US EPA

6311636 

Journal Article 

A global atmospheric chemistry model for the fate and transport of PFCAs and their precursors 

Thackray, CP; Selin, NE; Young, CJ 

2020 

Yes 

Environmental Science: Processes & Impacts
ISSN: 2050-7887
EISSN: 2050-7895 

Royal Society of Chemistry 

22 

2 

285-293 

English 

31942888 

10.1039/c9em00326f 

WOS:000519738100003 

https://search.proquest.com/docview/2363887420?accountid=171501
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is supplemented by 6589940 Supplemental data:

Perfluorocarboxylic acids (PFCAs) are environmental contaminants that are highly persistent, and many are bio-accumulative and have been detected along with their atmospheric precursors far from emission sources. The overall importance of precursor emissions as an indirect source of PFCAs to the environment is uncertain. Previous studies have estimated the atmospheric source of PFCAs using models and degradation pathways of differing complexities, leading to quantitatively different results. We present results from simulations of atmospheric PFCA formation and fate using the chemical transport model GEOS-Chem. We simulate the most up-to-date chemistry available to our knowledge for the degradation of the precursors fluorotelomer alcohol (FTOH), fluorotelomer olefin (FTO), and fluorotelomer iodide (FTI), as well as the deposition and transport of the precursors, intermediates and end-products of the formation chemistry. We calculate yields of C3-C13 PFCAs formed from 4 : 2 to 12 : 2 fluorotelomer precursors and their deposition to the surface. We find that the ratio of long-chain to short-chain PFCAs increases strongly with distance from source regions. We compare our model results to remote deposition measurements and mid-latitude rainwater measurements. The model captures the observed relationship between rainwater abundance and PFCA chain length, as well as the average deposition rates at mid-latitude and Arctic sites, but underestimates the deposition of PFDoA, PFDA, and TFA at mid-latitudes and PFNA at the Devon Ice Cap. We provide estimates of cumulative PFCA deposition globally. We find that given the most recent emission inventory, the atmospheric source of PFCAs is 6-185 tonnes per year globally and 0.1-2.1 tonnes per year to the Arctic. 

Environmental Studies; Latitude; Iodides; Atmospheric chemistry; Deposition; Emission; Chemistry; Contaminants; Polar environments; Degradation; Computer simulation; Organic chemistry; Intermediates; Rain water; Emission inventories; Atmospheric models; Chemical transport; Precursors; Biodegradation; Emissions; Arctic region