Spatial and seasonal variations in groundwater chemistry in the Owasawa river alluvial fan, Northeast Japan
Abstract
Monthly regular groundwater observations and analyses were conducted during the year of December 2017 - November 2018 to elucidate spatial and seasonal change in hydrochemistry of spring and well waters in the Owasawa river alluvial fan, located in the southern part of Hirosaki city, Aomori prefecture, Japan. Groundwater in the alluvial fan is dominated by Ca-HCO3 or Ca-SO4 type and increases the concentrations of Na+, Ca2+, Cl-, SO42- and NO3- along the flow paths from the apex to the toe of fan alluvial. The agricultural areas are expanding in the central part of fan alluvial, potentially impacting the groundwater quality due to significant nitrate fertilizer application. Furthermore, the seasonal variation of the NO3- and Cl- concentration seemed to be due to the effective transfer of surface polluted water. In snow and ice period, surface water hinder to recharge groundwater because the ice block the subsurface transport pathways. The δD and δ18O values of the samples are -65 to -56 ‰ and -10.5 to -7.9 ‰ versus SMOW, respectively. The isotopic trend of groundwaters is similar to the global meteoric water line, suggesting that either the water had a short residence time with little chance to interact with the local geology or that the waters have not reached high enough temperatures to initiate significant water/rock interactions.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H21J1880N
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0466 Modeling;
- BIOGEOSCIENCES;
- 1828 Groundwater hydraulics;
- HYDROLOGY;
- 1849 Numerical approximations and analysis;
- HYDROLOGY