Wet deposition of persistent organic pollutants (POPs) in Izmir, Turkey

Abstract

Concentrations of several polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), and polybrominated diphenyl ethers (PBDEs) were measured in precipitation (n = 33) at a suburban site in Izmir, Turkey. Total (dissolved + particle) volume weighted mean (VWM) concentrations for Σ₁₆PAHs, Σ₁₈PCBs, Σ₁₇OCPs, and Σ₇PBDEs were 785, 19.2, 50.5, and 29.6 ng l⁻¹, respectively. Low molecular weight (LMW) compounds (acenaphthylene, fluorene, phenanthrene) and congeners (PCB-18, 28, and 31) dominated the PAH and PCB concentrations, respectively. For PBDEs, BDE-209, and for OCPs, chlorpyrifos, a currently used pesticide, were the predominant compounds. Annual Σ₇PBDEs flux was 18.74 μg m⁻² year⁻¹. PBDE fluxes were mainly in dissolved phase for all congeners except BDE-209 which had comparable proportions in both phases. Annual flux for Σ₁₆PAHs was 497.4 μg m⁻² year⁻¹; higher molecular weight (MW) PAH fluxes had comparable amounts in both phases while lower MW ones were mostly in dissolved phase. Wet deposition fluxes for Σ₁₈PCBs and Σ₁₇OCPs were 9.40 and 31.94 μg m⁻² year⁻¹, respectively, and they were predominantly in dissolved phase. Wet deposition fluxes were compared to previously measured annual dry deposition fluxes at the study site to determine their relative contributions to annual total (dry particle + wet) deposition. Dry deposition was the major removal mechanism for most of the PAHs and PCBs contributing >80 % to total (wet + dry) deposition. However, both processes were comparable for PBDEs. Wet deposition was the predominant process for some OCPs such as α-chlordane, γ-chlordane, and trans-nonachlor while both processes were comparable for chlorpyrifos and heptachlor epoxide.