Size Distribution of Airborne Particle-Bound Polybrominated Diphenyl Ethers and Its Implications for Dry and Wet Deposition

Abstract

Size distribution of particles in part dictates the environmental behavior of particle-bound organic pollutants in the atmosphere. The present study was conducted to examine the potential mechanisms responsible for the distribution of organic pollutants in size fractionated particles and their environmental implications, using an e-waste recycling zone in South China as a case study. Size-fractionated atmospheric particles were collected at the heights of 1.5, 5, and 20 m near two residential apartments and analyzed for polybrominated diphenyl ethers (PBDEs). The concentrations of particle-bound ΣPBDE (sum of 18 PBDE congeners) were significantly greater at 5 and 20 m than those at 1.5 m. The size-fractionated distributions of airborne ΣPBDE displayed trimodal peaks in 0.10–0.18, 1.8–3.2, and 10–18 μm at 1.5 m but only an unimodal peak in 1.0–1.8 μm at 20 m height. Emission sources, resuspension of dust and soil, and volatility of PBDEs were important factors influencing the size distribution of particle-bound PBDEs. The dry deposition fluxes of particle-bound PBDE estimated from the measured data in the present study were approximately twice the estimated wet deposition fluxes, with a total deposition flux of 3000 ng m(–2) d(–1). The relative contributions of particles to dry and wet deposition fluxes were also size-dependent, e.g., coarse (aerodynamic diameters (Dp) > 1.8 μm) and fine (Dp < 1.8 μm) particles dominated the dry and wet deposition fluxes of PBDEs, respectively.

Size-dependent atmospheric deposition and inhalation exposure of particle-bound organophosphate flame retardants

“…S2-S6). This was different from our previous findings that airborne PBDEs displayed an unimodal peak in 1.0-1.8 m at 20 m height in the e-waste recycling zone [3] and 0.56-1.0 m at the heights of 100 and 150 m in urban Guangzhou [25]. The different size distribution profiles of OPFRs and PBDEs may be attributed to the widespread use of OPFRs as plasticizers, which disperses OPFRs into all sized particles more evenly compared to PBDEs.…”

“…There are two noteworthy findings from the measurements. First, the concentrations of particle-bound OPFRs were higher than those of PBDEs in the e-waste recycling zone [3]. Second, the difference of 8 OPFR concentrations between the e-waste recycling zone and urban Guangzhou was largely negligible compared to particle-bound PBDEs, unexpected and inconsistent with the prevailing perception that primitive processing of e-waste may have been a remarkable source of OPFRs in the environment as with PBDEs [23,24].…”

“…S1). The procedures for field sampling and sample analysis were similar to those described previously [3][4][5], and only a brief description is presented herein. Overall, 24 and 11 sets of size-fractionated samples (a total of 385 field particle samples) were collected in the e-waste recycling zone and Guangzhou, respectively.…”

“…Dry and wet deposition fluxes (F dry and F wet ) of particle-bound OPFRs were estimated following the same approach as our previous studies [3,25], i.e.,…”

“…As such, size distribution of particle-bound pollutants is a critical factor governing their fate in the atmosphere and associated human health risk. For example, coarse and fine particles contributed the most to the dry and wet deposition fluxes of particle-bound polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polycyclic aromatic hydrocarbons (PAHs), and polybrominated diphenyl ethers (PBDEs), respectively [2][3][4]. Smaller particles can penetrate into the deeper regions of lung and hence pose higher risk to human health than larger particles [4][5][6].…”