Carbon isotope ratios of methyl bromide and methyl chloride emitted from a coastal salt marsh

Citation:
Bill, M, Rhew RC, Weiss RF, Goldstein AH.  2002.  Carbon isotope ratios of methyl bromide and methyl chloride emitted from a coastal salt marsh. Geophysical Research Letters. 29

Date Published:

Feb

Keywords:

ch3br, fractionation, Ozone

Abstract:

[1] Methyl bromide (CH3Br) and methyl chloride (CH3Cl) play important roles in stratospheric ozone depletion, but their atmospheric budgets have large uncertainties. The analysis of stable isotope composition of methyl halides may provide useful independent information for further constraining their budgets. Here we report the first measurements of CH3Br and CH3Cl stable carbon isotope ratios emitted from a biogenic source under in situ conditions. CH3Br and CH3Cl emissions from the salt marsh plant Batis maritima showed a strong diurnal variation in delta(13)C, from -65parts per thousand during the daytime to --12parts per thousand at night. The minimum delta(13)C values were observed at midday, coinciding with the time of greatest emissions and ambient temperature. At night, when the emissions were much smaller, the stable carbon isotopic ratios of CH3Br and CH3Cl became enriched in C-13. The daily mean delta(13)C of CH3Br and CH3Cl emissions, weighted by emission rate, were -43parts per thousand and -62parts per thousand respectively.

Notes:

n/a

Website

DOI:

10.1029/2001gl012946

Scripps Publication ID:

1045