Assessment of Atmospheric Concentrations, Gas/Particle Partitioning, Cancer Risks, Sources, and Atmospheric Transport of PCDD/Fs in a Suburban Area of Bursa, Türkiye

Abstract

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are a very high-priority air pollutant group due to their ability to remain intact for a long time and pose serious threats to human and environmental health. Therefore; most of the PCDD/F research studies have been carried out in urban, industrial areas and in the vicinity of waste incineration plants where these pollutants are expected at high concentrations. There are few studies conducted in rural, semi-rural, and suburban areas worldwide, especially in Türkiye, and determining PCDD/F levels in these areas is very important for evaluating the atmospheric transport of these pollutants. In this study, a sampling campaign covering 12 months (June 2022-June 2023) was conducted in a suburban area in Bursa, Türkiye. Concentration values varied between 168.77 and 327.58 fg/m3. In terms of toxic equivalence, the average concentration was found to be 22.62 ± 3.21 fg I-TEQ/m3. This value was found to be comparable to the results reported for suburban and rural areas worldwide. The influence of the seasonal effect on concentrations was seen as the lower and upper-end concentration values of 17.15 and 26.54 fg I-TEQ/m3 were measured in summer and winter, respectively. A strong negative correlation (r=-0.84, p < 0.001) was observed between total concentration values and temperature while weak correlations were observed with other meteorological parameters. A positive correlation was found between low chlorinated congener gas phase concentrations and ambient temperature using Clausius-Clapeyron. PCDD/Fs were found to have existed in the particle phase at an average ratio of 75.05 ± 5.85%. It was determined that no equilibrium state was reached in the gas/particle partitioning and both adsorption and absorption mechanisms were effective in the transitions. In the study, the performance of 7 different gas/particle partitioning models was evaluated. According to their performance, the models were ranked as Harner-Bidleman ≈ Dachs-Eisenreich > Li-Ma-Yang > Junge-Pankow ≈ pp-LFER > QSPR > mp-pp-LFER. The performance of the models in the equilibrium (EQ), non-equilibrium (NE), and maximum partitioning (MP) domains were also analyzed. Principal Component Analysis (PCA) showed that the main pollutant source in the region is traffic emissions. Back trajectory analysis indicated that air masses were transported to the sampling point from the organized industrial zones. Although these air masses have an impact on the congener profile, it is found that the total concentrations are mainly characterized by congeners originating from traffic emissions. Cancer risk was calculated for primary school children, nursery school children, and adults, and values of 3.28×10− 8, 3.86×10− 8, and 3.97×10− 7 were obtained, respectively. With these values being less than 10− 6, it was determined that there would be no significant risk due to inhalation of PCDD/Fs in the area.