Atmospheric Chemistry of Perfluoroaldehydes (CxF2x+1CHO) and Fluorotelomer Aldehydes (CxF2x+1CH2CHO):  Quantification of the Important Role of Photolysis

Chiappero, Malisa S.; Malanca, Fabio Ernesto; Argüello, Gustavo A.; Wooldridge, Steven; Hurley, M. D.; Ball, James C.; Wallington, Timothy J.; Waterland, Robert L.; Buck, Robert C.

doi:10.1021/jp064262k

Cited by 52 publications

(52 citation statements)

References 41 publications

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“…Rate coefficients for the reactions in the PFCA formation mechanism are uncertain, affecting estimated yields. The atmospheric formation of PFCAs depends on reactions of fluorinated intermediates (Waterland and Dobbs, 2007;Chiappero et al, 2006) with commonly studied photochemical species, such as HO x and NO x species, as well as ultraviolet light. These species vary greatly over different environments in the atmosphere, affecting the quantity of lcPFCA produced.…”

Section: Introductionmentioning

confidence: 99%

Uncertainty and variability in atmospheric formation of PFCAs from fluorotelomer precursors

Thackray

Selin

2017

Atmos. Chem. Phys.

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Abstract. Perfluoroalkyl carboxylic acids (PFCAs) are environmental contaminants that are highly persistent, bioaccumulative, and have been detected along with their atmospheric precursors far from emissions sources. The importance of precursor emissions as an indirect source of PFCAs to the environment is uncertain. Modeling studies have used degradation mechanisms of differing complexities to estimate the atmospheric production of PFCAs, and these differing mechanisms lead to quantitatively different yields of PFCAs under differing atmospheric conditions. We evaluate PFCA formation with the most complete degradation mechanism to date, to our knowledge, using a box model analysis to simulate the atmospheric chemical fate of fluorotelomer precursors to long-chain PFCAs. In particular, we examine the variability in PFCA formation in different chemical environments, and estimate the uncertainty in PFCA formation due to reaction rate constants.We calculate long-chain PFCA formation theoretical maximum yields for the degradation of fluorotelomer precursor species at a representative sample of atmospheric conditions from a three-dimensional chemical transport model, and estimate uncertainties in such calculations for urban, ocean, and Arctic conditions using polynomial chaos methods. We find that atmospheric conditions farther from pollution sources have both higher capacities to form long-chain PFCAs and higher uncertainties in those capacities.Our calculations of theoretical maximum yields indicate that under typical Northern Hemisphere conditions, less than 10 % of emitted precursor may reach long-chain PFCA end products. This results in a possible upper bound of 2-50 t year −1 of long-chain PFCA (depending on quantity of emitted precursor) produced in the atmosphere via degradation of fluorotelomer products. However, transport to highyield areas could result in higher yields. While the atmosphere is a potentially growing source of long-chain PFCAs in the Arctic, oceanic transport and interactions between the atmosphere and ocean may be relatively more important pathways to the Arctic for long-chain PFCAs.

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Section: Introductionmentioning

confidence: 99%

Uncertainty and variability in atmospheric formation of PFCAs from fluorotelomer precursors

Thackray

Selin

2017

Atmos. Chem. Phys.

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“…The atmospheric lifetime of CF 3 CH 2 CHO with respect to UV photolysis has been estimated to be longer than 15 days (Sellevåg et al, 2004b;Chiappero et al, 2006). If the photolysis quantum yield ( λ ) of the fluorinated aldehyde depends on total pressure, the photolysis of CF 3 CH 2 CHO could be more important than reported at higher altitudes in the troposphere.…”

Section: Tropospheric Lifetimes Of Cfmentioning

confidence: 99%

“…Similarly to Cl atoms , major products of the OH-reactions with CF 3 CH 2 CHO and CF 3 (CH 2 ) 2 CHO are likely to be the corresponding fluorinated acids, CF 3 (CH 2 ) x C(O)OH, and CF 3 CHO and CF 3 CH 2 CHO, respectively, in clean atmospheres. Like CF 3 CHO, UV photolysis products of CF 3 (CH 2 ) x CHO at 308 nm (near the absorption maximum) are likely to be those from the radical channel, yielding formyl radical (HCO) and a fluoroalkyl radical, CF 3 (CH 2 ) x (Chiappero et al, 2006). Further reactions of all the species formed in such degradation processes may have a slight contribution to smog formation.…”

Section: Tropospheric Lifetimes Of Cfmentioning

confidence: 99%

Tropospheric photooxidation of CF3CH2CHO and CF3(CH2)2CHO initiated by Cl atoms and OH radicals

et al. 2010

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Abstract. The absolute rate coefficients for the tropospheric reactions of chlorine (Cl) atoms and hydroxyl (OH) radicals with CF 3 CH 2 CHO and CF 3 (CH 2 ) 2 CHO were measured as a function of temperature (263-371 K) and pressure (50-215 Torr of He) by pulsed UV laser photolysis techniques. Vacuum UV resonance fluorescence was employed to detect and monitor the time evolution of Cl atoms. Laser induced fluorescence was used in this work for the detection of OH radicals as a function of reaction time. No pressure dependence of the bimolecular rate coefficients, k Cl and k OH , was found at all temperatures. At room temperature k Cl and k OH were (in 10 −11 cm 3 molecule −1 s −1 ): k Cl (CF 3 CH 2 CHO) = (1.55±0.53); k Cl (CF 3 (CH 2 ) 2 CHO) = (3.39±1.38); k OH (CF 3 CH 2 CHO) = (0.259±0.050); k OH (CF 3 (CH 2 ) 2 CHO) = (1.28±0.24).A slightly positive temperature dependence of k Cl was observed for CF 3 CH 2 CHO and CF 3 (CH 2 ) 2 CHO, and k OH (CF 3 CH 2 CHO). In contrast, k OH (CF 3 (CH 2 ) 2 CHO) did not exhibit a temperature dependence over the range investigated. Arrhenius expressions for these reactions were: The atmospheric impact of the homogeneous removal by OH radicals and Cl atoms of these fluorinated aldehydes is discussed in terms of the global atmospheric lifetimes, taking into account different degradation pathways. The calculated lifetimes show that atmospheric oxidation of CF 3 (CH 2 ) x CHO are globally dominated by OH radicals, however reactions initiated by Cl atoms can act as a source of free radicals at dawn in the troposphere.

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“…The OH initiated oxidation of trans-CF 3 CH=CHF gives CF 3 CHO and HC(O)F in yields of approximately 100%. CF 3 CHO is removed from the atmosphere via photolysis and, to a lesser extents, reaction with OH radicals (Chiappero et al, 2006) and addition of water to give the hydrate . Photolysis gives CF 3 and HCO radicals (Chiappero et al, 2006) while reaction with OH gives CF 3 CO radicals.…”

Section: Atmospheric Chemistry and Environmental Impact Of Trans-cf 3mentioning

confidence: 99%

“…CF 3 CHO is removed from the atmosphere via photolysis and, to a lesser extents, reaction with OH radicals (Chiappero et al, 2006) and addition of water to give the hydrate . Photolysis gives CF 3 and HCO radicals (Chiappero et al, 2006) while reaction with OH gives CF 3 CO radicals. CF 3 radicals will add O 2 to give CF 3 O 2 radicals which are then converted into COF 2 (Wallington et al, 1994) which hydrolyzes to give CO 2 and HF.…”

Section: Atmospheric Chemistry and Environmental Impact Of Trans-cf 3mentioning

confidence: 99%

Atmospheric chemistry of trans-CF3CH=CHF: products and mechanisms of hydroxyl radical and chlorine atom initiated oxidation

et al. 2008

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Abstract. Smog chamber/FTIR techniques were used to study the products and mechanisms of OH radical and Cl atom initiated oxidation of trans-CF3CH=CHF in 700 Torr of N2/O2 diluent at 295±1 K. Hydroxyl radical initiated oxidation leads to the formation of CF3CHO and HC(O)F in yields which were indistinguishable from 100% and were not dependent on the O2 partial pressure. Chlorine atom initiated oxidation gives HC(O)F, CF3CHO, CF3C(O)Cl, and CF3C(O)CHFCl. The yields of CF3C(O)Cl and CF3C(O)CHFCl increased at the expense of HC(O)F and CF3CHO as the O2 partial pressure was increased over the range 5–700 Torr. The results are discussed with respect to the atmospheric chemistry and environmental impact of trans-CF3CH=CHF.

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Atmospheric Chemistry of Perfluoroaldehydes (C_xF₂_x₊₁CHO) and Fluorotelomer Aldehydes (C_xF₂_x₊₁CH₂CHO): Quantification of the Important Role of Photolysis

Cited by 52 publications

References 41 publications

Uncertainty and variability in atmospheric formation of PFCAs from fluorotelomer precursors

Uncertainty and variability in atmospheric formation of PFCAs from fluorotelomer precursors

Tropospheric photooxidation of CF<sub>3</sub>CH<sub>2</sub>CHO and CF<sub>3</sub>(CH<sub>2</sub>)<sub>2</sub>CHO initiated by Cl atoms and OH radicals

Atmospheric chemistry of trans-CF<sub>3</sub>CH=CHF: products and mechanisms of hydroxyl radical and chlorine atom initiated oxidation

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Atmospheric Chemistry of Perfluoroaldehydes (CxF2x+1CHO) and Fluorotelomer Aldehydes (CxF2x+1CH2CHO): Quantification of the Important Role of Photolysis

Cited by 52 publications

References 41 publications

Uncertainty and variability in atmospheric formation of PFCAs from fluorotelomer precursors

Uncertainty and variability in atmospheric formation of PFCAs from fluorotelomer precursors

Tropospheric photooxidation of CF&lt;sub&gt;3&lt;/sub&gt;CH&lt;sub&gt;2&lt;/sub&gt;CHO and CF&lt;sub&gt;3&lt;/sub&gt;(CH&lt;sub&gt;2&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt;CHO initiated by Cl atoms and OH radicals

Atmospheric chemistry of trans-CF&lt;sub&gt;3&lt;/sub&gt;CH=CHF: products and mechanisms of hydroxyl radical and chlorine atom initiated oxidation

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Atmospheric Chemistry of Perfluoroaldehydes (C_xF₂_x₊₁CHO) and Fluorotelomer Aldehydes (C_xF₂_x₊₁CH₂CHO): Quantification of the Important Role of Photolysis

Tropospheric photooxidation of CF<sub>3</sub>CH<sub>2</sub>CHO and CF<sub>3</sub>(CH<sub>2</sub>)<sub>2</sub>CHO initiated by Cl atoms and OH radicals

Atmospheric chemistry of trans-CF<sub>3</sub>CH=CHF: products and mechanisms of hydroxyl radical and chlorine atom initiated oxidation