Spatial and temporal characteristics of atmospheric CO2 and CH4 concentrations in Chungcheongnam-do, South Korea

To monitor climate change and support carbon neutrality, seven greenhouse gas monitoring stations were established in Chungcheongnam-do, South Korea. These were located in two urban areas (Cheonan and Asan), three industrial areas (Seosan, Dangjin and Boryeong), and two agricultural areas (Nonsan and Hongseong). From October to December 2024, carbon dioxide (CO₂ ) and methane (CH₄) concentrations were measured as representative greenhouse gases. The average CO₂ concentration across the seven areas was 458.1 ppm, with the highest observed in Dangjin at 465.0 ppm, and CO₂ concentrations tended to be higher in urban areas. Local factors, such as the location of the measurement site (e.g., city center vs. suburbs) and nearby pollution sources significantly influenced the concentrations. The average CH₄ concentration was 2.205 ppm, with the highest concentration in Dangjin at 2.259 ppm. While CO₂ and CH₄ concentrations varied by region, they generally increased from evening to early morning and decreased during the daytime. CO₂ showed a stronger correlation with nitrogen dioxide (NO₂) and carbon monoxide (CO) than did CH₄. CO₂ enhancement (ΔCO₂) varies depending on the definition of background concentration using direct measurements at background sites or statistical lower-bound values. This suggests that careful consideration is needed when applying different methodologies to study and assess the distribution characteristics of greenhouse gases.