| Summary: | 博士 === 國立中山大學 === 海洋地質研究所 === 84 === Humic substances can absorb the energy of solar radiation and
transfer it to produce singlet oxygen in aqueous system.
Singlet oxygen has higher reactivities to oxidize many organic
compounds than the ground state triplet oxygen. In this
research, the photooxidization of 4 different kinds of
polycyclic aromatic hydrocarbons (PAHs), including naphthalene
, anthracene, phenathrene and pyrene were studied. Humic
substances can act as photosensitizer in the photoreaction of
PAHs. The photooxidization rate of PAHs in humic water was
faster than that without the existance of humic substances. The
effects of soil humic substances are higher than those of the
marine ones. The more rings the PAHs have, the slower
photooxidization is. Changes in salinity and pH do not alter
the photooxidization rates of PAHs, however, the higher
concentration of humic substances or higher temperature can
speed up the sensitized photoreaction. The addition of Ni2+ or
Cu2+ can retard the indirect photoreaction rate, but the
addition of Zn2+ makes no difference. Comparing the
photoreaction rates irradiated with light sources of 546nm or
435nm wavelength, faster reaction rate was observed for the
light with shorter wavelength. The PAHs themselves can also
produce singlet oxygen under irradiation even without humic
substances. The reactivities of PAHs to 3O2 are in the
following order : naphthalene > anthracene > phenanthrene >
pyrene. For 1O2, the reactivities are : naphthalene >
anthracene > phenanthrene > pyrene.
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