Changes in concentrations of 131I, 134Cs and 137Cs in leafy vegetables, soil and precipitation in Tsukuba city, Ibaraki, Japan, in the first 4 months after the Fukushima Daiichi nuclear power plant accident

Abstract

Concentrations of 131I: iodine-131, 134Cs: cesium-134 and 137Cs: cesium-137 in leafy vegetables, soil and precipitation after the Fukushima Daiichi nuclear power plant accident were investigated at Tsukuba city, approximately 170 km from the nuclear power plant. The first precipitation after the accident was on March 21–23, 2011, and contained an amount of radionuclides. The concentration of 131I in leafy vegetables, particularly spinach (Spinacia oleracea L.), was significantly increased because of dry deposition of the first radioactive plume. The concentrations of 131I, 134Cs and 137Cs in soil were significantly increased by the first precipitation on March 21–23; however, the contribution of precipitation to the concentrations of 131I, 134Cs and 137Cs in leafy vegetables was smaller than that in soil. Changes in the concentrations of 131I, 134Cs and 137Cs differed between spinach and komatsuna (Japanese mustard; Brassica campestris var. peruviridis).