摘要：It was found that Lake Nurume has the structure composed of two water layers differing in chemical composition. Concentrations of major dissolved components in the upper layer are nearly the same as those of sea water and the lower layer has 1.5 times greater major ion concentration than sea water. Formation of this two-layer structure can be ascribed to the following processes. The major ion concentration and chemical composition of the pond water and the geographical position of Lake Nurume, suggest that the lower layer was made by concentration of the original pond water which was sea water in the past, and then sea water flowed into the pond to make the upper layer.
