Carbon dioxide and methane supersaturation in lakes of semi-humid/semi-arid region, Northeastern China. (August 2016)

• Record Type: Journal Article
• Authors: Wen, Zhidan; Song, Kaishan; Zhao, Ying; Jin, Xiuliang
• Is Part Of: Atmospheric environment. Volume 138(2016)
• Page Start: 65
• Page End: 73
• Publication Date: 2016-08
• Subjects: Carbon dioxide -- Methane -- Carbon cycling -- Lakes; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2016.05.009
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: Understanding concentrations of carbon dioxide (CO2 ) and methane (CH4 ) in lakes is an important part of a comprehensive global carbon budget. We estimated data on the partial pressure of CO2 ( p CO2 ) and CH4 ( p CH4 ) from sampling with 95 lakes in semi-humid/semi-arid region of Northeastern China during ice-free period. Both p CO2 and p CH4 varied greatly among the study sites. p (CO2 ) values in these lakes ranged from 21.9 to 30, 152.3 μatm (n = 403), and 91% of lakes in this survey were supersaturated with CO2 . p (CH4 ) values ranged from 12.6 to 139, 630.7 μatm with all sites in this study of CH4 sources to the atmosphere during the ice-free period. The collected urban lakes samples exhibited higher p CO2 and p CH4 than wild lakes samples. Either the mean value of p (CO2 ) or p (CH4 ) in saline waters is higher than in fresh waters. Correlation analysis implied that the partial pressure of the GHGs (CO2 and CH4 ) showed statistically correlations with water environment indicators like pH, dissolved organic carbon (DOC), total nitrogen (TN), total phosphorus (TP), and chlorophyll a ( Chla ). However, the most of the relationships showed a high degree of scatter, only pH might be used as the predictor of the gas partial pressure based on the result of this study ( r p CO2 = −0.437, p < 0.01, n = 382; r p CH4 = −0.265, p < 0.01, n = 400). Furthermore, salinity could be a good predictor for p (CO2 ) and p (CH4 ) in 83 freshwater lakes in our study ( r p CO2 = 0.365, r p CH4 = 0.323, p < 0.01, n = 348). The mean CO2 flux increased with the decreasing lake area size. The calculated annual areal carbon emission rate is 560.2 g C m −2 from 95 lakes in Northeastern China. We could not extrapolate carbon emission from these lakes to the boreal region or a wider scale because of the change of environmental conditions. Highlights: Both p CO2 and p CH4 varied greatly in 95 lakes of Northeastern China. 91% of lakes were supersaturated with CO2 and CH4 during the ice-free period. Urban lakes samples exhibited higher p CO2 and p CH4 than wild lakes samples. Both p CO2 and p CH4 showed statistically correlations with water environment indexes. The mean CO2 flux increased with the decreasing lake area size.