Polycyclic aromatic hydrocarbons in post-fire soils of drained peatlands in western Meshchera (Moscow region, Russia)

摘要

Polycyclic aromatichydrocarbons (PAHs) are priority pollutants that arrive in the environmentfrom numerous anthropogenic and natural sources, but the data on theirnatural sources including wildfires remain insufficient. The level ofcontamination and the composition of PAHs in soils of the areas affected bywildfires were studied in this work. The study was conducted in the Moscowregion (Russia) in areas occupied by drained peatland and strongly damaged byfires in 2002, 2010 and 2012. The features of PAH accumulation and theprofile distributions in histosols and histic podzols after the fires ofdifferent times were analyzed. It was shown that new soil horizons formedafter the fires – Cpir, Hpir and incipient O horizons – and that thesehorizons differ in PAH accumulation rate. Maximal total concentrations of 14PAHs were detected in charred peat horizons Hpir (up to 330 ng g?1)and in post-fire incipient O horizons (up to 180 ng g?1), but thehigh-molecular-weight PAHs (benz(ghi)perylene, benz(a)pyrene,benz(k)fluoranthene) were revealed only in charry peat horizons. The trendsof higher PAH concentrations were found in cases when smoldering combustionresulted in rather thick residual peat horizons. In cases of almost completepyrogenic destruction of He horizons, total PAH concentrations were no morethan 50 ng g?1. Also, PAH accumulation in upper horizons of soils nearthe sites of the latest fires was observed.