Episodic Particulate Sulfate and Sulfur Dioxide on the Southwestern Japan Coast in March and April 2010

Abstract

Particulate sulfate in PM 2.5 , sulfur dioxide (SO 2 ) and size-segregated aerosol particle number concentrations were measured at a site (32� 19′N, 129� 59′E) on the southwestern Japan coast from 5 March to 10 April, 2010. Results show frequent episodic increases of sulfate and SO 2 . Compared to the average concentration of sulfate 4.4±2.7 μg m -3 in the whole observation period, episodic sulfate reached 10.5-20.1 μg m -3 . The variation of sulfate always synchronized with aerosol particles in the size range of 0.1-0.5 μm, indicating the episodic sulfate was a consequence of the increase of the sub-micron particles. SO 2 did not have remarkable increase in any episodes of sulfate increase. During the passage of low pressure systems which loaded Asian dust in postfrontal air, concentrated sulfate appeared right behind the front but before dust arrival, suggesting the dominance of dustfree particulate sulfate. Weather and backward trajectory analyses revealed that air parcels with high sulfate passed eastern and northeastern China or Korean peninsula before arriving at the site. In contrast, those with high SO 2 passed an active volcano, Mt. Sakurajima, about 100 km in the south, suggesting the SO 2 was more likely from the volcanic emission. The ratio of sulfate to total sulfur compounds (SO 4 2-)/(SO 4 2-+ +SO 2 ) was 0.31-0.89 in continentally originated air while was 0.25-0.43 in the air having passed the volcano, showing more efficient conversions of SO 2 to sulfate in the air from the continent. The close dependence of the conversion on humidity in the continentally originated air was confirmed.

Factors Controlling the Variation of Aerosol Surface Area Concentrations Measured by a Diffusion Charger in Fukuoka, Japan

“…Many active volcanoes exist around the Kyushu region, especially in southern Kyushu. Volcanic activity can introduce SO2 into the air, and volcanic SO2 can be converted into sulfate [46]. It would, thus, be possible that excess sulfate converted from volcanic SO2 had a significant effect on the increase in sulfate in Fukuoka on these two days.…”

Semi-Continuous Measurements of Sulfate in Fine Particles in Central Japan: On High Concentration Events and Comparison with Measurement Concentrations by a Commercial Sulfate Monitor

“…The results of the comparative measurements in this study are consistent with the laboratory experimental results in which the conversion efficiency of ammonium sulfate ((NH4)2SO4) to SO2 in the SPA converter was approximately 80 % (Schwab et al 2006); they also support the comparison of the SPA measurement with the two-week average concentration obtained by an Andersen sampler (Watanabe et al 2013). In addition to the authors' reports (Watanabe et al 2013(Watanabe et al , 2015Watanabe and Yamazaki 2020), there have been other sulfate measurements using the SPA method in Japan, such as those by Nagatani et al (2012). The values achieved by dividing the SPA measurement data by 0.8 are considered to be close to the correct sulfate concentrations.…”

“…In early August 2020, extremely high concentrations of PM2.5 due to the eruption of Nishinoshima were observed, especially in western Japan, which SOLA, 2024, Vol.20, 34-38(TBA), doi: 10.2151/sola.2024 3 caused a major social problem (Fukuoka University 2020; Watanabe et al 2021). High concentrations of sulfate aerosols and sulfur dioxide (SO2) due to the smoke of Sakurajima volcano have also been reported sometimes (Nagatani et al 2012;Nakagomi et al 2015;Watanabe et al 2015Watanabe et al , 2016Yoshino et al 2016).…”

“…One of the instruments for automatically measuring sulfate particles is a commercial sulfate monitor (Sulfate Particle Analyzer, SPA). Because the SPA is a simple device and relatively easy to operate, it has been used for monitoring at remote locations (Watanabe et al 2010(Watanabe et al , 2013(Watanabe et al , 2015Nagatani et al 2012;Watanabe and Yamazaki 2020). To evaluate the accuracy of the SPA measurements, it is necessary to compare them with measurements by the filter method, a method that is quite reliable.…”