Japan Geoscience Union Meeting 2018

Presentation information

[EJ] Evening Poster

A (Atmospheric and Hydrospheric Sciences) » A-HW Hydrology & Water Environment

[A-HW23] Residence time of groundwater / surface water and water / mass cycle processes in watershed

Thu. May 24, 2018 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Maki Tsujimura(Faculty of Life and Environmental Sciences, University of Tsukuba), Shigeru Mizugaki(PWRI Public Works Research Institute), Masanori Katsuyama(京都大学農学研究科, 共同), Maksym Gusyev(International Centre for Water Hazard Risk Management, Public Works Research Institute)

[AHW23-P06] Spatial distribution of residence time and total number of prokaryotes in spring water in headwater catchments underlain by different lithology

*Yuki Imaizumi1, Maki Tsujimura1, Chisato Yamamoto1, Ayumi Sugiyama1, Mahiro Ogawa1, Koichi Sakakibara1, Kenji Kato2, Shigeru Mizugaki3, Masanori Katsuyama4, Takuya Yamada4, Shinjiro Yano5, Naoya Sasakura5, Maksym Gusyev6, Uwe Morgentem7, Michael Kilgour Stewart7 (1.University of Tsukuba, 2.Shizuoka University, 3.Civil Engineering Research Institute for Cold Region, 4.Kyoto University, 5.Suntory Global Innovation Center, 6.ICHARM, 7.GNS Science, New Zealand)

Keywords:Chlorofluorocarbons, Sulfur hexafluoride, total number of prokaryotes, residence time, groundwater storage

The residence time in the spring water and groundwater is principle to understand the groundwater flow system in the mountainous area. Chlorofluorocarbons (CFCs) and Sulfur hexafluoride (SF6) are useful as the tracers for age dating of the young groundwater, especially it is effective in the headwaters Japan, where the young groundwater less than 50 years is dominant. Also, a possibility of microbe as a tracer for groundwater flow path has been investigated recently, however, there are few studies focusing on the relationship between residence time and total number of prokaryotes in the groundwater in different lithology. In this study, we focused on the spring water, and estimated the residence time using CFCs and SF6 as tracers, and counted the total number of prokaryotes in mountainous headwater catchments underlain by granite, sedimentary rock, basalt, and serpentine, Japan, and spring located Christchurch area underlain by marine sediment, New Zealand. We aim to investigate the spatial distribution of the residence time and the microbe information in the spring water focusing on the groundwater flow dynamics in Japan and New Zealand. The residence time in granite area ranged from 2.2 years to 29.4 years and that in sedimentary rock area ranged from 7.8 years to 15.5 years. The total number of prokaryotes ranged from 103 to 105 cells/mL in granitic area and 104 to 106 cells/mL in sedimentary rock area. The total number of prokaryotes in the spring water with younger residence time tends to show wide variation in values ranging from 103 to 106 cells/mL, whereas that of older spring water tends to converge on 103 cells/mL. Generally, the groundwater with older residence time has deeper groundwater flow path, also, there is a report that the total number of prokaryotes in the groundwater decreases with depth. Therefore, we could find a relationship between the residence time and total number of prokaryotes. In addition, the total number of prokaryotes tends to be smaller as the groundwater storage becomes larger. It seems to be explained by the groundwater flow characteristics mentioned above.