土壤理化性质对发电厂周边土壤Cd生物有效性的影响

Effects of Soil Physicochemical Properties on Cd Bioavailability in the Soil Around Power Plants

该研究旨在通过对土壤理化性质与Cd有效性之间的关系的研究,甄别影响Cd在土壤-水稻系统迁移转化的主要因素,为稻田Cd的污染控制提供科学依据。采集韶关发电厂周边的土壤样品和相应的水稻样品,分析土壤和水稻样品的Cd含量,以及土壤中Cd的各种形态和土壤理化性质,并分析它们之间的相关性。结果显示,(1)随着土壤中无定形铁氧化物以及游离态铁氧化物含量的增加,土壤中的Cd的生物有效性降低,表明土壤中铁形态深刻地影响着Cd的生物有效性。(2)土壤中硅的形态也是影响Cd在土壤-水稻体系迁移的重要因素,土壤中有效态硅和无定型硅具有抑制水稻吸收Cd的作用。(3)土壤pH降低会促进结合在土壤固相中的Cd(如碳酸盐结合态、铁锰氧化物结合态)发生溶解,因而随着土壤pH值的降低,土壤中生物可利用性的Cd含量会逐渐加大,表明土壤pH是影响Cd在土壤-水稻体系迁移的重要因素。综上,土壤理化性质对土壤中Cd的生物可利用性有重要影响,进而影响了水稻对Cd的吸收和积累。

The aim of this study was to identify the main influencing factors of Cd migration and transformation in soil-rice system by analyzing the interactions between soil physicochemical properties and Cd availability.The conclusions can potentially provide a scientific foundation for the remediation of Cd pollution in rice fields.Soil and rice samples were collected around the Shaoguan Power Plant.The concentration and speciation of Cd in the collected samples were analyzed,and the physicochemical properties of the soil samples were characterized.The results indicate that:(i)the bioavailability of Cd in the soils was decreased with the increase of amorphous iron oxides and free iron oxides;(ii)the uptake of Cd by rice was inhibited by the available silicon and amorphous silicon in the soil;(iii)the decrease of soil pH promoted the dissolution of Cd(e.g.carbonate-bound Cd,iron/manganese-bound Cd),and the bio-availability of Cd in the soils was increased with the decrease of soil pH.Overall,soil physicochemical properties(e.g.iron and silicon species and soil pH)have an important influence on the bioavailability of Cd in soil,which further affect the absorption and accumulation of Cd in rice.