杂交稻和常规稻对复合污染稻田土壤砷镉提取效果差异研究
Study on the Difference of Arsenic and Cadmium Extraction Effect between Hybrid Rice and Conventional Rice in Co-contaminated Paddy Soil
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摘要: 摘要:为实现对稻田土壤砷(As)、镉(Cd)污染的同步移除,利用根箱实验,选取代表性杂交稻(HR)和常规稻(CR)品种作为修复材料进行提取。为了评估种植HR和CR的提取效果,以未种植水稻土壤作为对照(CK),利用孔隙水采集器在其全生育期内采集并监测土壤水溶态As、Cd含量的变化;分别在水稻分蘖期、成熟期采用扩散梯度薄膜技术(Diffusive Gradients in Thin-films,DGT)原位实时测定根际土壤剖面有效态 As、Cd 浓度;收获时利用分级提取法分析土壤As、Cd赋存形态及总量变化,并分析植株各部位的As、Cd累积量。结果表明:水稻生长能够有效消耗土壤中生物有效态As、Cd,且HR较CR表现出更高效的As、Cd同步富集能力。水稻成熟期,种植HR处理的土壤中DGT-As(扩散梯度薄膜提取态As)浓度较种植CR处理和CK分别下降69%和71%,DGT-Cd(扩散梯度薄膜提取态Cd)浓度分别降低35%和58%;HR和CR收获后土壤总As含量分别减少8%和1%,总Cd含量分别减少31%和14%;HR对土壤As、Cd的单株去除量分别为CR的1.2倍和4.5倍;每年种植两季HR对土壤As、Cd的移除率分别为CR的1.2倍和4.3倍。研究显示,种植HR对As、Cd具有更高效的提取能力,可优先作为修复材料对稻田土壤生物有效态As、Cd进行专性提取减量,为As、Cd复合污染稻田土壤清洁提供了一条有益路径;但还需结合水分优化管理、施加促溶剂等方式形成修复链,进一步提高修复效率,缩短修复年限。
Abstract: Abstract: In order to achieve co-removal of arsenic (As) and cadmium (Cd) from paddy soils, rhizotron experiment were carried out with representative hybrid rice (HR) and conventional rice (CR) cultivars as remediating materials for As and Cd co-extraction. To evaluate the difference in the extraction effect of planting HR and CR, soil without rice growth was included as control (CK). Porewater samplers were used to collect and monitor changes in soil soluble As and Cd content during the entire period of rice growth. At tillering and maturity stage, the diffusive gradients in thin-films (DGT) was employed for in situ real-time monitoring the dynamic profile As and Cd. At harvest, the changes in soil As and Cd fractions and total amount were revealed by sequential extraction, and As and Cd accumulation in rice tissues were determined. The results showed that rice growth could deplete bioavailable As and Cd from paddy soils, and HR exhibited more efficient bioaccumulation capacity compared with CR. At maturity stage, compared to CR growth treatment and CK, the average concentration of soil DGT-As decreased by 69% and 71%, and soil DGT-Cd decreased by 35% and 58% in HR growth treatment, respectively. Removal of HR and CR decreased soil total As by 8% and 1%, while soil Cd was reduced by 31% and 14%. The removal of soil As and Cd by each HR plant was 1.2 and 4.5 times that of CR, respectively, which were linked to 1.2 and 4.3 times higher removal rates of soil As and Cd by HR, respectively, than by CR with 2 crops per year. Based on the present results, planting HR had a greater ability to extract soil As and Cd, which could be preferentially used as remediation material for specific extraction and thus reduction of rice-available As and Cd from paddy soils. This provides a useful pathway for cleaning and safe utilization of paddy soils with As and Cd co-contamination. However, it will be necessary to combine moisture optimization management and application of pro-solvent to form a restoration chain to further improve the restoration efficiency and reduce the restoration years.-
Key words:
- hybrid rice (HR) /
- conventional rice (CR) /
- extraction /
- arsenic (As) /
- cadmium (Cd) /
- paddy soil
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