・ Volcanic ash may be natural fertilizer through weathering ( efflorescence )
Natural volcanic ashes are quite full of adsorption, they fall with various metallic ions and gases.
During an eruption, not only large quantities of vapors but also various gases such as carbon dioxide, nitrogen, hydrogen sulfide, sulfur dioxide, chlorine are issued from a crater.
They selectively adsorb various matters dependently on individual natures.
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