210Po bioaccumulation in coastal sand dune wild legumes—Canavalia spp. of southwest coast of India

Abstract

In view of considerable natural background radioactivity reported from southwest coast of India, the current study documents bioaccumulation of ²¹⁰Po in two dominant coastal sand dune perennial mat-forming wild legumes, Canavalia cathartica and C. maritima. Root, stem, leaf, mature beans, dry seeds and rhizosphere sand were analyzed for ²¹⁰Po concentration. ²¹⁰Po activity decreased in the order of leaves > roots > seeds > stems > beans. The highest ²¹⁰Po activity was recorded in rhizosphere sand samples (5.78–5.88 Bq kg⁻¹) followed by the leaf samples (3.27–3.07 Bq kg⁻¹), while it was lowest in mature beans (0.13–0.20 Bq kg⁻¹). ²¹⁰Po activities or tissue moisture between plant species were not significantly different (p > 0.05; t-test). But ²¹⁰Po activity vs. moisture differed significantly in all tissues (p = 0.0001), vegetative tissues (root, stem and leaf) (p = 0.0016), seeds (p = 0.0393) and proteins in seeds (p = 2.355 × 10⁻⁶) indicating the importance of moisture and protein in ²¹⁰Po accumulation. Although ²¹⁰Po has affinity for proteins, it did not concentrate too much in seed proteins of Canavalia. Concentration of ²¹⁰Po in mature beans is at safe levels as fisher folk only consume tender pods occasionally. ²¹⁰Po activity in Canavalia is compared with other plant materials. As the landraces of C. cathartica and C. maritima are distributed throughout pantropical coastal areas, the current study emphasizes on considering them as bioindicators to monitor ²¹⁰Po in coastal sand dune biomes and in turn the health of coastal population.