2017年9月东海海水和大气中挥发性有机硫化物的浓度分布及其来源

Concentration distributions of volatile organic sulfur compounds and their sources in the seawater and overlying atmosphere of the East China Sea in September 2017

挥发性有机硫化物(volatile organic sulfur compounds,简称VSCs)是硫循环的主要参与者,在全球气候变化和大气化学中发挥重要作用.于2017年9月运用冷阱捕集气相色谱和气-质联用法对东海海水与大气中3种重要的VSCs即羰基硫(COS)、二甲基硫(DMS)、二硫化碳(CS2)的浓度进行了测定,并计算了它们的海-气通量.研究结果表明,秋季东海表层海水中COS、DMS和CS2的浓度平均值分别为(0.14±0.08)、(3.58±2.81)和(0.06±0.06) nmol·L^-1.大气中COS、DMS和CS2的平均浓度分别为(414.9±107.4)×10^-12、(39.7±29.9)×10^-12和(92.9±55.6)×10^-12,COS是大气中含量最丰富的VSCs.相关性分析表明,海水中DMS与CS2存在相关性,推测两者具有相似的来源途径.大气中COS和CS2的浓度相关性较为显著,显示大气中CS2是COS的主要源.此外,海水中COS、DMS和CS2都呈过饱和状态,海-气通量平均值分别为(0.45±0.58)、(13.15±12.66)和(0.20±0.22)μmol·m^-2·d^-1,表明秋季东海是大气中3种VSCs的源.

Volatile organic sulfur compounds (VSCs) are main participants of the sulfur cycle and play significant roles in global climate change and atmospheric chemistry. The concentrations of three main VSCs including carbonyl sulfide (COS), dimethyl sulfide (DMS) and carbon disulfide (CS2) in the seawater and overlying atmosphere of the East China Sea were determined by Purge and Trap-Gas Chromatography during September 2017. Moreover, the sea-to-air fluxes of VSCs were also calculated in the study period. The average concentrations of COS, DMS and CS2 in the surface water of the East China Sea were (0.14±0.08)、(3.58±2.81) and(0.06±0.06) nmol·L^-1, respectively. The average concentrations of COS, DMS and CS2 in the atmosphere over the East China Sea were (414.9±107.4)×10^-12,(39.7±29.9)×10^-12,(92.9±55.6)×10^-12, respectively, and COS was the most abundant VSC in the atmosphere. The correlation analysis showed that there was a correlation between the DMS and CS2 concentrations in the seawater, which might be due to their similarity in source pathways. Besides, a significant correlation was found between the COS and CS2 concentrations in the atmosphere, revealing that CS2 is the main source of COS. In addition, all concentrations of COS, DMS, and CS2 in seawater were supersaturated, and their average sea-to-air fluxes were (0.45±0.58)、(13.15±12.66) and(0.20±0.22)μmol·m^-2·d^-1, respectively, indicating that the East China Sea acted as an essential source for atmospheric VSCs in the study period.