Atsuyuki OHTA (DSc), Geochemist, Chief Senior Researchers in Geological Survey of Japan, AIST

Research interests

Speciation of minor metals in soils and sediments, particle transfer from land to marine environment, statistical analysis of geochemical data (geochemical map)

Current job

XAFS spectroscopy

• Evaluation of local coordiantion and speciation of lanthanoid complexes using XANES spectra <view>

Speciation study of metal elements in soil, lake, stream and marine sediments

• Cr speciation in geochemical reference materials <view>
  Fate of contaminant Cr6+ in sediments and soil
• Cu speciation in geochemical reference materials <view>
  Identification and quantification of various chemical species in sediments and soil
• Zn speciation in geochemical reference materials <view>
  Difficulty in identifing Zn speciation quantitatively in sediments and soil

Analytical chemistry

• Selecting suitable Be carrier minerals for the measurement of low-level 10Be  < view>
• Optimizing the Pratt-type titrimetric method to determine FeO in geochemical reference materials <view>

Geochemical mapping

• Application of geochemical maps for provenance study < view>
  Watershed analysis for geochemical mapping in Japan;
  Classification of stream sediment samples by the dominant lithology in a drainage basin
• Land and marine geochemical maps of the Kyushu region, western Japan <view>
  Transformation process of sandy sediments on the shelf by strong oceanic current;
  Chemical index of source rock composition in marine sediments

Fundamental study on regional geochemical maps of 87Sr/86Sr ratios

• Grain-size variations in 87Sr/86Sr and elemental concentrations of stream sediments < view>
  Influence of weathering process on 87Sr/86Sr of stream sediments
• Comparing the 87Sr/86Sr of the bulk and exchangeable fractions in stream sediments <view>
  For provenance analysis of food production and archaeological substances