Radionuclides and stable elements in vegetation in Australian arid environments: Concentration ratios and seasonal variation

Data on the uptake of elements and radionuclides by flora from soils in arid environments are underrepresented in international databases, especially when comparing across seasons. This study improved the understanding on the uptake of natural uranium-series radionuclides, as well as more than 30 elements, in a range of Australian native flora species that are internationally representative of an arid/semi-arid zone (e.g. Acacia, Astrebla, Atriplex, and Dodonea). Results indicate that the soil-to-plant uptake ratios were generally higher when compared with international data for grasses and shrubs from more temperate environments. The majority of the elemental concentrations in grasses were higher in winter than in summer and the opposite trend was found in shrubs, which suggests that the season of collection potentially introduces variability in the reported concentration ratios. The data also suggest that grasses, being dominant and widespread species in arid zones, may be effective as a reference organism to ensure comparative assessment across sites of interest. The results of this study will improve the confidence of environmental assessments in arid zones. [Display omitted] •Concentration ratios are higher but within a factor of 10 of the reference values.•Collecting soil and flora within the same season reduces the seasonal effect.•Concentration ratios in grasses were higher in winter than summer.•Concentration ratios in shrubs were higher in summer than winter.•Obtaining concentration ratios for two different seasons improved risk assessment.