Red mud based passivator reduced Cd accumulation in edible amaranth by influencing root organic matter metabolism and soil aggregate distribution. (15th April 2021)

• Record Type: Journal Article
• Authors: Xu, Zhimin; Lu, Ziyan; Zhang, Liangshi; Fan, Hanyun; Wang, Yifan; Li, Junwei; Lin, Yanlin; Liu, Hui; Guo, Shihong; Xu, Mingyu; Wang, Junfeng
• Is Part Of: Environmental pollution. Volume 275(2021)
• Publication Date: 2021-04-15
• Subjects: Red mud based passivator -- Acidic Cd-Polluted soil -- Cd speciation -- Root metabolic response -- Soil aggregates; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2021.116543
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Red mud was a highly alkaline hazardous waste, and their resource utilization was a research hotspot. In this study, influencing mechanisms of red mud based passivator on the transformation of Cd fraction in acidic Cd-polluted soil, photosynthetic property, and Cd accumulation in edible amaranth were investigated based on the evaluation of Cd adsorption capacity, root metabolic response, and soil aggregate distribution. Results showed that red mud exhibited good Cd adsorption capacities at about 35 °C and pH 9 in an aqueous solution, and the adsorption behavior of red mud on Cd in rhizosphere soil solution was considered to have some similarity. In the soil-pot trial, red mud application significantly facilitated edible amaranth growth by enhancing the maximum photochemical efficiency and light energy absorption by per unit leaf area by activating more reaction centers. The main mechanisms of rhizosphere soil Cd immobilisation by red mud application included: i) the reduction of mobilized Cd caused by the increasing negative surface charge of soil and precipitation of Cd hydroxides and carbonates at high pH; ii) the increase of organics-Cd complexes caused by the increasing –OH and –COOH amounts adsorbed on the surface of rhizosphere soil after red mud application; and iii) the decrease of available Cd content in soil aggregates caused by the increasing organic matters after red mud application. This study would provide the basis for the safe utilization of red mud remediating acidic Cd-polluted soil. Graphical abstract: Image 1 Highlights: Red mud addition increased photosynthetic property and facilitated plant growth. Red mud addition changed soil chemical characteristics effecting Cd speciations. Root metabolism up-regulation caused by red mud addition increased soil organics-Cd fraction. Red mud addition reduced available Cd in high-risk soil aggregates (0.02–0.25 mm).