Temporal Change in Atmospheric Polycyclic Aromatic Hydrocarbons in Particulate Matter from an Urban Location of Osaka, Japan: Estimation of Causes of a Significant Increase in their Concentrations in the Winter Season

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Forty-five compounds of ambient polycyclic aromatic hydrocarbons (PAHs) in particulate matter were examined at an urban location of Osaka, Japan, over the period of one year from April 2001 to March 2002. A comparative survey was performed at a roadside location of Shijonawate, located in eastern Osaka. PAH concentrations at the two locations decreased from spring to summer, and increased in winter. The maximum total PAH concentrations of >100ng m<SUP>-3</SUP> were observed on 15∼16 January at the both locations. However, the use of automobile with diesel engine, estimated to be main emission sources of PAHs, was almost constant at the roadside location during the measuring period. Total PAH concentrations show negative correlations between ambient temperature, sunshine quantity and wind speed. Therefore, possible causes of the increase in PAH concentrations in the winter season is the enhancement of condensation of low-molecular-weight PAHs onto the surface of PM, the depression of the photolytic degradation and the appearance of atmospherically stable layer. In particular, from an estimation of potential temperature gradient, an abnormally strong stablelayer would form on 15∼16 January, resulting in the significantly high PAH concentrations on that day.
Japan Society for Environmental Chemistryの論文