Sun, Heyang, Yu, Ruihong, Liu, Xinyu, Zhang, Zhuangzhuang, Ren, Xiaohui, Li, Xiangwei, Qi, Zhen, Wang, Jun, Guo, Zhiwei, Zhu, Penghang, Lu, Xixi, and Cui, Baoshan
• The dynamics of CO 2 and CH 4 partial pressures are co-regulated by various nutrients. • CO 2 and CH 4 emission from lakes decreased and increased with longitude, respectively. • Freshwater lakes emit mainly CH 4 , while salt lakes are main contributor of CO 2. • NPP, NDVI and human activities enhance CH 4 emissions but reduce CO 2 emissions. Lakes are important component of the regional carbon cycle and a significant sources of greenhouse gases (GHGs) to the atmosphere. However, the regional variations in carbon dioxide (CO 2) and methane (CH 4) emissions, as well as the factors regulating these emissions are poorly constrained. To investigate the regional GHG emission from lakes and their potential influencing factors, we conducted field measurements in 13 lakes in Inner Mongolia from July to August 2020. We found that the studied lakes were predominantly sources of atmosphere CO 2 and CH 4. The CO 2 partial pressure (p CO 2) exhibited supersaturation in 80 % of samplings, but all samplings of CH 4 partial pressure (p CH 4) showed supersaturation. Moreover, the average p CH 4 is 40 times greater than that in the atmosphere. The lakes emitted substantial amounts CO 2 and CH 4 with average values of 25.8 ± 4.9 mmol m−2 d−1 and 2.1 ± 0.3 mmol m−2 d−1, respectively. At the regional scale, the dynamics of p CO 2 and p CH 4 are regulated by combination of various environmental factors. CO 2 emissions from studied lakes decreased with the catchment net primary productivity (NPP), normalized difference vegetation index (NDVI), and nighttime lights which is indicative of urbanization. Conversely, CH 4 fluxes increased with NPP, NDVI, and nighttime lights. We conclude that terrestrial carbon-cycling related variables and human activities significantly affect CO 2 and CH 4 emissions from lakes by transporting different nutrients, but they show opposite trends. Our results also exhibited that the freshwater lakes are the main contributors of CH 4 , while saline lakes are the main contributors of CO 2. We suggest that increased human activity leads to changes in terrestrial carbon-cycle related processes which affects lake carbon emissions by altering the amount of nutrients input to the lakes. [ABSTRACT FROM AUTHOR]