Distribution characteristics of dissolved iron concentration and redox potential in groundwaters in the central Tokyo district

Abstract

Groundwater in urban area has a great potential in the near future for certain purposes including water for emergency uses, non-potable domestic consumption, landscape, and spraying. In order to evaluate the potential based on the groundwater quality, the concentration of dissolved iron and redox potential were measured with their spacial distribution in the aquifer using 103 groundwater samples in central Tokyo. Groundwater samples obtained from unconfined Musashino gravel layers and confined Kazusa layers had comparatively high redox potential and low concentration of dissolved iron, which met the drinking water quality standard of 0.3 mg/L as total iron. On the contrary, groundwater abstracted from unconfined Yurakucho layers and Tokyo layers, had low redox potential and high dissolved iron concentration most of which was in the form of ferrous iron. These results suggested that iron removal may be required for the future uses of groundwaters that contain high iron concentration in the central Tokyo district.