Development of a Passive Sampling/Monitoring Device Suitable for Acid Gas in Atmospheric Environment in China and Its Field Evaluation

点击翻译按钮获取中文摘要

A new type of passive sampler, which can easily determine sulfur dioxide (SOィイD22ィエD2) and nitrogen dioxide (NOィイD22ィエD2) simultaneously air, has developed. The passive sampling method for analysis of SOィイD22ィエD2 has more difficult than NOィイD22ィエD2 chiefly because of following two problems. The first one is that SOィイD22ィエD2 has high absorptivity. Therefore, it is much absorbed in the materials used as the absorption and diffusion filter in sampler, and the second one is that the sulfate ion, to which absorbed SOィイD22ィエD2 is oxidized, is usually contained in filter used as sampler parts. Thus, blank concentration of sulfur ion is sampler is higher. As a result of exposure experiments using a wind tunnel to evaluate the materials used as absorption and diffusion filter, the passive sampler which polyethelene membrane is used as an absorption layer, and polyethylene and polypropylene as the first and second diffusion layer was found to have the most suitable sampler for analyzing SOィイD22ィエD2 and NOィイD22ィエD2. The precision and detection limit of this method was found to be satisfactory. The method established in this study has been applied to the evaluation of air quality at the five major cities in China since September 1997.The passive samplers are easily influence by wind. However, the newly developed samplers are found to have minimum influence by sampling conditions such as wind, humidity and temperature. So this method is applied to investigate the air in six cities, Beijing, Lonzhou, Wuhan, Dalian, Shenyang which are high in China. The concentrations of SOィイD22ィエD2 and NOィイD22ィエD2 are two days averages. These obtained data has good agreement with the annual average concentration. The weekly change of SOィイD22ィエD2 and NOィイD22ィエD2 concentration (7 days average) in Beijing. Since temperature dropped, SOィイD22ィエD2 and NOィイD22ィエD2 concentrations tend to increase. One of the causes of it is the increase of using coal for heating.