Distributions of fossil fuel originated CO2 in five metropolitan areas of Korea (Seoul, Busan, Daegu, Daejeon, and Gwangju) according to the Δ14C in ginkgo leaves

We collected a batch of ginkgo (Ginkgo biloba Linnaeus) leaf samples at five metropolitan areas of Korea (Seoul, Busan, Daegu, Daejeon, and Gwangju) in 2009 to obtain the regional distribution of fossil fuel originated CO2 (fossil fuel CO2) in the atmosphere. Regions assumed to be free of fossil fuel CO2 were also selected, namely Mt. Chiak, Mt. Kyeryong, Mt. Jiri, Anmyeon Island, and Jeju Island and ginkgo leaf samples were collected in those areas during the same period. The Δ14C values of the samples were measured using Accelerator Mass Spectrometry (AMS) and the fossil fuel CO2 ratios in the atmosphere were obtained in the five metropolitan areas. The average ratio of fossil fuel CO2 in Seoul was higher than that in the other four cities. The leaves from the Sajik Tunnel in Seoul recorded the highest FFCTC (fossil fuel CO2 over total CO2 in atmosphere), 13.9 ± 0.5%, as the air flow of the surrounding neighborhood of the Sajik Tunnel was blocked.