Measurements of atmospheric &#x00394;¹⁴CO₂ along the R/V <i>Xuelong</i> cruise track from Zhongshan Station &#x00028;Antarctica&#x00029; to Shanghai

Abstract

During January-March 2011, 29 atmospheric Δ 14 CO 2 samples were measured along the R/V Xuelong cruise track from Zhongshan Station (69.37 S, 76.38 E; Antarctica) to Shanghai. The extent of fossil fuel contamination in the samples was evaluated by comparison with contemporary hemispheric-scale averages of Δ 14 CO 2 , together with transport analysis and consideration of the d 13 CO 2 levels in the samples. Generally, the Δ 14 CO 2 levels along the route south to 40.67 S were lower than the hemispheric-scale average. Circumpolar deep water (CDW) upwelling, stratosphere-troposphere transport (STT), and regional transport associated with the Fukushima nuclear power plant (NPP) accident in Japan on 12 March 2011 were found to have influenced Δ 14 CO 2 levels at the sampling sites. In comparison with the atmospheric Δ 14 CO 2 level (45.7 ± 3.5& (1r)) measured in the coastal region of East Antarctica, CDW upwelling caused reduction of $10& in Δ 14 CO 2 in two cross sections: 62.0-64.0 S along 74.0 E and 51.7-54.0 S along 80.5-84.0 E. Conversely, STT-enhanced Δ 14 CO 2 was $7& ($3&) at Zhongshan (around 45.0 S). The linkage was supported by a certain Model-3/CMAQ simulation that indicated dispersion of radionuclides from the Fukushima NPP accident over the East Asian region, which explained the individual high Δ 14 CO 2 (52&) level on 29 March 2011 in Shanghai.