Gaseous and particulate portions of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and coplanar polychlorinated biphenyles (Co-PCBs) in the atmosphere were collected using hi-volume and low-volume samplers in order to investigate their gas-particle partitioning. The gas-particle ratios of PCDDs and PCDFs (PCDD/Fs) were found to increase with temperature and decrease as the number of substituted chlorine atoms increased. Specifically it was found that gas-particle ratios for the TeCDD/Fs and PeCDD/Fs homologues varied substantially between summer and winter. On the other hand, for almost OCDD/F, the gas-particle partitioning shifted towards the particulate phase throughout the year. Although the gas-particle partitioning ratio for Co-PCBs homologue showed a similar tendency, for a given number of chlorine atoms, the ratio was considerably higher in Co-PCBs than in that of PCDD/Fs. Furthermore, the position of chlorine substitution in a given homologue also influenced the gas-particle partitioning. Some isomers of PCDD/Fs and Co-PCBs in particular were observed to have a higher ratio of gas partitioning compared to isomers with much chlorine. The flow rate and sampling period might affect the gas-particle partitioning; slightly higher values were observed when using the low-volume sampler.

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To examine the effects on metal material by acid deposition, the measurement of the rainwater components and a leaching test of metal sample plates were conducted in Isogo (urban site: Yokohama City) and Doushi (mountainous site: Yamanashi Prefecture). On the basis of these measurement data, the influence of volcanic gases from Miyakejima on rainwater components and on metal corrosion was evaluated.
In Isogo, the annual mean pH value of rainwater collected from September 2000 to August 2001 (after volcanic gases were released) was lower than those collected from September 1999 to August 2000 (before volcanic gases were released). The annual deposition amounts increased 2.1 times for _nssSO₄^2- (non sea salt SO₄^2-) and increased 1.9 times for _nssCl^- (non sea salt Cl^-). Corresponding to these, the annual elusion amounts of Cu²⁺, Pb²⁺, Zn²⁺, Fe³⁺ from the metal plates (bronze, copper, carbon steel) increased 1.7 to 2.6 times. By the dissolution of these metal ions, the weight of the copper plate decreased markedly.
In Doushi, the pH value of rainwater was higher than Isogo, and the deposition amount of _nssSO₄^2-and the elusion amounts of Cu²⁺, Pb²⁺, Zn²⁺ from the bronze plate were lesser by about 1/2 to 1/3 those of Isogo. But, the tendency before and after volcanic gas evolution was the same as Isogo, indicating that the effect of volcanic gases also reached the mountainous area.

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In July 2000, a volcanic eruption took place on Miyake Island (Miyakejima), 150 kmsouth of metropolitan Tokyo, after last erupting 17 years ago. Volcanic gases released by this eruption were transported toward the main Japanese Island of Honshu. High SO₂ concentrations and acidic precipitations were detected at various locations in Japan. Atmospheric bulk depositions in Bunkyo were collected and SO₄^2- concentrations and δ³⁴S were measured, to study the influence of volcanic emission on the bulk deposition chemistry. The S0₄^2-_nss concentrations and deposition flux increased with activity of Miyakejima volcano. Air mass trajectory at 850hPa passed over the Kanto area from Miyakejima.δ³⁴S_nss values tended to increase since August 2000, reaching values close to the δ³⁴S value of volcanic ashes from Miyakejima (about 6‰). Also, 634Snss values of bulk deposition in Ohta and δ³⁴S_nss values of aerosol in Wako showed an increasing trend. These results demonstrate that the Miyakej ima eruption may have an important influence on bulk deposition chemistry in Bunkyo. We roughly calculated the contribution ratio of S0₄^2- in Miyakejima eruption using δ³⁴S values. As a result the highest contribution ratio was over 90% from October 1 to 3, 2000.

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In order to simulate the behavior of atmospheric chemical species in detail, a three-dimensional chemical transport model coupled with a mesoscale meteorological model was developed and applied to the atmospheric diffusion of volcanic gases from Miyake Island. PSU/NCAR MM5 was used to calculate meteorological field, and the processes for atmospheric chemical species, e.g., advection, eddy diffusion, chemical reaction, and deposition, were added to MM5.
In this paper, the relationship between the behavior of volcanic gases and meteorological Conditions and the effect of volcanic gases on concentration of SO₂ in the Kanto, Chubu, and Kansai Districts were investigated during the period of August and September 2000.
The comparison of simulated results with observations showed that the model reproduced a suitable meteorological field, increased surface concentration of SO₂ due to volcanic gases, and wet deposition of sulfate. The simulation indicated that cyclones, typhoons, fronts, and traveling anticyclones around Japan played an important role in advecting volcanic gases to Honshu, the main island of Japan. Volcanic gases covered most of the calculation domain and increased the monthly average concentration of SO₂.

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An analytical procedure to which the multiderivatives of the atmospheric absorption spectrum and of absorption cross section spectra are applied has been proposed in order to retrieve atmospheric constituent concentrations. In this study, the proposed method was evaluated by applying it to real atmospheric absorption spectra. Preceding the evaluation, an open light path spectrometer for acquiring atmospheric absorption spectra was developed. The instrument consisted of an artificial light source, a telescope for both emitting and receiving light, a reflector, and a spectrometer. Absorption spectra can be acquired in the spectral region from UV to visible. The instrument can achieve a high signal to noise ratio and high-speed sampling because it is equipped with a two-dimensional CCD detector. To evaluate the applicability of the proposed procedure, measurements of concentrations of NO₂, O₃, SO₂, and HCHO were carried out together with other instruments. The results of the comparisons showed good agreement for all species.

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The concentration profiles of NH₄⁺, NO₃^-, S0₄^2- particles with diameters under 2.5 pm above canopy were observed in a Japanese red pine forest located in Gunma prefecture, Japan, during the period from February through October, 2002. From the results of measurements, deposition velocities for those fine particles were estimated by using the concentration gradient method. In results, extreme large values of estimated deposition velocities for NH₄⁺ and NO₃^- were obtained in summer. Those extreme large values seemed to be influenced by the evaporation of NH₃ and HNO₃ from NH₄NO₃ particles near the canopy. In addition, negative concentration gradients were observed in several measurement periods for all fine particles. Those negative values for gradient could be explained by the formation of new particles near the canopy. However, except for those measurement periods, the mean values of obtained deposition velocities were NH₄⁺: 1.30 cms^-1, N0₃^-: 0.84, SO₄^2-: 0.84 cm s^-1, which are consistant with those reported for forests in the United States and Europe. On the other hand, the estimated deposition velocities were three times as large as those estimated by the empirical formula which was used in the model for evaluating deposition of acidic substances.

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