Seasonality of airborne bacterial population in South Korea

Airborne bacteria are a critical yet highly dynamic component of atmospheric ecosystems, shaped by the interplay between local sources and long-range transport. Over a three-year monitoring period in Busan, South Korea, we quantified airborne bacterial populations using quantitative PCR and high-throughput sequencing. Bacterial concentrations fluctuated substantially (2.8–5.8 log₁₀ copy·m^-3), with pronounced peaks in spring and minima during summer. These fluctuations mirrored the temporal trends of both local PM₁₀ and desert-derived PM₁₀ transported from arid regions thousands of kilometers away. Time-series analyses further revealed robust, synchronized annual cycles for bacterial abundance, desert PM₁₀, and local PM₁₀ (P<0.05), with parametric modeling capturing a four-week lag between desert dust emissions and subsequent local microbial peaks. Structural equation modeling provided quantitative confirmation that both local generation and regional dispersal significantly influenced airborne bacterial dynamics (P<0.05), with regional dispersal predominating during peak spring dust storm periods. Together, our findings underscore the major role of transcontinental dust transport in shaping atmospheric bacterial communities, often surpassing local contributions.