Anthropogenic Releases of Radiocarbon and its Concentration Burden in Environment

摘要

The radiocarbon (14C) concentrations in air and vegetation samples around a nuclearresearch reactor were studied.Objective: 14C concentrations in the air and vegetation samples around the nuclear researchreactor were measured to assess its 14C burden on the environment.Methods: Air samples were collected by converting CO2 into Na2CO3 by using a specifiedsystem. Leaf samples were carbonized to convert organic carbon into inorganic carbonates.The samples were converted into carbamate through carbosorb systems with 74% efficiency.The fractionation of 14C for each sample was corrected and normalized to a 13C compositionof -25‰ Pee Dee Belemnite.Results: 14C concentrations in the air and vegetation samples around the nuclear researchreactor were found to range from 158 to 406 Bq/Kg and 162 to 339 Bq/kgC, respectively.The highest concentrations of 14C were found in the samples close to the reactor and alongthe prevailing wind direction. The specific activities of the samples decreased with an increasein the distance from the reactor and in the opposite to prevailing wind direction. Inaddition to the distance from the reactor and wind direction, the local Suess effect was anadditional factor affecting the 14C activities in the air and vegetation samples.Conclusion: One can conclude that other than the 14C emissions from the nuclear reactor,local Suess effects and climatic factors (wind directions) dilute and disperse 14C concentrationsin the atmosphere and consequently decrease its availability for uptake and accumulationby plants at 4-5 km aerial distance from the point of release in prevailing wind direction.