2 research outputs found
Particle Size Distribution of Halogenated Flame Retardants and Implications for Atmospheric Deposition and Transport
This
study investigates the distribution of polybrominated diphenyl
ethers (PBDEs), hexabromocyclododecane (HBCD) and a group of novel
flame retardants (NFRs) on atmospheric aerosols. Two high volume cascade
impactors were used to collect particulate fractions of ambient air
over a one year period at urban and rural sites. The majority of FRs
were found on the finest aerosols (<0.95 μm). Concentrations
of HBCD were higher than those of ΣPBDEs. Moreover, we noted
seasonality and spatial differences in particle size distributions,
yet a large portion of the observed differences were due to differences
in particulate matter (PM) itself. When normalized by PM, the size
distributions of the FRs exhibited much greater heterogeneity. Differences
existed between the FR distributions by molecular weight, with the
higher molecular weight FRs (e.g., BDE-209, Dechlorane Plus) distributed
more uniformly across all particulate size fractions. The seasonal,
spatial, and compound-specific differences are of crucial importance
when estimating dry and wet deposition of FRs as smaller aerosols
have longer atmospheric residence times. Estimated wet and dry deposition
of four representative FRs (BDE-47, BDE-209, HBCD, and Dechlorane
Plus) using size-segregated aerosol data resulted in lower deposition
estimates than when bulk aerosol data were used. This has implications
for estimates of long-range atmospheric transport and atmospheric
residence times, as it suggests that without size-specific distributions,
these parameters could be underestimated for FRs
Diurnal Variations of Air-Soil Exchange of Semivolatile Organic Compounds (PAHs, PCBs, OCPs, and PBDEs) in a Central European Receptor Area
Concentrations
of polycyclic aromatic hydrocarbons (PAHs), polychlorinated
biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated
diphenyl ethers (PBDEs) in air and soil, their fugacities, and the
experimental soil-air partitioning coefficient (<i>K</i><sub>SA</sub>) were determined at two background sites in the Gt.
Hungarian Plain in August 2013. The concentrations of the semivolatile
organic compounds (SOCs) in the soil were not correlated with the
organic carbon content but with two indirect parameters of mineralization
and aromaticity, suggesting that soil organic matter quality is an
important parameter affecting the sorption of SOCs onto soils. Predictions
based on the assumption that absorption is the dominant process were
in good agreement with the measurements for PAHs, OCPs, and the low
chlorinated PCBs. In general, soils were found to be a source of PAHs,
high chlorinated PCBs, the majority of OCPs and PBDEs, and a sink
for the low chlorinated PCBs and γ-hexachlorocyclohexane. Diurnal
variations in the direction of the soil-air exchange were found for
two compounds (i.e., pentachlorobenzene and <i>p,p</i>′-dichlorodiphenyldichloroethane),
with volatilization during the day and deposition in the night. The
concentrations of most SOCs in the near-ground atmosphere were dominated
by revolatilization from the soil