Fig 1 - uploaded by Ronald G Prinn
Content may be subject to copyright.
MOZARTv4.5 model output at the observation grid cells (Northern Hemisphere-solid line and Southern Hemisphere-dashed line) for the reference run using emissions based on EDGARv4.2 (yellow lines) and the final derived emissions (blue lines). The open circles are the atmospheric observations (Northern Hemisphere-grey and Southern Hemisphere-light blue), with the vertical lines being the associated observational uncertainty. The detection limits for the instruments are shown as the grey shading, with dark grey for the SIO instrument and the light grey for the CSIRO instrument.
Source publication
Global emission estimates based on new atmospheric observations are presented for the acylic high molecular weight perfluorocarbons (PFCs): decafluorobutane (C[subscript 4]F[subscript 10]), dodecafluoropentane (C[subscript 5]F[subscript 12]), tetradecafluorohexane (C[subscript 6]F[subscript 14]), hexadecafluoroheptane (C[subscript 7]F[subscript 16]...
Contexts in source publication
Context 1
... reference run of modeled mole fractions using the bottom-up estimates from EDGARv4.2 (see Sect. 2.2) in MOZARTv4.5 are presented in Fig. 1; the reference mod- eled mole fractions are lower than the atmospheric observa- tions for the high molecular weight PFCs. In particular, the reference run produces modeled mole fractions that are 20 times and over a 1000 times too low for C 4 F 10 and C 5 F 12 , respectively. For C 5 F 12 this is due to the global annual emis- sions ...
Context 2
... 16 and C 8 F 18 are not reported to UNFCCC; however based on our results, their emissions are larger than those of C 4 F 10 and C 5 F 12 and should be con- sidered in future inventories. MOZARTv4.5 was run using the derived emissions and produced modeled mole fractions that were much closer to the observations (as required in the inversion), see Fig. 1. Figure 5 shows the residuals of the final runs (take as the observed mole fractions minus the final modeled mole frac- tions) using the derived emissions. Most of the residuals are within the estimated observational error and no significant trends in the residuals are found, confirming that the derived emissions represent an improved ...
Citations
... The most consistent feature of all PFAS is that their perfluorocarbon moieties break down very slowly (or even do not) under environmental conditions (Wang et al. 2018;Wang et al. 2017). Existing studies have estimated that PFAS such as perfluoroalkanes have lifetimes up to thousands of years (Ivy et al. 2012). Therefore, PFAS can be present in the environment for centuries or longer, even if the PFAS productions, applications, and environmental releases cease immediately. ...
In modern buildings, abundant synthetic materials and products are used to meet various demands of occupants. A vast of semi-volatile organic compounds (SVOCs) are added as additives or solvents to facilitate the production of, or enhance the performance of, these materials and products, leading to the ubiquity of SVOCs in indoor environments. SVOCs can be slowly emitted from these sources and then be partitioned among gas phase and various indoor surfaces. Due to their strong partitioning between air and surfaces, SVOCs have long indoor persistence (days to years, or even more). Human exposure to some SVOCs have been proved to be associated with diverse health risks, which have led to product reformulations in some cases. However, few knowledges about the indoor fate, human exposure, and the associated health risks are currently available for many other widely used SVOCs as well as the increasing number of emerging SVOCs. This chapter provides an overview on the usage, basic physicochemical properties, and adverse health effects of four classes of SVOCs that have been frequently/newly investigated in the past 20 years, including (1) phthalate esters (PAEs) and their alternatives, (2) brominated flame retardants (BFRs), (3) organophosphate flame retardants (OPFRs), and (4) per- and polyfluoroalkyl substances (PFAS). Overall, this chapter aims to emphasize the importance of investigating SVOC pollution in indoor environments.
... CF 4 (tetrafluoromethane), C 2 F 6 (hexafluoroethane), C 3 F 8 (octafluoropropane), C 4 F 10(a) and C 4 F 10(b) , C 5 F 12(a) and C 5 F 12(b) , C 6 F 14(a) and C 6 F 14(b) are classified as the saturated fluorocarbons. Due to their long lifetimes and strong absorption in the infrared atmospheric window region, perfluorocarbons (PFCs) are included as one of the 6 classes of greenhouse gases under the Kyoto Protocol to the United Nations' Framework Convention on Climate Change (UNFCCC) [42]. The global warming potentials (GWPs) of PFCs on a 100-year time horizon is three to four orders of magnitude higher than that of carbon dioxide, with the high ranges from 6500 to 9300 shown in Table 7 [43]. ...
C6F12O (1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)pentan-3-one) is one of the most potential alternative insulation medium to SF6 due to its excellent electrical strength and environmental effect. Although several works on the insulation and decomposition properties of C6F12O have been carried out in recent years, the detailed decomposition pathways and mechanism of C6F12O haven’t been revealed up to now. A comprehensive analysis of the decomposition mechanism of C6F12O is performed through high-level quantum chemistry calculations with DFT and TST in this paper. The results show that more than ten decomposition products are formed. C4F10(a), C5F12(b), and CO can be used for evaluating slight failures. C3F8, C2F6, C2F4, C3F6, C4F10(b), C5F12(a), C6F14(a) and C6F14(b) etc. can be taken as typical products when a general failure is caused in the equipment. CF4 can be used as a basis for determining whether a serious failure has occurred in the gas-insulated electrical equipment. According to the analysis, primary decomposition products such as C4F10(a) and C5F12(b) have relatively high dielectric strength. Besides, the concentration of decomposition products of C6F12O is low to have a major impact on the overall electrical performance at normal conditions. However, the insulation properties of C6F12O gas mixtures after the prolonged operation or multiple arc extinctions deserve further investigation. In the view of human safety and environmental effect, several toxic products such as C2F4, CO, and C3F6 should be effectively managed and handled with care. This paper could provide a theoretical basis for related engineering applications.
... PFCs are a part of the 1997 Kyoto Protocol and are covered in the 2014 revised F-Gas regulation of the European Union (EU), which will be a part of the Nationally Determined Contribution of the EU to the Paris Agreement. However, substantial discrepancies have been found between emissions derived from atmospheric background measurements and reported emissions (specifically for the compounds focused on in this study; see Laube et al., 2012;Oram et al., 2012;Ivy et al., 2012b;Mühle et al., 2019). The gas-chromatographic separation of isomers is a useful development that may give some insight into, for example, the identity and potential commonality of sources and possibly a better understanding of the changes in sources with time. ...
... Emission rates for n-C 4 F 10 and n-C 5 F 12 are comparable to each other in terms of both trend and magnitude, which is consistent with previous work Ivy et al., 2012b) (Fig. 8). Emissions of both compounds initially rise steadily to peak at around 0.30 Gg yr −1 in the mid-1990s, after which they decrease. ...
... Maximum emission rates reported in Laube et al. (2012) are 0.27 Gg yr −1 for n-C 4 F 10 and 0.31 Gg yr −1 n-C 5 F 12 , which agrees within the uncertainties of the current work. A similar conclusion is valid for the maximum emissions rates in Ivy et al. (2012b) (Fig. 8). In order to fit the observed mixing ratios, emission rates are required to have stabilised in the last decade. ...
Perfluorocarbons (PFCs) are potent greenhouse gases with global warming potentials up to several thousand times greater than CO2 on a 100-year time horizon. The lack of any significant sinks for PFCs means that they have long atmospheric lifetimes of the order of thousands of years. Anthropogenic production is thought to be the only source for most PFCs. Here we report an update on the global atmospheric abundances of the following PFCs, most of which have for the first time been analytically separated according to their isomers: c-octafluorobutane (c-C4F8), n-decafluorobutane (n-C4F10), n-dodecafluoropentane (n-C5F12), n-tetradecafluorohexane (n-C6F14), and n-hexadecafluoroheptane (n-C7F16). Additionally, we report the first data set on the atmospheric mixing ratios of perfluoro-2-methylpentane (i-C6F14). The existence and significance of PFC isomers have not been reported before, due to the analytical challenges of separating them. The time series spans a period from 1978 to the present. Several data sets are used to investigate temporal and spatial trends of these PFCs: time series of air samples collected at Cape Grim, Australia, from 1978 to the start of 2018; a time series of air samples collected between July 2015 and April 2017 at Tacolneston, UK; and intensive campaign-based sampling collections from Taiwan. Although the remote “background” Southern Hemispheric Cape Grim time series indicates that recent growth rates of most of these PFCs are lower than in the 1990s, we continue to see significantly increasing mixing ratios that are between 6 % and 27 % higher by the end of 2017 compared to abundances measured in 2010. Air samples from Tacolneston show a positive offset in PFC mixing ratios compared to the Southern Hemisphere baseline. The highest mixing ratios and variability are seen in air samples from Taiwan, which is therefore likely situated much closer to PFC sources, confirming predominantly Northern Hemispheric emissions for most PFCs. Even though these PFCs occur in the atmosphere at levels of parts per trillion molar or less, their total cumulative global emissions translate into 833 million metric tonnes of CO2 equivalent by the end of 2017, 23 % of which has been emitted since 2010. Almost two-thirds of the CO2 equivalent emissions within the last decade are attributable to c-C4F8, which currently also has the highest emission rates that continue to grow. Sources of all PFCs covered in this work remain poorly constrained and reported emissions in global databases do not account for the abundances found in the atmosphere.
... The liquefaction temperature of the decomposition products is lower than that of C 6 F 12 O, and the concentration of the product is much lower than that of C 6 F 12 O. The main products are Perfluorinated compounds (PFCs), which impact the environment [29]. However, the GWP of the product is less than that of SF 6 . ...
This paper explores the decomposition characteristics of a new type of environmentally friendly insulating gas C6F12O and N2 mixed gas under AC voltage. The breakdown behavior of 3% C6F12O and N2 mixed gas in quasi-uniform field was investigated through a breakdown experiment. The self-recovery of the mixed gas was analyzed by 100 breakdown experiments. The decomposition products of C6F12O and N2 under breakdown voltage were determined by gas chromatography–mass spectrometer (GC-MS). Finally, the decomposition process of the products was calculated by density functional theory, and the ionization energy, affinity, and molecular orbital gap of the decomposition products were also calculated. The properties of the decomposition products were analyzed from the aspects of insulation and environmental protection. The experimental results show that the 3% C6F12O and N2 mixed gas did not show a downward trend over 100 breakdown tests under a 0.10 MPa breakdown voltage. The decomposition products after breakdown were CF4, C2F6, C3F6, C3F8, C4F10, and C5F12. The ionization energies of several decomposition products are more than 10 eV. The Global Warming Potential (GWP) values of the main products are lower than SF6. C2F6, C3F8, and C4F10 have better insulation properties.
... Using various gap-filling procedures, reconstruction and extensions, this dataset aims to reflect observational evidence of both recent flask and in situ observations from the worldwide network of NOAA ESRL and AGAGE stations, as well as Antarctic and Greenland ice core and firn data over the last 2000 years, where available. Furthermore, many detailed literature studies (Arnold et al., 2013Aydin et al., 2010;Ivy et al., 2012;Martinerie et al., 2009;Montzka et al., 2015;Mühle et al., 2010;Oram et al., 2012;Sturrock et al., 2002;Trudinger et al., 2004Trudinger et al., , 2016Velders and Daniel, 2014;Vollmer et al., 2016;Worton et al., 2006) for radiatively less important species are compared with our data product in the fact-sheet figures for the specific gases (Table 12 and Figs. S1-S40 in Supplement), or synthesized where direct observational records from the above networks were not available. ...
... Specifically, if a global mean is provided, we use that global mean in conjunction with our derived and regressed latitudinal gradients. In the case of hemispheric data points, we adapt the latitudinal gradient to match the literature studies, as in the case of C 4 F 10 , C 5 F 12 , C 6 F 14 , C 7 F 16 or C 8 F 18 , where we based both the global mean and latitudinal gradients on the data of Ivy et al. (2012). Other key studies used were Velders and Daniel (2014), the data underlying the WMO Ozone Assessment Report (2014), Arnold et al. (2013Arnold et al. ( , 2014, Trudinger et al. (2004), Mühle et al. (2010Mühle et al. ( , 2009), Montzka et al. (2011), updated time series by (updated at ftp://ftp.cmdl.noaa.gov/hats/Total_Cl_ ...
... Other key studies used were Velders and Daniel (2014), the data underlying the WMO Ozone Assessment Report (2014), Arnold et al. (2013Arnold et al. ( , 2014, Trudinger et al. (2004), Mühle et al. (2010Mühle et al. ( , 2009), Montzka et al. (2011), updated time series by (updated at ftp://ftp.cmdl.noaa.gov/hats/Total_Cl_ Br/), the recent study by Vollmer et al. (2016) in regard to Halons and by Trudinger et al. (2016) in regard to PFCs, and others (Arnold et al., 2013Ivy et al., 2012;Montzka et al., 2015;Mühle et al., 2010;Oram et al., 2012;Trudinger et al., 2016;Velders and Daniel, 2014;Vollmer et al., 2016;Worton et al., 2007), as indicated in the gas-specific fact-sheet figures (Figs. S1-S40 with references provided in Table 12). ...
Atmospheric greenhouse gas (GHG) concentrations are at unprecedented, record-high levels compared to the last 800 000 years. Those elevated GHG concentrations warm the planet and – partially offset by net cooling effects by aerosols – are largely responsible for the observed warming over the past 150 years. An accurate representation of GHG concentrations is hence important to understand and model recent climate change. So far, community efforts to create composite datasets of GHG concentrations with seasonal and latitudinal information have focused on marine boundary layer conditions and recent trends since the 1980s. Here, we provide consolidated datasets of historical atmospheric concentrations (mole fractions) of 43 GHGs to be used in the Climate Model Intercomparison Project – Phase 6 (CMIP6) experiments. The presented datasets are based on AGAGE and NOAA networks, firn and ice core data, and archived air data, and a large set of published studies. In contrast to previous intercomparisons, the new datasets are latitudinally resolved and include seasonality. We focus on the period 1850–2014 for historical CMIP6 runs, but data are also provided for the last 2000 years. We provide consolidated datasets in various spatiotemporal resolutions for carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), as well as 40 other GHGs, namely 17 ozone-depleting substances, 11 hydrofluorocarbons (HFCs), 9 perfluorocarbons (PFCs), sulfur hexafluoride (SF6), nitrogen trifluoride (NF3) and sulfuryl fluoride (SO2F2). In addition, we provide three equivalence species that aggregate concentrations of GHGs other than CO2, CH4 and N2O, weighted by their radiative forcing efficiencies. For the year 1850, which is used for pre-industrial control runs, we estimate annual global-mean surface concentrations of CO2 at 284.3 ppm, CH4 at 808.2 ppb and N2O at 273.0 ppb. The data are available at https://esgf-node.llnl.gov/search/input4mips/ and www.climatecollege.unimelb.edu.au/cmip6. While the minimum CMIP6 recommendation is to use the global- and annual-mean time series, modelling groups can also choose our monthly and latitudinally resolved concentrations, which imply a stronger radiative forcing in the Northern Hemisphere winter (due to the latitudinal gradient and seasonality).
Poly- and perfluoroalkyl substances (PFASs) are a group of anthropogenic chemicals with an aliphatic fluorinated carbon chain. Due to their durability, bioaccumulation potential, and negative impacts on living organisms, these compounds have drawn lots of attention across the world. The negative impacts of PFASs on aquatic ecosystems are becoming a major concern due to their widespread use in increasing concentrations and constant leakage into the aquatic environment. Furthermore, by acting as agonists or antagonists, PFASs may alter the bioaccumulation and toxicity of certain substances. In many species, particularly aquatic organisms, PFASs can stay in the body and induce a variety of negative consequences, such as reproductive toxicity, oxidative stress, metabolic disruption, immunological toxicity, developmental toxicity, cellular damage and necrosis. PFAS bioaccumulation plays a significant role and has an impact on the composition of the intestinal microbiota, which is influenced by the kind of diet and is directly related to the host’s well-being. PFASs also act as endocrine disruptor chemicals (EDCs) which can change the endocrine system and result in dysbiosis of gut microbes and other health repercussions. In silico investigation and analysis also shows that PFASs are incorporated into the maturing oocytes during vitellogenesis and are bound to vitellogenin and other yolk proteins. The present review reveals that aquatic species, especially fishes, are negatively affected by exposure to emerging PFASs. Additionally, the effects of PFAS pollution on aquatic ecosystems were investigated by evaluating a number of characteristics, including extracellular polymeric substances (EPSs) and chlorophyll content as well as the diversity of the microorganisms in the biofilms. Therefore, this review will provide crucial information on the possible adverse effects of PFASs on fish growth, reproduction, gut microbial dysbiosis, and its potential endocrine disruption. This information aims to help the researchers and academicians work and come up with possible remedial measures to protect aquatic ecosystems as future works need to be focus on techno-economic assessment, life cycle assessment, and multi criteria decision analysis systems that screen PFAS-containing samples. New innovative methods requires further development to reach detection at the permissible regulatory limits.
The c-C4F8 gas is considered to have great potential as a gaseous medium for gas-insulated equipment, due to its good insulation properties and its relatively low greenhouse gas potential (GWP) relative to SF6. However, the decomposition is an important indicator of its use in equipment. In this paper, the decomposition characteristics of c-C4F8 and the influence by oxygen have been explored through experiments and theoretical calculations. Firstly, the breakdown test of mixed gas was carried out and the precipitated elements of the electrodes and breakdown products of gas mixture were analyzed by X-ray photoelectron spectroscopy (XPS) and gas chromatography mass spectrometry (GC-MS). At the same time, the differences in decomposition products have also been studied when a small amount of O2 was present. The path and mechanism of c-C4F8 decomposition is then discussed, based on density functional theory (DFT). The results show that the black powdery substance descends on the electrode surface after the breakdown of the mixture of c-C4F8/N2 gas containing O2, and its main constituent elements are C, O and F. O2 can promote the decomposition of c-C4F8. The mixture with O2 produced a large number of additional toxic and corrosive COF2 in addition to generating more CF4, C2F4, C2F6, C3F6 and C3F8. The GWP values of the products are lower than SF6. Comprehensive insulation properties and decomposition characteristics, c-C4F8 should not be mixed with dry air for use, and the oxygen content should be strictly controlled in c-C4F8 mixed gas.
We present the organization, instrumentation, datasets, data interpretation, modeling, and accomplishments of the multinational global atmospheric measurement program AGAGE (Advanced Global Atmospheric Gases Experiment). AGAGE is distinguished by its capability to measure globally, at high frequency, and at multiple sites all the important species in the Montreal Protocol and all the important non-carbon-dioxide (non-CO2) gases assessed by the Intergovernmental Panel on Climate Change (CO2 is also measured at several sites). The scientific objectives of AGAGE are important in furthering our understanding of global chemical and climatic phenomena. They are the following: (1) to accurately measure the temporal and spatial distributions of anthropogenic gases that contribute the majority of reactive halogen to the stratosphere and/or are strong infrared absorbers (chlorocarbons, chlorofluorocarbons – CFCs, bromocarbons, hydrochlorofluorocarbons – HCFCs, hydrofluorocarbons – HFCs and polyfluorinated compounds (perfluorocarbons – PFCs), nitrogen trifluoride – NF3, sulfuryl fluoride – SO2F2, and sulfur hexafluoride – SF6) and use these measurements to determine the global rates of their emission and/or destruction (i.e., lifetimes); (2) to accurately measure the global distributions and temporal behaviors and determine the sources and sinks of non-CO2 biogenic–anthropogenic gases important to climate change and/or ozone depletion (methane – CH4, nitrous oxide – N2O, carbon monoxide – CO, molecular hydrogen – H2, methyl chloride – CH3Cl, and methyl bromide – CH3Br); (3) to identify new long-lived greenhouse and ozone-depleting gases (e.g., SO2F2, NF3, heavy PFCs (C4F10, C5F12, C6F14, C7F16, and C8F18) and hydrofluoroolefins (HFOs; e.g., CH2 = CFCF3) have been identified in AGAGE), initiate the real-time monitoring of these new gases, and reconstruct their past histories from AGAGE, air archive, and firn air measurements; (4) to determine the average concentrations and trends of tropospheric hydroxyl radicals (OH) from the rates of destruction of atmospheric trichloroethane (CH3CCl3), HFCs, and HCFCs and estimates of their emissions; (5) to determine from atmospheric observations and estimates of their destruction rates the magnitudes and distributions by region of surface sources and sinks of all measured gases; (6) to provide accurate data on the global accumulation of many of these trace gases that are used to test the synoptic-, regional-, and global-scale circulations predicted by three-dimensional models; and (7) to provide global and regional measurements of methane, carbon monoxide, and molecular hydrogen and estimates of hydroxyl levels to test primary atmospheric oxidation pathways at midlatitudes and the tropics. Network Information and Data Repository: http://agage.mit.edu/data or http://cdiac.ess-dive.lbl.gov/ndps/alegage.html (https://doi.org/10.3334/CDIAC/atg.db1001).
