In situ cadmium removal from paddy soils by a reusable remediation device and its health risk assessment in rice

Abstract Passivation is widely used in the remediation of cadmium (Cd) polluted soils. However, this technique could only reduce the bioavailability of soil Cd rather than remove Cd from the soils. Herein, it is crucial to develop an efficient in-situ technique to remove soil Cd, and further to uncover its effect and mechanism on crops and soil environment. In this study, a soil pot experiment was employed to investigate the effects of a well-designed reusable device on in situ Cd removal from the two paddy soils (red soil and brown soil), rice (Oryza sativa L) growth, and the associated health risk of Cd. The device contained three typical soil Cd amendments including cation exchange resin (CER), biochar (BC), and steel slag (SS). Each of the soil amendments was combined with slow-release fertilizer (SRF) or conventional compound fertilizers (CF). The results indicated that the device with CER, BC, and SS decreased soil Cd by 12.6%, 16.2%, and 19.8%, respectively. Thus, it reduced the rice Cd accumulation by 30.6%, 16.1%, and 29%, and increased the rice yield by 70.3%, 42.6%, and 55.4%, respectively. This could be stemmed from the improvement of photosynthesis and the reduction of oxidative damage, as well as the increase in the relative abundance of soil beneficial microbial community. Moreover, the grey correlation degrees and human health risk index (HRI) indicated that the in-situ removal device could diminish the health risk of Cd in rice. The findings reported in this work could provide a new solution to remediate heavy metal contaminated soils.