Effects of Fe oxides and their redox cycling on Cd activity in paddy soils: A review

Cadmium (Cd) contamination of soils is a global problem, particularly in paddy soils. Fe oxides, as a key fraction of paddy soils, can significantly affect the environmental behavior of Cd, which is controlled by complicated environmental factors. Therefore, it is necessary to systematically collect and generalize relevant knowledge, which can provide more insight into the migration mechanism of Cd and a theoretical basis for future remedi-ation of Cd contaminated paddy soils. This paper summarized that (1) Fe oxides influence Cd activity through adsorption, complexation, and coprecipitation during transformation; (2) compared with the flooded period, the activity of Cd during the drainage period is stronger in paddy soils, and the affinity of different Fe components for Cd was distinct; (3) Fe plaque reduced Cd activity but was associated with plant Fe2+ nutritional status; (4) the physicochemical properties of paddy soils have the greatest impact on the interaction between Fe oxides and Cd, especially with pH and water fluctuations.

Automated summary

Cadmium (Cd) contamination of soils, especially in paddy soils, is a global problem. Fe oxides, as a key fraction of paddy soils, play a significant role in influencing the environmental behavior of Cd. This paper summarized the impact of Fe oxides on Cd activity during transformation, the difference in Cd activity between flooded and drainage periods, the relationship between Fe plaque and plant Fe2+ nutritional status, and the influence of physicochemical properties of paddy soils on the interaction between Fe oxides and Cd.