Historical trends of N-cyclohexyl-2-benzothiazolamine, 2-(4-morpholinyl)benzothiazole, and other anthropogenic contaminants in the urban reservoir sediment core

A new potential molecular marker, N-cyclohexyl-2-benzolhiazolamine (NCBA), was discovered in Various environmental matrices (i.e., road dusts, runoff- and river-water particles, river sediments, aerosols) taken in Tokyo, Japa n. Concurrent determination of this compound together with 2-(4-morpholinyl )benzothiazole (24MoBT), previously proposed marker of road dust, demonstra ted that both compounds are widely distributed in the urban environment (si milar to ng/g to similar to mu g/g), derived from Vehicle tire tread, and t ransported in the environments in the same way. To assess utilities of NCBA and 24MoBT as molecular markers for vehicle-derived contaminants, these co mpounds were analyzed in a sediment core from the Chidorigafuchi Moat of Im perial Palace, situated in the center of Tokyo. Remarkable is that NCBA exi sted at higher concentrations than 24MoBT near the surface (0-6 cm depth) a nd bottom parts (16-24 cm depth) of the region where BTs were detected hut lower in the middle parts (6-16 cm depth). Dating of the core by using Cs-1 37 and tetrapropylene-based alkylbenzenes (TABs) revealed the two changeove rs coincide well with changes in the production history of vulcanization ac celerators containing the compounds. The dated downcore profile of Sigma BT s (sum of 24MoBT and NCBA) showed positive correlation with the traffic dat a in Tokyo Metropolitan Area. These results indicate the usefulness of NCBA and 24MoBT as time markers for recent sections of sediment cores and as mo lecular markers for reconstructing the history of traffic-induced contamina tion.