FY2017 Results of the Radioactive Material Monitoring in the Water Environment March 2019 Ministry of the Environment Contents Outline .......................................................................................................................................................... 5 1) Radioactive cesium ................................................................................................................... 6 (2) Radionuclides other than radioactive cesium .......................................................................... 6 Part 1: National Radioactive Material Monitoring Water Environments throughout Japan (FY2017) ....... 10 1 Objective and Details ........................................................................................................................... 10 1.1 Objective .................................................................................................................................. 10 1.2 Details ...................................................................................................................................... 10 (1) Monitoring locations ............................................................................................................... 10 1) Public water areas ................................................................................................................ 10 2) Groundwater ......................................................................................................................... 10 (2) Targets ..................................................................................................................................... 11 (3) Frequencies and periods ........................................................................................................ 11 (4) Conducted analyses................................................................................................................ 11 (5) Evaluation of measurement results ........................................................................................ 11 1) Comparison with the past measurement trends .................................................................... 11 2) Measures to be taken when a value deviating from the past measurement trends was detected ....................................................................................................................................... 12 2)-1 Release of preliminary values ........................................................................................... 12 2)-2 Detailed analyses and release of the results .................................................................... 12 (6) Disclosure of measurement results ....................................................................................... 13 2 Survey Methods and Analysis Methods .............................................................................................. 23 2.1 Survey methods ....................................................................................................................... 23 (1) Public water areas .................................................................................................................. 23 (2) Groundwater .......................................................................................................................... 24 2.2 Analysis methods ..................................................................................................................... 24 3 Results ................................................................................................................................................. 26 3.1 Detection of total β radioactivity and γ-ray emitting radionuclides .......................................... 26 (1) Public water areas .................................................................................................................. 26 1) Water ..................................................................................................................................... 26 2) Sediment ............................................................................................................................... 28 (2) Groundwater .......................................................................................................................... 30 3.2 Discussion regarding detected radionuclides .......................................................................... 32 (1) Detection of naturally occurring radionuclides ....................................................................... 32 1) Correlation between activity concentrations of K-40 in water samples and seawater ......... 32 2) Uranium and thorium series radionuclides in sediment samples ......................................... 35 (2) Detection of artificial radionuclides ........................................................................................ 38 1) Cs-134 and Cs-137 in water samples from public water areas ........................................... 38 2) Cs-134 and Cs-137 in sediment samples from public water areas ...................................... 39 i (i) Comparison with past Post-Earthquake Monitoring results within the same prefectures .... 40 (ii) Comparison with past Post-Earthquake Monitoring results for nearby locations ................ 42 (iii) Comparison with the data obtained from the Monitoring of Levels, etc. ............................ 43 3) Cs-134 and Cs-137 in groundwater ...................................................................................... 45 3.3 Survey to check annual variation ............................................................................................. 46 Part 2: Radioactive Material Monitoring in Water Environments in and around Fukushima Prefecture (FY2017) ..................................................................................................................................................... 52 1 Objective and Details ........................................................................................................................... 52 1.1 Objective .................................................................................................................................. 52 1.2 Details ...................................................................................................................................... 52 (1) Locations ................................................................................................................................ 52 (2) Targets .................................................................................................................................... 52 (3) Frequencies and periods ....................................................................................................... 52 (4) Conducted analyses............................................................................................................... 52 (5) Compilation and evaluation of results .................................................................................... 52 2 Survey Methods and Analysis Methods .............................................................................................. 54 2.1 Survey methods ....................................................................................................................... 54 2.2 Analysis methods ..................................................................................................................... 54 3 Outlines of the Results ........................................................................................................................ 55 3.1 Detection of radioactive cesium ............................................................................................... 55 (1) Public water areas (water) ..................................................................................................... 55 (2) Groundwater .......................................................................................................................... 55 (3) Public water areas (sediment) ............................................................................................... 55 1) Overall trends ........................................................................................................................ 55 2) Status by location .................................................................................................................. 56 3.2 Detection of radionuclides other than radioactive cesium ....................................................... 58 (1) Sr-89 and Sr-90 ...................................................................................................................... 58 (2) Other artificial radionuclides ................................................................................................... 58 4 Results ................................................................................................................................................. 59 4.1 Radioactive cesium .......................................................................................................................... 59 4.1 -1 Water .................................................................................................................................... 59 (1) Public water areas .................................................................................................................. 59 1) Rivers ...................................................................................................................................