Thirteen years of observations on biomass burning organic tracers over Chichijima Island in the western North Pacific: An outflow region of Asian aerosols

Abstract

East Asia is the world's greatest source region for the emission of anthropogenic aerosols and their precursors due to the rapid industrialization and intensive biomass burning (BB) activities. BB emits specific organic tracers such as levoglucosan, mannosan, and galactosan, which are produced by pyrolysis of cellulose and hemicellulose and then transported downwind to the western North Pacific by westerly winds. Here we present long-term observations of BB tracers over the remote Chichijima Island in the western North Pacific (WNP) from 2001 to 2013. Elevated concentrations of BB tracers by an order of magnitude were found in midautumn to midspring with winter maxima, which are strongly involved with the atmospheric transport by westerly winds from the Asian continent to the WNP, as supported by backward trajectory analyses. Throughout the observations, we found an increase in the averaged concentrations of BB tracers from 2006 to 2013, which is mainly caused by enhanced BB events in Asian urban and rural areas, as supported by enhanced fire/hot spots in East Asia via satellite images. We also found that the period of the high concentrations was prolonged from 2006 to 2013. Comparison between monthly averaged concentrations of BB tracers and backward air mass trajectories clearly demonstrates that the winter/spring maxima over Chichijima are involved with the seasonal shifting of atmospheric circulation followed by downwind transport of BB aerosols to the WNP. High abundances of BB tracers over the WNP indicate that BB-laden air masses can be transported to remote marine environments.

Long-term (2001–2012) trends of carbonaceous aerosols from a remote island in the western North Pacific: an outflow region of Asian pollutants

“…5g). This observation is consistent with the study of Verma et al (2015), who observed a significant enhancement of levoglucosan (a good biomass burning tracer, e.g., Simoneit, 2002) during 2006-2013 over the sampling site. Therefore, all these results demonstrate that the contributions of biomass burning emissions to carbonaceous aerosols have increased significantly over the western North Pacific whereas the contributions of fossil fuel combustion have decreased.…”

“…2). Verma et al (2015) reported significant concentrations of levoglucosan during summer in Chichijima (in the absence of East Asian outflows), which were attributed to the occasional transport of biomass burning influenced air masses from southeast Asia, as inferred from the air mass trajectories and fire spot data during 2001-2013. Therefore, carbonaceous aerosols over Chichijima strictly follow the seasonal wind patterns in the western North Pacific.…”

“…1. Therefore, the observation at Chichijima is useful for studying the long-range transport of East Asian pollutants and their heterogeneous chemistry over the western North Pacific (Boreddy et al, 2014;Verma et al, 2015). In this study, we discuss the long-term trends in the concentrations of carbonaceous aerosols (EC, OC, and water-soluble organic carbon (WSOC)) and their ratios during 2001-2012 in addition to seasonal variations.…”

“…To better understand the influence of heterogeneity in air masses to carbonaceous aerosols, we computed daily 7-day isentropic air mass back trajectories at an altitude of 500 m for each month using a Hybrid Single Particle LagrangianIntegrated Trajectory (HYSPLIT) model (Draxler and Rolph, 2013) (Verma et al, 2015). From winter (December-February) to spring (March-May), the air masses carry continental air pollutants and dusts from East Asia to the sampling site in the Pacific by a long-range atmospheric transport (Fig.…”

Tracing atmospheric transport of soil microorganisms and higher plant waxes in the East Asian outflow to the North Pacific Rim by using hydroxy fatty acids: Year‐round observations at Gosan, Jeju Island

“…Recent studies have documented the impact of mineral dust from East Asian Deserts on the Yellow Sea and South China through long‐range atmospheric transport during the spring [ Tan et al , ]. Likewise, several studies have documented the impact of biomass burning emissions in China and Siberia to the aerosol composition over the North Pacific [ Ding et al , ; Verma et al , ; Zhu et al , ] and the Japanese Islands [ Pavuluri et al , ] during winter and spring, as assessed by the analyses of 14 C and biogenic organic tracers in aerosols. Therefore, a large temporal variability of β ‐ and ω ‐hydroxy FAs over Gosan during spring can be explained by different contributions from Mongolian desert dust and higher plant waxes from Siberia.…”