Motor vehicle combustion emissions of molecular hydrogen (H
2), carbon monoxide (CO), and carbon dioxide (CO
2) were measured during a 6-week period from November 2004 to January 2005 in Gubrist ...Tunnel, Switzerland, to determine vehicle emission factors for these trace gases and the ratios of the concentration growths
Δ
H
2
/
Δ
CO
and
Δ
H
2
/
Δ
CO
2
in the tunnel under real-world highway driving conditions. For H
2, molar mixing ratios at the tunnel exit were found to be 7–10
ppm (parts-per-million,
10
-
6
) during rush hours. Mean emission factors of
E
H
2
=
49.7
(
±
16.5
)
mg
km
-
1
,
E
CO
=
1.46
(
±
0.54
)
g
km
-
1
, and
E
CO
2
=
266
(
±
69
)
g
km
-
1
were calculated.
E
H
2
was largest during weekday rush-hour traffic, a consequence of the more frequent accelerations in congested traffic when fuel combustion is not optimal.
E
H
2
was smaller for heavy-duty vehicles (HDV) compared to light-duty vehicles (LDV), a finding which was attributed to the diesel vs. gasoline engine technology. The mean
Δ
H
2
/
Δ
CO
molecular ratio was
0.48
±
0.12
. This ratio increased to
∼
0.6
during rush hours, suggesting that H
2 yield is favored relative to CO under fuel-rich conditions, presumably a consequence of an increasing contribution of the water–gas-shift reaction. The mean
Δ
H
2
/
Δ
CO
2
molecular ratio was
4.4
×
10
-
3
but reduced to
2.5
×
10
-
3
when the relative HDV abundance was at maximum. Using three different approaches, road traffic H
2 emissions were estimated for 2004 for Switzerland at 5.0–6.6
Gg and globally at 4.2–8.1
Tg. Despite projections of increasing traffic, Swiss H
2 emissions are not expected to change significantly in the near future, and global emissions are likely to decrease due to improved exhaust gas clean-up technologies.
We report in situ atmospheric measurements of hydrofluorocarbon HFC‐43‐10mee (C5H2F10; 1,1,1,2,2,3,4,5,5,5‐decafluoropentane) from seven observatories at various latitudes, together with measurements ...of archived air samples and recent Antarctic flask air samples. The global mean tropospheric abundance was 0.21 ± 0.05 ppt (parts per trillion, dry air mole fraction) in 2012, rising from 0.04 ± 0.03 ppt in 2000. We combine the measurements with a model and an inverse method to estimate rising global emissions—from 0.43 ± 0.34 Gg yr−1 in 2000 to 1.13 ± 0.31 Gg yr−1 in 2012 (~1.9 Tg CO2‐eq yr−1 based on a 100 year global warming potential of 1660). HFC‐43‐10mee—a cleaning solvent used in the electronics industry—is currently a minor contributor to global radiative forcing relative to total HFCs; however, our calculated emissions highlight a significant difference from the available reported figures and projected estimates.
Key Points
2012 global tropospheric abundance of HFC‐43‐10mee is 0.21 ppt
2012 growth rate is 15 ppq yr−1, and emission rate is 1.13 Gg yr−1
CO2 equivalent emissions of 1.9 Tg yr−1 are comparable to HFC‐365mfc and HFC‐236fa
•HFC-134a is the most abundant HFC in the atmosphere.•First retrievals of HFC-134a from ground-based FTIR solar absorption spectra.•Relative trends show a rise of more than 7 % in the last ...decades.•Retrievals are validated by comparison with three independent datasets.
Successive regulations on the production and consumption of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) have led to the use of hydrofluorocarbons (HFCs) as substitution products. Consequently, these potent greenhouse gases are now controlled under the Kigali Amendment (2016) to the Montreal Protocol. HFC-134a is the preferred substitute to CFC-12 as a refrigerant and is the most abundant HFC in the atmosphere today. This work presents the first retrievals from ground-based Fourier Transform InfraRed (FTIR) high-resolution solar absorption spectra, recorded at the Jungfraujoch station as part of the Network for the Detection of Atmospheric Composition Change (NDACC). To verify these retrievals, the FTIR time series was compared to three other datasets: a simulation of the TOMCAT 3-D chemical transport model, the Fourier Transform Spectrometer on board the Atmospheric Chemistry Experiment (ACE-FTS) L2 v5.2 retrievals, and the Jungfraujoch in-situ surface observations conducted within the Advanced Global Atmospheric Gases Experiment (AGAGE) network. The overall trends of HFC-134a (2004–2022) were analyzed to assess the relative growth rates of this atmospheric compound. These trends are 7.34 ± 0.16 %/year (FTIR), 7.12 ± 0.05 %/year (TOMCAT), 7.29 ± 0.16 %/year (ACE-FTS), and 6.61 ± 0.05 %/year (in-situ). The relative trends are in good agreement, so these novel FTIR retrievals are validated. Consequently, this strategy could be implemented at other NDACC sites to achieve a quasi-global detection of this species using the FTIR remote sensing technique.
This paper presents the estimation of Chinese emissions of HCFC-22 and CFC-11 in 2009 by an inverse modeling method based on in-situ measurement data from the Shangdianzi Global Atmosphere Watch ...（GAW） Regional Station （SDZ） and atmospheric transport simulations. After inversion （a-posteriori） estimates of the Chinese emissions in 2009 increased by 6.6% for HCFC-22 from 91.7 （± 83.6） to 98.3 （± 47.4） kt/yr and by 22.5% for CFC-11 from 13 （±12.6） to 15.8 （±7.2） kt/yr compared to an a-priori emission. While the model simulation with a-priori emissions already captured the main features of the observed variability at the measurement site, the model performance （in terms of correlation and mean-square-error） improved using a-posteriori emissions. The inversion reduced the root-mean-square （RMS） error by 4% and 10% for HCFC-22 and CFC-11, respectively.
We have developed an analytical technique for the simultaneous measurement of the four trace gases sulfur hexafluoride (SF
6) and the chlorofluorocarbons CCl
2F
2 (CFC-12), CCl
3F (CFC-11) and CCl
...2FCClF
2 (CFC-113) in water and air. Water samples are flame sealed into 350-ml glass ampoules which allow storage and sampling in locations where field measurements are not practical. For analysis, these ampoules are stripped of dissolved gases after their stems are cracked in an enclosed chamber such that the headspace fraction in the ampoule is included in the measurement. The extracted gases are then trapped cryogenically and are separated on packed columns. CFC-11 and CFC-113 are measured on one electron capture detector (ECD), while SF
6 and CFC-12 are cryofocussed on a second trap and analyzed on a second ECD. Detection limits for seawater samples are about 0.015 fmol kg
−1 for SF
6, 0.010 pmol kg
−1 for CFC-12, 0.014 pmol kg
−1 for CFC-11, and 0.024 pmol kg
−1 for CFC-113. This analytical technique also allows for analysis of air samples with low concentrations or at low pressures. Results from a profile in the northeastern Pacific Ocean show that SF
6 partial pressure ages are consistent with those of CFC-11 and CFC-12 over the age range covered by this profile. From this, we infer that SF
6 is useful for the dating of recently ventilated waters, thus complementing the dating of older waters using CFCs. Earlier reports of the degradation of CFC-113 in oxygenated water are supported by our results for samples stored in ampoules.
High precision measurements of three chlorofluorocarbons (CFCs), three hydrochlorofluorocarbons (HCFCs), six hydrofluorocarbons (HFCs), three perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) ...were made at five Chinese background stations from January 2011 to December 2012. Their station means in the background air were 239.5 ± 0.69 parts-per-trillion dry-air mole fraction mixing ratios (ppt) for CFC-11, 536.5 ± 1.49 ppt for CFC-12, 74.66 ± 0.09 ppt for CFC-113, 232.1 ± 4.77 ppt for HCFC-22, 23.78 ± 0.29 ppt for HCFC-141b, 22.92 ± 0.42 ppt for HCFC-142b, 11.75 ± 0.43 ppt for HFC-125, 71.32 ± 1.35 ppt for HFC-134a, 13.62 ± 0.43 ppt for HFC-143a, 9.10 ± 1.26 ppt for HFC-152a, 25.45 ± 0.1 ppt for HFC-23, 7.28 ± 0.48 ppt for HFC-32, 4.32 ± 0.03 ppt for PFC-116, 0.63 ± 0.04 ppt for PFC-218, 1.36 ± 0.01 ppt for PFC-318, and 7.67 ± 0.03 ppt for SF6, respectively, which were comparable with those measured at the two Northern Hemisphere (NH) AGAGE stations: Mace Head, Ireland (MHD) and Trinidad Head, California, USA (THD). Compared with our results for earlier years from in-situ measurement at SDZ, background-air mixing ratios of CFCs are now declining, while those for HCFCs, HFCs, PFCs, and SF6 are still increasing. The ratios of the number of sampling events in which measured mixing ratios were elevated above background (pollution events) relative to the total sample frequency (POL/SUM) for CFCs, HCFCs, and HFCs were found to be station dependent, generally LAN > SDZ > LFS > XGL > WLG. The enhancement (△, polluted mixing ratios minus background mixing ratios) generally show distinct patterns, with HCFCs (40.7–175.4 ppt) > HFCs (15.8–66.3 ppt)> CFCs (15.8–33.8 ppt)> PFCs (0.1–0.9 ppt) at five stations, especially for HCFC-22 ranging from 36.9 ppt to 138.2 ppt. Combining with the molecular weights, our findings imply biggest emissions of HCFCs in the regions around these Chinese sites compared to HFCs and CFCs, while the smallest of PFCs, consistent with CFCs being phased out and replaced with HCFCs in China. In addition, relative emission strengths (emission was expressed by mole fractions) of these halocarbons in China were inferred as HCFC-22 > HCFC-141b > HFC-134a > HCFC-142b for the Yangtze River Delta (YRD) and as HCFC-22 > HCFC-142b > HCFC-141b ≈ HFC-134a in the North China Plain (NCP).
Display omitted
•Atmospheric halogenated compounds were measured at five stations in China.•Mixing ratios were distinguished as in polluted and background air, respectively.•Background mixing ratios were comparable with those at two AGAGE stations.•In China, background CFCs are declining while increased for other compounds.
We capture the first atmospheric appearance of HFC‐245fa (CHF2CH2CF3), a new foam blowing agent. Our results from the high‐altitude observatory at Jungfraujoch, Switzerland, show a rapid growth of ...this substance in the northern hemispheric troposphere from 0.28 ppt in July 2004 to 0.68 ppt at the end of 2005, which corresponds to an overall increase of >90% per year. By combining our observations with an atmospheric 3‐box model we estimate a southern hemispheric trend for this trace gas which we compare to observations at southern hemisphere mid‐latitudes. We also estimate a global HFC‐245fa emissions increase from 2100–2400 tonnes in 2003 to 5100–5900 tonnes in 2005. Pollution episodes are relatively rare at Jungfraujoch compared to other hydrofluorocarbons thereby confirming the limited use of HFC‐245fa in Europe. Back trajectory analysis reveals the largest potential European sources of HFC‐245fa in northern Italy and northeastern Spain.
As a substitute for methyl bromide (CH3Br), sulfuryl fluoride (SO2F2) is widely used and shows an increasing trend in global atmospheric mixing ratio. Long-term measurements of SO2F2 were conducted ...at 10 stations of the China Meteorological Administration. The SO2F2 mixing ratios of background events at five observation sites with long sequences (9 or 10 years) showed a similar increasing trend, which was also similar to the measurements at Mace Head in Ireland, a global background station of the Advanced Global Atmospheric Gases Experiment (AGAGE) network. The background mixing ratios of SO2F2 increased from 1.8 ppt in 2011 to 2.6 ppt in 2019. From 2010 to 2016, the enhanced mixing ratios above background of all the 10 stations exhibited an increasing trend before 2017, while there are no obvious trends from 2017 to 2019. The highest enhanced mixing ratios appeared at Lin'an (LAN) and Jiangjin (JGJ) in all years, mainly due to production and application of SO2F2 in the Yangtze River Delta and the Sichuan Basin. Also, the two stations are closer to sources than other stations. The Concentration Weighted Trajectory (CWT) was applied to identify the possible source areas associated with SO2F2 pollution events. The potential source areas identified at the 10 stations covered the main economic zones of China. Additionally, the total SO2F2 emissions of China and key emission regions from 2011 to 2019 were estimated by a tracer-ratio method, using carbon monoxide (CO) as a reference tracer. The estimated total SO2F2 emission of China was 0.49 ± 0.49 Gg yr−1 during 2011 to 2016 and 0.32 ± 0.32 Gg yr−1 during 2017 to 2019, and China's per capita SO2F2 emissions were lower than global averages during 2011-2019.
•The long-term atmospheric mixing ratios of sulfuryl fluoride in China were reported for the first time.•Sulfuryl fluoride emissions of key regions and Chinese totals were estimated by trace ratio method.•Both enhanced sulfuryl fluoride mixing ratios in Eastern China and the national emissions have declined in recent years.
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