Transport and transformation of total reactive nitrogen over the East China Sea

Abstract

[1] Ground-based measurement of total reactive nitrogen (NO y ), NO y(g) (gas phase NO x + HNO 3 ), and particulate NO 3 À was carried out at the Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS) in Okinawa, Japan, from spring to winter in 2006. The concentrations of NO y , NO y(g) , and particulate NO 3 À were simultaneously high in spring but low in summer. This difference was mainly caused by air mass history, which was strongly associated with the typical weather pattern observed in the east Asian region for each season. The chemical transformation process of particulate NO 3 À during transport was examined using the data measured at Qingdao, China, in spring 2006. As the transport time of air masses increased, particulate NO 3 À continuously shifted from fine mode to coarse mode. It was found that the chemical transformation of particulate NO 3 À was mainly associated with the transport time of air masses, the geographical position of CHAAMS, and the transition from NH 4 NO 3 to gas phase HNO 3 . In air masses from Qingdao, China, the ratio of NO y concentration observed at CHAAMS to that at Qingdao was about 0.1, which was lower than that of SO y (SO 2 + nss-SO 4 2À ). Sulfate was found in fine particles at CHAAMS in contrast to particulate NO 3 À . As the lifetimes of NO y and SO y depend on the particle size, the difference in chemical transformation process during transport largely influences the abundance of transported NO y . The variations of NO y(g) and particulate NO 3 À were analyzed when dust plumes reached CHAAMS. The presence of dust causes the formation of particulate NO 3 À in coarse mode from NO y(g) and an increase of its fraction in NO y . The effect of volcanic activity on particulate NO 3 À concentration was also analyzed. It is suggested that particulate NO 3 À escaped to gas phase HNO 3 through the uptake of abundant volcanic H 2 SO 4 by aerosols.

Observation of atmospheric aerosols at Mt. Hua and Mt. Tai in central and east China during spring 2009 – Part 1: EC, OC and inorganic ions

“…Hua and 0.9 ± 0.5 at Mt. Tai, while SOC/EC ratio at the sites was 1.5±1.3 and 2.4±1.3, respectively, suggesting that carbonaceous aerosols in east coastal China is more oxidized, which is consistent with the enhanced concentration of glyoxal, a photo-oxidation product of volatile organic compounds (VOCs), over the NCP region as reported by satellite observation (Wittrock et al, 2006) and is ascribed to the high levels of oxidants such as O 3 and NO x and VOCs in the region (Akimoto, 2003;Fu et al, 2008;Hatakeyama et al, 2005;Streets and Waldhoff, 2000;Takiguchi et al, 2008). The ratio of SOC/POC at Mt.…”

“…The increased coarse fraction of nitrate at Mt. Hua can be explained by an increased adsorption of gaseous HNO 3 onto alkaline particles due to more dust in the region (Takiguchi et al, 2008). As seen in Table 2, NH + 4 (12 ± 8.9 µg m −3 ) at Mt.…”

A Gaseous Nitric Acid Analyzer for the Remote Atmosphere Based on the Scrubber Difference/NO-Ozone Chemiluminescence Method

“…Indeed, the concentrations of particulate nitrate were reported to be comparable to those of gaseous HNO3 at Cape Hedo. 1 Therefore, the air mass during the observation period would be well-aged air. Although discussion on the results of this observation will be described in a future article, it has been demonstrated by these observations that gaseous HNO3 can be observed in remote areas using this instrument.…”

“…The details of the observational site are described elsewhere. 1,[22][23][24] Briefly, the site is located near Cape Hedo, the northernmost point of the Okinawa Main Island. The population in Kunigami Village, where the observational site is located, is only ~6000.…”

“…1 Its main removal processes are deposition (both wet and dry) and uptake on aerosol surfaces. Therefore, HNO3 would be one of the species involved in transboundary pollution, such as "acid rain".…”