Radium in New Zealand agricultural soils: Crop uptake and estimation of current and future ionising radiation dose.

Crop uptake of Ra over a range of key New Zealand agricultural and horticultural growing areas was analysed to establish the dietary implications of an increase in soil Ra activity concentrations. Thirty crop samples, covering both feed and food commodities, were quantified for Ra activity concentrations, and concentration ratio (CRs) from the soil activity were calculated. The calculated CRs correlated with international default values for estimating crop uptake.

Radium in New Zealand agricultural soils: Phosphate fertiliser inputs, soil activity concentrations and fractionation profiles.

Phosphate ores can contain high levels of U and its decay products. Of these decay products Ra is an important environmental contaminant, while Ra from  Th day may also be present, albeit at lower activity concentrations. Acid processing of phosphate ore to triple superphosphate elutes a large proportion of the Ra from the final product.

Changes in 1-aminocyclopropane-1-carboxlate (ACC) oxidase expression and enzyme activity in response to excess manganese in white clover (Trifolium repens L.).

To examine the effect on Mn treatment on the ACO gene family of white clover [Trifolium repens (L.) cv. Grasslands Challenge], rooted stolon cuttings were maintained in modified Hoaglands medium, at pH 5.

Mercury volatilisation and phytoextraction from base-metal mine tailings.

Experiments were carried out in plant growth chambers and in the field to investigate plant-mercury accumulation and volatilisation in the presence of thiosulphate (S2O3)-containing solutions. Brassica juncea (Indian mustard) plants grown in Hg-contaminated Tui mine tailings (New Zealand) were enclosed in gastight volatilisation chambers to investigate the effect of ammonium thiosulphate ([NH4]2 S2O3) on the plant-Hg volatilisation process. Application of (NH4)2 S2O3 to substrates increased up to 6 times the Hg concentration in shoots and roots of B.