Philippine Journal of Science
150 (3): 847-854, June 2021
ISSN 0031 – 7683
Date Received: 13 Oct 2020

Grass/Soil Concentration Ratios (CRs) of Natural
²²⁶Ra, ²³²Th, and ⁴⁰K in Vetiveria zizanioides
(Vetiver Grass) in Thailand

Chittranuch Chantarot¹, Harinate Mungpayaban²,
and Kiadtisak Saenboonruang¹*

¹Department of Applied Radiation and Isotopes, Faculty of Science
Kasetsart University, Bangkok 10900 Thailand
²Office of Atoms for Peace, Bangkok 10900 Thailand

*Corresponding author: kiadtisak.s@ku.th

ABSTRACT

This work investigated the grass/soil concentration ratios (CRs) of natural radionuclides (226Ra, 232Th, and 40K) in vetiver grass collected from three different regions of Thailand using an HPGe (high-purity germanium) gamma spectrometer. The sampled grass blades were divided into three equal parts to investigate the dependence of grass/soil CRs on the positions of grass blades. The results showed that 40K had the highest grass/soil CRs due to being an essential nutrient for most plants, with ranges of 1.12–7.92, in comparison with 226Ra and 232Th that had ranges of 0.32–1.48 and 0.20–1.31, respectively. In addition, the results indicated that the natural radionuclides investigated were uniformly transferred and accumulated throughout grass blades (p < 0.05), which implied the independence of CRs on the section of the leaf. Furthermore, it was found that the soil samples collected from the central region of Thailand had the highest activity concentrations in all radionuclides, mainly due to a primary composition of dark clay, leading to the highest contents of potassium and calcium (Total K and Total Ca, respectively), and the highest cation exchange capacity (CEC) that led to high concentrations of nutrients and radionuclides. Based on the results from this work, the vetiver grass presented potentials to be utilized as radionuclide absorbers in polluted soil and water due to its high CRs in comparison with other reported plants.