Multielement analysis of insoluble particulates in solar salt by ICP-AES and ICP-MS in relation to geochemical consideration

The multielement determination of major-to-trace elements in insoluble part iculates of solar salt was carried out by ICP-AES and ICF-MS. A solar salt sample (30 g) was dissolved in 11 of pure water to adjust its solution sali nity to be almost the same as that of seawater. When the solar salt sample solution was filtered using a membrane filter (pore size 0.45 mu m), the re sidue on the filter was defined as the insoluble particulates and the filtr ate as the soluble constituents. The insoluble particulates were decomposed together with the membrane filter by an acid digestion method using HNO3, HF, and HClO4. As a result, 36 elements in the insoluble particulates could be determined at % to sub-mu g g(-1) levels by ICP-AES and ICP-MS. Taking into consideration the present results along with the analytical results fo r the soluble constituents reported in a previous paper, alkali elements, a lkaline earth elements, Ma and Cd were found mainly in the soluble constitu ents of solar salt, while Al, Ti, V, Fe, Co, Ga, Y Sn, and rare-earth eleme nts (REEs) were found in the insoluble particulates. Iron, Co, Y, Sn, and R EEs in the insoluble particulates were partly leached into the acid solutio n when the solar salt sample was dissolved in a 0.1 M HNO3 solution. Thus, it is considered that these elements are dissolved as colloidal matter adso rbed on particulates in seawater. On the other hand, because Mn, Cu, Zn, an d Pb were found in both the insoluble particulates and the soluble constitu ents, these elements in the insoluble particulates were easily leached in a 0.1 M HNO3 solution. These results indicate that Mn, Cu, Zn, and Pb are co ntained as acid-soluble forms in the insoluble particulates. Moreover, the relative abundances of the elements normalized to the Al concentrations in the insoluble particulates of solar salt and the marine sediment standard m aterial (NIES No. 12) showed a good linear correlation, which suggests that the insoluble particulates in solar salt are an origin of marine sediment.