Fig. 5From: Atmospheric radioactivity over Tsukuba, Japan: a summary of three years of observations after the FDNPP accidentActivity ratio of 137Cs/90Sr in monthly depositions since March 2011 at the MRI. The temporal changes do not show a clear decreasing or increasing trend. The arrow shows the month during which an anomalous deposition of 90Sr was observed. Except for the anomaly, the 137Cs/90Sr activity ratio fluctuated from approximately 150 to 6700Back to article page