Temporal and Spatial Pattern of Ambient Nitrogen Dioxide Concentration in Forest and Urban Areas, Korea

The ambient concentrations of nitrogen dioxide (NO 2) at 65 forest areas were measured every month using passive diffusive samplers from 2002 to 2009 and were compared to those at urban areas in order to investigate the characteristics of temporal and spatial distributions of NO 2 from the forest and urban areas. The annually averaged concentrations of NO 2 gradually decreased for both areas. The average concentration of NO 2 in the forest areas was 8.0 ppb, which was lower than that in the urban areas (i.e., 19.4 ppb) and the ecological standard level of the European Union (i.e., 14.6 ppb). The monthly average of NO 2 concentration depicted seasonal variations particularly in the urban areas, showing higher concentration in winter and lower concentration in summer. Strong locality of NO 2 concentration distribution illustrates that the locations near the metropolitan areas (e.g., Gyeonggi and Chungnam provinces) had the highest concentration during the measurement period. A significant positive correlation between NO x emissions and NO 2 concentration was observed, suggesting that the magnitude and proximity to sources of atmospheric nitrogen oxides would be important controlling factors