Wet Deposition of Fission-Product Isotopes to North America from the Fukushima Dai-ichi Incident, March 2011

Abstract

Using the infrastructure of the National Atmospheric Deposition Program (NADP), numerous measurements of radionuclide wet deposition over North America were made for 167 NADP sites before and after the Fukushima Dai-ichi Nuclear Power Station incident of March 12, 2011. For the period from March 8 through April 5, 2011, wet-only precipitation samples were collected by NADP and analyzed for fission-product isotopes within whole-water and filterable solid samples by the United States Geological Survey using gamma spectrometry. Variable amounts of (131)I, (134)Cs, or (137)Cs were measured at approximately 21% of sampled NADP sites distributed widely across the contiguous United States and Alaska. Calculated 1- to 2-week individual radionuclide deposition fluxes ranged from 0.47 to 5100 Becquerels per square meter during the sampling period. Wet deposition activity was small compared to measured activity already present in U.S. soil. NADP networks responded to this complex disaster, and provided scientifically valid measurements that are comparable and complementary to other networks in North America and Europe.

Cesium-134 and 137 activities in the central North Pacific Ocean after the Fukushima Dai-ichi Nuclear Power Plant accident

“…Uniformly distributed 134 Cs within a 50-100 m thick mixed layer with activity of 10 Bq m −3 represents fallout of 500-1000 Bq m −2 . Although representative of only a very small area from the Pacific, it would be orders of magnitude higher than wet deposition of 0.47-180 Bq m −2 of 134 Cs measured on the North American continent (Wetherbee et al, 2012). Based on available data, these are the highest observed inventories and deposition rates in the far-field Pacific outside of the immediate vicinity of Fukushima.…”

Short-term dispersal of Fukushima-derived radionuclides off Japan: modeling efforts and model-data intercomparison

“…1 of Kristiansen et al, 2012; Table 5 of Stohl et al, 2012; National Atmospheric Deposition Program; Fig. 1 of Wetherbee et al, 2011), and while the nearshore (within 30 km of the coast) ocean discharge was monitored by both the Japanese government (MEXT, 2011b) and the power company (TEPCO, 2011) for the first few…”

Cadmium and other elements in tissues from four ungulate species from the Mackenzie Mountain region of the Northwest Territories, Canada

“…Macdonald et al (2007) used 134 Cs as a marker to estimate the amount of longer-lived 137 Cs (t½¼ 30.2 years) in barren-ground caribou in Canada from the Chernobyl reactor accident in 1986. Emissions from the Fukushima nuclear plant began on March 12, 2011 and the plume reached North America on approximately March 19, 2011 (Wetherbee et al, 2012). Cesium isotopes were among the major isotopes released from the beginning of the accident, with equal amounts of 134 Cs and 137 Cs (i.e., 134 Cs: 137 Cs ¼1) (Wetherbee et al, 2012).…”

“…A second objective is to investigate the factors behind the accumulation of elements, including Cd, in the four ungulate species by correlating elemental patterns with the diets in each ungulate species inferred from stable isotope signatures in muscle samples, and to examine interspecific and intertissue relationships with other metals and radionuclides. Due to the timing of the study in 2011, muscle tissues were also analysed for man-made radioisotopes (e.g., 134 Cs and 137 Cs) that were dispersed during the reactor accident in Fukushima Japan in March, 2011 (Wetherbee et al, 2012).…”