Top-down and bottom-up estimates of anthropogenic methyl bromide emissions from eastern China

Abstract. Methyl bromide (CH3Br) is a potent ozone-depleting substance (ODS) that has both natural and anthropogenic sources. CH3Br been used mainly for preplant soil fumigation, post-harvest grain timber structural fumigation. Most non-quarantine pre-shipment (non-QPS) uses were phased out by 2005 non-Article 5 (developed) countries 2015 Article (developing) under the Montreal Protocol on Substances Deplete Ozone Layer; some have continued critical-use exemptions (CUEs). Under protocol, individual nations are required to report annual data production consumption quarantine–pre-shipment (QPS) uses, non-QPS CUEs United Nations Environment Programme (UNEP). In this study, we analyzed high-precision, in situ measurements of atmospheric mole fractions obtained at Gosan station Jeju Island, South Korea, from 2008 2019. The background atmosphere declined 8.5±0.8 ppt (parts per trillion) 7.4±0.6 2019 rate -0.13±0.02 yr?1. At Gosan, also observed periods persistent (pollution events) elevated above decreasing continental air masses China. Statistical back-trajectory analyses showed these pollution events predominantly traced back emissions eastern Using an interspecies correlation (ISC) method with reference trace species CFC-11 (CCl3F), estimate China average 4.1±1.3 Gg yr?1 2008–2019, approximately 2.9±1.3 higher than bottom-up emission estimates reported UNEP. Possible non-fumigation sources – rapeseed biomass burning assessed, it was found discrepancy most likely due unreported or incorrectly QPS fumigation uses. These confined account 30 %–40 % global emissions. They delays introduction alternatives, such as sulfuryl fluoride (SO2F2), heat, irradiation, possible lack industry awareness need regulation use.