Environmental radioactivity baseline in Ho Chi Minh City, Vietnam: A five-year (2018–2022) multi-matrix monitoring study

Authors:
  • MNMai Van Nguyen
    Mai Van Nguyen
  • VDVan-Hoang Dao
    Van-Hoang Dao
  • TNTuyen Duc Ninh
    Tuyen Duc Ninh
  • HNHoang-Long Nguyen
    Hoang-Long Nguyen
  • BNBang Thai Van Nguyen
    Bang Thai Van Nguyen
  • NDNhan Thanh Thi Doan
    Nhan Thanh Thi Doan
  • DHDoanh Van Ho
    Doanh Van Ho
  • HLHuu-Loi LE
    Huu-Loi LE
  • NNNam Hoai Van Nguyen
    Nam Hoai Van Nguyen
  • SOSong Quang Ong
    Song Quang Ong
  • TVTien Van Vo
    Tien Van Vo
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Abstract
A five-year (2018-2022) monitoring programme of naturally occurring radioactive material (NORM) was implemented in Ho Chi Minh City (HCMC; population ~9.3 million) to establish the first measurement-based environmental radioactivity baseline for a Vietnamese megacity. Atmospheric aerosol, surface soil, surface water, and indoor 222Rn were investigated at eight spatially representative stations. Activity concentrations were determined using high-purity germanium (HPGe) gamma-ray spectrometry, gas-flow proportional alpha/beta counting, CR-39 solid-state nuclear track detectors, and RAD7 continuous radon spectrometry under harmonised quality assurance protocols. Aerosol radionuclide concentrations remained temporally invariant over the monitoring period (Kruskal-Wallis, p>0.10), with mean activities of 0.15-0.20 µBq m-3 (238U), 0.16-0.19 µBq m-3 (232Th), and 0.11-0.12 µBq m-3 (40K). Soil activities showed significant inter-district variability (p<0.05), ranging from 19.9-48.3 Bq kg-1 (238U), 28.1-66.5 Bq kg-1 (232Th), and 227-509 Bq kg-1 (40K), consistent with sedimentary provenance rather than anthropogenic inputs. Gross beta activity concentrations in Saigon River water (0.159-0.187 Bq L-1) and Tan Quy Dong wastewater treatment plant influent (0.419 ± 0.015 Bq L-1) were below the WHO screening level (1 Bq L-1). Indoor 222Rn concentrations exhibited a geometric mean of 23 Bq m-3, corresponding to annual effective doses of 0.54-0.82 mSv y-1. Radiological indices (Raeq: 117.4-150.8 Bq kg-1; ELCR: 0.235-0.296 × 10-3) indicate low radiological risk relative to regional urban environments. No anthropogenic radionuclides were detected. The dataset provides a reference baseline supporting UNSCEAR reporting and future environmental impact assessments associated with Vietnam’s nuclear energy development.

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