| Summary: | 博士 === 國立中山大學 === 海洋環境及工程學系研究所 === 103 === The distribution, partitioning and air-water exchange fluxes of polycyclic aromatic hydrocarbons (PAHs) were determined in the Hengchun Peninsula of southern Taiwan. The concentrations of total PAH in atmosphere (t-PAH; gas + particulate) and seawater (dissolved + particulate) ranged from 0.43～4.40 ng m-3 and 2.1 ~34.3 ng L-1, respectively. The highest levels of t-PAH concentrations in atmosphere were found during the NE season. Long-range transport and rainfall scavenging mechanisms could contribute to seasonal variations atmospheric t-PAH concentrations. There was significant spatial difference in PAH concentrations in seawater among the sampling stations. The higher t-PAH concentrations were found in estuary stations of Hunwan. The variations of t-PAH concentrations in seawater of Hunwan were influenced by land runoff.
The PAH compositional pattern, principal component analysis (PCA) and results from back trajectories demonstrated the major sources of atmospheric PAHs in Hengchun Peninsula, southern Taiwan were vehicular emissions. The seasonal variations in PAH concentration and composition were influence by Asian monsoon system. Gas-particle partition coefficients (Kp) of PAHs were well-correlated with the sub-cooled liquid vapor pressures (PoL), suggesting that the gas-particle partition of PAHs follows the characteristic of PAHs. The shallower slopes of log Kp versus log PoL suggest the presence of non-exchangeable fraction of PAHs in particle, likely associated to the soot carbon phase. The PAH compositional pattern, isomeric ratios and PCA of the Hengchun Peninsula coasts suggested that the source of PAHs in the Hengchun Peninsula coastal waters mostly from petroleum. The significant spatial difference between the spring and summer samples might be affected by a combination of land runoff and coastal currents. The partition coefficients between the particulate and dissolved phase (logKoc) were positively correlated with their logKow values, and higher than predicted values. The results suggest that the PAH associated with particles are present the extremely strongly bound, which could be attributed to the present of soot-like particles.
Air–water exchange fluxes of 4 polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in air and water samples from two sites in Hengchun Peninsula, from January to December 2010. The net fluxes of phenanthrene and pyrene were volatilization from water to air, and fluoranthene and chrysene were absorption from air to water. Due to PAH annual fluxes though air-water exchange, the seawater in Hengchun Peninsula is a source of low molecular weight PAHs and a reservoir of high low molecular weight PAHs.
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