Prediction of As and Cd dissolution in various soils under flooding condition

• Published in: The Science of the total environment Vol. 948; p. 174853
• Main Authors: Ge, Jingwen, Wu, Song, Wu, Haotian, Lin, Jianyu, Cai, Yijun, Zhou, Dongmei, Gu, Xueyuan
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20.10.2024
• Subjects: Anaerobic; Arsenic; Dissolution; Prediction; Waterlogged soil; Arsenic; Waterlogged soil; Dissolution; Prediction; Anaerobic
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.174853

Although the mobility of arsenic (As) and cadmium (Cd) in soils during the flooding-drainage process has been intensively studied, predicting their dissolution among various soils still remains a challenge. After comprehensively monitoring multiple parameters related to As and Cd dissolution in 8 soils for a 60-day anaerobic incubation, the redundancy analysis (RDA) and structural equation model (SEM) were employed to identify the key factors and influencing pathways controlling the dynamic release of As and Cd. Results showed that pH alone explained 90.5 % Cd dissolution, while the dissolved-Fe(II) and 5 M-HCl extractable Fe(II) jointly only explained 50.6 % As dissolution. After data normalization, the ratio of Fe(II) to 5 M-HCl extracted total Fe (i.e. FetotII/Fetot) significantly improved the correlation to R2 = 0.824 (p < 0.001) with a fixed slope of 0.393 among the 8 soils. Our results highlight the crucial role played by the reduction degree of total iron contents in determining both the reduction and dissolution of As during flooding. In contrast, dissolved-Fe(II) was too vulnerable to soil properties to be a stable indicator of As dissolution. Therefore, we propose to replace the dissolved-Fe(II) with this novel ratio as the key index to quantitatively assess the kinetic change of As solubility potential across various soils under flooding conditions. [Display omitted] •The Fe(II)/Fetot was found to be the best index for dynamic As dissolution in 8 soils.•Soil pH was confirmed to be the best index for dynamic dissolution of Cd in 8 soils.•The reduction ratio of total Fe controls both reduction and adsorption of As in soils.•A regression model was proposed to describe the reductive release of As across soils.