Atmospheric distribution of polycyclic aromatic hydrocarbons and deposition to Galveston Bay, Texas, USA

Estimates of the atmospheric deposition to Galveston Bay of polycyclic arom atic hydrocarbons (PAHs) are made using precipitation and meteorological da ta that were collected continuously from 2 February 1995 to 6 August 1996 a t Seabrook, TX, USA. Particulate and vapor phase PAHs in ambient air and pa rticulate and dissolved phases in rain samples were collected and analyzed. More than 95% of atmospheric PAHs were in the vapor phase and about 73% of PAHs in the rain were in the dissolved phase. Phenanthrene and napthalene were the dominant compounds in air vapor and rain dissolved phases, respect ively, while 5 and 6 ring PAH were predominant in the particulate phase of both air and rain samples. Total PAH concentrations ranged from 4 to 161 ng m(-3) in air samples and from 50 to 312 ng l(-1) in rain samples. Temporal variability in total PAH air concentrations were observed. with lower conc entrations in the spring and fall (4-34 ng m (-3)) compared to the summer a nd winter (37-161 ng m(-3)). PAHs in the air near Galveston Bay are derived from both combustion and petroleum vaporization. Gas exchange from the atm osphere to the surface water is estimated to be the major deposition proces s for PAHs (1211 mug m(-2) yr(-1)), relative to wet deposition (130 mug m(- 1) yr(-1)) and dry deposition (99 mug m(-1) yr(-1)). Annual deposition of P AHs directly to Galveston Bay from the atmosphere is estimated as 2 t yr(-1 ). (C) 2001 Elsevier Science Ltd. All rights reserved.