Additional Groundwater Sampling and Analysis in the Investigation of Deep Groundwater (DH-15 Hole)

Hama, Hiroshi*; Yamada, Tsuyoshi*; Ide, Mitsuyoshi*; Takahashi, Eiichiro*; Yamamoto, Katsuya*; Nakajima, Toshihide*; Watabe, Takeo*

JNC TJ7440 2005-074, 270 Pages, 1995/05

JNC-TJ7440-2005-074.PDF:17.59MB
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In 1997, DH-5 hole was drilled at P.N.C.(present J.N.C.) Toki Branch of Tono Geoscience Centr in Gifu prefecture. The borehole was drilled to a depth of 502.3 meters in Toki granite in order to investigate the deep groundwater. This report describes the investigation of the groundwater conducted at depth from 323.8 to 330.8 meters to make clear geological, hydrogeological and geochemical characteristics of study area. The investigation includes the following items;i) Sampling of the groundwaterii) Measurement of physical chemistry parameters of the groundwater in the borehole iii) Chemicaal analysis of the main composition of the groundwater during the continuous samplingiv) Chemical analysis of the groundwater It has become clear the following points;* The physical chemistry parameters of groundwater was alkalic, low deoxidize and buffer ability. There were few total ions and sulfide ions in the groundwater.* The isotopic analysis showed that the groundwater was regarded as rainwater in origin on the side of the Pacific Ocean and was relatively young with the age of a few decades.* According to the tri-linear diagram, the groundwater was classified into Ca(HCOtype. Based on hydrochemical facies, the groundwater was classified into Casup+ Naand HCOClSOin the cation and anion facies, respectively.* Nitrite oxidizing bacteria, nitrite reducing bacteria and nitrate reducing bacteria were detected in the groundwater by the bacteria analysis.