Estimation of the transport of persistent organic pollutants via air-water exchange
requires precise field concentrations from advanced experimental techniques and
adequate physic-chemical parameters generated from proper methods. In this study,
concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated
biphenyls (PCBs) and hexachlorobenzene (HCB) in the ambient air and water column
of Kaohsiung Harbor lagoon were measured and used to determine the air-water
exchange fluxes of these compounds from December, 2003 to January, 2005. The
Whitman¡¦s thin-film model was used by taking temperature and salinity corrected
Henry¡¦s law constants into the model to calculate the fluxes. In addition, particulate
concentrations and composition in the ambient air and water column were used to
apportion PAH sources and dry particle deposition of PAHs, PCBs and HCB.
Instantaneous air-water exchange fluxes of PAHs, PCBs and HCB were calculated
from twenty-two pairs of air and water samples. The highest net volatile (+3560 ng
m-2 day-1) and absorptive (-1230 ng m-2 day-1) PAH fluxes in this study were both
obtained from the three-ring PAH, phenanthrene on April 7 and January 27 in 2004,
respectively. Differences of flux magnitude and direction between dry and rain season
were obvious for PAHs in this study. Most net fluxes of PCB homologues and HCB in
this study are from water to air (net volatilization). The highest net volatile flux
observed was +172 ng m-2 day-1 (dichlorobiphenyl) in December, 2003 due to
elevated wind speed and dissolved concentration, while the only net absorptive flux
observed in this study was -0.03 ng m-2 day-1 (dichlorobiphenyl) in January, 2004.
Mean daily PAH diffusive fluxes were -727 ng m-2 day-1 influx in dry season but +808
ng m-2 day -1 efflux in rain season and integrated 3.6 kg and 4.0 kg of PAHs were
absorbed into and emitted from harbor lagoon surface waters in dry and rain seasons,
respectively. The net PCBs and HCB fluxes suggest that the annual sum of 69 PCBs
and HCB measured in this study were mainly volatile (57.4 and 28.3 ¡Ñ103 ng m-2 yr-1,
respectively) and integrated 1.5 kg and 0.76 kg of PCBs and HCB emitted from
harbor lagoon surface waters to ambient atmosphere in the year.
Sources apportionment by the isomer ratios, PAHs in the air phase were mainly
from grass, wood and coal combustion and some from liquid fuel combustion. Unlike
that in air phase, fluoranthene / fluoranthene + pyrene ratios of water phase suggest
PAHs were from incomplete-combusted fuel particles emitted from vehicle exhaust.
Principal component analysis (PCA) extracted three meaningful PCs for air and water
samples, respectively. For the air samples, the three major sources suggested by three
sources are vehicular emissions, volatilization to the air from contaminated soil or
waters and the coal-burning emission. Among the water samples, the three major
sources suggested by three sources are vehicular emissions, oil spill source and
coal-burning emission. Air particulate concentrations of PAHs, PCBs and HCB were
also used to calculate their dry particle deposition. Throughout our sampling
campaigns, PAH dry particle fluxes were quite comparable to fluxes of air-water
exchange. On the contrary, PCB and HCB dry particle deposition flux were negligible
comparing to their air-water exchange fluxes. Our results suggest PAHs exhibits
strong absorptive or weaker volatile fluxes in the dry season but the opposite in the
rain season. However, for PCBs and HCB, Kaohsiung Harbor water is potentially an
important source to ambient air.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0727107-073713 |
| Date | 27 July 2007 |
| Creators | Fang, Meng-der |
| Contributors | Wei-Hsien Wang, Jia-Jang Hung, Chon-Lin Lee, Jen-Fon Jen, Jen-Taie Shiea, Huey-Ing Chen |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0727107-073713 |
| Rights | withheld, Copyright information available at source archive |
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