Atmospheric stability of arsine and methylarsines

Adrien Mestrot, John K. Merle, Alessandro Broglia, Joerg Feldmann, Eva M. Krupp

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

Arsenic (As) occurs in a variety of different chemical forms, among them volatile (gaseous) species, usually referred to as arsine and methylarsines. Here we demonstrate that arsine and methylarsines are stable in air in concentrations at the mu g/L gas level. We determined half-lives of approximately 8 h under daytime conditions (UV light) for all methylated arsines, while the same species were found to be considerably more stable in night-time (dark) conditions. Arsine (AsH3) showed under both day and night-time conditions, considerably higher stabilities than methylated arsines. We show here that volatile As species seem stable enough to travel considerable distances in the atmosphere from a point source before converting into nonvolatile, oxidized compounds. Also, the degradation pathway leading to the conversion to nonvolatile compounds was investigated using computational chemistry. Arsine and methylarsines reactions with the hydroxyl radical (center dot OH) as well as As-C and As-H bonds strengths in the species studied were modeled. Results showed that conversion could not be explained by H abstraction, nor by OH addition. Moreover, it was found that As-C and As-H bonds strengths are not the determining factor responsible for the decrease in stability with ascending methylation of the different volatile arsine species, as previously suggested.

Original languageEnglish
Pages (from-to)4010-4015
Number of pages6
JournalEnvironmental Science & Technology
Volume45
Issue number9
DOIs
Publication statusPublished - 1 May 2011

Keywords

  • ambient air
  • trimethylarsine
  • thermochemistry
  • oxidation
  • antimony
  • benzene

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