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

摘要

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,Cs-137 and(210)Pb come from two different origins of anthropogenic and geogenic, respectively. Since the(137)Cs and(210)Pb(excess)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(137)Cs, 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(137)Cs. Awareness of the range of possible changes of(137)Cs and(210)Pb(excess)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(137)Cs and(210)Pb(excess)in undisturbed soil and presents some regression equations for different climates and latitudinal zones of the world. Based on the results, the inventory of(137)Cs in undisturbed soil can be estimated statistically acceptable only in two latitudinal zones of 16 degrees-25 degrees N and 26 degrees-35 degrees N. While due to the small amount of data and the impossibility of data separation for different zones and climates, the inventory of(210)Pb(excess)can be estimated statistically acceptable given all the data without considering the latitudinal zones. The estimations of the inventories of(137)Cs and(210)Pb(excess)in undisturbed soil is statistically acceptable in two temperate and continental climates and only temperate climate, respectively.