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During the Fukushima Daiichi Nuclear Power Plant accident, tiny particles a few micrometers in diameter, known as highly radioactive cesium-rich microparticles (CsMPs), were released into the environment. Because these particles contain highly concentrated radioactive cesium, understanding their health impacts when inhaled and how they dispersed through the environment has been an important issue. In this study, we analyzed soil samples collected from 100 locations across F

Satoshi Utsunomiya received the 2025 Society Award from the Japan Association of Mineralogical Sciences (JAMS), the highest honor conferred by the society. The award recognizes sustained and internationally significant contributions to the advancement of mineralogical sciences and research on Earth and planetary materials.

Satoshi Utsunomiya was awarded the 2025 Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology (MEXT), Japan (Research Category). This national honor recognizes individuals or groups who have conducted original research or made inventions with significant potential to advance science and technology in Japan.

Following the 2011 Fukushima Daiichi nuclear accident, we discovered and characterized cesium-rich microparticles (CsMPs) that transport highly concentrated radionuclides in the environment. Using atomic-scale electron microscopy and isotopic analyses, we revealed embedded fuel nanofragments containing uranium and plutonium within these particles. Our work established quantitative methods to track CsMP dispersion and laid the foundation for advanced nuclear forensics.

We investigate how minerals, nanoparticles, and microorganisms interact to control radionuclide mobility at uranium mill tailings sites. Our research revealed nanoscale sequestration of U, As, and Ra through ferrihydrite–silica aggregation and fungal biogenic manganese oxides. By integrating geochemistry and geomicrobiology, we clarify natural attenuation mechanisms relevant to nuclear legacy management.

We apply atomic-resolution electron microscopy to reveal how gold and toxic elements occur at the nanoscale in ore minerals. Our pioneering work demonstrated that “invisible” gold in arsenian pyrite forms nanoparticles controlled by arsenic content and nanoscale phase separation. This nanogeoscience framework is now being applied to gold deposits in Taiwan, including the historic Chinkuashi mining district.

We use atomic-resolution electron microscopy to reveal previously unseen occurrences of trace and radioactive elements in geological and environmental materials. Our work includes the first direct imaging of Pb in Archean zircon and radioactive Cs atoms in solid materials, as well as nanoscale studies of radiation damage in nuclear waste forms. By integrating TEM with NanoSIMS and synchrotron-based analyses, we are establishing new multi-scale approaches in geochemistry.