FY2016 Results of the Radioactive Material Monitoring in the Water Environment March 2018 Ministry of the Environment Contents Outline .......................................................................................................................................................... 1 Part 1: National Radioactive Material Monitoring in the Water Environment in the Whole of Japan (FY2016) ...................................................................................................................................................................... 5 1 Objective and Details ............................................................................................................................. 5 1.1 Objective .................................................................................................................................... 5 1.2 Details ........................................................................................................................................ 5 2 Survey Methods and Analysis Methods .............................................................................................. 18 2.1 Survey methods ....................................................................................................................... 18 2.2 Analysis methods ..................................................................................................................... 19 3 Results ................................................................................................................................................. 21 3.1 Detection of total β radioactivity and γ-ray emitting radionuclides .......................................... 21 (1) Public water areas .................................................................................................................. 21 1) Water ..................................................................................................................................... 21 2) Sediments ............................................................................................................................. 23 (2) Groundwater .......................................................................................................................... 25 3.2 Consideration regarding detected radionuclides ..................................................................... 27 (1) Detection of naturally occurring radionuclides ....................................................................... 27 1) Correlation between activity concentrations of K-40 and salinity ......................................... 27 2) Uranium and thorium series radionuclides ........................................................................... 30 (2) Detection of artificial radionuclides ......................................................................................... 33 1) Cs-134 and Cs-137 in sediments ......................................................................................... 33 2) Cs-134 and Cs-137 in water ................................................................................................. 41 3) Cs-134 and Cs-137 in groundwater ...................................................................................... 41 3.3 Survey to check annual variation ............................................................................................. 42 Part 2: Radioactive Material Monitoring in the Water Environment in and around Fukushima Prefecture (FY2016) ..................................................................................................................................................... 46 1 Objective and Details ........................................................................................................................... 46 1.1 Objective .................................................................................................................................. 46 1.2 Details ...................................................................................................................................... 46 2 Survey Methods and Analysis Methods .............................................................................................. 48 2.1 Survey methods ....................................................................................................................... 48 2.2 Analysis methods ..................................................................................................................... 48 3 Outline of the Results .......................................................................................................................... 49 3.1 Detection of radioactive cesium ............................................................................................... 49 3.2 Detection of radionuclides other than radioactive cesium ....................................................... 52 4 Results (Radioactive cesium (Cs-134 and Cs-137)) ........................................................................... 53 4.1 Water ........................................................................................................................................ 53 (1) Public water areas .................................................................................................................. 53 1) Rivers .................................................................................................................................... 53 i 2) Lakes ..................................................................................................................................... 53 3) Coastal areas ........................................................................................................................ 53 (2) Groundwater .......................................................................................................................... 53 4.2 Sediments ................................................................................................................................ 60 (1) Public water areas (rivers) ..................................................................................................... 60 (2) Public water areas (lakes) ...................................................................................................... 60 (3) Public water areas (coastal areas) ........................................................................................ 60 4.3 Detection of radioactive materials in sediments by location .................................................... 67 (1) Evaluation policy .................................................................................................................... 67 (2) Concentration levels in sediment samples from rivers, lakes, and coastal areas and their changes by prefecture ................................................................................................................. 70 (2)-1 Rivers .................................................................................................................................. 70 (2)-2 Lakes ................................................................................................................................. 105 (2)-3 Coastal areas .................................................................................................................... 131 (3) Conclusion............................................................................................................................ 142 5 Results (Radionuclides Other than Radioactive Cesium) ................................................................. 151 5.1 Radioactive strontium (Sr-90 and Sr-89) ............................................................................... 151 (1) Public water areas ................................................................................................................ 151 (2) Groundwater ........................................................................................................................ 155 5.2 Other γ-ray emitting radionuclides ......................................................................................... 156 Part 3: Other Radioactive Material Monitoring Conducted Nationwide (FY2016) ................................... 158 1 Outline of the Monitoring ................................................................................................................... 158 1.1 Covered monitoring ................................................................................................................ 158 1.2 Compilation methods ............................................................................................................. 158 2 Results ............................................................................................................................................... 161 2.1 Water ...................................................................................................................................... 161 (1) Inland water .......................................................................................................................... 161 (2) Seawater .............................................................................................................................. 162 2.2 Sediments .............................................................................................................................. 163 (1) Inland water sediments (river sediments) ...........................................................................