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Workshop on “Solving the Mystery of Carbon Tetrachloride” Zürich, Switzerland 5-6 October 2015 Review of Emissions of Carbon Tetrachloride from Industrial and Other Sources Tekn. Dr. Husamuddin Ahmadzai, Chartered Engineer (IMM), Chartered Professional (FAusIMM), Swedish Environmental Protection Agency and Nordic Environment Finance Corporation Abstract Carbon tetrachloride (CCl4, CTC) is a controlled ozone-depleting substance under the Montreal Protocol. According to the Protocol’s agreements most emissive uses of CTC have been phased-out. However, many specific uses of CTC are still exempted and are sources for continued release to the environment and the atmosphere. Exemptions have been granted on an understanding that controlled substances originating from inadvertent or coincidental production during a manufacturing process, from unreacted feedstock, or use as process agents, presence in products as trace impurity, or emissions during handling are insignificant quantities. Such quantities, for a worst case, have been reported (TEAP 1994) to be of the range 0.1 - 0.5 percent for CTC feedstock and process related emissions and about 0.006 percent are released as trace impurities in the finished product. Overall process and trace impurity related emissions of ODS was reported to be 7,145 ODP-tonnes (1992) projected to decrease to 5,841 ODP tonnes by 2000. Emissions of CTC were included in the above and estimated to be 1,440 ODP tonnes in 1992 and expected to reduce to 771 ODP tonnes by 2000. International studies, however, are indicating that the global concentration of CTC in the atmosphere is much greater than what is being expected from the known sources. Recent reporting suggests CTC sources to be contributing up to about 40,000 - 90,000 tonnes annually. The UNEP Scientific Assessment Panel has revised the atmospheric lifetime for CTC in their OEWG report (2012) resulting in a revision of emission rate to about 10,000-20,000 tonnes per annum, CTOC (2015) estimates emissions to be about 8,000 -12,000 tonnes per annum. While these figures reduce the discrepancy between the two types of estimates, an anomaly remains. This review will provide information that infers emissions discrepancy may partly be explained by under-rated emission levels also. In some cases, e.g. in the production of chlorinated rubber (CR) and chloro-sulphonated polyolefin, CTC emissions have been, historically, of the order of 650-1200 kg CTC/tonne product (65 - 120 percent) compared to reported 0.04 to 3 kg CTC/tonne product (0.005 - 0,3 percent emission rate) for well operated plants. For the case of CR, 2-10 percent of the CTC may remain in the product and eventually emitted with the use of the product. Estimation of CTC emission sources thus needs to address processes, monitoring and adequate reporting where CTC is a by- and/or co-product, where it is used as a feedstock or process agent/solvent, nature of continuous and/or batch processes, and handling of CTC. CTC is also used for laboratory and analytical uses and there are quantities are associated with stocks and banks. Inadvertently produced, unwanted or contaminated CTC is destroyed or converted to other substances and such waste processing may have inefficient destruction efficiency. Steps to minimize emissions of CTC include avoidance of the creation of such emissions, reduction of emissions using practicable control technologies or process changes, containment, recovery from equipment during servicing and recycle or destruction of the waste including that redundant at the end-of-life of the equipment/process.
Evaluation of CCl4 Atmospheric Loss Process, Lifetime, and Uncertainties James B. Burkholder – Poster to be presented by TBD Earth System Research Laboratory, Chemical Sciences Division, National Oceanic and Atmospheric Administration, Boulder, Colorado, USA. [email protected] Eric L. Fleming NASA Goddard Space Flight Center, Greenbelt, Maryland, USA and Science Systems and Applications, Inc., Lanham, Maryland, USA. [email protected] In this work, a summary of the atmospheric (gas-phase) loss processes for CCl4 and 2-D model1 calculations used to evaluate the contributions of the loss process and local and global atmospheric lifetimes will be presented. This work was part of the SPARC2 (2013) Report on the Lifetimes of Stratospheric Ozone-Depleting Substances (Chapter 3), which built on results from recent laboratory studies and the recommendations from the NASA/JPL data evaluation.3 Short wavelength UV photolysis in the stratosphere was shown to be the predominant, >98%, atmospheric loss process for CCl4. Stratospheric loss due to reaction with O(1D) accounts for the majority of the rest of the loss, while reactive loss with the OH radical and Cl atom are calculated to be extremely small. The global annually averaged atmospheric lifetime of CCl4 was calculated to be 48.7 years. The 2σ range in the calculated lifetime based solely on the uncertainty in the model kinetic and photochemical input parameters was evaluated to be 45.2–52.3 years, ±7.3%. This range is significantly smaller than the total range due to all sources of uncertainty (~+/-20-30%) given in SPARC (2013). The atmospheric chemistry and associated lifetime of CCl4 are, therefore, defined very well by the accuracy of the available kinetic and photochemical data. References: (1) Fleming, E. L.; Jackman, C. H.; Stolarski, R. S.; Douglas, A. R. A Model Study of the
Impact of Source Gas Changes on the Stratosphere for 1850-2100. Atmos. Chem. Phys. 2011, 11, 8515-8541, doi:10.5194/acp-11-8515-2011.
(2) Ko, M. K. W.; Newman, P. A.; Reimann, S.; Strahan, S. E.; Plumb, R. A.; Stolarski, R. S.; Burkholder, J. B.; Mellouki, W.; Engel, A.; Atlas, E. L.; Chipperfield, M.; Liang, Q. Lifetimes of Stratospheric Ozone-Depleting Substances, Their Replacements, and Related Species, SPARC Report No. 6, WCRP-15/2013, 2013, http://www.sparc-climate.org/publications/sparc-reports/sparc-report-no6/.
(3) Sander, S. P.; Abbatt, J.; Barker, J. R.; Burkholder, J. B.; Friedl, R. R.; Golden, D. M.; Huie, R. E.; Kolb, C. E.; Kurylo, M. J.; Moortgat, G. K.; Orkin, V. L.; Wine, P. H. Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies, Evaluation Number 17, JPL Publication 10-6, Jet Propulsion Laboratory, California Institute of Technology Pasadena, California, 2011, http://jpldataeval.jpl.nasa.gov.
The ocean sink and other constraints on the budget of atmospheric CCl4 James H. Butler1, Shari A. Yvon-Lewis2,7, Jürgen M. Lobert3,7, Daniel B. King4,7, Stephen A. Montzka1 , John L. Bullister5, Valentin Koropalov6,James W. Elkins1, Bradley D. Hall1, Lei Hu1,2, Yina Liu2,8
, 1Global Monitoring Division, NOAA Earth System Research Laboratory, Boulder, CO, USA 80305; 2Department of Oceanography, Texas A&M University, College Station, TX, USA 77843; 3Entegris Inc., Franklin, MA, USA 02038; 4Chemistry Department, Drexel University, Philadelphia, PA, USA 19104; 5NOAA Pacific Marine and Environmental Laboratory, Seattle, WA, USA 98115; 6Roshydromet, Moscow, RU, 7Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA 80309; 8Marine Chemistry & Geochemistry, Woods Hole Oceanographic Institution, MA, USA, 02543
Presenting Author: James H. Butler
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Abstract: Observations made on 17 research cruises from 1987-2010, ranging in latitude from 60o N to 77o S in Pacific, Atlantic, and Southern Ocean surface-waters indicate that atmospheric CCl4 is consumed in large amounts by the ocean. Observed undersaturations, corrected for physical effects, were -5% to -10%. The atmospheric flux required to sustain these undersaturations is 15-27 Gg y-1, a loss rate implying a partial atmospheric lifetime with respect to the oceanic loss of 108 (79-137) y and suggesting that 20-37% of atmospheric CCl4 is lost to the ocean. Large undersaturations in intermediate depth (400-800 m) waters associated with reduced oxygen levels, observed in this study and by numerous other investigators, indicate that CCl4 is consumed ubiquitously at mid-depth, presumably by microbiota. Although this subsurface sink creates a gradient that drives a downward flux of CCl4, the gradient flux alone is not sufficient to explain the observed surface undersaturations, suggesting a possible biological sink for CCl4 in surface waters of the ocean as well. If we consider the overall ocean sink, the less robustly-determined soil sink (195y), and the removal rate of CCl4 in the stratosphere (44-50 y), the mid-range estimate of the atmospheric lifetime of CCl4 would be 28 (+/-3) y, thus not significantly different from that used in the past four quadrennial assessments [ 26 (23-33) y ]. These results strongly suggest that a large source of atmospheric CCl4 has not been identified. To be consistent with firn air records and the observed interhemispheric gradient of atmospheric CCl4, most of the unidentified source would have to be anthropogenic.
Carbon Tetrachloride over Eastern Himalaya in India: A Well Deviation from
Global Trend
Abhijit Chatterjee*a, Chirantan Sarkara, Dipanjali Majumdarb, Anjali Srvastavac and Sibaji Rahaa
aBose Institute, Kolkata and Darjeeling, India
bNational Environmental Engineering Research Institute, Kolkata, India cNational Environmental Engineering Research Institute, Nagpur, India
An interesting observation was made on annual distribution of carbon tetrachloride (CTC) during a first ever ground-based study on volatile organic compounds (VOC) over eastern Himalaya in India during July, 2011-June, 2012. The study was carried out over a high altitude hill station Darjeeling (27.01 degree N, 88.15 degree E, 2200 m asl) where weekly samples were collected using glass sampling tube containing charcoal and chromosorb. The analysis was done by thermal desorption followed by detection by GC-MS in accordance with USEPA TO-17 compendium method. Interestingly, the annual CTC concentration was found to be 30 ppt which is much lower than the global mean values (~90 ppt) during the said period. However, CTC varied from the values below its detection limit (10 ppt) to 275 ppt during the entire study period. However, ~10 % of the sampling days showed very low (< 20 ppt) and very high (> 110 ppt) CTC concentrations. CTC concentration values mostly accumulated in the range of 25-35 ppt and occasionally in the range of 90-110 ppt. The most important and interesting observation is that all the higher values were associated to the air masses arriving from W/NW (Indo-Gangetic Plains) and S/SE directions (Bangladesh, Kolkata etc) i.e. the regions of high industrial population as no industries exist in and around Darjeeling. Although, CTC was fully banned from 2010, India started the regulation of its use probably from late 2012. Thus, CTC over eastern part of India was found to maintain a good source-receptor relationship at least in 2011-2012. This study thus strongly suggest that ground-based in-situ observations on CTC over India (at least over eastern part and Himalaya) need to be increased vis-à-vis the satellite-based observations, model-based simulation studies and other remote sensing observations. This will in turn help us to better understand and minimize the uncertainties used in the models. At very least, such ground-based observations have much importance over ecologically and geographically important regions like Himalaya to better understand the source-receptor relationship. *Presenting author ([email protected])
Forward and Inverse Global Modelling of CCl4
Chris Wilson1,2, Wuhu Feng1,3, Qing Liang4,5, and Martyn Chipperfield1*
1. School of Earth and Environment, University of Leeds, Leeds, UK
2. National Centre for Earth Observation, University of Leeds, Leeds, UK
3. National Centre for Atmospheric Science, University of Leeds, Leeds, UK 4. NASA Goddard Space Flight Center, Greenbelt, MD, USA 5. Universities Space Research Association, Columbia, MD, USA * Presenting author
We have performed simulations with the TOMCAT off-line 3-D chemical transport model (CTM) aimed at further quantifying the imbalance in our understanding of the CCl4 budget over recent years. The model is forced by ECMWF ERA-Interim meteorology and parameterises the atmospheric loss of CCl4, principally through photolysis. Emissions in the forward model are the same as those used in Liang et al. (2014), allowing direct comparison with that study. We will present results from forward and inverse experiments. Results from the forward model run will be compared with surface observations and satellite profiles in the stratosphere. Inverse experiments will be performed by two methods (i) simple synthesis inversion and (ii) full 4D-variational assimilation (Wilson et al., 2014). Results of the study will show to what extent quantification of the known imbalance in the CCl4 budget may be sensitive to 3D model parameters (e.g. transport and mixing) and, through the inverse modelling, possible geographical region(s) for the apparent missing sources. Liang, Q., P.A. Newman, J.S. Daniel, S. Reimann, B.D. Hall, G. Dutton, and L.J.M. Kuijpers,
Constraining the carbon tetrachloride (CCl4) budget using its global trend and inter-hemispheric gradient, Geophys. Res. Lett., 41, 5307–5315, doi:10.1002/2014GL060754, 2014.
Wilson, C., M.P. Chipperfield, M. Gloor, and F. Chevallier, Development of a variational flux inversion system (INVICAT v1.0) within the TOMCAT chemical transport model, Geosci. Model Dev., 7, 2485-2500, doi:10.5194/gmd-7-2485-2014, 2014.
Atmospheric Carbon Tetrachloride Enhancements Measured in Texas J.S. Daniel, E. Atlas, J. Brioude, J.B. Gilman, J.A. de Gouw, W.C. Kuster, M. Trainer It is likely that missing atmospheric sources is at least part of the explanation for the current global CCl4 budget imbalance. We will present CCl4 observations from whole air samples taken on board the NOAA WP-‐3D aircraft as well as on the NOAA research vessel, the Ronald H. Brown, made in 2006 during the Texas Air Quality Study/Gulf of Mexico Atmospheric Composition and Climate Study. Some of these data show significant enhancements relative to the global background. In addition to providing information about the location of point sources, we will also show correlations with other compounds to gain insight into possible emissions processes.
To be presented at the Workshop on ‘Solving the Mystery of Carbon Tetrachloride’, 5-6 October 2015, Zurich, Switzerland
Australian carbon tetrachloride (CCl4) emissions: a paradigm for a ‘missing’ CCl4 source of possible global significance?
P. Fraser1, B. Dunse1, P. Krummel1, P. Steele1 and A. Manning2
1CSIRO Oceans and Atmosphere Flagship, Aspendale, Victoria, Australia 2UK Meteorological Office, Exeter, UK
In Chapter 1 of the Scientific Assessment of Ozone Depletion: 2014 (Carpenter and Reimann, 2014), ‘bottom-up’ estimates of global carbon tetrachloride (CCl4) emissions (~10 Gg/yr), based on fugitive emissions from the production, use and destruction of CCl4, as recorded by UNEP (with some adjustments and additions), fall well short (currently by about 50 Gg/yr) of ‘top-down’ estimates of global emissions (~60 Gg/yr) derived from AGAGE and NOAA global atmospheric observations.
Australian production of carbon tetrachloride (CCl4) ceased in the 1980s and Australian consumption of CCl4 effectively ceased in the early 1990s, when imports were severely restricted, following Australia’s ratification of the Vienna Convention (1987) and Montreal Protocol (1989). However the long-term AGAGE CCl4 record at Cape Grim (1978-2015; Xiao et al., 2010; Krummel et al., 2014) shows significant, but relatively small, CCl4 emissions from South East Australian urban and industrial centres (Dunse et al., 2005; Fraser et al., 2014; Figure 1).
Australia’s contribution to the global fugitive emissions described above is essentially zero, so where do the Australian emissions come from? This paper will report an update of current CCl4 emissions from the Melbourne/Port Phillip/Latrobe Valley region of South East Australia, based on Cape Grim in situ GC-ECD CCl4 data, using inter-species correlation and regional transport modeling (NAME/InTEM) (Dunse et al., 2005; Manning et al., 2011, Fraser et al., 2014). We attempt to identify the location and nature of these sources within the Melbourne/Port Phillip region, using in situ GC-MSD measurements of CCl4 at CSIRO, Aspendale. The possible global significance of these emissions will be discussed.
Figure 1. Australian CCl4 emissions (3 yr average) obtained from AGAGE GC-ECD CCl4 observations at Cape Grim, Tasmania (1994-2014), using interspecies correlation (ISC) and inverse modeling via the Lagrangian particle dispersion model NAME/InTEM (Dunse et al., 2005; Manning et al., 2011; Fraser et al., 2014; CSIRO unpublished data).
References
Dunse, B., P. Steele, S. Wilson, P. Fraser & P. Krummel, Trace gas emissions from Melbourne Australia, based on AGAGE observations at Cape Grim, Tasmania, 1995-2000, Atmospheric Environment, 39, 6334-6344, 2005.
Fraser, P., B. Dunse, A. Manning, R. Wang, P. Krummel, P. Steele, L. Porter, C. Allison. S. O’Doherty, P. Simmonds, J. Mühle & R. Prinn, Australian carbon tetrachloride (CCl4) emissions in a global context, Environ. Chem., 11, 77-88, 2014.
Krummel, P., P. Fraser, P. Steele, N. Derek, C. Rickard, J. Ward, N. Somerville, S. Cleland, B. Dunse, R. Langenfelds, S. Baly & M. Leist, The AGAGE in situ program for non-CO2 greenhouse gases at Cape Grim, 2009-2010, Baseline Atmospheric Program (Australia) 2009-2010, N. Derek P. Krummel & S. Cleland (eds.), Australian Bureau of Meteorology and CSIRO Marine and Atmospheric Research, Melbourne, Australia, 55-70, 2014.
Carpenter, L. & S. Reimann (Lead Authors), Update on Ozone-Depleting Substances (ODSs) and Other Gases of Interest to the Montreal Protocol, Chapter 1 in Scientific Assessment of Ozone Depletion: 2014, Global Ozone Research and Monitoring Project – Report No. 55, 1.1-1.101, World Meteorological Organization, Geneva, Switzerland, 2014.
Manning, A., S. O’Doherty, A. Jones, P. Simmonds & R. Derwent, Estimating UK methane and nitrous oxide emissions from 1990 to 2007 using an inversion modelling approach, J. Geophysical Research, 116, d02305, doi:10.1029/2010JD014763, 2011.
Xiao, X., R. Prinn, P. Fraser, R. Weiss, P. Simmonds, S. O’Doherty, B. Miller, P. Salameh, C. Harth, P. Krummel, A. Golombek, L. Porter, J. Elkins, G. Dutton, B. Hall, P. Steele, R. Wang & D. Cunnold, Atmospheric three-dimensional inverse modelling of regional industrial emissions and global oceanic uptake of carbon tetrachloride, Atmos. Chem. Phys., 10, 10421-10434, 2010.
Current Trend in Carbon Tetrachloride from several NDACC FTIR stations James Hannigana, Mathias Palmb, Stephanie Conwayc, Emmanual Mahieud, Dan Smalee, Eric Nussbaumera, Kim Strongc, Justus Notholtb
a. National Center for Atmospheric Research, Boulder, CO, USA b. University of Bremen, Bremen, Germany c. University of Toronto, Toronto, Canada d. University of Leige, Liege, Belgium e. National Institute of Water and Atmospheric Research, Lauder, New Zealand
To obtain a global perspective on total column trends of Carbon Tetrachloride (CCl4) we use measurements from several stations of the ground-‐based NDACC (Network for the Detection for Atmospheric Composition Change, www.ndacc.org) from the Arctic to mid-‐latitudes. Data from Eureka (80ºN), Ny Alesund (79ºN), Thule (76ºN), Jungfraujoch (47ºN), Mauna Loa (20ºN) and Lauder (45ºS) are included. Retrievals for these stations were performed in a homogeneous manner in the 12µ spectral region of the solar absorption spectra routinely recorded at 0.0035cm-‐1 resolution. The retrieval follows the methods described in Rinsland [Rinsland et al., 2012] with some updates where specific accounting for CO2 linemixing must be applied in the forward model to achieve fitted residuals appropriate to the SNR & quality of the spectra. The observation starting dates for each site varies, but are all analyzed through 2014. The data used in the trends are daily averages from inhomogeneous sampling due to observing limitations of a required clear sky and which, in the Arctic is further limited by the polar night. A bootstrap resampling technique is used to statistically mitigate the sampling [Gardiner et al., 2008]. We will discuss the altitude sensitivity of the retrievals, the annual cycle and long-‐term, approximately 15 year trend in the data by latitude. Rinsland, C. P., et al.: Decrease of the carbon tetrachloride (CCl4) loading above Jungfraujoch, based on high resolution infrared solar spectra recorded between 1999 and 2011, Journal of Quantitative Spectroscopy and Radiative Transfer, 2012, 113(11), 1322–1329, doi:10.1016/j.jqsrt.2012.02.016 Gardiner, T., et al.: Trend analysis of greenhouse gases over Europe measured by a network of ground-‐based remote FTIR instruments, J. Atmospheric Chemistry and Physics, 2008, 8, 22, 6719-‐6727, doi:10.5194/acp-‐8-‐6719-‐2008
Soil uptake of CCl4: flux estimates and uptake mechanisms. Authors: James Happell, Yudania Mendoza, Kelly Goodwin Presented by J. Happell
Static flux chamber measurements of CCl4 uptake by soils in boreal,
subtropical and tropical forests have been made by our group. Previous partial lifetime (τsoil) estimates of soil uptake have ranged from 90 (Happell and Roche, 2003) to 195 years (Montzka et al, 2011). In the work here, the rate of CCl4 uptake was calculated from 453 flux chamber measurements using an exponential fit to the chamber CCl4 concentration change with time. This analysis indicated that the flux rate estimate in Happell and Roche (2003) was overestimated by 2.75, yielding a new estimate of τsoil for CCl4 of 245 years. Significant correlations of CCl4 uptake to temperature, soil moisture, or time of year were not observed. This work provides additional evidence that CCl4 uptake by soils is a common process and needs to be considered when developing an atmospheric budget for this compound.
We also conducted incubation experiments to investigate the soil removal mechanism. Atmospheric concentrations of CCl4 were removed by bulk aerobic soils from tropical, subtropical, and boreal environments. Removal of CCl4 and removal of CH4 were compared to explore whether the two processes were linked. Removal of both gases was halted in laboratory samples that were autoclaved, dry heated, or incubated in the presence of HgCl2. In marl soils, treatment with antibiotics such as tetracycline and streptomycin caused partial inhibition of CCl4 (50%) and CH4 (76%) removal, but removal was not affected in soils treated with nystatin or myxothiazol. These results indicated that bacteria contributed to the soil removal of CCl4 and that microeukaryotes may not have played a significant role. Amendments of methanol, acetate, and succinate to soil samples enhanced CCl4 removal by 59%, 293%, and 72%, respectively. Additions of a variety of inhibitors and substrates indicated that nitrification, methanogenesis, or biological reduction of nitrate, nitrous oxide, or sulfate (e.g., occurring in possible anoxic microzones) did not play a significant role in the removal of CCl4. Methyl fluoride inhibited removal of CH4 but not CCl4, indicating that CH4 and CCl4 removals were not directly linked. Furthermore, CCl4 removal was not affected in soils amended with MeF suggesting that the observed CCl4 removal was not significantly mediated by methanotrophs.
Towards improving the ACE-FTS retrieval of carbon tetrachloride Jeremy J. Harrison1,2, Chris D. Boone3, Peter F. Bernath4
(1) Department of Physics and Astronomy, University of Leicester, Leicester, United
Kingdom
(2) National Centre for Earth Observation (NCEO), University of Leicester, Leicester, United
Kingdom
(3) Department of Chemistry, University of Waterloo, Waterloo, Canada
(4) Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, United
States of America
The Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS), on
board the SCISAT satellite, has been recording solar occultation spectra through the Earth’s
atmospheric since 2004 and continues to take measurements with only minor loss in
performance. The ACE-FTS measures a range of chlorine ‘source’ gases, including CCl3F
(CFC-11), CCl2F2 (CFC-12), CHF2Cl (HCFC-22), CH3Cl and CCl4. However, the current
ACE-FTS v3.5 CCl4 retrieval is biased high by ~ 20–30%, largely due to spectroscopic
errors in the CCl4 absorption cross-section dataset and inadequacies in the lineshapes of
interfering species, such as a Q-branch of CO2 for which line mixing parameters are not
known.
Preparation is underway for a new processing version of ACE-FTS data, v4.0, which will use
a better a priori CO2 VMR profile than v3.5 for the pressure-temperature retrievals, enabling
more accurate trends to be derived from ACE-FTS data. Additional improvements for the
CCl4 retrieval will include a more judicious microwindow selection, an improved accounting
for a number of water lines with bad fitting residuals overlapping the heart of the CCl4
spectral feature, and the use of new laboratory spectroscopic measurements of CCl4, which
improve upon the absorption cross-section dataset used for v3.5. This presentation will
focus on these improvements and provide a status update on the development of the ACE-
FTS v4.0 CCl4 retrieval scheme.
Carbon tetrachloride (CCl4) emission estimates for China: an inventory for 1992-2014 and a
projection to 2030
Pengju BIE1, Li LI1, Zhifang LI1, Jianxin HU*,1
1 Collaborative Innovation Center for Regional Environmental Quality, College of
Environmental Sciences and Engineering, Peking University, Beijing, 100871, China.
* Corresponding author phone: 86 10 62756593; email: [email protected] (J.Hu).
Abstract
We estimated the emissions of carbon tetrachloride (CCl4 or CTC) in Mainland China from
1992 to 2030, using an emission factor approach based on surveyed and projected production and
consumption data. Historically, annual total CCl4 emissions have ascended since 1992, reaching a
tipping point of 11.05±0.80Gg/yr in 2004, and descended to ca. 1.74±0.09 Gg/yr in 2010 as a
result of the phase-out of CTC pursuant to the requirement of the Montreal Protocol.
Approximately 90% of the historical emissions came from chemical industrial processes where
CCl4 was used as a processing agent. In the future, annual emissions will remain at a lower level
of 0.49 Gg/yr ~ 0.82 Gg/yr. The bulk of future CCl4 emissions will originate from the use of CCl4
as feedstock in producing tetrachloroethylene and hydrofluorocarbons (HFCs); moreover, its
share is anticipated to increase at an average rate of 2.88%/yr. Given this, major future regulatory
and technical efforts are encouraged to restrict exhaust release fulfilling the China’s law of
prevention and control of atmospheric pollution, and to reduce the leakage in operation to
accomplish the Montreal Protocol. Our estimates are believed to be reliable since there is a
significant correlation (p<0.01) between the estimated annual emissions and the literature-
reported atmospheric CTC mixing ratios during same period 1992-2014. However, it should be
noted the mixing ratios maintained a stable level at about 100ppt while the emission showed a
significant decrease from 7.13±0.05Gg/yr of 2009 to 0.6Gg/yr or so. This disagreement could be
a consequence of the long lifetime of CTC or the existence of storage emission or other poorly
quantified sources.
Atmosphere-derived carbon tetrachloride emission from the US during 2008 - 2012 L. Hu1,2, S. A. Montzka2, B. R. Miller1,2, A. E. Andrews2, J. B. Miller1,2, S. Lehman3, C. Sweeney1,2, S. Miller4, K. Thoning2, C. Siso1,2, E. Atlas5, D. Blake6, J. A. de Gouw1,7, J. B. Gilman1,7, W. C. Kuster1,7, G. Dutton1,2, J. W. Elkins2, B. D. Hall2, D. Godwin8, H. Chen9, M. L. Fischer10, M. Mountain11, T. Nehrkorn11, S. C. Biraud12, M. S. Torn12, and P. Tans2 1. Cooperative Institute for Research in Environmental Sciences, University of Colorado-Boulder, Boulder, CO, USA; 2. NOAA Earth System Research Laboratory, Global Monitoring Division, Boulder, CO, USA; 3. Institute of Arctic and Alpine Research, University of Colorado-Boulder, Boulder, CO, USA; 4. Department of Global Ecology Carnegie Institution, Stanford University, CA, USA; 5. Rosenstiel School of Marine & Atmospheric Science, University of Miami, FL, USA; 6. School of Physical Sciences, University of California – Irvine, CA, USA; 7. NOAA Earth System Research Laboratory, Chemical Science Division, Boulder, CO, USA; 8. US Environmental Protection Agency, Washington DC, USA; 9. Centre for Isotope Research, University of Groningen, Groningen, The Netherlands; 10. Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA; 11Atmospheric and Environmental Research, Lexington, MA, USA; 12Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA Global atmospheric observations suggest substantial ongoing emissions of carbon tetrachloride (CCl4) despite a 100% phase-‐out of production for dispersive uses since 1996 in developed countries and 2010 in other countries. Little progress has been made in understanding the causes of these ongoing emissions or identifying their contributing sources. This study uses the expanded national CCl4 flask air sampling network from the National Oceanic and Atmospheric Administration (NOAA) over the US to quantify national and regional emissions of CCl4. Average national total emissions of CCl4 between 2008 and 2012 determined from these observations and an ensemble of inversions range between 2.5 and 6.1 Gg yr-1. This emission is substantially larger than the mean of 0.06 Gg/yr reported to the US EPA Toxics Release Inventory over these years, suggesting that under-reported emissions or non-reporting sources make up the bulk of CCl4 emissions from the US. But while the inventory does not account for the magnitude of observationally-derived CCl4 emissions, the regional distribution of derived and inventory emissions is similar. Furthermore, when considered relative to the distribution of uncapped landfills or population, the variability in measured mole fractions was most consistent with the distribution of industrial sources (i.e., those from the Toxics Release Inventory). Our results suggest that emissions from the US only account for a small fraction of the global on-going emissions of CCl4 (30 - 80 Gg yr-1 over this period). Finally, to ascertain the importance of the US emissions relative to the unaccounted global emission rate we considered multiple approaches to extrapolate our results to other countries and the globe.
1
Workshop “Solving the mystery of CTC” Zurich (CH), 5-6 October 2015
Abstract CTC reported production and consumption data, which part of the mystery ? Lambert Kuijpers (TEAP-RTOC) Since CTC is a controlled substance under the Montreal Protocol, data on total production, feedstock production and consumption have to be reported annually by all Parties. For this presentation, the UNEP reported CTC data on total and feedstock production have been analysed for the period 1995-2013 in an aggregated form, globally as well as separately for the developed and developing country groups. For the year 2013, it can be calculated that reported CTC feedstock production is in the order of 100,000 tonnes for both groups of countries, stable for the developed, with a 10-15% annual growth trend for the developing countries. Analysis of the reporting of global data, as well as the aggregated developed and developing country data will show the limits originating from the reporting to UNEP. This will include a brief analysis on regional breakdowns. Emissions data are not reported to UNEP, but best estimates on emissions occurring from various uses will be presented for both the developed and developing county groups. The presentation will conclude with a brief discussion in how far these reported production and estimated emission data can shed more light on the CTC mystery.
CCl4 measurement by satellite with the infrared sounder MetOp/IASI
Authors :
Myriam PEYRE (corresponding author : [email protected]), Olivier LEZEAUX,
Claude CAMY-PEYRET, Bernard TOURNIER, Pascal PRUNET, NOVELTIS (FRANCE)
Presentation : Olivier LEZEAUX
IASI is an infrared sounder aboard MetOp satellites. It is designed to measure the thermal
infrared spectrum emitted by the Earth. Its very high spectral resolution allows to potentially
detect in the measurement the signal of many atmospheric trace gases, including CCl4. On a
polar orbit, the instrument provides global Earth coverage twice a day. The work presented here
addresses the capability of IASI to measure CCl4 atmospheric content at global/regional scales
and its space/time variability.
A first theoretical analysis has allowed to determine and analyse the CCl4 signature in the IASI
spectrum, as well as its expected sensitivity to typical atmospheric variability. The IASI
measurement clearly contains useful information, however the signal is also sensitive to other
elements that disturb CCl4 signal and make the retrieval process complex. These elements are
basically water vapor content, surface (emissivity, temperature), temperature profile and
CO2 concentrations. It has been shown that IASI is not enough sensitive for measuring CCl4 in
the lower layers of the atmosphere, its maximal sensitivity being in the upper troposphere.
Simulations indicated that the retrieved mean mixing ratios potentially allow to detect
latitudinal gradients. This information could be useful for modelers to derive emissions
estimate.
Work on real data has been initiated to develop appropriate methods to extract and quantify
CCl4 signal from the measurement. A first tested approach is to remove the signal due to
perturbing elements by simulating the atmosphere at the measurement time. To this end, IASI
level 2 products provided by EUMETSAT are used. The CCl4 content is tentatively estimated
by comparing observed and simulated signal. First results indicate that differences between
simulated and observed signal due to other sources than CCl4 (uncertainties on water vapor, on
surface parameters, model error, …) are still too important, and avoid a proper extraction of the
useful information with this method. Other approaches, based on the direct use of measured
spectra only are currently tested.
Global modeling of CCl4: How can we use airborne and ground-based measurements to constrain the emissions and atmospheric losses for CCl4?
Qing Liang1,2, Eric L. Fleming1,3, Paul A. Newman1, James Elkins4, Bradley D. Hall4, Geoff
Dutton4,5, Steve C. Wofsy6, Elliot Atlas7
1 NASA Goddard Space Flight Center, Greenbelt, MD USA 2 Universities Space Research Association, Columbia, MD, USA 3 Science Systems and Applications, Inc., Lanham, MD, USA 4 NOAA Earth System Research Laboratory, Global Monitoring Division, Boulder, CO, USA 5 Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Boulder, CO, USA. 6 Harvard University, Cambridge, MA, USA 7 University of Miami, Miami, FL, USA Carbon tetrachloride (CCl4), like many other regulated ozone-depleting substances, has a
long lifetime ~35 years. While CCl4 is relatively well mixed in the troposphere, its atmospheric distribution still displays significant spatial and seasonal variations, which reflect the intricate balance between surface emissions and stratospheric photolysis (the predominant atmospheric sink), ocean and land degradation. Thus, the observed spatial and temporal variations of CCl4 concentration in the atmosphere can be used in global chemistry models to constrain the sources and sinks of CCl4. For example, the inter-hemispheric gradient and long-term trend can be used to derive global emissions and total lifetime for CCl4, as demonstrated in Liang et al. (2014). For this work, we will further our modeling effort and use the atmospheric vertical profile of CCl4 to constrain its atmospheric photolysis lifetime. Second, we will use the observed seasonal variation of CCl4 at surface monitoring stations to improve the regional emissions from Asia, Europe, North America, respectively.
The rate CCl4 falls off with altitude in the stratosphere with respect to a reference gas, e.g. CO2, provides quantitative information of its atmospheric loss via photolysis. We will use the NASA GEOS-5 Chemistry Climate Model and the observed vertical profiles of CCl4 and CCl4-CO2 tracer-tracer correlation from balloon and high-altitude aircraft measurements to constrain the atmospheric photolysis lifetime for CCl4. In addition, we will conduct model sensitivity simulations using the NASA GSFC-2D model with varying photolytic loss rates to estimate the most likely range of photolysis lifetime based on the current best-estimate uncertainty in photolysis cross-section rates.
The seasonal cycle of CCl4 at a particular surface monitoring site reflects the combined influence of surface emissions and sinks as well as the injection of CCl4-depleted stratospheric air, and can differ greatly from place to place due to differences in their proximity to different sources and sinks. Thus the seasonal cycle at an observational site contains unique information that can be used to infer emissions and sinks. GEOSCCM model simulated CCl4 seasonality, driven with the emissions distribution from Xiao et al (2010), shows large discrepancies with that observed at almost all NOAA GMD and AGAGE stations, implying inaccurate estimate of emissions from individual regions. We will use a suite of tagged CCl4 tracers in the GEOSCCM model to track emissions from different geographic regions, e.g. North America, Europe, South and East Asia. The seasonality of modeled CCl4 and its contribution from individual tagged source regions will be compared and analyzed with the observed seasonal cycle at GMD and AGAGE stations to derive an optimized CCl4 emissions estimate.
Decrease of carbon tetrachloride (CCl4) over 2004-2013 as inferred from global occultation measurement with ACE-FTS
Emmanuel Mahieu1, Peter F. Bernath2, Christopher D. Boone3 and Kaley A. Walker3,4
1. Institute of Astrophysics and Geophysics – University of Liège, Belgium 2. Old Dominion University – Norfolk, VA 3. Department of Chemistry – University of Waterloo – ON 4. Department of Physics – University of Toronto – ON
In this contribution, we use infrared solar occultation measurements performed by the ACE-FTS (Atmospheric Chemistry Experiment – Fourier Transform Spectrometer) instrument onboard the SCISAT-1 Canadian satellite (Bernath et al., 2005). Since its launch in August 2003, this spectrometer has been in continuous operation with no significant degradation of its performance, and global measurements are available from late February 2004 onwards, spanning now more than a decade.
ACE-FTS achieves a spectral resolution of 0.02 cm-1 and covers the 750-4400 cm-1 range, encompassing the strong unresolved and broad CCl4 ν3 band around 796 cm-1, near a strong CO2 Q-branch affected by line-mixing (Rinsland et al., 2012). Systematic analysis of sunset and sunrise occultation measurements in the 787.5 – 805.5 cm-1 window (version 3.5; Boone et al., 2013) provides mixing ratio profiles of CCl4 in the 7 – 25 km altitude range, with mean vertical resolution of 2-3 km.
More than 24000 occultations have been included in the present study, covering the 85°N-85°S latitude range and updating the work of Allen et al. (2009). We determine a significant positive bias with respect to surface measurements by the AGAGE and NOAA networks, confirming the findings of Rinsland et al. (2012) when using ground-based column measurements at the Jungfraujoch station. However, when accounting for the systematic uncertainty affecting the CCl4 line parameters and the impact of the CO2 line-mixing, we show that it is possible to close the gap between the surface and remote-sensing measurements.
Focusing on the tropical observations near 9 and 17 km altitude, we characterize a significant yearly decrease for CCl4 (at the 2-sigma level) of -1.3 ppt (or -1.35%) over the last decade, in agreement with results from Jungfraujoch (updated from Rinsland et al., 2012) and the in situ networks (WMO 2014). Finally, we analyze ACE-FTS global data in order to check for possible contrasted evolutions of CCl4 in both hemispheres.
References
Allen, N. D. C., et al.: Global carbon tetrachloride distributions obtained from the Atmospheric Chemistry Experiment (ACE), Atmospheric Chemistry and Physics, 9(19), 7449–7459, doi:10.5194/acp-9-7449-2009, 2009.
Bernath, P. F., et al.: Atmospheric Chemistry Experiment (ACE): Mission overview, Geophysical Research Letters, 32(15), doi:10.1029/2005GL022386, 2005.
Boone, Chris D., et al., Version 3 Retrievals for the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS), The Atmospheric Chemistry Experiment ACE at 10: A Solar Occultation Anthology (Peter F. Bernath, editor, A. Deepak Publishing, Hampton, Virginia, U.S.A., 2013), 103-127, 2013.
Rinsland, C. P., et al.: Decrease of the carbon tetrachloride (CCl4) loading above Jungfraujoch, based on high resolution infrared solar spectra recorded between 1999 and 2011, Journal of Quantitative Spectroscopy and Radiative Transfer, 113(11), 1322–1329, doi:10.1016/j.jqsrt.2012.02.016, 2012.
WMO 2014, Ozone-Depleting Substances (ODSs) and Other Gases of Interest to the Montreal Protocol, Chapter 1 in Scientific Assessment of Ozone Depletion: 2014, Global Ozone Research and Monitoring Project – Report No. 55, World Meteorological Organization, Geneva, Switzerland, 2014.
European emissions of carbon tetrachloride based on high frequency atmospheric measurements and a Bayesian inversion method
Francesco Graziosi, Jgor Arduini, Francesco Furlani, Umberto Giostra and Michela Maione*
Dep. of Basic Sciences and Foundations (DiSBeF), University of Urbino, Urbino, Italy
European carbon tetrachloride emissions are estimated from high-‐frequency atmospheric observations at four European stations embedded in the Advanced Global Atmospheric Gases Experiment (AGAGE) network combined with a Bayesian inversion method. The inversion is based on 20-‐day backward simulations obtained with the FLEXPART Lagrangian particle dispersion model. An a priori emission field has been created based on emissions given in Xiao et al. (2010), who estimated global and regional emissions from 1996 to 2004 using AGAGE atmospheric data and 3D inverse modelling, applying a decreasing rate of 10% per year (Fraser et al., 2011). The a posteriori emission fluxes obtained using the inversion algorithm described in Stohl et al. (2009) have been then redistributed over the European geographic domain according to the population distribution Emission estimates are given for a nine-‐year period, from January 2006 to December 2013, from the whole European geographic domain and at the country (or groups of countries) level. A decline in emissions is observed over the study period, consistent with the implementation of the Montreal Protocol. In addition, the method allowed us to identify emission hot spots, in correspondence with industrial facilities. References Fraser P., Krummel P., Dunse B., Steele P., Derek N. and Allison C. (2011). Global and Australian emissions of ozone depleting substances, Report of the DSEWPaC research projects 2010–11. Australian Government Department of Sustainability, Environment, Water, Population and Communities Stohl, A., Seibert, P., Arduini, J., Eckhardt, S., Fraser, P., Greally, B.R., Lunder, C., Maione, M., Mühle, J., O'Doherty, S., Prinn, R.G., Reimann, S., Saito, T., Schmidbauer, N., Simmonds, P.G., Vollmer, M.K., Weiss, R.F., Yokouchi, Y., (2009). An analytical inversion method for determining regional and global emissions of greenhouse gases: sensitivity studies and application to halocarbons. Atmos. Chem. Phys. 9, 1597e1620. Xiao, X., et al. (2010). Atmospheric three-‐dimensional inverse modeling of regional industrial emissions and global oceanic uptake of carbon tetrachloride, Atmos. Chem. Phys., 10(21), 10,421–10,434, doi:10.5194/acp-‐10-‐10421-‐2010. *Presenting author: [email protected]
Potential Industrial Sources of Environmental Carbon Tetrachloride: An Overview Archie McCulloch Atmospheric Chemistry Research Group, University of Bristol, UK
Abstract Based on atmospheric measurements, emissions of carbon tetrachloride (CTC, CCl4) fell sharply from about 100,000 tonnes/year in the 1980s to between 40 and 50,000 tonnes/year around the turn of the century. They are now 30 to 40,000 tonnes/year. Sources of emission from consumption in dispersive uses and from use as process agents (both of which should be reported to the Montreal Protocol) together with fugitive losses from use as a chemical feedstock have been examined. During the period 1993 to 2005, these sources gave total emissions consistent with the atmospheric observations to within 9%; remarkable in view of the variability of the consumption data then. However, since 2005 the reported consumption in emissive uses has fallen significantly and since 2000 feedstock use has remained virtually constant at about 180,000 tonnes/year, an 80% reduction from the peak value in 1989. Currently, the reported consumption for dispersive uses and estimated losses from feedstock uses could account for maximum emissions of 5000 tonnes/year. Consequently, additional, unreported, emissions of approximately 30,000 tonnes/year are required to effect a balance with atmospheric observations. Having accounted for potential feedstock losses, possible industrial sources of the additional emissions are undeclared consumption or use as a process agent.
Archie McCulloch
Visiting Research Fellow in the Atmospheric Chemistry Research Group, School of Chemistry, University of Bristol UK.
Mail Address: Barrymore, Marbury Road, Comberbach, Northwich, Cheshire, UK CW9 6AU
Phone +44-1606891604 e-mail: [email protected]
Probing broad-scale atmospheric observations for clues to unraveling the carbon tetrachloride conundrum. S. Montzka1*, G. Dutton2, B. Hall1, E. Ray2, F. Moore2, B. Miller2, L. Hu2, J. Elkins1, J. Butler1 1 National Oceanic and Atmospheric Administration, Boulder, USA 2 Cooperative Institute in Environmental Sciences, Univ. of Colorado, Boulder, USA Atmospheric measurements provide an important means by which the effectiveness of production controls on long-lived substances can be assessed. They provide a means to address a primary question: Are global atmospheric concentrations changing as expected? For CCl4 the answer is clearly no; substantial discrepancies between global emissions derived from atmospheric observations and ‘potential’ emissions derived from reported production for dispersive uses have been noted since the late 1990s. The global mean and rate of change in lower-troposphere CCl4 mole fractions is well determined by the global sampling networks, but this is not necessarily true for gradients and signals on smaller scales that could provide additional insight into source or sink magnitudes and distributions. For example, how well determined is the gradient of CCl4 mole fractions across latitudes? Does this gradient inform us about the distribution of unknown sources? Can an accurate hemispheric (N – S) difference in CCl4 mixing ratios be estimated and can it be used to infer a global emission rate? To what extent are hemispheric differences and global rates of change influenced by natural emissions or variations in mass exchange between the stratosphere and troposphere? Here we will investigate observational data from multiple sources to understand which signals and conclusions are robust and reliable. Consideration of previously unpublished data from firn-air measurements, additional instruments, and unique sampling platforms allow for an improved understanding of the lower limit to preindustrial mole fractions and the current atmospheric gradients of CCl4. Multiple features of the observational data continue to point to appreciable ongoing CCl4 emissions in amounts substantially larger than implied by production data reported to the ozone secretariat. *presenter
Carbon tetrachloride content of chlorine-‐bleach-‐containing household products and implications for their use
Mustafa Odabasi a*, Tolga Elbir a, Yetkin Dumanoglu a, Sait C. Sofuoglu b
a Department of Environmental Engineering, Faculty of Engineering, Dokuz Eylul University, Tinaztepe Campus,
35160 Buca, Izmir, Turkey b Department of Chemical Engineering, Izmir Institute of Technology, 35430 Gulbahce-‐Urla, Izmir, Turkey
*Presenting author: e-‐mail: [email protected], phone: 90-‐232-‐301 7122, fax: 90-‐232-‐453 0922
ABSTRACT
It was recently shown that a substantial amounts of carbon tetrachloride (CCl4) is formed in chlorine-‐bleach-‐containing household products as a result of reactions of sodium hypochlorite with organic product components. Use of these household products results in elevated indoor air CCl4 concentrations. CCl4 in several chlorine-‐bleach-‐containing household products (plain, n=9; fragranced, n=4; and surfactant-‐added, n=29) from Europe and North America were measured in the present study. CCl4 concentrations ranged between 0.01 and 169 mg/L (23.2±44.3 mg/L, average±SD) and concentrations were the lowest in plain bleach, slightly higher in fragranced products and the highest in the surfactant-‐added products. Indoor air concentrations from the household use of bleach products (i.e., bathroom, kitchen, and hallway cleaning) were estimated using a simple box model. Estimated indoor air concentrations ranged between 0.30 and 1124 (82±194, average±SD) µg/m3, indicating substantial increases compared to background (0.27 µg/m3). Eventually, the majority of CCl4 in chlorine-‐bleach-‐containing household products is emitted to the atmosphere. Global annual CCl4 emissions from the use of chlorine-‐bleach-‐containing household products were estimated using the concentrations measured in this study and an average per capita consumption of 1 kg/year. Since the shares of product types (i.e., plain or surfactant added) were not known, emissions were estimated for two extreme cases: (i) plain bleach having the minimum CCl4 concentration, (ii) surfactant-‐added bleach having the maximum CCl4 concentration. For these cases global annual CCl4 emissions ranged between 0.06 and 1230 tons. CCl4 emissions from 14 European countries with a population of ~600 million and known country specific per capita household bleach consumptions were also estimated. Annual European CCl4 emissions ranged between 0.02 and 493 tons. Per capita household bleach consumptions are highly variable, ranging between 0.22-‐11.8 kg/year, and generally it is > 3 kg/year. This suggests that the global average per capita household bleach consumption may be higher than 1 kg/year and as a result global CCl4 emissions may be underestimated. Although the estimated global emissions are highly uncertain due to lack of detailed information on product type and usage amounts, the results of the present study indicated that household chlorine bleach use is an ongoing source of CCl4 emitting appreciable amounts to the atmosphere. Keywords: Chlorine bleach; carbon tetrachloride; global emissions.
China’sCarbontetrachloride(CCl4)emissiontrendestimatedfromatmosphericobservationsin2008‐2013
ShanlanLi1,SunyoungPark1,2,JensMühle3,Mi‐KyungPark1,ChunOkJo1
1KyungpookInstituteofOceanography,CollegeofNaturalSciences,KyungpookNationalUniversity,Daegu,SouthKorea2DepartmentofOceanography,CollegeofNaturalSciences,KyungpookNationalUniversity,Daegu,SouthKorea3ScrippsInstitutionofOceanography,UniversityofCaliforniaSanDiego,LaJolla,California,USA
AtmosphericconcentrationsofCCl4havebeendecreasingsincereachingapeakin1990,due to the phase‐out of CCl4 use in theMontreal Protocol’s non‐Article‐5 countries. TheArticle‐5countries,includingChinahadalsobeenrequiredtoeliminateCCl4by2010,butasanexemptionallowedundertheMontrealProtocoltothephase‐out,thechemicalfeedstockusecontinueswiththeincreasingmanufactureofHFC. In this study, we estimated the emission rates of CCl4 for China using an interspeciescorrelation method [Li et al., 2011] based on “top‐down” interpretation of atmosphericobservationsobtainedfromtheGosanstation(33oN,126oE)onJejuIsland,Korea.Thehigh‐precision and high‐frequency measurements of CCl4 were made continuously every twohours from 2008 to 2013 using a GC‐MSD coupled with an online cryogenic pre‐concentration system (“Medusa”) under the AGAGE program. To separate periods ofChineseemissioninfluencesfromthe6‐yeartimeseries,weidentifiedair‐masssegmentsoriginated from China using a back‐trajectory analysis. For the interspecies correlationmethod,themostsuitablereferencetracerforChineseemissionswasHCFC‐22,ofwhichtheannualemissionrates inChinawerederived independently froman inversioncalculationbasedonFLEXPARTtransportmodelanalysis.ThentheCCl4emissionrateswereestimatedbyusingtheempiricalcorrelationsbetweenobservedCCl4andHCFC‐22. OurresultsshowtheCCl4emissionsinChinabetween2008and2010wereintherange
between18.7±2.9and23.3±2.7ktyr‐1,andthentherewasastatisticallysignificantdeclinebyca.30%intheemissionfrom2010to2011,inconcurrencewiththescheduledphase‐outofCCl4.However,itisinterestingthattheemissionrateoftheyear2011hadleveledoffuntil2013,stillshowingasignificantemissionrateof16.2±4.4ktyr‐1,whilepost‐2010bottom‐upemissionsofCCl4inChinahavebeenreportedtobenearzero(Wangetal.,2009).ThisdiscrepancymaysuggestCCl4emissionsfromeithernon‐regulatedfeedstockuseorcleaningsolvent source. To identifykey industrial sources forCCl4 emissionsand theirpotentiallocations,wefurtheranalyzetheobservationdatabyusingaPositiveMatrixFactorizationmodelincombinationwithtrajectorystatistics[Lietal.,2014].Moredetailsarediscussedinthepresentation.Overall,CCl4emissionsfromChinaaccountforapproximately23%ofglobaltop‐down emissions derived from AGAGEmeasurements from 2008‐2012 (Fraser et al.,2014).
Terrestrial sinks and natural sources of carbon tetrachloride Robert Rhew In the atmospheric budget of carbon tetrachloride, the magnitude of the soil sink remains highly uncertain. In the last two Assessments, the range of CCl4 partial lifetimes with respect to soil was estimated at 195 years with a range of ~100 to 907 years. The source of the uncertainty was largely associated with tropical forest soils. Recently, Happell et al. (2014) provided a revised partial lifetime estimate of 245 years, based on a much larger set of field measurements. This revision would increase the total atmospheric lifetime of CCl4 from 26 to 27 years, assuming the partial lifetimes of stratospheric and oceanic loss remained the same (at 44 and 94 years, respectively). The uncertainty of the soil sink partial lifetime may be reduced through a meta-‐analysis of published studies to date. Although CCl4 emission sources are almost entirely anthropogenic, this compound can be synthesized naturally as well. The biosynthesis of CCl4 was first identified in the red alga Asparagopsis (McConnell and Fenical, 1977). Later field measurements showed CCl4 emissions from a salt marsh site covered in macroalgae (Rhew et al., 2008). However, emission rates do not appear to be globally significant. Reports of natural biological sources will be reviewed and assessed for their potential contribution to the atmospheric CCl4 budget. References: Happell, J., Y. Mendoza and K. Goodwin, 2014. A reassessment of the soil sink for atmospheric carbon tetrachloride based upon static flux chamber measurements. J. Atmos. Chem, 71(2): 113-‐123, doi: 10.1007/s10874-‐014-‐9285-‐x. McConnell, O. and W. Fenical, 1977. Halogen chemistry of the red alga Asparagopsis. Phytochemistry 16: 367-‐374. Rhew, R., B. Miller and R. Weiss, 2008. Chloroform, carbon tetrachloride and methyl chloroform fluxes in southern California ecosystems. Atmospheric Environment, 42: 7135-‐7140, doi: 10.1016/j.atmosenv.2008.05.038.
Global and regional estimates of carbon tetrachloride emissions using AGAGE observations Matt Rigby, Mark Lunt, Sunyoung Park, Shanlan Li, Alistair Manning, Ron Prinn, Simon O’Doherty, Qing Liang Observations from the Advanced Global Atmospheric Gases Experiment (AGAGE) provide information on carbon tetrachloride (CCl4) emissions at both global and regional scales. By examining trends in the global background concentration, we can derive the global fluxes using relatively simple models and inverse methods. However, these estimates are sensitive to the assumed global lifetime. In contrast, regional estimates can be derived that are insensitive to the lifetime, using the observed high-‐frequency signals measured at AGAGE sites close to major emissions sources. However, such approaches can only be used to determine emissions within a few hundred kilometres of each station. Using a two-‐dimensional model of atmospheric transport and chemistry, we derive a global flux of 57 (40–74) Gg/yr, when assuming a lifetime of 26 years, as recommended in the latest WMO Scientific Assessment of Ozone Depletion, or 36 (22–49) Gg/yr when a lifetime of 35 years (Liang et al., 2014) are assumed. To derive regional fluxes, we use the three-‐dimensional Numerical Atmospheric Modelling Environment (NAME), developed by the UK Met Office. Such models can be used to estimate fluxes at relatively high resolution, using high-‐frequency data from AGAGE observations. However, care must be taken to: a) minimise the influence of subjective choices made by the investigator on the outcome of the inversion; b) appropriately account for the uncertainty due to the chemical transport model; c) ensure that fluxes are derived at spatial and temporal scales that can be appropriately resolved by the data. We demonstrate new approaches using hierarchical Bayesian methods and reversible-‐jump Markov-‐chain Monte Carlo to address each of these issues. Based on these methods, we derive significant emissions from East Asia, focused particularly on China, which are of the order of 20 Gg/yr. Emissions from other regions close to AGAGE stations returned relatively small emissions in recent years. Our estimates for East Asia account for around one-‐third of the global budget, if the lifetime is 26 years and around one-‐half, if it is 35 years. It is likely that there are other areas of the world, such as India, Africa, South America or the east coast of the USA where significant emissions may exist, but to which the AGAGE network is not directly sensitive.
Summary of CTC presentation Zuerich October 2015: Industry perspective
CTC demand has not only confounded many critics, where there was an expectation that output would shrink to almost zero, but at present shows signs of stabilising at some 180-200 ktpa and has clear indications of growth... this of course being to non-controlled (chemical intermediate) applications. The number refers to production or use, and not to emissions.
In this paper we will review
• fatal production from chloromethanes: how to assess it in general and then how major individual plants individually treat it. We will review the major producing areas. We will note that chloromethanes plants, whilst minimising CTC now, were frequently set up to make CTC deliberately to source the growing CFC industry.
• fatal production from perchloroethylene plants and the global and localised scale • deliberate production of CTC using CS2 technology: all such plants have in fact closed • Incidence of CTC in waste streams and how they are handled (Examples). • Other potential anthropogenic sources of CTC
We will then review consumption patterns of CTC:
• Use to chemical intermediates such as in perchlorination, reduction to other chloromethanes (chloroform, methyl chloride)
• Use in Kharasch reactions notably to make pesticides and new generation hydrofluorocarbons and hydrofluoro-olefins
• "Use" to incineration whereby the resultant HCl may be used in downstream and vital chemical reactions
We will then attempt to display a mass balance.
We will speculate for audience participation on the CTC that is generated in waste streams that may be uncontrolled, that may arise from swimming pools, or from the use of bleaching tablets in conjunction with washing fluids in laundry applications.
David Sherry
Director, NSA Ltd
Overview of University of California, Irvine CCl4 observations: Trends and outliers Isobel J. Simpson, Nicola J. Blake, Simone Meinardi, and D. R. Blake Department of Chemistry, University of California, Irvine, CA 92697 The University of California, Irvine (UCI) has measured carbon tetrachloride (CCl4) concentrations in whole air samples as part of our global monitoring network since 1978 and in support of aircraft field campaigns since 1990. In addition we have made numerous CCl4 measurements during urban studies throughout this period, collecting samples in more than 75 cities worldwide. Our remote global monitoring data show that post-Montreal Protocol CCl4 mixing ratios have decreased along with other regulated halocarbons. However, unlike CFC-11 and CFC-12, the CCl4 samples still routinely have outliers, suggesting ongoing release. For example, in 2014 UCI measured a global average CCl4 mixing ratio of 82.3 ± 0.1 pptv, with outliers of up to 90 pptv at remote receptor sites such as Hawaii and western North America. Our aircraft and urban data can help shed light on these observations by identifying potential emission regions and their changes with time. As an example, in 2012 we collected air samples in Saudi Arabia, a highly polluted yet understudied region of the world. Whereas CCl4 levels in background Saudi Arabian air (86.7 ± 0.1 pptv) were similar to background levels recorded by our global monitoring network at a similar time and latitude (86.4 ± 0.9 pptv), the average CCl4 mixing ratio in Mecca was 92.5 ± 0.8 pptv, with maximum levels of 108 pptv, indicating ongoing CCl4 emissions in this region. By contrast, ground samples including various “source” samples (urban/industrial/oil & gas), were collected along the Colorado Front Range as part of the 2014 FRAPPÉ campaign. While background CCl4 levels during the campaign (82.7 ± 0.2 pptv) were again close to background levels from our global monitoring network for a similar latitude and season (82.2 ± 0.6 pptv), the average CCl4 mixing ratio during FRAPPÉ was only slightly elevated (at 85.3 ± 2.0 pptv) compared to background, and the maximum value was 92.8 pptv. These findings agree with the 2013 US airborne campaign SEAC4RS, which also exhibited only a relatively small number of CCl4 outliers. These and other results will be presented and discussed.
A historical perspective on primary and possible secondary sources of atmospheric Carbon Tetrachloride
Hanwant B. Singh, NASA Ames Research Center, USA
Atmospheric sources of Carbon Tetrachloride (CTC) have been controversial since its detection in the early 1970. Initial proposals were that it is globally uniformly distributed and its lack of current emissions and inferred lifetime indicated that it was likely of natural origin. Historical analysis of CTC use and emissions showed that atmospheric CTC was long-lived and mainly of man-made origin although small natural sources and sinks (e. g. oceans) could not be ruled out. This deduction was hard because a majority of emissions had occurred in early part of the 20th century when CTC was commonly used as a fumigant, a solvent, and a raw material for the manufacture of many chemicals. In the 1940’s adverse health effects of exposure to CTC became evident and its emissions were greatly curtailed and substituted with C2Cl4 which was thought to be much safer. There were smog chamber studies that showed that C2Cl4, a widely used solvent during the late 20th century, could produce CTC with up to a 7% yield. Subsequently it was discovered that this chemistry probably required Cl atoms and since Cl atoms were not abundant in the atmosphere actual yields based on OH oxidation were probably closer to 0.1%. CTC was subsequently banned by the Montreal Protocol to prevent stratospheric ozone depletion and its preferred substitute C2Cl4 was also banned by EPA for reasons of potential carcinogenicity and toxicity. CTC since has been measured in many airborne NASA campaigns in which plumes have been sampled from a variety of regions which may still be emitting CTC. I will briefly discuss this historical perspective of CTC and show some recent data that may shed light on its current sources or lack there off.
Contribution to "Solving the Mystery of Carbon Tetrachloride" Workshop
INVESTIGATING OCEANIC UPTAKE OF CCl4 USING GLOBAL DATA AND AN OCEAN BIOGEOCHEMISTRY MODEL
P. Suntharalingam, L. J. Carpenter, S.A. Andrews, S. C. Hackenberg, J.H. Butler, S.A. Yvon-‐Lewis, O. Andrews, E. Buitenhuis
Recent analyses of oceanic CCl4 saturation anomalies [Butler et al. 2011] have highlighted the need for a revised quantification of the oceanic sink of CCl4 and improved understanding of the processes governing this uptake and the controls on CCl4 distribution in the ocean interior. The oceanic CCl4 distribution is governed by a combination of processes including surface air-‐sea gas exchange, ocean circulation and water mass mixing, and hydrolysis [Wallace et al. 1994; Huhn et al. 2001]. In addition, recent analyses of covariance between oceanic CCl4 and Apparent Oxygen Utilisation (AOU) and other biological data (Data from J. Butler, NOAA-‐ESRL and L. Carpenter, University of York) suggest a significant role for a biologically mediated loss-‐process (as also suggested by previous studies, e.g., Wallace et al. 1994, Huhn et al. 2001, Yvon-‐Lewis et al. 2002).
Here we show data from the Atlantic, Pacific and Arctic Oceans [L. Carpenter, unpublished data] that, consistent with those of Butler et al. [2011], show persistent undersaturation of CCl4 in the oceans. In the Arctic Ocean, correlation of undersaturation with salinity indicate that physical processes, likely associated with sea-‐ice, moderate the CCl4 uptake. In the Atlantic, CCl4 was most strongly undersaturated in waters high in Chl-‐a content.
A specific focus of this investigation is to quantify the relative influences on ocean CCl4 of: (1) gas-‐exchange and physical circulation; (2) chemical hydrolysis; and (3) potential biologically-‐mediated loss processes. We show initial results from global ocean biogeochemistry model simulations (NEMO-‐PlankTOM) quantifying these contributions, and also use available surface and depth measurements to evaluate the relative influences of these processes on the observed oceanic CCl4 distribution.
References
Butler, J. H.; Yvon-‐Lewis, S. A.; Lobert, J. M.; King, D. B.; Montzka, S. A.; Koropalov, V., 2011, A Revised Look at
the Oceanic Sink for Atmospheric CCl4, American Geophysical Union, Fall Meeting 2011, abstract #A51A-‐0273.
Huhn, O., Roether, W., Beining, P., Rose, H., 2001. Validity limits of carbon tetrachloride as an ocean tracer.
Deep-‐Sea Res. 48, 2025–2049.
Wallace, D.W.R., Beining, P., Putzka, A., 1994. Carbon tetrachloride and chlorofluorocarbons in the South
Atlantic Ocean, 19 S. J. Geophys. Res. 99, 7803–7819.
Yvon-‐Lewis, S. A. and J. H. Butler, 2002, Effect of oceanic uptake on atmospheric lifetimes of selected trace
gases, J. Geophys. Res., 107(D20), 4414.
High time-resolution mixing ratios of atmospheric carbon tetrachloride. A case study in Northern Spain
Maite de Blasa*, Iratxe Uria‡, Maria Carmen Gómez, Marino Navazo, Lucio Alonso,
José Antonio García, Nieves Durana, Jon Iza, Jarol Derley Ramón School of Engineering, University of the Basque Country UPV/EHU, Bilbao, Spain. a University College of Technical Mining and Civil Engineering. University of the Basque Country, UPV/EHU, Bilbao, Spain. * Corresponding author. Contact information: e-mail address: [email protected] Address: Rafael Moreno 'Pitxitxi' 2, 48013 Bilbao, Spain. Tel.: +34 94 601 7812 ‡ Presenter Abstract Since the restriction of CTC under the Montreal Protocol, its average mixing ratio has been thoroughly studied. Most high resolution measurements correspond to background areas in order to study its long-term trend after the banning. The novelty of this work is supported by the fact that high resolution measurements of CTC were performed in two non-background sites in Northern Spain: 1- An urban area (Bilbao), using an auto-GC-MS during one year (March 2007 − February 2008), and 2- A rural area (Valderejo), using an auto-GC-FID covering almost five years (January 2003 − December 2005, July 2010 − June 2011, and January − June 2015). Auto-GC systems were set up to measure up to 67 volatile organic compounds (VOCs) in Bilbao and 65 VOCs in Valderejo, resulting that CTC coeluted with a traffic related hydrocarbon, 3,3-dimethylpentane (33dmpna). In the GC-MS CTC and 33dmpna were resolved by using the Selected Ion Monitoring (SIM) mode, an option not available for the GC-FID. A procedure to determine 33dmpna on FID chromatograms was developed by de Blas et al. [1], using the mixing ratio of a well resolved isomer, the 2,3-dimethylpentane (23dmpna). Although 33dmpna mixing ratio was most of the time negligible in Valderejo, the procedure was applied to amend the CTC mixing ratios when necessary (1,3% of the cases). Hourly CTC yearly mean mixing ratios were 0.16 ppbv in Bilbao (N=3,290) and between 0.11 and 0.13 ppbv in Valderejo (N=16,051), slightly higher than the overall background values in the Northern Hemisphere such as Mace Head (average 0.089 ppbv for 2003-2013 years [2]). CTC mixing ratios did not decrease during the observed period. Indoor measurements confirmed the use of chlorine-bleach products for cleaning purposes as an indoor source of CTC in Bilbao, but other potential sources of CTC will also be detailed on the paper. References [1] de Blas M, Gómez MC, Navazo M, Alonso L, Durana N, Iza I (2014). Estimation of
unidentified non-methane hydrocarbons in urban air based on highly correlated compound pairs. Atmospheric Environment 98, 629-639
[2] World Meteorological Organization (WMO). 2014. Global Atmosphere Watch. World Data Centre for Greenhouse Gases. WDCGG Data Summary. [cited 2015 Jul 17]. Available from: http://ds.data.jma.go.jp/gmd/wdcgg/
Carbon Tetrachloride from space by MIPAS Envisat
E. Eckert1, N. Glatthor1, T. von Clarmann1, U. Grabowski1, A. Linden1, and S. Kellmann1
presenter: Thomas von Clarmann
1Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research, Karlsruhe,Germany
The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat was a highspectral resolution infrared limb emission sounder for measurement of atmospheric trace species.It provided global altitude-resolved fields of constituent abundances from 2002-2012. Carbontetrachloride (CCl4) is analyzed using its ν3 band which has an interference from the signal of theCO2 Q branch at 792 cm−1. This implies that line mixing in the CO2 signature has to beconsidered in the radiative transfer calculations. Useful measurements can be made in the uppertroposphere and lower stratosphere. In the stratosphere, CCl4 mixing ratios decrease rapidly withaltitude. In this talk, global CCl4 maps at selected altitudes will be presented and differences inmixing ratios between the Envisat period and balloon-borne measurements in 1992 will bediscussed.
1
Abstract for Solving the Mystery of Carbon Tetrachloride
Long Term Observation of Carbon Tetrachloride at CMA Network in China Bo Yao1*, Martin K. Vollmer2, Lingxi Zhou1, Xiaoling Zhang3, Zhiqiang Ma3, Fan Dong3, Hongyang Wang1,
Zhenbo Zhang1, Stefan Reimann2
1.Chinese Academy of Meteorological Sciences, China Meteorological Administration, Beijing, China;
2.Empa, Swiss Federal Laboratories for Material Science and Technology, Laboratory for Air Pollution and
Environmental Technology, Dübendorf, Switzerland;
3. Environmental Meteorology Forecast Center of Beijing-Tianjin-Hebei, Chinese Meteorological
Administration, Beijing, China. * give presentation
Abstract
Long term CCl4 in-situ measurement was conducted by an in-situ GC-ECDs system at the Shangdianzi
Global Atmosphere Watch regional station in China since 2006 using the technique from System for
Observation of Greenhouse Gases in Europe and Aisa (SOGE-A). The background concentrations were
decreasing from 90.3 ppt in 2007 to 86.3 ppt in 2010, consistent with those obtained at NH stations of
Advanced Global Atmospheric Gases Experiment (AGAGE), with the decreasing rate at 1.4 ppt/yr. However,
the enhanced polluted concentrations were increased from 5.1 ppt in 2007 to 7.4 ppt in 2011.
Furthermore, weekly samples were collected at 5 background stations at network of China Meteorological
Administration (CMA) and analyzed by the Medusa-GC/MS system using the technique from AGAGE since
2010. The stations were Waliguan in Qinghai (WLG), Shangdianzi in Beijing (SDZ), Lin’an in Zhejiang
(LAN), Longfengshan in Heilongjiang (LFS) and Xiangri-la in Yunnan (XGL). There are limited pollution
events in WLG and XGL with more than 95% of all the valid data being selected as background data for
January 2011 to December 2012. However, the ratios of polluted events of LAN, SDZ and LFS were 76.1%,
64.9%, 30.4% in 2011 and 83.3%, 76.1%, 18.6% in 2012. The enhanced median concentrations were 6.9,
12.5, 5.4 ppt in 2011 and 9.0, 11.1, 4.2 ppt in 2012. The polluted concentrations of CCl4 show significant
correlation with polluted CO data. The ratios between enhanced CCl4 and enhanced CO concentrations
(ΔCCCl4/ΔCCO) during pollution events were 0.0170×10-3, 0.0126×10-3, 0.0047×10-3 at LAN, SDZ and LFS,
respectively, indicating that different ratios should be used in different Chinese regions for emission estimate
by trace ratio method using CO as a tracer.
During one-year campaign from September 2012 to September 2013, enhanced concentrations of 7.8 ppt
(9.1%) and 4.2 ppt (4.9%) were found at two stations in Beijing urban and suburban area. Daily cycles with
night maximum were observed at both stations by high frequency sampling from April 1 to April 4, 2014.
The elevated night-day differences reached 25 ppt and 27 ppt for urban and suburban stations, respectively,
revealing there was relatively high consumption and emission of CCl4 in Beijing.