Relationship between Mean Annual Precipitation and Inventories of Fallout Radionuclides (¹³⁷Cs and ²¹⁰Pb<inf>excess</inf>) in Undisturbed Soils around the World: A Review

Abstract

© 2020, Pleiades Publishing, Ltd. Abstract—: Concurrent with the Chernobyl accident along the explosions caused by nuclear tests and advances in nuclear sciences, researchers around the world have been trying to examine the potential of fallout radionuclides for accurate estimation of soil erosion and redistribution. The inadequacy of the existence of radionuclides and the complexity of factors affecting the amount of these elements in soil are among the important limiting factors in usage of radionuclide materials in soil erosion studies. As the most widely used radionuclides in soil erosion studies, 137Cs and 210Pb come from two different origins of anthropogenic and geogenic, respectively. Since the 137Cs and 210Pbexcess reach the soil surface mainly through precipitation, the climate and latitude play important roles on the existence of radionuclides in the soil. Due to the location of the point sources of 137Cs, the coordinates of the site under consideration and the wind regimes can also be very important to affect the precipitation and consequently, the inventories of 137Cs. Awareness of the range of possible changes of 137Cs and 210Pbexcess in undisturbed soil is an important step to improve and validate soil erosion estimation results. Accordingly, the present research reviews the data of the mean annual precipitation and inventory of 137Cs and 210Pbexcess in undisturbed soil and presents some regression equations for different climates and latitudinal zones of the world. Based on the results, the inventory of 137Cs in undisturbed soil can be estimated statistically acceptable only in two latitudinal zones of 16°–25° N and 26°–35° N. While due to the small amount of data and the impossibility of data separation for different zones and climates, the inventory of 210Pbexcess can be estimated statistically acceptable given all the data without considering the latitudinal zones. The estimations of the inventories of 137Cs and 210Pbexcess in undisturbed soil is statistically acceptable in two temperate and continental climates and only temperate climate, respectively.