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• 作者：Shohei Hattori ; Akari Toyoda ; Sakae Toyoda ; Sakiko Ishino ; Yuichiro Ueno ; Naohiro Yoshida
• 刊名：Analytical Chemistry
• 出版年：2015
• 出版时间：January 6, 2015
• 年：2015
• 卷：87
• 期：1
• 页码：477-484
• 全文大小：454K
• ISSN：1520-6882

文摘

Little is known about the sulfur isotopic composition of carbonyl sulfide (OCS), the most abundant atmospheric sulfur species. We present a promising new analytical method for measuring the stable sulfur isotopic compositions (未³³S, 未³⁴S, and 螖³³S) of OCS using nanomole level samples. The direct isotopic analytical technique consists of two parts: a concentration line and online gas chromatography-isotope ratio mass spectrometry (GC-IRMS) using fragmentation ions ³²S⁺, ³³S⁺, and ³⁴S⁺. The current levels of measurement precision for OCS samples greater than 8 nmol are 0.42鈥? 0.62鈥? and 0.23鈥?for 未³³S, 未³⁴S, and 螖³³S, respectively. These 未 and 螖 values show a slight dependence on the amount of injected OCS for volumes smaller than 8 nmol. The isotope values obtained from the GC-IRMS method were calibrated against those measured by a conventional SF₆ method. We report the first measurement of the sulfur isotopic composition of OCS in air collected at Kawasaki, Kanagawa, Japan. The 未³⁴S value obtained for OCS (4.9 卤 0.3鈥? was lower than the previous estimate of 11鈥? When the 未³⁴S value for OCS from the atmospheric sample is postulated as the global signal, this finding, coupled with isotopic fractionation for OCS sink reactions in the stratosphere, explains the reported 未³⁴S for background stratospheric sulfate. This suggests that OCS is a potentially important source for background (nonepisodic or nonvolcanic) stratospheric sulfate aerosols.