Observations of high levels of ozone-depleting CFC-11 at a remote mountain-top site in southern China

A field campaign was carried out in the autumn of 2017 to measure the CFC-11 concentrations at a remote mountain-top site in southern China. During the sampling period, the mixing ratios of CFC-11 (329 +/- 9 pptv) were considerably higher than both the regional backgrounds of East Asia (235 +/- 1 pptv) and the Northern Hemisphere backgrounds (230 +/- 1 pptv). Significantly high levels of CFC-11 were observed in late October, and the high CFC-11 concentrations correlate well with the concentrations of anthropogenic tracers. Further analysis indicates that the observed high levels of CFC-11 are largely due to contributions from the less developed regions in southwestern and central China, with only a minor fraction coming from the Pearl River Delta metropolitan region in southern China. The findings of this study suggest that unbalanced regional economic development and a lack of effective regulatory actions are likely the main factors for increased CFC-11 emissions in East Asia.