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No.26 (1978/09) >

Title :沖縄本島南部地区の水質
Title alternative :Study of Ground Waters on both GIJI and KIAN Watersprings in Southern OKINAWA
Authors :兼島, 清
大森, 保
山田, 保
Authors alternative :Kaneshima, Kiyoshi
Oomori, Tamotsu
Yamada, Tamotsu
Issue Date :Sep-1978
Abstract :The ground waters on both GIJI and KIAN have been collected, to discuss the geochemical nature of waters on southern OKINAWA during the last two years. In this paper, the time dependence of chemical compositions in ground waters on both watersprings collected from June 1976 to December 1977 was studied and discussed with the consideration of regional variation at clay and limestone areas. It was found out from this work that the ground waters at clay area were largely affected by rain-fall. The water level and K^+ ion concentration rised rapidly with the rain-fall but the concentration of Ca^<++> HCO^-_3, Mg^<++>, SiO_2, Cl^- and Na^+ ions decreased along with. The chemical compositions in waters at limestone area, however, remained comparatively unchanged as to compared with at clay area under the rain-fall of measured 90 mm. When it rained heavely through, the water level rised and the chemical compositions were affected considerably giving almost the same patterns with at clay area execpt for Na^+ and Cl^- ions. The K^+ ions in both areas seem to be contaminated from the human activities. Since the water at GIJI waterspring have not been used for long time, the water was pumped out completely with the intervals of once a week during from Sept. 19th to Nov. 28th to check the circulation of the ground water. After pumping up, the concentration of all chemical compositions in water changed largely. The result showed that the concentrations of Ca^<++>, Mg^<++>, HCO^-_3, SiO_2, Na^+ and Cl^- increased apparently whereas the K^+ and SO^=_4 ions decreased. The HCO^-_3, SiO_2, Na^+, Mg^<++> and K^+ concentrations are higher in clay area than at limestone area whereas the SO^=_4 concentration gave the lower values in clay area. The higher positive correlations among Ca^<++>, SiO_2, Mg^<++>, Na^+, Cl^- and HCO^-_3 with each other were observed in waters at GIJI area. The same correlations among Ca^<++>, SiO_2 and HCO^-_3 were observed in waters at KIAN area. These components in KIAN and GIJI areas were considered to be resulted from the interactions between water and limestone or clay materials at underground. The other components such as Na^+ and Cl^-, however, are affected by sea water significantly. The values of K^+ /Cl^- and SO^=_4/Cl^- ratios increased in inverse proportion to concentration of Cl^- in water on GIJI and KIAN areas. The geochemical considarations of excess Ca^<++>, Mg^<++>, Na^+, SO^=_4 and K^+ were discussed in detail in this paper.
Type Local :紀要論文
Publisher :琉球大学理工学部
URI :http://hdl.handle.net/20.500.12000/24154
Citation :琉球大学理工学部紀要. 理学編 = Bulletin of Science & Engineering Division, University of Ryukyus. Mathematics & natural sciences no.26 p.53 -83
Appears in Collections:No.26 (1978/09)

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