The impact of bioaerosol trajectories on microbial community assembly and physicochemical dynamics in the atmosphere.

This study explored the assembly mechanisms and physicochemical dynamics of microbial communities within atmospheric bioaerosols, focusing on the influence of different aerial trajectories. Over two years, samples near Seoul were classified into 'North', 'Southwest', and 'Others' categories based on their aerial trajectories. Physicochemical analysis of the PM2.5 particles revealed distinct ion compositions for each cluster, reflecting diverse environmental influences. Microbial community analysis revealed that shared dominant bacterial phyla were present in all clusters. However, distinct taxonomic profiles and biomarkers were also evident, such as coastal bacteria in the 'Southwest' cluster correlating with wind speed, and arid soil-originated bacteria in the 'North' cluster correlating with cations. These findings demonstrate that biomarkers in each cluster are representative of the distinct environments associated with their aerial trajectories. Notably, cluster 'Southwest' the highest microbial diversity and a strong alignment with the neutral community model, suggesting a large influence of passive dispersal from marine environments. Contrarily, 'North' and 'Others' were more influenced by niche-dependent factors. This study highlights the complex interplay between environmental factors and microbial dynamics in bioaerosols and provides important insights for environmental monitoring and public health risk assessment.

Congener profiles and source-wise phase partitioning analysis of PCDDs/Fs and PCBs in Gyeonggi-do ambient air, South Korea.

The atmospheric concentrations and gas-particle partitioning of polychlorinated dibenzo-p-dioxins and furans (PCDDs/Fs) and polychlorinated biphenyls (PCBs) were investigated at two sites (Suwon and Ansan) in Gyeonggi-do, a heavily industrialized area of Korea, during the year 2010. The sum level (Σ17) of PCDDs/Fs and dioxin-like PCBs (dl-PCBs) in the ambient air at Suwon and Ansan ranged from 0.04 to 0.30 pg-TEQ·m(-3) (geometric mean: 0.09 pg-TEQ·m(-3)) and 0.17 to 0.63 pg-TEQ·m(-3) (geometric mean: 0.36 pg-TEQ·m(-3)), respectively. Moreover, the geometric mean concentrations of Σ180 PCBs at Suwon and Ansan were 233.6 pg·m(-3) and 274.2 pg·m(-3), respectively, and di-chlorinated biphenyls and tri-chlorinated biphenyls were the predominant homologs. Among the PCB congeners, 3,3'-dichlorobiphenyl (PCB-11) was the dominant species at both sites during all sampling periods, comprising up to 15.1% of Σ180 PCBs at Ansan and 24.6% at Suwon. We evaluated their gas-to-particle equilibriums by conducting regression between the particle-gas partition coefficient Kp (m(3)·ug(-1)) and the corresponding subcooled liquid vapor pressure (PL°). The slope (m) values for log-log plots of Kp vs. PL° were steeper in industrial areas owing to local source proximity. Moreover, owing to enhanced emissions from combustion-related sources at low temperatures, PCDD/Fs exhibited the largest deviation from the regression line of the particle-gas partition coefficient. Incinerators were found to be the primary emission source of atmospheric PCDDs/Fs, whereas re-evaporation from pre-existing environmental loads (e.g., storage areas or spilled soil and water bodies) was the dominant source for PCBs.

Field-measured uptake rates of PCDDs/Fs and dl-PCBs using PUF-disk passive air samplers in Gyeonggi-do, South Korea.

The collection of 2,3,7,8-substituted polychlorinated dibenzo-ρ-dioxins and dibenzo furans (PCDDs/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) using a polyurethane form (PUF)-disk passive air sampler (PAS) was investigated in urban-residential and industrial areas. This was performed to assess the feasibility of using this method as an alternative to an active air sampler (AAS). The PUF-disk PAS was exposed to ambient air over a period of 37-370 and 57-173 days in urban and industrial areas, respectively, together with AASs. The sum of total toxic equivalent quantity (TEQ) ΣPCDDs/Fs and Σdl-PCB was typically high in the industrial area, with values within the range 0.171-0.635 pg-TEQ/m(3), and 0.037-0.300 pg-TEQ/m(3) in the urban-residential area. To derive the time-weighted average (TWA) concentration from the PAS data accurately, it was estimated that the PAS deployed for less than 80 days was adequate to maintain linear accumulation conditions. PCDDs/Fs are mainly particle bound and showed low average uptake rates of 1.4m(3)d(-1), while dl-PCBs were slightly higher with 2.0m(3)d(-1) because of its high vapor pressure. Most of the congener concentrations measured using the PAS and AAS were within a factor of two, indicating that PASs can be used to monitor spatial and temporal variations in the concentrations of persistent organic pollutants (POPs) in the atmosphere.