2023 Volume 132 Issue 2 Pages Cover02_01-Cover02_02
This well is located in an alluvial lowland area in the western coastal part of Tokyo Bay. In Shinagawa area, there still remain a number of wells with hand pumps, which were used as domestic water sources in the past. This well is 9.1 m deep and its screen width is unknown. The hand pump on this well is covered with an orangecloth because it is currently out of order.
Although the public sewerage coverage ratio of Tokyo's Shinagawa area is 99.5% (Bureau of Sewerage Tokyo Metropolitan Government1)), the results of an end member mixing analysis (EMMA) based on the δ15N-NO3 and nitrogen concentration suggest sewage is seeping into the groundwater sampled from this well. And its Cl− concentration is higher than that of groundwater sampled in nearby areas. Meanwhile, other water quality results indicate a lower NO3− concentration (n.d. −5 mg/L), a higher HCO3− concentration (120-200 mg/L), and a lower ORPSHE (50-200 mV), despite seasonal variations, which are signs of denitrification under an anaerobic environment (Itoh et al., 2023).
(Photograph: Yuki ITOH; Explanation: Seongwon LEE)
Note
1) 東京都下水道局下水道100%普及達成年次表
https://www.gesui.metro.tokyo.lg.jp/living/a2/spread/tasseinennzi/index.html [Cited 2023/1/28].