PROBLEM TO BE SOLVED: To provide a material, when a silicic acid having high availability for diatoms is eluted as a nutrient salt for the diatoms, capable of efficiently supplying an ocean with the silicic acid in a use of an inorganic oxide material of a silicic system such as a slag for a hydrosphere.SOLUTION: An aquatic environment restoration material causes multiple silicic acids in a chemical state, which is useful for the diatoms, to elute into the hydrosphere by carbonating the surface of the inorganic oxide material of the silicic system such as a slag or making it coexist with carbonate.【課題】スラグなどケイ酸系の無機酸化物材料の水圏での利用において、ケイ酸をケイ藻類への栄養塩として溶出させる際に、ケイ藻類利用性の高いケイ酸を効率的に海洋に供給できる材料を提供する。【解決手段】スラグなどケイ酸系の無機酸化物材料の表面を炭酸化させるか又は炭酸塩と共存させることにより、無機酸化物材料からのケイ酸溶出時に炭酸イオンを共存させ、ケイ藻類に有用な化学状態のケイ酸をより多く水圏に溶出させる。【選択図】図１
