Atmospheric CO2 and its δ13C measurements from flask sampling at Lin'an regional background station in China

This study presents CO2 concentrations of air flask samples obtained at a regional background station Lin'an (LAN) in China from January 2009 to December 2013, as well as their stable isotope ratios (delta C-13) from January 2011 to December 2013. Background data is selected to represent background characteristics of atmospheric CO2 and delta C-13 over Yangzte River Delta. The annual mean background CO2 concentrations vary from 395.0 ppm in 2009 to 407.6 ppm in 2013, with a growth rate of 2.8 +/- 0.1 ppm yr(-1) over the study period, which is higher than the global average level. The annual mean values of delta C-13 vary from -8.55 parts per thousand in 2011 to -8.73 parts per thousand in 2013, with a growth rate of -0.029 + 0.010 parts per thousand y(-1). Seasonal cycles of CO2 concentrations and delta C-13 are observed to be obvious at LAN. The minimum and maximum values of mean seasonal CO2 cycle appear in August and January, respectively, with the peak-to-peak amplitude of 19.4 ppm. The sign of delta C-13 seasonal cycle is opposite to that of CO2, and the peak-to-peak amplitude is 0.85 parts per thousand. The isotopic signature of CO2 sources/sinks (delta(S)) is also discussed in this paper. The estimated Ss values for heating season (December-February) is -25.4 parts per thousand and for vegetative season is -21.3 parts per thousand (March -November) suggest the significant impact of fossil fuel combustions during winter heating season and biological activities during vegetative season. (C) 2015 Elsevier Ltd. All rights reserved.