『Abstract
　In order to elucidate the sources of metals in urbanized areas, metal contents and Pb isotope ratios were determined in road-side dust and sediments samples collected from Tokyo, Osaka and Kyoto. The samples were leached using 1% HNO3 for metal concentrations and Pb isotopes analysis. Metal (Pb, Cd, Zn, As, Cr and Ni) concentrations and Pb isotopes (²⁰⁶Pb, ²⁰⁷Pb and ²⁰⁸Pb) in the solutions were analyzed by Inductively Coupled Plasma-Mass Spectrometry (ICP-MA). The extent of anthropogenic contribution to road-side dust was assessed by comparing the metal concentration values in road-side dust of the sample sites to those of Okinawa, an unpolluted road-side dust site due to low traffic density. Considering a Pb background of 21.0 ppm measured in the Okinawan road-side dust, Pb in road-side dust of Tokyo was found to be about twelve times higher which may indicate Pb pollution in the streets of Tokyo. The contaminated road-side dust can be transported into pond and river sediments during runoff and rainfall events. The concentrations of anthropogenic Pb in road-side dust and sediment were compared to those of other metals (Cd, Zn, As, Cr and Ni). There was a positive correlation found between Pb with Cd, Ni and Zn concentrations in sediment which suggests a common origin. The range of the Pb isotope ratios in road-side dust agreed well to that in the sediments (²⁰⁷Pb/²⁰⁶Pb = 0.8644-0.8688 and ²⁰⁸Pb/²⁰⁶Pb = 2.1044-2.170) suggesting that sediments may be contributed and transported by mean of road-side dust. Moreover, Pb isotope ratios (²⁰⁸Pb/²⁰⁶Pb and ²⁰⁷Pb/²⁰⁶P) confirmed that Pb pollution in the road-side dust and sediments was contributed the combination of battery and solder products.

Keywords: Metal; Road-side dust; Sediment; Tokyo; Okinawa; Pb isotope ratios』

1. Introduction
2. Geological setting
3. Materials and methods
　3.1. Sample collection
　3.2. Procedure for leaching
　3.3. ICP-MS analysis
4. Results and discussion
　4.1. Metal contents in road-side dust and sediment
　4.2. Lead isotope ratios in road-side dust and sediment
5. Conclusion
Acknowledgements
References