Stable isotope composition of sulfates in aerosol particles collected in the Southern California Air Basin

Abstract

Aerosol particles were collected at Lennox and Duarte in the Southern California Air Basin with Sierra and, or, Misco cascade impactors at night on 24 July and 25 July 1979, respectively. The concentrations of sulfate, nitrate, and chloride and the ${}^{34}\text{S}{}^{32}\text{S}$ ratios (as δ³⁴S) of sulfate in these aerosols were determined. A pronounced and repetitive minimum of δ ³⁴S value in the 0.95- to 1.5-μm fraction was observed at both collection sites. An inverse relationship between the δ ³⁴S values and sulfate concentration and a significant correlation between the δ ³⁴S values and chloride content were observed in these samples. The results indicate admixture of marine and industrial sulfate in the aerosol particles.