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ID 14183
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title alternative
Discharge process of groundwater with highly concentrated nitrogen to the beach
creator
林 政輝
竹井 務
峯 孝樹
斎藤 光代
重枝 豊実
吉田 浩二
subject
discharge process
dissolved nitrogen
groundwater
slopy beach
NDC
Pollution. Environmental engineering
abstract
To clarify discharge process of groundwater with highly concentrated nitrogen into the sea, we observed subsurface flow and nitrate flux with tidal variation, using piezometer method. We installed a paire of piezometers with various depths at 3 plots on a relatively slopy beach in Ikuchijima Island, measured hydraulic head and collected water at all piezometers and a well at distance of 100m to landward from the shoreline inland area at two hours interval from 6-am to 6-pm on June 6, 2004. Water samples were analyzed for Cl-and DN(Dissolved Nitrogen), respectively. Groundwater discharge was confirmed at the vicinity of shoreline, mixing with seawater. Because it stopped during the High tide, groundwater contribution ratio increased below the shoreslope. Nitrogen concentration in groundwater at the landward well was high, whereas, it declined in the subsurface water below the shoreline. We estimated the DN concentration of beach subsurface water, based on the mixing process of inland groundwater with seawater. The calculated one was extremely higher than actual one. Theses results suggest denitrification on the beach. In addition, based on this research, the difference between calculated and actual ones was large in stagnant subsurface water with high groundwater contribution ratio during the high tide. We confirmed the dynamics of nitrate decline and two types of water mixing processes with tidal variation.
journal title
Memoirs of the Faculty of Integrated Arts and Sciences, Hiroshima University. IV, Science reports
volume
Volume 30
start page
87
end page
96
date of issued
2004-12
publisher
広島大学総合科学部
contributor
国立情報学研究所
issn
1340-8364
ncid
SelfDOI
language
eng
nii type
Departmental Bulletin Paper
HU type
Departmental Bulletin Papers
text version
publisher
department
Graduate School of Integrated Arts and Sciences
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