About YOKOTA KYOHEI
About volcanic ash
About content(quantity)
About water pollutants
About volcano
About water quality test
About water quality standard
About pollution monitoring
About Mt.Asosan
About elution amount
About Water quality research and measurement in general
About Geochemistry of lithosphere in general
About 河川水質
About 火山灰
About 降灰
About 阿蘇山
About 噴火