Immobilization of soil Cd by sulfhydryl grafted palygorskite in wheat-rice rotation mode: A field-scale investigation

• Published in: The Science of the total environment 2022-06, Vol.826, p.154156-154156, Article 154156
• Main Authors: Wu, Yiqian, Yang, Huimin, Wang, Miao, Sun, Lu, Xu, Yingming, Sun, Guohong, Huang, Qingqing, Liang, Xuefeng
• Format: Article
• Language: English
• Subjects: Cadmium - analysis; Immobilization; Magnesium Compounds; Oryza - chemistry; Rotation; Silicon Compounds; Soil - chemistry; Soil Pollutants - analysis; Sulfhydryl Compounds; Sulfhydryl grafted palygorskite; Triticum
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.154156

The safe utilization of heavy metal contaminated farmland has attracted extensive attention of the whole society, and there is an urgent need to develop novel high-efficiency amendments. To clarify the actual remediation effect and potential for large-scale application of sulfhydryl grafted palygorskite (SGP) in Cd polluted soil in wheat-rice rotation mode, a field-scale experiment was conducted. SGP at the dosages of 0.5 g/kg–2.0 g/kg could reduce gain Cd contents by 27.15–59.05% and 16.16–79.47% for wheat and rice, respectively. The maximal decreases of soil available Cd figured out by DTPA extraction in wheat and rice season were 58.18% and 33.67%, respectively. The immobilization ratio for Cd was much more than that of trace elements, including Fe, Mn, Cu, and Zn, Ni. SGP showed an effective immobilization rate for soil Cd under the interference of many elements in the soil, pointing to the targeting and selectivity of its high-efficiency immobilization. It had no lifting effect on soil pH but decreased zeta potentials of soil particles. The sorption of Cd2+ on SGP amended soil could be fitted by the second-order kinetic model and Langmuir isotherm, and the changes of thermodynamic parameters showed SGP strengthened the fixation. SGP made the biological accumulation coefficient and transfer factor of rice grain drop dramatically but had no noticeable effect on these parameters of winter wheat, indicating different botanical responses. SGP as a novel immobilization amendment may provide an efficient and sustainable solution for the remediation of contaminated soil in wheat-rice rotation mode in field-scale. Sulfhydryl grafted palygorskite (SGP) could decrease soil available Cd and reduce Cd accumulation in wheat and rice grains significantly in wheat-rice rotation mode in field-scale demonstration. The changes of thermodynamic parameters revealed that SGP strengthened the sorption of Cd2+ on soil particles and made exchangeable Cd fraction transform into easily reducible FeMn oxide associated Cd. SGP showed significant immobilization rate for soil Cd under the interference of a large number of elements such as Fe, Mn, Cu and Zn in the soil, and had no negative impact on the normal growth of crops, indicating the targeting and selectivity of its high-efficiency immobilization. SGP had no inhibition effects on the transfer of Cd in wheat but inhibited that process in rice significantly. [Display omitted] •SGP has excellent immobilization effect in field s