碘是一种化学性质活泼的卤族元素,在自然界只能以化合状态存在。碘的化合物分散度大、溶解性强,所有的碘化物都溶于水,所以在陆地上流动性大,迁移能力强。在地球化学演化中,碘单向集中在地表大气圈、水圈和生物圈。地壳中的碘可以不经过成岩成矿直接由火山喷出地表。 Iodine is a chemically active halogen element that exists in nature only in a compound state. Iodine compound dispersion, solubility, all of the iodide are soluble in water, so the flow of land on the large, strong migration ability. In geochemical evolution, iodine unidirectionally concentrates on the surface atmosphere, hydrosphere and biosphere. The iodine in the crust can be ejected directly from volcanoes without diagenesis and mineralization.