CONICET | Buscador de Institutos y Recursos Humanos

The 16 PAHs included in the US EPA priority pollutants list (mutagenic and carcinogenic properties) are commonly monitored in the environment. The levels of these compounds in soil and air are mainly controlled by air-soil exchange which has an important role in controlling the transport and redistribution between the atmosphere and the terrestrial environment. Then, the main aim of this work was to study the PAHs? air-soil exchange. For this, XAD-2-resin based passive air samplers were deployed at 10 sampling sites of the SW of Buenos Aires Province, including sites under heavy anthropic pressure, agroindustry exploitation and the petrochemical industry), from Apr. 2015 to May. 2016. Resin cartridges were quarterly replaced and analyzed. Simultaneously, soil samples were collected manually at 0?5 cm depth from the surface in the study sites.All collected samples were Soxhlet extracted (1:1 mixture of Hex:Ace) for 8 h. Following the concentrating step making use of a rotary evaporator, the extracts were then fractionated and cleaned up by an alumina/silica gel column. Hex and DCM were used in the elution of PAHs. The PAH fraction was finally concentrated to 1 ml under a gentle stream of pure nitrogen. The concentrations of 16 PAHs in the extracts were determined by a GC/MS under SIM. Soil organic matter (OM) and density were determined by means of calcination and a pycnometer, respectively. Finally, soil to air fugacity ratios were calculated using fS/fA= (CS ρS/KSA) /CA (Cetin et al., 2017).Considering that the fS/fA value, for a system in equilibrium, is 1, results showed that soil and air were not in equilibrium for PAHs. The fS/fA for each PAHs was < 1, indicating that the soil acted as a sink for these PAHs and that the gas-phase deposition occurred from air to soil during the sampling period. This deposition was dominated by HMW-PAHs, with fS/fA 4,3E-05 times smaller than LMW-PAHs. Then, results showed a net accumulation into the soil.