Sulfur isotope homogeneity of oceanic DMSP and DMS.
Proc Natl Acad Sci U S A
; 110(46): 18413-8, 2013 Nov 12.
Article
em En
| MEDLINE
| ID: mdl-24167289
ABSTRACT
Oceanic emissions of volatile dimethyl sulfide (DMS) represent the largest natural source of biogenic sulfur to the global atmosphere, where it mediates aerosol dynamics. To constrain the contribution of oceanic DMS to aerosols we established the sulfur isotope ratios ((34)S/(32)S ratio, δ(34)S) of DMS and its precursor, dimethylsulfoniopropionate (DMSP), in a range of marine environments. In view of the low oceanic concentrations of DMS/P, we applied a unique method for the analysis of δ(34)S at the picomole level in individual compounds. Surface water DMSP collected from six different ocean provinces revealed a remarkable consistency in δ(34)S values ranging between +18.9 and +20.3. Sulfur isotope composition of DMS analyzed in freshly collected seawater was similar to δ(34)S of DMSP, showing that the in situ fractionation between these species is small (<+1). Based on volatilization experiments, emission of DMS to the atmosphere results in a relatively small fractionation (-0.5 ± 0.2) compared with the seawater DMS pool. Because δ(34)S values of oceanic DMS closely reflect that of DMSP, we conclude that the homogenous δ(34)S of DMSP at the ocean surface represents the δ(34)S of DMS emitted to the atmosphere, within +1. The δ(34)S of oceanic DMS flux to the atmosphere is thus relatively constant and distinct from anthropogenic sources of atmospheric sulfate, thereby enabling estimation of the DMS contribution to aerosols.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Água do Mar
/
Sulfetos
/
Compostos de Sulfônio
/
Isótopos de Enxofre
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Israel