶解氧(DO)密切相关，而河流中fCO₂主要与有机碳(OC)和总氮(TN)相关，这凸显了不同内陆水域类型fCO₂的不同控制机制。此外，课题组人员发现水体大小对fCO₂水平起着重要的调节作用，小水域是CO₂通量的热点。此外，广泛的城市化和农业活动可能会增加河流的二氧化碳排放，但可能会减轻湖泊的二氧化碳排放。然而，这些因素对内陆水域二氧化碳排放的综合影响需要进一步评价。基于外推法，研究人员重新估算出中国内陆水域的CO₂排放总量约为117.3Tg yr^-1，可抵消中国陆地碳汇总量的4.6%-12.8%。

附：英文原文

Title: Characteristics and influencing factors of CO₂ emission from inland waters in China

Author: Ting ZHOU, Xiaofeng WANG, Zuolin XIAO, Zhaoyin QING, Xianxiang LI, Jilong WANG, Ziyi QUE

Issue&Volume: 2024/05/08

Abstract: Inland water bodies, being the most active biogeochemical cycle reactors, play a pivotal role in the global carbon cycle and CO₂ budget. This study integrates existing observation dataset of CO₂ flux (fCO₂) in rivers, lakes and reservoirs in China, to elucidate their spatial-temporal patterns and key influencing factors and to reappraise the significance for regional carbon balance. It showed that, the fCO₂ in rivers, lakes and reservoirs in China presented significant variability with large range of 379.3–4947.6, 160.1–785.0 and 74.0–1603.1mg CO₂ m^-2 h ^-1, respectively. The median of the fCO₂ in rivers was of 228.5mg CO₂ m^-2 h ^-1, observably higher than these in lakes and reservoirs (26.0 and 28.3mg CO₂ m^-2 h ^-1, respectively). The fCO₂in rivers and reservoirs exhibited similar decreasing trend from south to north as a result of universal climate restraint, the averaged fCO₂ in Pearl River and Yangtze River basins showed much higher than that in Northeastern rivers. While, the averaged fCO₂ in the Mongolia-Xinjiang lake district and the Northeast lake district were higher than other lake districts, followed by the Qinghai-Xizang lake district, and the Eastern and Yungui lake district were generally low, contradicting the climatic restriction. The water primary production enhancement resulting from human activities was the main driver of spatial variation in thefCO₂ in lakes. Meanwhile, the fCO₂ in rivers presented seasonal pattern with higher wet season than dry season, while opposite patterns were found in lakes and reservoirs. Seasonal temperature, precipitation and water primary production were main factors. Furthermore, it showed pH was a key factor indicating the variability of the fCO₂ levels either in rivers, lakes or in reservoirs. In lakes, the fCO₂ is closely linked to chlorophyll a (Chl-a) and dissolved oxygen (DO), whereas, the fCO₂ in rivers is primarily associated with organic carbon (OC) and total nitrogen (TN), highlighting the diverse controlling mechanisms of fCO₂ in various inland water types. In addition, we found that water body sizes play an important role in regulating the fCO₂ levels, and small waters act as hotspots of CO₂ flux. Additionally, widespread urbanization and agricultural activities may enhance CO₂ emissions from rivers but potentially mitigating that from lakes. Nevertheless, the comprehensive impact of these factors on CO₂ emissions in inland water requires further evaluation. Based on the extrapolation method, we re-estimated that the total CO₂ emission of inland waters in China is approximately 117.3Tgyr^-1, which could offset 4.6%–12.8% of the total land carbon sink in China.

DOI: 10.1007/s11430-023-1286-5

Source: https://www.sciengine.com/SCES/doi/10.1007/s11430-023-1286-5