Distribution of ²¹⁰Po in spice plants cultivated by conventional farming

To study the distribution of ²¹⁰Po concentrations in various parts of spice plants cultivated by conventional farming in Nilgiris, South India and estimate effective radiation dose received.

Parts of plant such as leaf, fruit, seed, flower bud and rhizome of selected spice plants cultivated at various locations in the study area have been collected for estimation of ²¹⁰Po concentration. Organic materials in known mass of processed samples have been removed by chemical method. ²¹⁰Po concentration in the digested sample has been electrostatically deposited on pre-polished silver disks at constant temperature. ZnS(Ag) detector-based alpha counting system with minimal detectable value 3.2 mBq has been used for estimation of ²¹⁰Po activity concentration.

Leaves of Curcuma longa have registered a high concentration of 45.6 ± 4.5 Bq kg^-1 of ²¹⁰Po and rhizome of Allium sativum has registered a low value of 4.7 ± 0.8 Bq kg^-1. Leaves of spice plants have registered higher concentration of ²¹⁰Po than their fruits, seeds, flower buds or rhizomes. Soil to plant transfer factor of ²¹⁰Po has been found to vary from 0.13 for rhizome of A. sativum to 2.23 corresponding to leaf of C. longa. Concentration of ²¹⁰Po estimated in leaves and mean leaf areas of spice plants has been found to have a correlation coefficient of 0.83, which indicates that absorption of ²¹⁰Po deposited on surface area of leaves is the main source of this isotope in plant parts.

Consumption of various parts of spice plant does not pose significant radiological risk as effective dose received by the general public as ²¹⁰Po has been found to vary from 6.34 to 46.05 µSv y^-1, less than the value recommended by ICRP.