A proton microprobe scanning across the vertebra of a flat fish,Paralichthys olivaceus

Elemental distributions across the vertebra of a flat fish were determined by a 100×300 μm proton scanning microprobe. By normalizing with proton currents, 22 elements demonstrated characteristic patterns in locality; Si, Ca, Cr, Ga, Sr, and I were homogeneous across the vertebral centrum, whereas concentrations of P, Ti, V, Co, Ni, Cu, Hg, Se, and Br were increasingly higher toward the inside of the centrum. Opposite results were obtained for S and Cl, and especially Fe, which showed gradually lower concentrations toward the center. The K, Mn, and Zn were higher in concentration at both edges, showing a minimum value at the middle of the vertebra centrum, where Pb was at a maximum in its distribution. The fact that such a thin intervertebrale membrane contains relatively large amounts of Cl, K, Ca, Fe, Zn, Pb, Br, and I is interesting.