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Background variations of atmospheric CO 2 and carbon‐stable isotopes at Waliguan and Shangdianzi stations in China
Author(s) -
Liu LiXin,
Zhou LingXi,
Vaughn Bruce,
Miller John B.,
Brand Willi A.,
Rothe Michael,
Xia LingJun
Publication year - 2014
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2013jd019605
Subject(s) - environmental science , latitude , atmospheric sciences , northern hemisphere , sink (geography) , southern hemisphere , seasonality , middle latitudes , climatology , carbon sink , biosphere , ecosystem , geography , ecology , biology , geology , cartography , geodesy
Using observational data from 2007 to 2010 at the Waliguan and Shangdianzi stations in China, atmospheric CO 2 , its δ 13 C composition, and their potential relationship with sources and sinks are studied. Results suggest that at Waliguan (WLG) station, both CO 2 and δ 13 C possess long‐term trends and seasonal cycles that correlate well with each other. CO 2 and δ 13 C interannual variations indicate terrestrial ecosystem source‐sink seasonal features in the midlatitude to high‐latitude Northern Hemisphere. CO 2 annual means vary from 384.0 ppm to 390.2 ppm and increase in an approximately linear manner with a mean annual growth rate of 2.1 ± 0.1 ppm. The δ 13 C annual means vary from −8.30‰ to −8.35‰ and decrease almost linearly with a mean annual rate of −0.02‰ ± 0.001‰. Under the given conditions of terrestrial biosphere and anthropogenic activities at Shangdianzi (SDZ) station, the CO 2 annual means vary from 385.1 ppm to 390.6 ppm and approximately increase linearly with a mean annual growth rate of 1.8 ± 0.1 ppm. The peak‐to‐peak annual seasonal amplitude is 23.0 ppm. The δ 13 C annual means vary from −8.27‰ to −8.36‰ between 2009 and 2010. Mean values of −25.44‰ ± 0.72‰ and −21.70‰ ± 0.67‰ for the respective sources are obtained at WLG and SDZ. The estimated δ s values are more negative in winter and spring than in summer and autumn at WLG. While because substantial C 4 photosynthesis taking place in summer and biomass burning strongly contribute in winter, the estimated δ s values at SDZ are unusually heavier throughout the year and more positive than those at WLG.