Atmospheric CO2 concentrations and Delta C-13 measurements along a hemispheric course (1998/99, Italy to Antarctica)

Continuous measurements of atmospheric CO2 concentrations were carried out along three ship routes from Italy to Antarctica in 1994/95, 1996/97 and 1998/99. The growth rate of CO2 for four latitudinal belts with arbitrarily chosen boundaries is reported for the three expeditions. The northernmost belt shows the largest growth rate between 1996 and 1998 (close to 6 ppm /yr) while southern belts show an almost constant growth rate of 1.7 ppm/yr. Anthropogenic activities clearly affect both CO2 concentrations and growth rates. Delta C-13 C measurements were carried out on CO2 from 23 flask air samples collected during the 1998/99 expedition. Apart from negative values observed in highly polluted areas, a negative trend is observed across the Antarctic Convergence Area with no changes in the atmospheric concentration of CO2. The hypothesis of a biochemical origin of these light carbon isotope values is suggested. (Author)