Atmospheric distributions and deposition of polycyclic aromatic hydrocarbons (PAHS), polychlorinated biphenyls (PCBS), and organochlorine pesticides to Galveston Bay and Corpus Christi Bay, Texas.

摘要

Atmospheric, precipitation, and meteorological data were collected from February 2, 1995 to August 6, 1996 at Galveston Bay and from August 20, 1998 to September 16, 1999, at Corpus Christi Bay to estimate atmospheric deposition of PAHs, PCBs and chlorinated pesticides.; More than 95% of atmospheric PAHs were in the vapor phase. Phenanthrene and napthalene were the dominant compounds in vapor and dissolved phases, respectively, while 5 and 6 ring compounds were predominantly present on the particulate fraction. PAHs in the air are derived from both combustion activities and vaporization of petroleum. Gas exchange between the atmosphere and surface water is estimated to be the major deposition process for PAHs in Galveston Bay while wet deposition is dominant in Corpus Christi Bay. Annual deposition of PAHs directly to the bay and from the watershed was small compared to the typical oil spill and land run off.; In Galveston Bay, vapor tPCB in air contained high portion of PCBs containing 3 chlorines, while dissolved tPCBs in rain contained high portion of PCBs containing 4 chlorines. α- and γ-HCHs, α- and γ-chlordanes, 4,4′-DDT, and dieldrin were the pesticides and metabolites found predominantly in air and rain samples. Elevated concentrations of PCBs in the air occurred when temperatures were high and wind came from urban and industrialized areas (S, SW, NW, and W of the site). Other pesticides showed no notable temporal variation. When winds originated from the Gulf of Mexico (southeasterly), lower concentrations of organochlorines were found in the air samples. Outgassing of historical inputs of PCBs from Galveston Bay to the atmosphere appears to be the dominant process.; In Corpus Christi Bay, monthly variations in the concentrations of PAHs and PCBs in the air were not significant (p > 0.05). The estimation of atmospheric deposition indicates that Corpus Christi Bay is acting as a net sink for PAHs and as a net source for PCBs to the atmosphere, The daily and annual gas exchange fluxes of most pesticides appear to be approaching the equilibrium between atmosphere and bay water (flux in is nearly equal to flux out).; The results of this study show that contaminants circulate between environmental compartments and our understanding of these important exchange processes are limited.