[A-HW31] Water Environment and Geology in Urban Areas

[AHW31-P04] Investigation of the origin of microplastics detected in shallow groundwater in downtown Shinagawa, Tokyo, Japan

★Invited Papers

*Yuki Itoh¹, Seongwon Lee², Masaya Yasuhara² (1.Graduate School of Geo-Environmental Science, Rissho University , 2.Faculty of Geo-Environmental Science, Rissho University)

Keywords:Microplastics (MPs), urban area, shallow groundwater, sewage leakage

Microplastics (MPs) concentrations and type of MPs in shallow groundwater in the densely populated Kita-Shinagawa area and Minami-Shinagawa area, coastal lowland along Tokyo Bay, were studied. Groundwater samples were collected in July 2024 (wet summer season) from the wells of less than 12 m deep and about 500 m apart from the coastline. The results revealed that MPs (fibers and particles) were contained in its groundwater at a concentration as high as 75.8 L-1. Representative MPs were analyzed using FT-IR, and they were identified as PAA, PAN, Polyester, PEUR, PE, PET, PP and PVAc. Considering sewage leakage is responsible for more than 20% of shallow groundwater recharge at some wells in the summer of 2024 (Itoh et al., 2025), it is most likely that origin of MPs detected in the wells in this study is attributed to domestic sewage leakage, one of the important sources of urban groundwater recharge. Underground leaking rainwater pipes also are likely to be another possible pathway that brings MPs into groundwater.
This work was supported by the Sasakawa Scientific Research Grant from The Japan Science Society and Research Support Fund (Type 2) from Rissho University Research Promotion and Community Collaboration Center.