Re-construction and updating our understanding on the global weapons tests 137Cs fallout

Abstract

Global nuclear weapons tests fallout of 137Cs in the northern hemisphere has been documented in the UNSCEAR (United Nations Scientific Committee on the Effect of Atomic Radiation) reports. However, many questions have arisen during the past three to four decades; e.g. the water column inventory of 137Cs in the North Pacific Ocean was two to three time higher than the cumulative decay corrected fallout at the same latitude as stated in the UNSCEAR reports. Here we show more precise spatial distribution of global 137Cs fallout primarily on the basis of global measurements in rain, seawater and soil, as data from 10 degrees x 10 degrees grids. A typical feature of geographical distribution is that two high global 137Cs fallout areas exist in the northern hemisphere, where the highest 137Cs fallout was observed in the globe. These areas correspond to crossovers of areas where larger precipitation amounts were expected and where higher stratosphere-troposphere exchange was expected. Our new estimate of 765 +/- 79 PBq as global 137Cs fallout for the northern hemisphere is 1.4 times higher than that of 545 PBq in the UNSCEAR reports.

Cesium, iodine and tritium in NW Pacific waters – a comparison of the Fukushima impact with global fallout

“…The main input into this part of the ocean occurred in the early 1960s due to wet and dry deposition of 137 Cs, after large-scale atmospheric nuclear weapons tests were carried out during 1961-1962 by the former Soviet Union at Novaya Zemlya in the Kara Sea (Livingston and Povinec, 2002). The major deposition of 137 Cs occurred in the mid-latitudes of the Northern Hemisphere, and specifically in the NW Pacific Ocean where large wet depositions were observed (Aoyama et al, 2006). The NW Pacific Ocean has therefore been well known as the area with the highest deposition of global fallout radionuclides into the ocean (Povinec et al, 2005a;Inomata et al, 2009).…”

“…Fortunately, the pre-Fukushima 137 Cs concentrations in NW Pacific waters were well established (Povinec et al, 2005a;Aoyama et al, 2006). Two marine radioactivity databases were developed: one at the International Atomic Energy Agency's Environment Laboratories in Monaco (the GLOMARD/MARIS database; Povinec et al, 2004Povinec et al, , 2012b and the second one at the Meteorological Research Institute 5484 P. P. Povinec et al: Cesium, iodine and tritium in NW Pacific waters in Tsukuba (the HAM database; Aoyama and Hirose, 2004 Fig.…”

When did the Anthropocene begin? A mid-twentieth century boundary level is stratigraphically optimal

“…This testing is the major cause of distribution of human-made radionuclides over the globe. The small particles of radioactive debris from nuclear explosions (global fallout) were injected into the stratosphere where they circulate globally and re-entry from the troposphere to the Earth's surface being deposited worldwide (Ritchie and McHenry, 1990;Aoyama et al, 2006).…”

Improvement of 137Cs analysis in small volume seawater samples using the Ogoya underground facility

“…1 137 Cs is one of the most useful traces of water motion in the ocean because the ocean input process is well characterized; the major input of 137 Cs in the ocean occurred in 1962-64 as approximately a single injection and the geographic distribution of 137 Cs injection was re-constructed from fallout and inventories in the soil and in the water column data. 2 The spatial distribution and temporal changes of 137 Cs in seawater reflect motion of seawater such as advection and diffusion because most of the 137 Cs exists as a dissolved form in seawater. The data of 137 Cs in seawater has been accumulated as databases such as HAM and GLOMARD.…”