Presumption of the Source of Lead Contaminated Soil by Isotope Analysis with Sequential Extraction

Abstract

Isotope analysis of lead in fractions (1–5), fractionated by a sequential extraction procedure for contaminated soil found in the ground of Asahikawa and Iwamizawa stations of Hokkaido Railroad Company (JR Hokkaido), have been carried out. The amounts of lead in fractions 3 and 4 were relatively larger than that in the other fractions. The lead isotope ratio of the fraction 1–4 for each soil sample was different from that of each fraction 5. The lead isotope ratio of fractions 1–4 of Iwamizawa soil was not the same as those of Asahikawa. The isotope ratio of lead in white metal which was used as an axle bracket of freight car, was close to those of fractions 1–4 of Iwamizawa soil. The presence of tin was found in Iwamizawa soil, and the ratio of the amount of tin to lead in the soil was near the ratio of that in a kind of WM. Therefore, it is presumed that the source of contamination with lead in Iwamizawa soil is due to the WM used previously in JR Hokkaido. Tin was not detected in Asahikawa soil. Thus, the source may be different from that of Iwamizawa.