Surveying recent literature on the dry deposition of atmospheric aerosols, a few papers are picked up to examine contributions from several processes which are usually ignored or given little attention. They are interception, electrostatic interaction, rebound and re-suspension. Importance of improving the model for deposition to forests is emphasized, and a wind-tunnel experiment for verifying the multi-layer model is introduced. Further the effects of particle size variation and particle — gas interaction on the deposition are reviewed. Finally a problem in the application of the inferential method is pointed out, which has not so far been given much attention but may be a source of serious error.
Comprehensive research on the dry deposition of gaseous and particulate substances in the atmosphere was conducted in forests in the Kanto district, Japan. On the basis of the data collected during the last decade, we analyzed atmospheric deposition of acidifying components to the Japanese cedar forest ; dry deposition of sulfur to the coniferous forest ; deposition velocity of particulates to a forest using the concentration gradient method; and dry deposition of sulfur using meteorological data and land-use type data. In this paper, we describe the design of CRIEPI's dry deposition monitoring systems, meteorological and geological factors affecting the dry deposition of gaseous and particulate, and the present status of dry depostion monitoring in Japan.
We first make a brief review of the concentration gradient method, a technique which has so far been frequenty used for the dry deposition measurement, and explain why it is difficult to apply this method to aerosol deposition measurement. Then we show that the difficulty can be overcome by a new technique, relaxed eddy accumulation (REA) method, and we propose a concrete device implementing REA method for aerosol dry deposition measurement. A few results from the observation of aerosol deposition on a snow surface by means of this device are presented.
We expressed the vertical flux of a scalar quantity in terms of the conditional expectation of the scalar concentration for given vertical wind velocity, and also gave a general expression of Businger coefficient b in REA method on the basis of a polynomial expression for the conditional expectation. Then we estimated the values of the b coefficient for several cases of the conditional expectation and the vertical wind distributions.
The polytetrafluoroethylene (PTFE) filter has been recommended for the measurement of mass concentration of ambient fine particles smaller than 2.5 μm (PM2.5) . Since the PTFE filter tends to be negatively charged, the electrical charge would introduce serious error in the evaluation of PM2.5 concentration with electric microbalances. The present work investigated the influence of filter charge on the determination of filter mass as well as a method which minimizes the error due to the electrical charge, using the PTFE filter of 140 mg weight with a support ring. It was found that that attractive electrostatic force exerting between filter and microbalance greatly influences the measured mass of filter and that the use of neutralizer can reduce the error, effectively. The use of filter measurement kit, which shields the electrical field from the filter, was also effective for reducing the error in the mass measurement of filter.
Chronic obstructive pulmonary disease (COPD) is currently one of the major causes of death in the world. Further increases in the prevalence and mortality rates for the disease are predicted in the coming decades in Japan. The major causes of this increase are past smoking behavior and the aging of the population. COPD is a disease state characterized by airflow limitation. Airflow limitation is associated with an abnormal inflammatory response of the lungs to noxious particles or gases. Smoking is the single greatest independent risk factor for the development of COPD. In this article, we review the pathogenesis, pathology and pathophysiology of COPD. We also review the effects of cigarette smoking and smoking cessation on age-related pulmonary function decline, and prevalence of emphysema detected by thoracic CT screening.