Recent work has shown that dry deposition and gas
exchange of semivolatile organic compounds in the Great
Lakes is important. However, there is no generally
accepted method for collecting particulate dry deposition
or gas exchange. In this work the Water Surface Sampler
(WSS) was modified and used in combination with dry
deposition plates to measure the particulate dry deposition
and gas exchange of PAHs. Simultaneous dry deposition
and ambient air samples were collected between June and
October 1995 in Chicago, IL. Total (particulate + gas)
fluxes were measured with the WSS, while particulate
fluxes were measured with dry deposition plates. Average Σ14-PAH and particulate Σ14-PAH fluxes were 360 ± 146 μg/m2 d and 144 ± 60 μg/m2 d, respectively. Gas-phase fluxes,
determined by subtracting the dry deposition plate fluxes
(particulate) from WSS fluxes (particulate + gas), averaged
170 ± 72 μg/m2 d. The measured particulate dry deposition
and gas exchange fluxes were substantially higher
than those previously reported for the Great Lakes and
nonurban areas, probably due to the significantly higher
ambient PAH concentrations found in Chicago. Particulate
phase overall dry deposition velocities calculated using
the dry deposition fluxes and ambient concentrations averaged
6.7 ± 2.8 cm/s. This value is higher than values estimated
using dry deposition models; however, it is in good
agreement with values determined using similar techniques.
Near-ground air (26 substances) and surface seawater (55 substances) concentrations of persistent toxic substances (PTS) were determined in July 2012 in a coordinated and coherent way around the Aegean Sea based on passive air (10 sites in 5 areas) and water (4 sites in 2 areas) sampling. The direction of air-sea exchange was determined for 18 PTS. Identical samplers were deployed at all sites and were analysed at one laboratory. hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs) as well as dichlorodiphenyltrichloroethane (DDT) and its degradation products are evenly distributed in the air of the whole region. Air concentrations of p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE) and o,p′-DDT and seawater concentrations of p,p′-DDE and p,p′-DDD were elevated in Thermaikos Gulf, northwestern Aegean Sea. The polychlorinated biphenyl (PCB) congener pattern in air is identical throughout the region, while polybrominated diphenylether (PBDE)patterns are obviously dissimilar between Greece and Turkey. Various pollutants, polycyclic aromatic hydrocarbons (PAHs), PCBs, DDE, and penta-and hexachlorobenzene are found close to phase equilibrium or net-volatilisational (upward flux), similarly at a remote site (on Crete) and in the more polluted Thermaikos Gulf. The results suggest that effective passive air sampling volumes may not be representative across sites when PAHs significantly partitioning to the particulate phase are included.
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