Organochlorine pesticides and polychlorinated biphenyls in air and soil across Azerbaijan

Abstract

Concentrations of selected organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) are reported in air and surface soil in an extensive spatial survey across Azerbaijan, a country bordering the Caspian Sea with a history of OCP production and extensive use. Polyurethane foam disc passive air samplers (PAS) were deployed during October–November 2008 with soil samples collected in July 2009. Levels of Σ₇PCB in ambient air were generally low (mean of 0.046 ng m⁻³, n = 13) and comparable to concentrations reported in countries within Eastern Europe and similar to or lower than concentrations reported in urban air in the UK and other western countries. Surprisingly, PCB concentrations in rural/background soil fell below the method detection limits at most sites, although concentrations were 0.209 and 0.071 ng Σ₇PCB g⁻¹ dry weight (dw) for two urban sites, again comparable to PCB levels measured at background sites in Europe. Levels of α-HCH, β-HCH, γ-HCH and p,p′-DDT/E were elevated in ambient air across Azerbaijan in comparison to PAS-derived concentrations reported elsewhere, with concentrations of α-HCH in air ranging from 0.085 to 2.699 ng m⁻³ and p,p′-DDE, 0.037–2.290 ng m⁻³. High concentrations of OCPs occurred at several of the urban sites and at sites in proximity to old pesticide storage facilities with concentrations in soil >0.1 μg g⁻¹ dw for p,p′-DDE and p,p′-DDT at several sites. The ratio of p,p′-DDT/p,p′-DDE was close to unity in the soil at these sites, but elsewhere, the ratio was <1, indicating a weathered DDT pattern, which was also reflected in the air at all sites. A fugacity approach revealed the strong likelihood of net soil-to-air transfer at the majority of sites for all OCPs. The calculated annual fluxes or loading to the atmosphere from a rural/agricultural area (representing land as vineyards and cotton cultivation) were estimated to be on the order of ≈10–100 kg year⁻¹ for the HCH isomers (including the β -isomer) and p,p′-DDE. The high levels of OCPs in soils, particularly in the vicinity of obsolete-pesticide storage facilities and at select urban sites are of concern and warrant regular monitoring activities and the development of containment or mitigation strategies.