A trace amount of lead on adsorbent Mg6Fe2(OH)(16)(CO3)(.)3H(2)O was selectively monitored by XAS combined with a fluorescence spectrometer. In the presence of dominant scattered and emitted X-rays derived from heavy elements (Fe and Mg), large quantities of heavy elements predominantly absorb the incident photons and the X-ray fluorescence derived from trace amounts of elements is very weak compared to scattered + emitted X-rays derived from heavy elements. Pb Lalpha(1) emission was counted during XAS measurements with a fluorescence spectrometer of energy resolution of 1.1 eV. The obtained spectrum was compared to the spectra for standard Pb2+ compounds. The ion exchange mechanism FeO(OH) + Pb2+ --> FeO-OPb+ + H+ was rejected, but a eutectic mixture of PbCO3 and Pb(OH)(2) may be coagulated on the basic surface of adsorbent.