9:45 AM - 10:00 AM
[HTT16-04] Distribution of trace element concentrations in groundwater and spring water near coastal and inland area of Fukushima prefecture
Keywords:coastal area of Fukushima prefecture, groundwater flow, water quality, stable isotopes of oxygen and hydrogen, trace elements
The salination or water quality change for some parts of groundwater neat the coastal area in Fukushima prefecture was occurred which was caused by the tsunami of the 2011 off the Pacific coast of Tohoku Earthquake. As a result of investigation from April 2012, it was obviously that multiple groundwater flows were existed and it was related with the depth of groundwater or aquifer. The recharge area of groundwater and spring water were mainly divided into two groups by the oxygen and hydrogen stable isotopes and dissolved component concentration of water; one is plateau near the coastal area, the other is highland around the Abukuma mountains (Yabusaki, 2020). This result agrees with the residence time estimated by the CFCs and SF6. Furthermore, it may be more cleared by using the multiple tracers.
The 51 trace elements of groundwater, spring water and river water in this study area sampled from April in 2014 to August in 2020 were analyzed by ICP-MS (Agilent 7500cx). As a result of analysis, concentration of B, Al, Mn, Fe, Zn, Sr and Ba was relatively high in some sites. Especially, Mn and Fe were extremely high near the coastal area (exceed 500 μg/L of Mn and exceed 10,000 μg/L of Fe), it is probably influenced by the local geological condition. Sr concentration for all sites was from 10 to 900 μg/L, it was higher near the coastal area in Minami-soma City and Shinchi Town than the inland area. In the former area was affected by the tsunami. Sr concentration of sea water is very high about 7.8 mg/L (Nozaki, 1997), so the Sr concentration near the coastal area might be high caused by the tsunami. Because in these sites water quality indicated Na-Cl and dissolved concentration was relatively high, this result suggested mentioned earlier. As a result of trace element analysis, it is considered trace element concentration reflected the difference of geology and residence time, and also influence of tsunami.
In future, we will measure the 87Sr/86Sr of groundwater and spring water in this study area, and will consider the recharge area and groundwater flow system by using the multi-tracer methods.
(References)
Yabusaki, S. (2000): Yabusaki, S. (2020): Characteristics of water quality and estimation of the recharge area in the northern part of the coastal area, Fukushima prefecture. Journal of Groundwater Hydrology, 62(3), 449-471.
Nozaki, Y. (1997): Updated (1996 version) table of the elements in seawater and its remarks. Bulletin of the Society of Sea Water Science, Japan., 51(5), 302-308.
The 51 trace elements of groundwater, spring water and river water in this study area sampled from April in 2014 to August in 2020 were analyzed by ICP-MS (Agilent 7500cx). As a result of analysis, concentration of B, Al, Mn, Fe, Zn, Sr and Ba was relatively high in some sites. Especially, Mn and Fe were extremely high near the coastal area (exceed 500 μg/L of Mn and exceed 10,000 μg/L of Fe), it is probably influenced by the local geological condition. Sr concentration for all sites was from 10 to 900 μg/L, it was higher near the coastal area in Minami-soma City and Shinchi Town than the inland area. In the former area was affected by the tsunami. Sr concentration of sea water is very high about 7.8 mg/L (Nozaki, 1997), so the Sr concentration near the coastal area might be high caused by the tsunami. Because in these sites water quality indicated Na-Cl and dissolved concentration was relatively high, this result suggested mentioned earlier. As a result of trace element analysis, it is considered trace element concentration reflected the difference of geology and residence time, and also influence of tsunami.
In future, we will measure the 87Sr/86Sr of groundwater and spring water in this study area, and will consider the recharge area and groundwater flow system by using the multi-tracer methods.
(References)
Yabusaki, S. (2000): Yabusaki, S. (2020): Characteristics of water quality and estimation of the recharge area in the northern part of the coastal area, Fukushima prefecture. Journal of Groundwater Hydrology, 62(3), 449-471.
Nozaki, Y. (1997): Updated (1996 version) table of the elements in seawater and its remarks. Bulletin of the Society of Sea Water Science, Japan., 51(5), 302-308.