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Concentration of Natural Radionuclides in Calendula Officinalis L. Flowers

Tsvetelina Stefanova, Syana Dimova, Nina Arhangelova, Yordanka Eneva


Introduction: Flowers of Calendula officinalis L., are widely used in folk medicine for number of medical conditions, such as wound healing, jaundice, blood purification, and as an antispasmolitic. Natural radionuclides are being absorbed together with water and minerals from soil and atmosphere by plants. Transfer of radionuclides represents a radiological risk to humans. The study of radionuclides concentration is of great significance. The aim of this work is to investigate radioactive contamination levels in Calendula officinalis L. Transfer coefficients of radionuclides from soil to herb were determined for the terrain around the village of Yagnilo, Northeast Bulgaria.

Materials and Methods: Samples of flowers of Calendula officinalis L. were collected in July. Soil sample was obtained from 10 cm ground depth where calendula grows. Flowers and soil were air exsiccated and levigated. Measurements of dry powdered flowers of calendula and soil were carried out with a low-background gamma-ray Ge(Li) spectrometer at the University of Shumen. The obtained gamma spectra were processed with the computer program Anges. Radioisotopes are determined by their energies. The transfer factors of soil-plant were calculated.

Results: Values for the specific activity of natural radioisotopes in calendula flowers and soil were obtained. Photopeaks of intense gamma emission from uranium series nuclides, 214Bi and 214Pb, thorium series nuclides 228Ac and 208Tl and gamma transition of 40K were observed. Artificial radionuclides of technogenic origin were not found.

Conclusions: Specific activities of radionuclides were compared to maximum levels of natural radionuclides. Public health is not at risk having in mind these levels. Transfer factors (TFs) were in the range of 1 up to 50.


gamma-ray spectrometry, Calendula officinalis L., natural radionuclides, soil


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