Abstract
Particle size is an important parameter in terms of human health effects, fate and transport of pollutants associated with particulate matter (PM). Persistent organic pollutant (POP) (i.e., PAHs, PCBs, PBDEs, and OCPs) concentrations were measured on fine (dp < 2.5 µm) and coarse (2.5 µm < dp < 10 µm) aerosol samples collected at two (Urban and Industrial) sites in Izmir, Turkey. POP concentrations were ~2 times higher at the Industrial site due to the local sources (i.e., scrap processing iron-steel plants, ship-breaking activities, a petroleum refinery, and a petrochemical plant) that were recently shown to be hot spots emitting these pollutants. The size distribution of particle-phase POPs indicated that they were mostly (> 50%) associated with fine PM. The larger contribution of all POP compounds to fine PM could be attributed to the higher sorption capacity of fine PM because of its relatively higher organic matter content compared to coarse PM. Fine PM fraction of POPs significantly increased with octanol-air partition coefficient (KOA) (p < 0.01) since larger KOA values favor the partitioning of POPs to PM. Relationships between fine PM percent and meteorological parameters (i.e., temperature and wind speed) were also investigated. Fine PM percent decreased with temperature and the correlations were significant for 51% of the compounds (p < 0.01), suggesting that the decrease in KOA with increasing temperature results in less partitioning to PM. Fine PM fraction also decreased with wind speed (p < 0.01 for the 52% of the compounds) that could be attributed to increased resuspension of contaminated coarse particles with increasing wind speed. Using the experimental deposition velocities reported for several POPs in the study area it was shown that dry particle deposition velocity significantly decreases with increasing fine PM fraction (p < 0.01). This indicates that the increase in fine fraction of POPs with decreasing volatility may have important implications for their environmental fate and transport.
Highlights
Atmospheric persistent organic pollutants (POPs) may be predominantly in the gas/particle-phase or distributed between two phases, depending on their physicochemical properties and temperature (Harner and Shoeib, 2002; Li et al, 2008)
Fine particulate matter (PM) fraction of POPs significantly increased with octanol-air partition coefficient (KOA) (p < 0.01) since larger KOA values favor the partitioning of POPs to PM
Fine PM percent decreased with temperature and the correlations were significant for 51% of the compounds (p < 0.01), suggesting that the decrease in KOA with increasing temperature results in less partitioning to PM
Summary
Atmospheric persistent organic pollutants (POPs) may be predominantly in the gas/particle-phase or distributed between two phases, depending on their physicochemical properties (i.e., supercooled liquid vapor pressure- PL, octanol–air partition coefficient-KOA) and temperature (Harner and Shoeib, 2002; Li et al, 2008). There are only a few studies investigating the size distribution of atmospheric PCBs (Xu et al, 2005; Chrysikou et al, 2009; Han et al, 2010), OCPs (Wang et al, 2008; Chrysikou et al, 2009; Fu et al, 2009; Xu et al, 2011; Coscolla et al, 2014), and PBDEs (Deng et al, 2007; Mandalakis et al, 2009; Zhang et al, 2012b) Most of these studies have reported that POPs were mostly associated with fine particles, non-volatile higher molecular weight compounds being in a greater extent. There have been no studies investigating the effect of meteorological parameters (i.e., temperature and wind speed) and KOA on size distribution of particulate POPs
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