Bioavailability Assessment and Accumulation by Five Garden Flower Species Grown in Artificially Cadmium-Contaminated Soils

Abstract

Many studies have been conducted on phytoextraction; however, non-native hyperaccumulator species are not suitable for the natural environment of Taiwan in many cases. Drawing upon previous results, the growth and heavy metal accumulation in artificially cadmium-contaminated soils were compared for five local garden flower species. The treatments included a control (CK), 9.73 ± 0.05 mg kg−1 (Cd-10), and 17.6 ± 0.8 mg kg−1 (Cd-20). All plants were harvested at 35 days after transplanting and analyzed for Cd content. Cd accumulation in the shoot of French marigold (Tagetes patula L.) and Impatiens (Impatiens walleriana Hook. f.) grown in Cd-20 treatment were 66.3 ± 6.5 and 100 ± 11 mg kg−l, which equated to a removal of 0.80 ± 0.11 and 0.60 ± 0.37 mg Cd plant−1, respectively. The maximum Cd accumulation of Impatiens reached the threshold value (100 mg kg−l) characteristic of a Cd hyperaccumulator and its bioconcentration factor (BCF) and translocation factor (TF) were greater than one. Impatiens therefore has the potential to hyperaccumulate Cd from Cd-contaminated soils. With the exception of Garden verbena, significant relationships were found between Cd concentrations in soil extracted by 0.05 M EDTA, 0.005 M DTPA, and 0.01 M CaCl2 and the concentration of Cd in the shoots of the tested garden flowers.