17 research outputs found
Polycyclic aromatic hydrocarbons in post-fire soils of drained peatlands in western Meshchera (Moscow region, Russia)
Polycyclic aromatic
hydrocarbons (PAHs) are priority pollutants that arrive in the environment
from numerous anthropogenic and natural sources, but the data on their
natural sources including wildfires remain insufficient. The level of
contamination and the composition of PAHs in soils of the areas affected by
wildfires were studied in this work. The study was conducted in the Moscow
region (Russia) in areas occupied by drained peatland and strongly damaged by
fires in 2002, 2010 and 2012. The features of PAH accumulation and the
profile distributions in histosols and histic podzols after the fires of
different times were analyzed. It was shown that new soil horizons formed
after the fires â Cpir, Hpir and incipient O horizons â and that these
horizons differ in PAH accumulation rate. Maximal total concentrations of 14
PAHs were detected in charred peat horizons Hpir (up to 330 ng gâ1)
and in post-fire incipient O horizons (up to 180 ng gâ1), but the
high-molecular-weight PAHs (benz(ghi)perylene, benz(a)pyrene,
benz(k)fluoranthene) were revealed only in charry peat horizons. The trends
of higher PAH concentrations were found in cases when smoldering combustion
resulted in rather thick residual peat horizons. In cases of almost complete
pyrogenic destruction of He horizons, total PAH concentrations were no more
than 50 ng gâ1. Also, PAH accumulation in upper horizons of soils near
the sites of the latest fires was observed
Brown carbon aerosols from burning of boreal peatlands: microphysical properties, emission factors, and implications for direct radiative forcing
The surface air warming over the Arctic has been almost twice as much as the
global average in recent decades. In this region, unprecedented amounts of
smoldering peat fires have been identified as a major emission source of
climate-warming agents. While much is known about greenhouse gas emissions
from these fires, there is a knowledge gap on the nature of particulate
emissions and their potential role in atmospheric warming. Here, we show
that aerosols emitted from burning of Alaskan and Siberian peatlands are
predominantly brown carbon (BrC) â a class of visible light-absorbing organic
carbon (OC) â with a negligible amount of black carbon content. The mean
fuel-based emission factors for OC aerosols ranged from 3.8 to 16.6âŻgâŻkg<sup>â1</sup>. Their mass absorption efficiencies
were in the range of 0.2â0.8âŻm<sup>2</sup>âŻg<sup>â1</sup> at 405âŻnm (violet) and dropped sharply to 0.03â0.07âŻm<sup>2</sup>âŻg<sup>â1</sup>
at 532âŻnm (green), characterized by a mean
Ă
ngström exponent of ââââŻ9. Electron microscopy images of the
particles revealed their morphologies to be either single sphere or
agglomerated âtar ballsâ. The shortwave top-of-atmosphere aerosol
radiative forcing per unit optical depth under clear-sky conditions was
estimated as a function of surface albedo. Only over bright surfaces with
albedo greater than 0.6, such as snow cover and low-level clouds, the
emitted aerosols could result in a net warming (positive forcing) of the
atmosphere