Carbon isotope measurements of atmospheric CO2at a coastal station in Antarctica

Abstract

A 3-years series of weekly 3-days integrated CO₂ samples analysed for ¹³C/¹²C isotopic ratio is presented, as well as a 2-years continuous sample series of 1-2 weeks integration time, analysed for C¹⁴ activity. The samples have been collected at the German Georg von Neumayer research station situated at the Antarctic coast at 70°s. 8°W. The ¹³C measurements show a slightly decreasing trend in δ¹³C of -0.038 * 0.009‰,/year as is to be expected due to the global fossil fuel CO₂ release. A significant seasonal variation is not detectable in the ¹³C record. The ∆¹⁴C activity of the atmospheric C0₂ samples is constantly lower by -11 ± 2‰, if compared to the northern hemisphere clean air level. The opposite effect should be expected from an observed C0₂ concentration difference of about 3-4 ppm between the two hemispheres if due to ¹⁴C free fossil fuel CO₂. A total (supposedly regional) ∆¹⁴C depletion of about -20‰, to -25‰, compared to low latitudes in the southern hemisphere, can be attributed to exchange of atmospheric C0₂ with low ¹⁴C surface water (∆¹⁴C = - 100‰,) due to upwelling in the circum polar region between 50°s and 70°s. This effect can qualitatively be reproduced by a simple one-dimensional atmospheric model. DOI: 10.1111/j.1600-0889.1987.tb00273.x