ALBERT

Description: Northeast Asia including China, Korea, and Japan is one of the world's largest fossil fuel consumption regions. Seoul, Korea, is a megacity in Northeast Asia. Its emissions of air pollutants can affect the region, and in turn it is also affected by regional emissions. To understand the extent of these influences, major sources of ambient particulate PAHs in Seoul were identified and quantified based on measurements made between August 2002 and December 2003. The chemical mass balance (CMB) model was applied. Seven major emission sources were identified based on the emission data in Seoul and Northeast Asia: Gasoline and diesel vehicles, residential coal use, coke ovens, coal power plants, biomass burning, and natural gas (NG) combustion. The major sources of particulate PAHs in Seoul during the whole measurement period were gasoline and diesel vehicles, together accounted for 31% of the measured particulate PAHs levels. However, the source contributions showed distinct daily and seasonal variations. High contributions of biomass burning and coal (residential and coke oven) were observed in fall and winter, accounting for 63% and 82% of the total concentration of PAHs, respectively. Since these sources were not strong in and around Seoul, they are likely to be related to transport from outside of Seoul, from China and/or North Korea. This implies that the air quality in a mega-city such as Seoul can be influenced by the long range transport of air pollutants such as PAHs.

Description: The accurate stream flow composition simulated by different models is rarely discussed, and few studies addressed the model behaviors affected by the model structures. This study compared the simulated stream flow composition derived from two models, namely HBV and TOPMODEL. A total of 23 storms with a wide rainfall spectrum were utilized and independent geochemical data (to derive the stream composition using end-member mixing analysis, EMMA) were introduced. Results showed that both hydrological models generally perform stream discharge satisfactory in terms of the Nash efficiency coefficient, correlation coefficient, and discharge volume. However, the three simulated flows (surface flow, interflow, and base flow) derived from the two models were different with the change of storm intensity and duration. Both simulated surface flows showed the same patterns. The HBV simulated base flow dramatically increased with the increase of storm duration. However, the TOP-derived base flow remained stable. Meanwhile, the two models showed contrasting behaviors in the interflow. HBV prefers to generate less interflow but percolates more to the base flow to match the stream flow, which implies that this model might be suited for thin soil layer. The use of the models should consider more environmental background data into account. Compared with the EMMA-derived flows, both models showed a significant 2 to 4 h time lag, indicating that the base-flow responses were faster than the models represented. Our study suggested that model intercomparison under a wide spectrum of rainstorms and with independent validation data (geochemical data) is a good means of studying the model behaviors. Rethinking the characterization of the model structure and the watershed characteristics is necessary in selecting the more appropriate hydrological model.

Description: Northeast Asia including China, Korea, and Japan is one of the world's largest fossil fuel consumption regions. Seoul is a megacity in Northeast Asia and its emissions of air pollutants can affect the region and is also affected by the regional emissions. To understand the degree of this relationship, major sources of ambient particulate PAHs at Seoul, Korea were identified and quantified based on the measurement data between August 2002 and December 2003. The chemical mass balance (CMB) model was applied. Seven major emission sources were identified based on the emission data in Seoul and Northeast Asia: Gasoline and diesel vehicles, coal residential, coke oven, coal power plant, biomass burning, natural gas (NG) combustion. The major source of particulate PAHs at Seoul on the whole measurement period was gasoline and diesel vehicles, accounted for 31% of the measured particulate PAHs levels. However, the source contributions showed distinct seasonal variations. High contributions of biomass burning and coal (residential and coke oven) were shown in fall and winter accounted for 63% and 82% of the total PAHs concentration, respectively. Since these sources were not strong in and around Seoul, these might be related to transport from outside of Seoul, from China and/or North Korea. It implies that the air quality in the large urban city such as Seoul can be influenced by the long range transport of air pollutants such as PAHs.