Atmospheric Occurrence and Deposition of Polycyclic Aromatic Hydrocarbons in the Northeast Tropical and Subtropical Atlantic Ocean

Atmospheric transport and deposition of polycyclic aromatic hydrocarbons (PAHs) over tropical oceans has not yet been studied even though tropical oceans account for 35% of the global oceans. Here we show the results from measurements of gas- and aerosol-phase PAHs and dry deposition samples in the...

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Bibliographic Details
Published in:Environmental science & technology 2007-08, Vol.41 (16), p.5608-5613
Main Authors: Del Vento, Sabino, Dachs, Jordi
Format: Article
Language:English
Subjects:
Aerosols
Applied sciences
Atlantic Ocean
Atmosphere - chemistry
Atmospheric aerosols
Atmospheric pollution
Chemistry
Exact sciences and technology
Oceans
Particulate Matter
Pollutants physicochemistry study: properties, effects, reactions, transport and distribution
Pollution
Polycyclic aromatic hydrocarbons
Polycyclic Aromatic Hydrocarbons - analysis
Pressure
Tropical Climate
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Summary:Atmospheric transport and deposition of polycyclic aromatic hydrocarbons (PAHs) over tropical oceans has not yet been studied even though tropical oceans account for 35% of the global oceans. Here we show the results from measurements of gas- and aerosol-phase PAHs and dry deposition samples in the NE tropical Atlantic Ocean atmosphere, a region between 26° and 21° N, off shore of the Saharan desert. The results show that PAHs concentrations are high at the coastal ocean (15−20 ng m-3 for sum of 27 gas-phase individual PAHs) and decrease by a factor of 2−3 at open ocean (26° W). The spatial variability observed is consistent with dilution, reaction, and deposition during transport. Atmospheric dry deposition velocities ranged between 0.1 and 0.3 cm s-1 with higher deposition velocities for the more volatile PAHs. Outbreaks of Saharan Dust significantly increase the deposition rates of PAHs. The occurrence and deposition of PAHs in tropical regions is complex and results from the interplay of a number of processes, such as wind speed, aerosol loads, important sources from West Africa, processes controlling the diurnal variability, and sequestration driven by high primary productivity regions. The measured average atmospheric residence times of gas- and aerosol-phase PAHs are 3.7 and 3.5 days, respectively.
ISSN:0013-936X
1520-5851
DOI:10.1021/es0707660