While
observations at global background sites in east Asia suggested
unexpectedly increased emissions of trichlorofluoromethane (CFC-11)
after 2012 in eastern China, particularly in Shandong province, there
is a lack of local monitoring data to constrain the emission estimates.
Here we report observations of ambient CFC-11 during 2012–2018
in Shandong province at five sites, including three rural sites and
two background sites [one at Tuoji Island (TJI) in the Bohai Sea and
the other at Mount Tai (MT), 1534 m above sea level]. The mixing ratios
of CFC-11 at rural sites were 17–23% above the global background
levels at Mauna Loa, Hawaii, and observations at MT and TJI revealed
larger enhancements occurring in air masses traveling through the
polyurethane foam industry region of the Shandong Peninsula. On the
basis of the ratios of CFC-11 to tracers such as carbon monoxide (CO),
chloroform (CHCl3), and carbon tetrachloride (CCl4) at the MT and TJI sites, the estimated emissions of CFC-11 in eastern
China ranged from 12.0 ± 1.6 to 20.8 ± 3.9 Gg year–1 with an average of 14.7 ± 4.3 Gg year–1 in
2014 and 2017–2018. These tracer-based estimates may represent
the upper limits due to relatively higher ratios of CFC-11 to tracers
in the hot spot province.