Satoshi Utsunomiya

A major challenge to the development of a fundamental understanding of transport and retardation mechanisms of trace metal contaminants (<10 ppm) is their identification and characterization at the nanoscale. Atomic-scale techniques, such as conventional transmission electron microscopy, although powerful, are limited by the extremely small amounts of material that are examined. However, recent advances in electron microscopy provide a number of new analytical techniques that expand its applicat

Exposure to airborne particulates containing low concentrations of heavy metals, such as Pb, As, and Se, may have serious health effects. However, little is known about the speciation and particle size of these airborne metals. Fine- and ultrafine particles with heavy metals in aerosol samples from the Detroit urban area, Michigan, were examined in detail to investigate metal concentrations and speciation. The characterization of individual particles was completed using high-angle annular dark-f

Particulates emitted from coal-burning power plants typically contain very small amounts of uranium (<10 ppm). Because of the extremely low concentrations, the form of the uranium has been unknown. Using a variety of advanced electron microscopy techniques, we have identified for the first time nanocrystals of uraninite, UO2+x, encapsulated in carbonaceous matter (< or = 50 nm) similar to fullerene. We have also identified, for the first time, closely associated fullerenes, C60. The "carbon-cage

Trace U was released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) during the meltdowns, but the speciation of the released components of the nuclear fuel remains unknown. We report, for the first time, the atomic-scale characteristics of nanofragments of the nuclear fuels that were released from the FDNPP into the environment. Nanofragments of an intrinsic U-phase were discovered to be closely associated with radioactive cesium-rich microparticles (CsMPs) in paddy soils collected ∼4 km

A new mode of arsenic incorporation into arsenian pyrite has been discovered. Electron microprobe analyses and elemental maps of arsenian pyrite from Pueblo Viejo, Dominican Republic, show that its chemical composition varies from (Fe0.998As0.003)1.001S2 to (Fe0.963As0.050Cu0.003Ag0.001)1.017S2 and that arsenic is inversely correlated with Fe. High-resolution transmission electron microscopy (HRTEM) images show that some arsenic in this pyrite is present as nanoscale inclusions of amorphous As-

Colloid-like nanoparticles in groundwater have been shown to facilitate migration of several radionuclides: (239,240)Pu, 137Cs, (152,154, 155)Eu, and 60Co. However, the exact type of nanoparticle and the speciation of the associated radionuclides has remained unknown. We have investigated nanoparticles sampled from the far-field at the Nevada Test Site, Nevada, utilizing advanced electron microscopytechniques, including high-angle annular dark-field scanning TEM (HAADF-STEM). Fissiogenic element

Highly radioactive cesium-rich microparticles (CsMPs) were released from the Fukushima Daiichi nuclear power plant (FDNPP) to the surrounding environment at an early stage of the nuclear disaster in March of 2011; however, the quantity of released CsMPs remains undetermined. Here, we report a novel method to quantify the number of CsMPs in surface soils at or around Fukushima and the fraction of radioactivity they contribute, which we call "quantification of CsMPs" (QCP) and is based on autoradi

Radioactive Cs isotopes (137Cs, t1/2 = 30.07 y and 134Cs, t1/2 = 2.062 y) occur in severely contaminated soils within a few km of the Fukushima Dai-ichi nuclear power plant at concentrations that range from 4×10^5 to 5×10^7 Bq/kg. In order to understand the mobility of Cs in these soils, both bulk and submicron-sized particles elutriated from four surface soils have been investigated using a variety of analytical techniques, including powder X-ray diffraction analysis (XRD), scanning electron mi