Detoxification difference of cadmium between the application of selenate and selenite in native cadmium-contaminated soil

Cadmium (Cd) has strong mobility and could cause toxicity to plants, and selenium (Se) can effectively detoxify Cd stress. However, differences in the detoxification effects of different species and dosages of exogenous Se on Cd and its mechanism are still unclear. In this study, a pot experiment was conducted to determine the effects of different rates of selenite and selenate application on radish growth, the uptake and translocation of Cd, and the fractions of Cd transformation in native Cd-contaminated soil. Results indicated that the decrease in radish biomass in selenate treatment was significantly greater than that in selenite treatment at a high Se application rate (2.5 mg center dot kg(-1)) (p < 0.05). In contrast to selenite treatments, the application of selenate significantly increased the translocation of Cd from radish roots to shoots (p < 0.05). Cadmium concentration and its bioaccumulation factor in radish decreased gradually with increasing selenite application rates, while these values decreased at low Se rate (1 mg center dot kg(-1)) and increased at high Se rate for selenate treatment. Different Se application rates resulted in Cd fractions distributions to change in soil. Therefore, the application of selenite treatment had a greater detoxification effect on Cd in soil than that in selenate treatment, and the double toxic effect was observed between Se and Cd in high selenate treatment (2.5 mg center dot kg(-1)). Combined with human health risk asseeement, the application of 2.5 mg center dot kg(-1) selenite could be a good approach for detoxification in native Cd-contaminated soil used in this study.

Automated summary

This study found that selenate treatment had a significantly better detoxification effect on Cd in radish growth compared to selenite treatment, with increased translocation of Cd from roots to shoots at high Se application rates.