The 38th Global COE Special Seminar was held on December 7, 2011. Dr. Masaharu Tanimizu, Deputy Leader of the research group of isotope geochemistry in Kochi Institute for Core Sample Research, JAMSTEC delivered a lecture on the “Current situation on methods of high-accuracy isotope analysis of metallic elements – Suitability as an environmental indicator”. Dr. Tanimizu firstly gave a brief explanation on isotopes (stable and radioactive) and its application for scientific researches. Secondly, he introduced the recent progress in the isotope analysis of metallic elements using Multicollector-Inductively Coupled Plasma Mass Spectrometer (MC-ICP-MS) which makes possible both high-accuracy and high-sensitivity isotope measurements of heavy elements.

In the lecture, Dr. Tanimizu presented multiple examples of his research and current projects using isotopes of metal elements such as lead (Pb), zinc (Zn), antimony (Sb), magnesium (Mg) etc. For example, isotope ratios of Pb (²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb) in Porites australiensis were used to determine the sources of Pb load and its long-term variation. The results suggested an increase in the input of Pb from China in recent years. In another project, isotope ratios of Zn were used to confirm the source of contaminant (e.g. aerosol, residue of smelting) in an industrial area. Besides, Dr. Tanimizu introduced results of an ongoing study on the dynamics of Sb in nature near an abandoned mine site in Ehime prefecture.

Dr. Tanimizu answered many questions asked after his talk. For example, he suggested the availability of Pb isotope for the study on beach litters. The seminar by Dr. Tanimizu was very informative to all the members because of the wide application of the technology. The seminar gave us a great opportunity to obtain knowledge on cutting edge technology and gave us ideas to generate new projects. The young scientists showed great enthusiasm which was very much encouraging.