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    Radiation Measurement Results of Sea Water Samples in Hong Kong Waters

    In response to the discharge of nuclear-contaminated water from Fukushima of Japan, the Hong Kong Observatory has increased the frequency of radiation monitoring of sea water samples in local waters since July 2023, from once a quarter to about once a month.

    During the period of enhanced monitoring, a total of 22 sea water samplings were conducted and the radiation measurement results did not show abnormalities. Details of the latest measurement are as follows:

    Sampling date Sampling depth(1) Type of analysis and measurement result(2)
    Tritium(3) Artificial gamma-emitting radionuclides
    7 April 2025 Upper level Not detected Not detected
    Middle level Not detected Not detected
    Lower level Activity about 0.7 Bq/L;
    within the range of measurement results over the past years(2)    		 Not detected
    Remarks:
    • (1) Sea water samples are collected at three depths, namely, the upper level (2.5 metres underneath the surface), the middle level (equidistant from the surface and the seabed) and the lower level (2.5 metres above the seabed).
    • (2) Based on the measurement results of the "Environmental Radiation Monitoring Programme" (ERMP) of the Observatory over the past years, the activity of tritium in sea water samples in Hong Kong waters is within 6 Bq/L, and no artificial gamma-emitting radionuclides have been detected. The methods of sampling and measurement, as well as the measurement results of the ERMP can be found in the programme This link will open in a new windowreports.
    • (3) After the collection of sea water sample, treatment of the sample is required for the radioactivity analysis of tritium. It takes about one week for the sample treatment and analysis.
    Updated on: 14 April 2025

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