Abstract
Water soluble ionic components in high concentrations of suspended particulate matter (SPM) were analyzed to understand secondary inorganic particle formation by using the tape filters of an automatic SPM sampler at a monitoring station in Kawasaki City. In Case I (April 12th to 13th, 2006) and Case II (April 18th to 19th, 2006), the generation and transportation of secondary inorganic particles was discussed considering the relationship between ion concentrations, simultaneously measured gas concentrations, and the results of a back trajectory analysis. In Case I, it was found that NO3- concentrations increased and Cl-concentrations decreased in high concentrations of SPM. From these results it was inferred that secondary inorganic particles, mainly formed by HNO3 gaseous coagulation and condensation into sea salt in humid air, contributed in part to the high concentrations of SPM in the city. In Case II, it was found that SO42- and Ca2+ concentrations increased in high concentrations of SPM, and the results of the back trajectory analysis showed that the air mass was transported from the Asian Continent to the Kanto Plain in Japan. Therefore, it has been inferred that the Asian dust from the Asian Continent contributed to the high concentrations of SPM in the city. Also, it was shown that the results from the tape filters and the practical use of relative data were useful in understanding the generation and transportation of secondary inorganic particles.
