Distributions of elements into natural salt from coastal seawater in a natural-salt preparation process

The distributions of major-to-ultratrace elements into natural salt from co astal seawater in a salt-preparation process were investigated by ICP-AES ( inductively coupled plasma atomic emission spectrometry) and ICP-MS (induct ively coupled plasma mass spectrometry) with preconcentration using a chela ting resin. The coastal seawater samples were collected off-shore near to t he Nie coast, where Agehama-made salt is produced by a classical Agehama me thod. Natural salt was produced from original coastal seawater in the labor atory in a similar manner to the Agehama method. First, the seawater sample s were filtered with a membrane filter (pore size of 0.45 mu m), and the el ements in the dissolved fraction (filtrate) and in the particulate fraction (particulate on the filter) were determined by ICP-AES and ICP-MS. The ana lytical results for seawater indicate that alkali elements, alkaline earth elements, and oxoanion-forming elements (V, Mo, W, U) were dominantly in th e dissolved fraction, while other elements such as Al, Fe, Pb and rare eart h elements were mostly in the particulate fraction. The elements in laborat ory-made salt and Agehama-made salt were also determined by ICP-XES and ICP -MS after dissolving them in a 0.1 M HNO3 solution. Although the concentrat ions of trace elements in laboratory-made salt and Agehama-made salt were a lmost at the same levels for 27 elements among 34 elements within a factor between ca. 1/5 and 5, Ba, Mn, Cd and Pb in Agehama-made salt were much hig her (8-30 fold) in concentration than those in the laboratory-made salt. Ba sed on the experimental results mentioned above, the distributions of major -to-ultratrace elements into natural salt from seawater were discussed, tak ing into consideration the preparation process of natural salt.