| Research Abstract |
The reaction products obtained from the mixture of 1-nitropyrene (1-NP) and Cl ion were investigated on three metallic oxides as soil components under xenon lamp irradiation in the presence of indoor air. These chemicals including 1-NP were extracted with benzene:ethanol (4:1, v/v) and analyzed by GC/MS. The amounts of 1-NP gradually decreased as the irradiation time elapsed on three metallic oxides [titanium dioxide (TiO_2), silicon dioxide (SiO_2) and aluminum oxide (Al_2O_3)). Especially, in TiO_2, 1-NP was decreased at high levels in comparison with the other two sorts of metallic oxides in all irradiation time. On the other side, six sorts of DNPs (1,3-, 2,4-, 1,2-, 1,6-, 1,8- and 1,7- DNP) were detected from the reaction products. In TiO_2 and Al_2O_3, all of six sorts of DNPs were detected, in SiO_2, five sorts of DNPs were confirmed except for 2,4-DNP. Especially, in TiO_2, 1,7-DNP was formed in rich amounts in comparison with the other two sorts of metallic oxides in all irrad
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iation time. We presumed that 4- and 2-NPs were generated from 1-NP by the photochemical reaction of OH radical, continuously 2,4-, 1,2- and 1,7-DNPs were formed by the nitration of these isomers. The formation of 2,4-, 1,2- and 1,7-DNPs was confirmed for the first time on the metallic oxides by photochemical reaction system of the 1-NP-NOx-CI ion. NOx in the indoor air was shown to be a nitrogen source to form DNPs in these metallic oxides. The yields and the formation patterns of DNPs differed in three metallic oxides as the irradiation time was extended. Hence, the nature of the photochemical reaction in the formation of DNPs differed depending on the type of metallic oxides. In SiO_2, mutagenicity was gradually increased up to 6 hrs irradiation and the mutagenic potency was exhibited 2.6 million revertants/total extract at 6 hr and then decreased to 1.5 million revertants/sample at 12 hrs. In Al_2O_3, mutagenicity was gradually increased as the irradiation time elapsed (1.64 million revertants/sample). In TiO_2, mutagenicity was rapidly decreased to 60 % at 10 min. and gradually decreased to 22% at 12 hrs. Three chloronitropyrenes (CNP) were produced in the reaction mixture. 1-Chloro-3-nitropyrene (1,3-CNP), 1,6-CNP and 1,8-CNP were detected in surface soil collected in Kyoto, Japan. First, 1,3-, 1,6- and 1,8-CNPs were synthesized by chlorination of 1-nitropyrene. Surface soil was collected in Kyoto, Japan and analyzed for 1,3-, 1,6- and 1,8-GNPs by two-dimensional high-performance liquid chromatography with fluorescence detection and a zinc on-line catalytic column. 1,3-CNP, 1,6-CNP and 1,8-CNP were detected in the ranges 9.2-13.8, 3.4-4.6 and 4.3-5.0 pg per gram of soil (n=2), respectively. Less
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