This paper presented a method to estimate the spatial distributions of fog water deposition and corresponding sulfur and nitrogen depositions. A two-dimensional fog deposition model (FDM) to predict the turbulent fog water flux was developed. The FDM-predicted turbulent fog water flux depended on the wind speed and forest parameters. Comparisons of FDM with measurement data showed that the model well reproduced the turbulent deposition of fog water during typical fog events in mountainous regions. In order to estimate fog deposition in the Kinki Region of Japan, FDM was utilized with the results derived from the 5th generation Mesoscale Model (MM5) and the Community Multiscale Air Quality model (CMAQ) in March 2005. In the mountainous areas, the ratios of fog water deposition to rainfall reached up to 22.5% (mean = 3.4 %). The amounts of S and NO_Y depositions through fog were equivalent to those through rainfall and more than those through dry deposition in some areas. A longer term prediction (1year ~) is required for further study because the contribution of fog may considerably vary with seasonal variations in the meteorology, air quality and vegetation structure.

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Parallel observations of the PM₁, submicron particles and PM_2.5 were carried out for four years from April 2005 in order to characterize the PM₁ in a suburb of metropolitan Tokyo. The PM₁ sampler was made using a Sharp cut cyclone (SCC). The PM₁ annual mean concentrations were in the range of 15.5-18.3 μg m^-3 and those of PM_2.5 were 19.4-22.5 μg m^-3. The PM₁ weekly mean concentrations had a high correlation with those of PM_2.5 (r = 0.92, n = 186) , and the ratios of PM₁ to PM_2.5 (PM₁/PM_2.5) were 0.84±0.11. The major chemical components of PM₁ were also compared to those of PM_2.5. The PM₁/PM_2.5 of NH₄⁺, SO₄^2-, and TC were almost constant and higher, 0.74-0.88 for the entire year. On the other hand, the ratios of Na⁺, Mg²⁺ and Ca²⁺ were variable. The lowest ratios of Mg²⁺ and Ca²⁺ were observed in the winter. Some of the surface soil particles floated by strong winds from the dry paddy and field after the harvest should be contained in the PM_2.5. While the correlation coefficients of NH₄⁺, Cl^-, NO₃^-, SO₄^2- and TC between PM₁ and PM_2.5 were greater than 0.90, those of Mg²⁺ and Ca²⁺ were particularly low, i. e., 0.17 and 0.10. The slope of the linear regression formula of Ca²⁺ was extremely low, i. e., 0.02. This means that PM₁ was not affected by the coarse particles contained in the PM_2.5. As a result, PM₁ was more suitable than PM_2.5 as an indicator to the evaluate fine particles from anthropogenic sources.

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Ozone and carbon monoxide were simultaneously observed since December 2008 at Suzu, the Noto Peninsula. We investigated the seasonal and diurnal variations of their concentrations in view of the long-range transport of air pollutants from the Asian continent. The O₃ and CO concentrations had spring-peaks and a summer-minimum in their seasonal variations. The air mass arriving at Suzu was classified into sectors of Russia, China, and Japan using the backward trajectory analysis. In the spring, the fractions of continental origin, that is, the Russia and China air mass origins were high, while those of the Japan air mass origin were high in the summer. The air mass that originated from China had high concentrations for both O₃ and CO during the observational period. On the other hand, the concentrations from the Russian air mass origin were lower than those from the Japanese air mass origin, even though Russia and China are on the same continent. The averaged diurnal variation of O₃ showed a maximum peak in the afternoon, while that of CO did not show any systematic variation. The air mass origins and the photochemical O₃ production during the long-range transport would cause the seasonal variation in the diurnal minimum concentrations of O₃. The monthly change of the O₃ increment in the daytime would indicate the photochemical O₃ production in the vicinity of the observational site. There was a high positive correlation between the O₃ increment in the daytime and integrated solar radiation.

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We evaluated a screening method for outliers in the routine monitoring data of photochemical oxidant (O_X) using potential ozone (PO). First of all, we demonstrated that the inter-site correlations of PO were high over a wide area around the investigated area, and that the correlations were higher with the shorter inter-site distances. In addition, the correlations in PO were higher than in O_X especially in the area with dense NO_X sources, implying similar PO data between the two neighboring sites independent of the strength of the NO_X emissions around the sites. A case study showed a good consistency in the hourly PO data between site A and site B spacing of about 3 km, however, some of the data shifted from the one-to-one correlation. There was a concern with the monitoring data of O_X or NO_X at site A or site B. Further comparison with another neighboring site (site C) determined that the O_X data at site A seemed to have a problem. In the same manner, we could detect possible outliers in the other data set in a different area. Accordingly, the comparison of the PO data between two or more sites could provide an efficient screening method for the outliers in NO_X as well as O_X.

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The perfluorooctane sulfanate (PFOS) concentrations and its weekly variations in an urban atmosphere were determined. Airborne particles (TSP) were collected on filters every day in July 3-29 (summer) and December 1-27 (winter), 2006 in Wako-shi Saitama prefecture, located northwest of Tokyo. They were extracted by methanol, and analyzed by LC/MS/MS. The PFOS recovery of this method was 90%, and the reproducibility was 13% (c.v.). The geometric mean concentrations of TSP in July (48 μg/m³) and in December (43 μg/m³) were almost the same. In contrast, the PFOS concentrations in July (6.8 pg/m³) were higher than in December (3.5 pg/m³). The PFOS concentrations in the atmosphere were lower on Saturdays and Sundays than the other weekdays in both summer and winter.

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To clarify the mechanism of ozone affecting rice yield, we investigated the grain yield and yield component response to the acceleration of flag leaf senescence by ozone exposure. Six rice cultivars showing different sensitivities to ozone were grown in glass houses under ambient air (daytime 12-h mean ozone concentration, 31 ppb) or ozone-added (77 ppb) conditions throughout the cropping season until harvest. The senescence of the flag leaves was remarkably accelerated in Kirara 397 and Kasalath, but only slightly in Koshihikari at the elevated ozone level. The grain weight per panicle in Kirara 397, Koshihikari, and Jothi was reduced with the elevated ozone exposure mainly due to the decreased grain number per panicle. The decreases in the 1000 grain weight and filled grain percentage by the elevated ozone were observed in Kirara 397 and Kasalath, respectively. However, these reductions only slightly affected the grain weight. These results suggested that poor ripening of the grains caused by the accelerated senescence had a slight effect on the yield reduction of the rice. In the present experiment, the reduction of the grain weight per panicle was offset by the increased number of panicles due to the elevated ozone treatment. It was considered that different ozone doses at each growth stage might affect the grain yield of rice.

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We continuously monitored the PM_2.5 mass concentrations at Fukue Island located in the western part of Kyushu, Japan, and analyzed one year of data since 9 September 2009, when an environmental standard was newly introduced. The observed annual average, 17.3 μg m^-3, was not readily concluded to exceed the long-term standard value (15 μg m^-3) when the uncertainty of the zero level was taken into account. On the other hand, the 98 percentile of the daily average values during the year was 56.5 μg m^-3, clearly exceeding the short-term standard value (35 μg m^-3). The backward trajectory analysis suggested that the influence from the Asian continent was strong for the high PM_2.5 days. The high PM_2.5 days were found irrespective of the detection of dust at the Nagasaki meteorological station. The influence of air pollution is implied from the association of high black carbon concentrations with the elevated PM_2.5 events.

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