Investigation of East Asian Emissions of CFC-11 Using Atmospheric Observations in Taiwan

Adcock, Karina E.; Ashfold, Matthew J.; Chou, Charles C.‐K.; Gooch, Lauren J.; Hanif, Norfazrin Mohd; Laube, Johannes C.; Oram, D. E.; Ou-Yang, Chang Feng; Panagi, Marios; Sturges, William T.

doi:10.1021/acs.est.9b06433

Cited by 18 publications

(20 citation statements)

References 21 publications

(131 reference statements)

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“…Until now, most studies of CFC changes are based on model simulations, which sometimes show large differences in the results among each other and with observations. Furthermore, the CFC monitoring network does not have high enough spatial resolution currently, so that the observational data used in models has to come from monitoring stations in adjacent regions or countries [8,14,20]. Therefore, the conclusion of increasing CFCs emissions in Eastern China remains uncertain and lacks further solid evidence from field measurements [20].…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the CFC monitoring network does not have high enough spatial resolution currently, so that the observational data used in models has to come from monitoring stations in adjacent regions or countries [8,14,20]. Therefore, the conclusion of increasing CFCs emissions in Eastern China remains uncertain and lacks further solid evidence from field measurements [20]. In this study, field samples at urban and rural residential sites, industrial areas, and municipal solid waste (MSW) landfills were collected in Shandong Province of the Eastern China, where densely industrial estates are distributed, during the period of October-December, 2017.…”

Section: Introductionmentioning

confidence: 99%

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Monitoring Chlorofluorocarbons in Potential Source Regions in Eastern China

Zhen

Yang

Zhou³

et al. 2020

Atmosphere

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Recent studies have indicated that Eastern China might be a potential source region of increased atmospheric chlorofluorocarbons (CFCs). To investigate this possibility, a field measurement was carried out from October to December 2017 for identifying the ambient concentration levels of representative trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), trifluorotrichloroethane (CFC-113), and tetrafluorodichloroethane (CFC-114) at the residential and municipal solid waste (MSW) landfills and industrial sites in Eastern China. The ambient mixing ratios of CFCs at residential sites were almost within 20% enhancement of the global background sites. The highest levels of CFCs were observed at the MSW landfill sites. Moreover, CFC-11 and CFC-113 concentrations at MSW landfills, which were in service, were two times higher than that at completed MSW landfills. Mean concentrations of 322 pptv for CFC-11, 791 pptv for CFC-12, 91 pptv for CFC-113, and 16 pptv for CFC-114 at various industrial sites were higher than that at residential sites, but they were obviously lower than that at MSW landfills in use. A poor intercorrelation between the CFCs indicated that they did not come from the same sources. Higher concentrations measured in this study compared with background sites indicates that MSW landfills could be an unintentional emission source and there are still substantial amounts of CFCs being stored in banks that may discharge CFCs into the atmosphere in Eastern China.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Monitoring Chlorofluorocarbons in Potential Source Regions in Eastern China

Zhen

Yang

Zhou³

et al. 2020

Atmosphere

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“…However, recent studies highlight the need for continued, careful monitoring of CFCs. Montzka et al (2018) found evidence for a recently emerged source of atmospheric CFC-11, with subsequent studies tracing these emissions largely to north-east China (Rigby et al, 2019;Adcock et al, 2020). In addition, Adcock et al (2018) found increasing mole fractions of CFC-113a.…”

Section: Introductionmentioning

confidence: 85%

Stratospheric carbon isotope fractionation and tropospheric histories of CFC-11, CFC-12 and CFC-113 isotopologues

Thomas¹,

Laube²,

Kaiser³

et al. 2020

Preprint

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Abstract. We present novel measurements of the carbon isotope composition of CFC-11 (CCl3F), CFC-12 (CCl2F2), and CFC-113 (CF2ClCFCl2), three atmospheric trace gases that are important for both stratospheric ozone depletion and global warming. These measurements were carried out on air samples collected in the stratosphere – the main sink region for these gases – and on air extracted from deep polar firn snow. We quantify, for the first time, the apparent isotopic fractionation, εapp(13C), for these gases as they are destroyed in the high- and mid-latitude stratosphere: εapp(CFC-12, high-lat) = (−20.2 ± 4.4) ‰ and εapp(CFC-113, high-lat) = (−9.4 ± 4.4) ‰, εapp(CFC-12, mid-lat) = (−30.3 ± 10.7) ‰, and εapp(CFC-113, mid-lat) = (−34.4 ± 9.8) ‰. Our CFC-11 measurements were not sufficient to calculate εapp(CFC-11) so we instead used previously reported photolytic fractionation for CFC-11 and CFC-12 to scale our εapp(CFC-12), resulting in εapp(CFC-11, high-lat) = (−7.8 ± 1.7) ‰ and εapp(CFC-11, mid-lat) = (−11.7 ± 4.2) ‰. Measurements of firn air were used to construct histories of the tropospheric isotopic composition, δT(13C), for CFC-11 (1950s to 2009), CFC-12 (1950s to 2009), and CFC-113 (1970s to 2009) – with δT(13C) increasing for each gas. We used εapp(high-lat), which were derived from more data, and a constant isotopic composition of emissions, δE(13C), to model δT(13C, CFC-11), δT(13C, CFC-12), and δT(13C, CFC-113). For CFC-11 and CFC-12, modelled δT(13C) was consistent with measured δT(13C) for the entire period covered by the measurements, suggesting no dramatic change in δE(13C, CFC-11) or δE(13C, CFC-12) has occurred since the 1950s. For CFC-113, our modelled δT(13C, CFC-113) did not agree with our measurements earlier than 1980. While this discrepancy may be indicative of a change in δE(13C, CFC-113), it is premature to assign one. Our modelling predicts increasing δT(13C, CFC-11), δT(13C, CFC-12), and δT(13C, CFC-113) into the future. We investigated the effect of recently reported new CFC-11 emissions on background δT(13C, CFC-11) by fixing model emissions after 2012, and comparing δT(13C, CFC-11) in this scenario to the model base case. The difference in δT(13C, CFC-11) between these scenarios was 1.4 ‰ in 2050. This difference is smaller than our model uncertainty envelope and would therefore require improved modelling and measurement precision, as well as better quantified isotopic source compositions, to detect.

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“…However, a large increase in global CFC-11 emissions from 2012-2017 was discovered (Montzka et al, 2018;Rigby et al, 2019;Montzka et al, 2021), suggesting illicit CFC-11 production despite the global ban on production and consumption under the MP beginning in 2010. This surprisingly large increase in CFC-11 emissions attracted great attention from scientists, policy makers, and industrial experts around the world (Montzka et al, 2018;Rigby et al, 2019;Dhomse et al, 2019;Ray et al, 2020;Adcock et al, 2020;Keeble et al, 2020;Chen et al, 2020), who sought information to enable rapid mitigation of the unexpectedly enhanced CFC-11 emissions and ensure no significant delay in the recovery of stratospheric ozone. Despite the international effort to understand the origin of this large global emission increase in CFC-11, only a portion of the emission rise (60 ± 40 %) could be explained by emission increases from eastern mainland China (Rigby et al, 2019;Adcock et al, 2020;Park et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Continental-scale contributions to the global CFC-11 emission increase between 2012 and 2017

Montzka²,

Moore

et al. 2022

Atmos. Chem. Phys.

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Abstract. The detection of increasing global CFC-11 emissions after 2012 alerted society to a possible violation of the Montreal Protocol on Substances that Deplete the Ozone Layer (MP). This alert resulted in parties to the MP taking urgent actions. As a result, atmospheric measurements made in 2019 suggest a sharp decline in global CFC-11 emissions. Despite the success in the detection and mitigation of part of this problem, regions fully responsible for the recent global emission changes in CFC-11 have not yet been identified. Roughly two thirds (60 ± 40 %) of the emission increase between 2008–2012 and 2014–2017 and two thirds (60 ± 30 %) of the decline between 2014–2017 and 2019 were explained by regional emission changes in eastern mainland China. Here, we used atmospheric CFC-11 measurements made from two global aircraft surveys – the HIAPER (High-performance Instrumented Airborne Platform for Environmental Research) Pole-to-Pole Observations (HIPPO) in November 2009–September 2011 and the Atmospheric Tomography Mission (ATom) in August 2016–May 2018, in combination with the global CFC-11 measurements made by the US National Oceanic and Atmospheric Administration during these two periods – to derive global and regional emission changes in CFC-11. Our results suggest Asia accounted for the largest fractions of global CFC-11 emissions in both periods: 43 (37–52) % during November 2009–September 2011 and 57 (49–62) % during August 2016–May 2018. Asia was also primarily responsible for the emission increase between these two periods, accounting for 86 (59–115) % of the global CFC-11 emission rise between the two periods. Besides eastern mainland China, temperate western Asia and tropical Asia also contributed significantly to global CFC-11 emissions during both periods and likely to the global CFC-11 emission increase. The atmospheric observations further provide strong constraints on CFC-11 emissions from North America and Europe, suggesting that each of them accounted for 10 %–15 % of global CFC-11 emissions during the HIPPO period and smaller fractions in the ATom period. For South America, Africa, and Australia, the derived regional emissions had larger dependence on the prior assumptions of emissions and emission changes due to a lower sensitivity of the observations considered here to emissions from these regions. However, significant increases in CFC-11 emissions from southern hemispheric lands were not likely due to the observed increase of north-to-south interhemispheric gradients in atmospheric CFC-11 mole fractions from 2012–2017.

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Investigation of East Asian Emissions of CFC-11 Using Atmospheric Observations in Taiwan

Cited by 18 publications

References 21 publications

Monitoring Chlorofluorocarbons in Potential Source Regions in Eastern China

Monitoring Chlorofluorocarbons in Potential Source Regions in Eastern China

Stratospheric carbon isotope fractionation and tropospheric histories of CFC-11, CFC-12 and CFC-113 isotopologues

Continental-scale contributions to the global CFC-11 emission increase between 2012 and 2017

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