WU Mei1,2, LI Shehong1, LIAO Jie1,2, XUE Lili1,3, HU Feng1,2, YANG Qihao4, ZHAO Zhenjie1,5
(1. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;
2. University of Chinese Academy of Sciences, Beijing 100049, China;
3. School of Environmental Science and Engineering, Yancheng Institute of Technology, Yancheng, 224001, China;
4. Foshan Iron Man Environmental Technology Co, Ltd, Foshan, 528000, China;
5. Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guizhou, 550025, China)
Abstract：This research aimed to study the effects of different composite iron-based passivators on the remediation of high arsenic (As) soil and select the most appropriate technology with better effects on passivating arsenic in soil and inhibiting arsenic accumulation in rice grains so that provided scientific basis for the high arsenic soil remediation and management in the southwest Guizhou Province. The rice pot experiments of three commercially available composite iron-based passivators (composite iron-based biochar (A), iron-based biochar (B) and iron potassium-based humic acid (C)) remediation effects on the high arsenic soil from southwestern Guizhou were carried out, which including the changes of available arsenic and species in soil and arsenic content in rice grains under different dosages (0.67g/kg, 1.34 g/kg, 2.68 g/kg, 5.36 g/kg). The results show that the three composite iron-based passivators can increase soil pH and passivate soil arsenic in different degrees. The passivation rate reached 26.2% when using the passivator C at the dosage of 5.36 g/kg. Each treatment changed the occurrence of soil arsenic and reduced the non-obligate adsorbed As, obligate adsorbed As and amorphous and weakly crystalline Fe/Al oxide bound state As to varying degrees, for passivation agent A and B, they mainly changed As to crystalline Fe/Al oxide bound state, for C treatment, it mainly changed As to residual form. Each treatment significantly inhibited the arsenic content in polished rice. Compared with the control, the reduction rate of rice arsenic reached 48.6% when compound passivator A at the dosage of 1.34 g/kg. Because the soil arsenic passivation rate can’t fully characterize the rice's accumulation capacity, it should’ be used as the only inspection index for soil arsenic remediation. Therefore, the soil passivation rate and the influence on arsenic accumulation in rice grains should be comprehensively considered when evaluating different soil remediation techniques.
Key words：southwestern Guizhou; complex iron-based passivators; high arsenic soil; rice; remediation
EARTH AND ENVIRONMENT Vol.50, No.6, Tot No.350, 2022, Page 909
