Masaharu TANIMIZU

Major research field

All of materials consist of about 90 elements in the periodic table. My curiosity is to understand circulation mechanism (such as residence time, flux, and budges) of various inorganic elements in the earth surface, from crust and sea floor to the stratosphere. Nowadays emission of anthropogenic elements to the environment is one of the most important concerns to us typically after the industrial revolution. Increase of atmospheric CO₂ is a well-known case, but that is also true for heavy/metallic elements. Anthropogenic lead (Pb) input is the most terrible case, and the earth’s surface is heavily polluted due to leaded gasoline exhaust from automobiles via atmosphere in the 20^th century. Addition of this toxic Pb compound is highly restricted in the developed countries from the 1970’s for the human health, but still operated in some developing countries for a higher performance of gasoline in the engines. My current research is focused on detection of special and temporal variation of anthropogenic elements in the environment using state-of-the-art analytical instruments.

Typical samples are lake sediments, peat, coral, seawater, ground water and so on. To distinguish heavy elements originated from natural sources (e.g. soil, volcanic ash), precise isotope ratios of elements like Zn, Ni, Hg, B, and Sb are determined by mass spectrometry as well as their concentrations and chemical species. Their chemical behavior in various environments is estimated from the information, and will be applied for a better understanding of potential future environmental impact.

Main research themes

• Determination of natural isotopic variation of heavy elements among environmental samples
• Development of chemical purification techniques of analyte from high matrix samples
• Development of precise isotopic determination of heavy elements

Major publications

1. Tanimizu, M., Sohrin, Y., and Hirata, T. Heavy element stable isotope ratios: analytical approaches and applications (invited review). Anal. Bioanal. Chem., 405, 2771-2783, (2013).
2. Tanimizu, M., Sugiyama, N., Ponzevera, E., and Bayon, G. Determination of ultra-low ²³⁶U/²³⁸U isotope ratios by tandem quadrupole ICP-MS/MS. J. Anal. At. Spectrom., 28, 1372-1376, (2013).
3. Inoue, M. and Tanimizu, M. Anthropogenic lead inputs to the western Pacific during the 20th century. Sci. Total Environ., 406, 123-130, (2008).
4. Tanimizu, M., Asada, Y., and Hirata, T. Absolute isotopic composition and atomic weight of commercial zinc using inductively coupled plasma mass spectrometry. Anal. Chem., 74, 5814-5819, (2002).
5. Takano, S., Tanimizu, M., Hirata, T., and Sohrin, Y. Isotopic constraints on biogeochemical cycling of copper in the ocean. Nature Comm., 5, No.1663 (2014).
6. Yoshimura, T., Tanimizu, M., Inoue, M., Suzuki, A., Iwasaki, N., and Kawahata, H. Mg isotope fractionation in biogenic carbonates of deep-sea coral, benthic foraminifera and hermatypic coral. Anal. Bioanal. Chem., 401, 2755-2769 (2011).