Measurements of atmospheric Δ¹⁴CO₂ along the R/V Xuelong cruise track from Zhongshan Station (Antarctica) to Shanghai

Abstract

During January–March 2011, 29 atmospheric Δ¹⁴CO₂ 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 Δ¹⁴CO₂, together with transport analysis and consideration of the δ¹³CO₂ levels in the samples. Generally, the Δ¹⁴CO₂ 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 Δ¹⁴CO₂ levels at the sampling sites. In comparison with the atmospheric Δ¹⁴CO₂ level (45.7 ± 3.5‰ (1σ)) measured in the coastal region of East Antarctica, CDW upwelling caused reduction of ∼10‰ in Δ¹⁴CO₂ 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 Δ¹⁴CO₂ 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 Δ¹⁴CO₂ (52‰) level on 29 March 2011 in Shanghai.

Keywords:

• atmospheric
• Δ¹⁴CO₂
• Xuelong cruise
• CDW upwelling dilution
• STT
• Fukushima NPP accident

Acknowledgements

We greatly appreciate the contributions of two anonymous reviewers that helped improve the quality of the manuscript. We thank James Buxton MSc from Liwen Bianji, Edanz Group China (www.liwenbianji.cn/ac), for editing the English text of this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by the Science and Technology Development Fund of the Chinese Academy of Meteorological Sciences under grant No. 2018KJ004. The in situ collection work was undertaken during the R/V Xuelong cruise supported by the 27^th CHINARE. The programme of polar environmental investigations and evaluation under grant No. 2016-04-01 partly supported the MBL Δ¹⁴CO₂ measurements performed in the laboratory.