Spatial distribution of radiocarbon around the heat power facilities

Abstract

Objective. We studied the spatial distribution of 14C due to CO2 emissions when burning the fossil fuel at the heat power facilities. Materials and methods. Annual grass samples were collected at a fixed distance from the sources of CO2 industrial emissions — the Nyvky district boiler plant in Kyiv (chimney height of 30 m) and around the Trypilska HPP in Ukrainka (chimney height of 80 m). Grass samples were washed with hot water in order to prevent impact of possible surface contamination, and then samples were ground and dried in an oven at 150°C. For benzene production the samples were exposed to a chain of chemical transformations (carbon-carbide-acetylene-benzene). For lithium carbide production we applied a vacuum pyrolysis method. 14C specific activity in the benzene samples were measured by liquid scintillation spectrometer Quantulus 1220TM. Results. 14C depletion in the atmosphere near the sources of CO2 emissions at the expense of the fossil fuel has a distinct local character and depends on natural factors causing their spatial distribution: power of source, chimney height, and wind direction. The maximum impact of CO2 emissions, caused by the combustion of fossil fuel, was observed at a distance of 400-800 m to the north of Trypilska TPP which complied with the more prevailing wind direction in this area, and the spatial distributions differed for the fall and spring seasons. The spatial distribution of 14C near the Nyvky boiler plant demonstrated the maximum depletion of 14С at a distance of 100 m to the west from the source which also complied with the more prevailing wind direction. A relationship between a value of the impact of fossil fuels on the 14C activity concentration in the grass around the source and intensity of emission source, the height of the chimney, the distance from the source, and the prevailing wind direction was confirmed. The obtained results demonstrate the prospects f or the use of the annual plants as a marker for the study of CO2 emissions in the air near the source, the TPP in particular. Under conditions of a large city at the simultaneous impact of many sources of CO2 emissions due to combustion of the fossil fuels, we need a clear understanding of the background components (natural and technogenic).