Abstract:

To study the long-term stability of cadmium passivation in farmland soil by applying mineral passivators, in this paper, four passivators were prepared from lime, sepiolite, bentonite, maifanite and biochar, and the field test method was used to apply passivators once at the rate of 2250 kg/hm² to planting early rice and late rice for two consecutive years, to compare the changes of available cadmium in soil and the content of cadmium in rice. The results showed that the passivation stability of the four passivators on soil cadmium was P> H> M>S. Among them, the influence of passivator P on the pH of farmland soil was more lasting, and the cadmium content of rice in the field applied with passivator P was <0.2 mg/kg, so passivator P had better long-term stability of soil cadmium passivation. The results could provide a theoretical basis for the remediation of heavy metal polluted farmland and the practical application of passivators.

Key words: passivation, stability, passivator, cadmium, available cadmium, minerals, rice