ADSORPTION OF AMMONIUM AND PHOSPHATE IONS AND EFFECT OF ION COMPONENTS IN GROUNDWATER BY ASO VOLCANIC ASH SOIL

Physical properties were examined about Aso volcanic ash soil which is considered to be the origin of Kuroboku soil in Kumamoto prefecture. It is revealed that the volcanic ash soil is low in Al2O3 ratio which means its capability of becoming ''active Al'', and is large in pore s ize and small in specific surface area. The adsorption of ammonium and phosphate ions on the Aso volcanic ash soil and accompanying elution of constituent elements were examined by passing a NH4H2PO4 solution ( 1-3000 mu g/ml) through a column (10 cm diameter and 75 cm long) of th e soil sample. The adsorbed amounts of NH4+ and PO43- were 0.042 and 0 .688 mg/g, respectively. Na+, K+, Ca2+, Mg2+, and SO42- were eluted fr om the ash soil were observed during the adsorption reaction by use of 1 mu g/ml of the NH4H2PO4 solution.