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To clarify the long-term trend of nitrogen (N) deposition, the existing monitoring data was analyzed at the regional and national level from 1976 to 2018. We used the data of annual N depositions from the National Institute for Environmental Studies, the Ministry of the Environment, the Forestry and Forest Products Research Institute, and the Japan Meteorological Agency. Annual median of national N wet deposition was 6.0 kg N ha⁻¹ in 1988 (n＝24) and increased to 7.6 kg N ha⁻¹ in 2000 (n＝92), then it was 7.6 kg N ha⁻¹ in 2010 (n＝82). In 2018 N wet deposition decreased to 6.2 kg N ha⁻¹ (n＝76). The state space model demonstrated that N wet deposition significantly increased, after which tended to decrease at Eastern Japan from 2004, at the Japan Sea area, and in the nation from 2012. Nitrogen dry deposition averaged 6.0±0.1 kgN ha⁻¹ year⁻¹ (n＝109), total N deposition; the sum of wet and dry deposition, was 11.5±1.6 kgN ha⁻¹ year⁻¹, N dry deposition ratio ranged from 0.41 to 0.61 during 2003-2018 based on the results of seven stations. Cumulative N deposition was estimated to have exceeded 300 kgN ha⁻¹ over the past 30 years.

HO2 uptake kinetics onto ambient aerosols play pivotal roles in tropospheric chemistry but are not fully understood. Field measurements of aerosol chemical and physical properties should be linked to molecular level kinetics; however, given that the HO2 reactivity of ambient aerosols is low, traditional analytical techniques are unable to achieve this goal. We developed an online approach to precisely investigate (i) the HO2 reactivity of ambient gases and aerosols and (ii) HO2 uptake coefficients onto ambient aerosols (ɣ) during 2019 air quality study (AQUAS) in Yokohama, Japan. We identified the effects of individual chemical components of ambient aerosols on ɣ. The results verified in laboratory studies on individual chemical components: transition metals play a key role in HO2 uptake processes and chemical components indirectly influence such processes (i.e., through altering aerosol surface properties or providing active sites), with smaller particles tending to yield higher ɣ values than larger particles owing to the limitation of gas phase diffusion is smaller with micrometer particles and the distribution of depleting species such as transition metal ions is mostly distributed in accumulation mode of aerosol. The modeling of ɣ utilized transition metal chemistry derived by previous studies, further confirming our conclusion. However, owing to the high NO concentrations in Yokohama, peroxy radical loss onto submicron aerosols has a negligible impact on O3 production rate and sensitivity regime.

We measured the lead (Pb) and sulfur (S) isotopic ratios in precipitation collected in Toyama Prefecture, Japan, to investigate their characteristics as tracers for trans-boundary air pollution. The Pb concentrations and isotopic ratios were measured by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). A relatively higher 207Pb/206Pb isotopic ratio (area 3: Northern China, 0.869 ± 0.003; area 4: Central China and Korea, 0.870 ± 0.006) was assumed to be related to Northern Asian sources, whereas the samples influenced by Japanese air mass showed a lower 207Pb/206Pb ratio (area 5: Japan, 0.863 ± 0.004). Sulfur ion was measured by Ion Chromatography (IC), and S isotopic ratios were measured by Mass Spectrometry. The S isotopic ratios' weighted average values (area 3: 4.9 ± 1.4‰; area 4: 6.3 ± 1.5‰) of the Asian continent showed a higher isotopic ratio than that of Japan (area 5: 3.6 ± 1.8‰). It was difficult to use the NO3−/non-sea-salt SO42 − (nss SO42 −) (N/S) ratio's weighted average values to distinguish the Japanese origin (area 5: 0.71) from the continental origin (area 3: 0.68, area 4: 0.66). We attempted to use the S isotopic ratio in addition to the lead isotopic ratio to characterize the transported East Asian air pollution, and as a result we found that the combination of these isotopic ratios was useful for identifying the origin of air pollution in the East Asian region.

Texto completo: acesso restrito. p. 1293–1308 Submitted by Edileide Reis (leyde-landy@hotmail.com) on 2014-01-13T15:13:59Z No. of bitstreams: 1 Gregory R Carmichael.pdf: 1253796 bytes, checksum: 9345158c493a45da2a2756470c6418a1 (MD5) Made available in DSpace on 2014-01-13T15:13:59Z (GMT). No. of bitstreams: 1 Gregory R Carmichael.pdf: 1253796 bytes, checksum: 9345158c493a45da2a2756470c6418a1 (MD5) Previous issue date: 2003 Measurements of gaseous SO2, NH3, and O3 using IVL passive sampler technology were obtained during a pilot measurement program initiated as a key component of the newly established WMO/GAW Urban Research Meteorology and Environment (GURME) project. Monthly measurements were obtained at 50 stations in Asia, Africa, South America, and Europe. The median SO2 concentrations vary from a high of 13 ppb at Linan, China, to