Remediation of arsenic-contaminated paddy soil by iron oxyhydroxide and iron oxyhydroxide sulfate-modified coal gangue under flooded condition
2022
Chen, Min | Liu, Ying | Zhang, Di | Zhu, Jianming | Chen, Xiaoyang | Yuan, Liang
Flooded condition enhances arsenic (As) mobility in paddy soils, posing an imminent threat to food safety and human health. Hence, iron oxyhydroxide and iron oxyhydroxide sulfate-modified coal gangue (CG-FeOH and CG-FeOS) were synthesized for remediation of As-contaminated paddy soils under a flooded condition. Compared to the control, CG-FeOH and CG-FeOS application decreased the soil pH by 0.10–0.80 and 0.13–1.63 units, respectively. CG-FeOH and CG-FeOS application significantly (P < 0.05) decreased available As concentration by 13.46–43.44% and 21.31–54.37%, respectively. CG-FeOH and CG-FeOS significantly (P < 0.05) reduced the non-specifically adsorbed and specifically adsorbed As fractions and increased As(V) proportion by 22.61–26.53% and 29.10–36.51%, respectively. Our results showed that CG-FeOH and CG-FeOS could change As geochemical fraction and valence state, consequently reducing available As concentration in paddy soils. Moreover, the sulfate could enhance the oxidation and co-precipitation of As with CG-FeOH. Compared to CG-FeOH, CG-FeOS was more effective in decreasing available As concentration and oxidizing As(III) to As(V). This study revealed that CG-FeOS is a potential amendment for As immobilization in paddy soils.
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