为治理镉砷污染农田土壤，选取湘南某矿区镉砷复合污染稻田土壤，以水稻盆栽实验研究了复合改良剂HZB（羟基磷灰石+沸石+改性秸秆炭）对土壤中镉（Cd）、砷（As）赋存形态以及水稻累积转运Cd和As的影响。结果表明，施用HZB能提高土壤pH 0.19～0.79个单位，阳离子交换量增加22.1%～60.4%；施用HZB使活性较大的酸提取态Cd含量降低了6.5%～22.9%，促进了Cd向难溶态的转变，可使有机结合态Cd增加2.5%～56.5%；施用HZB促进活性As向难溶型的钙型As转化，钙型As 含量增加2.8%～53.3%，也可使交换态As含量降低7.0%～39.5%，但当施用量超过4.0 g kg-1时则会增加交换态As含量。水稻根系对Cd的富集系数在0.65～1.21之间，对As的富集系数在0.033～0.049之间，富集Cd的能力大于As；谷壳对Cd的转运能力最大，而根系对As的转运能力最大；施用HZB有降低水稻根系富集Cd和As的能力。施用0.5～2.0 g kg-1的HZB 能降低水稻地上各部位中Cd和As含量；在2 g kg-1施用水平，水稻糙米中Cd和As含量均低于0.2 mg kg-1，达到国家食品污染物限量标准。%For remediation of paddy soil complexly contaminated with cadmium and arsenic,a pot experiment with rice planting in the paddy soil collected from southern Hunan Province,China,was conducted to study effects of a combined soil amendment,HZB(hydroxyhistidinet + zeolite + biochar) on chemical forms of Cd and As in the tested soil and on accumulation and translocation of Cd and As in rice. Results show that application of HZB significantly increased soil pH(by 0.19~0.79)and soil CEC (by 22.1%~60.4%). In addition,it reduced the content of labile soil acid soluble Cd by 6.5%~22.9% by promoting transformation of soil Cd from soluble to insoluble ones. As a result,the content of soil organic Cd increased by 2.5%~56.5%. Application of HZB also promoted transformation of soil As from soluble to insoluble,thus increasing the content of calcium-bonded As by 2.8%~53.3%,and reducing the content of soil exchangeable As by 7.0%~39.5%. However,when the application rate of HZB reached beyond 4.0 g kg-1,the content of soil exchangeable As turned upwards again. It was found in this experiment that Cd bioaccumulation factor(BAF)of rice roots varied in the range of 0.65~1.21,while As BAF in the range of 0.033~0.049,showing obviously that bioaccumulation capacity of the plants was greater for Cd than for As;that among various rice organs,rice husk was the highest in Cd transferring capacity,while root was in As transferring capacity;that application of HZB decreased the Cd and As bioaccumulation capacity of rice roots;that the application of,HZB at a rate of 0. 5~0.2 g kg-1 could significantly lower Cd and As contents in various rice organs;and that when 2 g kg-1 of HZB was applied,Cd and As contents in brown rice were both lower than 0.2 mg kg-1,meeting the requirement set in the National Food Standards(GB 2762-2012).
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