Impacts of the eruption of Miyakejima Volcano on air quality over far east Asia

Abstract

[1] A regional-scale Eulerian Model System for Soluble Particles (MSSP) was constructed to simulate environmental changes caused by a SO 4 2À increase as the result of the eruption of Miyakejima Volcano in the northwest Pacific Ocean. The measured volcanic SO 2 emission was 9 Tg yr À1 for a year from the beginning of the eruption, July 2000. It is equivalent to 70% of global volcanic emission and 6.9% of global anthropogenic emission. Seasonal variations of the volcanic sulfate increase, and change of gas-aerosol partitioning of NH 3 and pH decrease of precipitation were studied using the MSSP model for 1 year from September 2000 to August 2001, together with observations performed at Happo Ridge observatory in the mountainous area in central Japan. In winter, northwesterly wind prevails, and volcanic SO 4 2À was mainly transported southeastward to the Pacific Ocean while volcanic SO 4 2À was transported southwestward to Japan, Korea, and Taiwan, owing to the subtropical high-pressure system over the Pacific Ocean in summer. Temporal variations of SO 4 2À concentrations and gas-aerosol equilibrium of NH 3 at Happo Ridge were well-simulated. In the plume from the Asian continent, 98.7% of total SO 4 2À was anthropogenic, and 63.5% of NH 3 existed in aerosol phase as (NH 4 ) 2 SO 4 . In the volcanic plume, 95.5% was volcanic, excessive sulfate fixed 100% of NH 3 into aerosol phase, and aerosol was strongly acidified. Modeled annual mean pH of precipitation in Japan decreased by 0.3-1.0, which is equivalent to neutralization by yellow sand.

Spatial distribution of the source-receptor relationship of sulfur in Northeast Asia

“…SO 2 from shipping and biogenic sulfur compounds such as dimethyl sulfide (DMS), dimethyl disulfide (DMDS), COS, H 2 S, CS 2 and CH 3 SH from ocean surfaces were not considered in the study. The contribution of emission fluxes of those species to concentrations and depositions of SO 2 and sulfate over the region could be much smaller compared to anthropogenic SO 2 from China and that from Miyakejima volcano (Streets et al, 2003;Kajino et al, 2004). However, those can be a reason for the discrepancy between the simulation and the observation because the observation sites we selected are located at isolated islands or capes, surrounded by ocean.…”

“…The model could reproduce monthly NO − 3 concentrations in rainwater , hourly SO 2 and monthly nss-SO 2− 4 concentrations in rainwater affected by the Miyakejima Volcano Kajino et al, 2004), PM 2.5 , PM 10 , and the aerosol size distribution during dust events (Han et al, 2004) (Han et al, 2006), O 3 relevant trace species such as NO x and VOCs measured for the TRACE-P project (Han, 2007), and all of those species along with a model inter-comparison study for MICS-Asia Phase II Han et al, 2008 and references therein). Table 2 summarizes statistical analyses for comparisons between daily and monthly observations and simulation data at the six EANET remote monitoring stations depicted in Fig.…”

Development of the RAQM2 aerosol chemical transport model and predictions of the Northeast Asian aerosol mass, size, chemistry, and mixing type

“…The Regional Air Quality Model (RAQM) was developed at the Acid Deposition and Oxidant Research Center (currently named the Asia Center for Air Pollution Research), which focuses on such Asian air quality problems Han, 2007). The model has been used for various air pollution studies in Asia, such as studies of high oxidant, massive dust transport and volcanic sulfur episodes, and substantial modifications have been made upon comparing and evaluating with extensive long-term monitoring data Han, 2007;Han et al, 2004Han et al, , 2005Han et al, , 2006Kajino et al, 2004Kajino et al, , 2005 and with other models (Carmichael et al, 2008 and references therein). However, an aerosol dynamics module was not implemented in RAQM, and thermodynamic equilibrium was assumed for the gasaerosol partitioning of semi-volatile inorganic components, such as sulfate, nitrate and ammonium.…”

Secondary Acidification

“…Oyama, 139°32′E, 34°05′N, summit elevation 815 m ASL; Figure 2), 180 km south of Tokyo, Japan, beginning in July 2000 has resulted in the emission of huge amounts of sulfur dioxide. The annual mass of sulfur dioxide emitted was vast (9 Tg yr -1 ; Kajino et al, 2004), equivalent to half the annual anthropogenic emission from China in 2000 (20 Tg yr -1 , Streets et al, 2003). Gases, aerosols, and precipitation have been sampled at the Happo Ridge observatory (137°48′E, 36°41′N, 1,850 m ASL, 330 km north of the volcano; Figure 2) in the central mountainous region of Japan since May 1998, two years before the eruption began .…”