Characterization of Bacterial Communities in Aerosols over Northern Chinese Marginal Seas and the Northwestern Pacific Ocean in Autumn

The characteristics of the bacterial community structure in aerosols of different particle sizes over northern Chinese marginal seas and the northwestern Pacific Ocean in autumn were analyzed using high-throughput sequencing and the quantitative real-time PCR method based on 16S rRNA genes. Combined with environmental factors and air mass sources, the bacterial abundance, community diversity, composition and structural characteristics in aerosols were studied, which might provide a scientific evaluation for a comprehensive understanding of the characteristics, long-distance transmission and ecological effects of aerosols from coastal waters to the distant ocean (northwestern Pacific Ocean). At the junction of the South Yellow Sea and the East China Sea, the bacterial abundance in the aerosols was substantially affected by transmission of continental air masses and was higher than those in other samples, and the bacterial abundance in coarse particle (> 2.1 mu m) samples was significantly higher than that in fine particle (< 2.1 mu m) samples (P < 0.05). In contrast, aerosols collected at the northwestern Pacific Ocean (NWP5 site) were less affected by transmissions of continental air masses, and their bacterial abundance in coarse particle samples was significantly lower than that in fine particle samples. Significant differences in the richness and diversity of bacterial communities were observed among all samples (P < 0.05). The differences in the bacterial community in different sea areas were greater than those in the same sample with different particle sizes (P > 0.05). Among the environmental factors examined, a significant negative correlation was observed between bacterial community richness and temperature (P < 0.05), and the bacterial community diversity was significantly positively correlated with the concentration of K+ (P < 0.05). Canonical correspondence analysis showed that temperature, NH4+ concentration and SO42- concentration exerted significant effects on bacterial community structures (P < 0.01) in aerosols of different particle sizes over northern Chinese marginal seas and the northwestern Pacific Ocean.