Polycyclic aromatic hydrocarbons(PAHs) are one of major classes of organic pollutants that transport through air-sea exchange in the environment. The objectives of this study were to quantify the PAHs concentrations in air and seawater and calcu-late the exchange fluxes by using Whitman¡¦s two-film mode. Spatial and temporal distributions were also determined through the sampling strategy of this study. In ad-dition, particulate concentrations in the ambient air were used to estimate the dry de-position fluxes of PAHs.
Seasonal fluxes of PAHs in Gao-Ping coastal areas ranged from -2020 to +320 ng/m2day. The net gas exchange fluxes were negative (net absorption) in August, No-vember and March but positive (net volatilization) in May at Kaohsiung Harbor (KH), Off Shore (OFS) and Gao-ping River Estuary (GRE). Howerer negative exchange fluxes were found in each sampling month at Liu-Chiu Isle (LCI). In contrast, Lanyu Isle (LI) showed a different tend in exchange fluxes. It¡¦s exchange fluxes were all positive in each sampling month and ranged from the +121 to +1020 ng/m2day. Mostly the net fluxes of low molecular weight PAHs were volatile; while high molecular weight PAHs were absorptive. The compound with highest flux was mostly phenanthrene, therefore, it dominates the gas exchange fluxes in Gao-Ping coastal areas.
The highest average net gas exchange fluxes among stations were observed at LCI (-1650 ng/m2day) and decreased in the following order: GRE (-932 ng/m2day), KH (-824 ng/m2day), OFS (-523 ng/m2day), LI (+358 ng/m2day). Dry particle deposi-tion fluxes were higher in November and March. The high molecular weight PAHs were found predominant in these particles. Even adding up with the wet deposition, the magnitude of total deposition fluxes(dry+wet) were still lower than those of gas exchange. Therefor, gas exchange is the main transport pathway for PAHs in Gao-Ping coastal areas.
By identifying composition patterns of PAHs in each sample, source of PAHs in dissolved phase were mainly from traffic emission. However, KH is indicative of in-dustrial and petrogenic souces; while grass and wood combustion and petrogenic might be the dominant source of PAHs at LI. In gas phase, sources of PAHs were mostly from combustion, including traffic emission and diesel combustion. Finally, the transport pathway of the airflow was analyzed through back trajectory analysis. The results show that the PAH concentrations in gas phase might be affected by re-gional pollution in August and May, and long-rang atmospheric transport in March at Gao-Ping coastal areas and LI. Local origin was suggested for PAHs from Gao-Ping coastal areas in November and March.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0217111-181129 |
| Date | 17 February 2011 |
| Creators | Lin, Ju-Chieh |
| Contributors | Chien-Ming Chen, Chon-Lin Lee, Meng-Der Fang, Jin-Sing Lai |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0217111-181129 |
| Rights | not_available, Copyright information available at source archive |
Page generated in 0.0022 seconds