复合钝化材料对农田土壤砷有效性及白菜生长的影响

Effects of compound passivation material on soil arsenic availability and cabbage growth in farmland

  • 摘要: 【目的】探究施用不同复合钝化材料对贵州喀斯特地貌农田土壤砷(As)形态及蔬菜生长和品质的影响,筛选出能大幅降低蔬菜作物As含量的复合钝化材料,为As污染土壤的修复和安全利用提供理论依据。【方法】采用盆栽试验,以不施钝化剂为对照(CK),设添加铁矿粉+钢渣(AB)、铁矿粉+煤渣(AC)、铁矿粉+钢渣+煤渣(ABC)、铁矿粉+钢渣+腐殖质(ABD)、铁矿粉+钢渣+煤渣+腐殖质(ABCD) 5个复合钝化剂处理,种植小白菜收获后,利用原子荧光形态分析仪测定As在土壤中形态变化差异和白菜中的含量,分析不同复合钝化剂的钝化效果。【结果】与CK相比较,添加AB、AC、ABC和ABCD 4种复合钝化材料能显著降低土壤As有效态含量(P<0.05,下同),而ABD的钝化效果不显著(P>0.05),处理ABC的钝化率最高,为60.91%。供试土壤中残渣态As (O-As)和铝型As (Al-As)的比例呈逐渐增加趋势,比例范围分别为32.52%~34.88%和16.44%~28.17%;而易溶态As(AE-As)、铁型As(Fe-As)和钙型As(CaAs)比例呈下降趋势,比例范围分别为0.66%~1.50%、19.63%~31.28%和16.64%~17.15%。施用复合钝化剂的白菜生物量均显著提高,株高和株幅也相应有所增长,均达显著水平(除AC处理的株幅外),其中处理ABC的生物量增长达91.46%;地上部和地下部As含量的变化范围分别为0.306~0.588 mg/kg和0.622~1.592 mg/kg,有效抑制白菜地上部和地下部对As的累积,其中,处理AB、AC、ABC和ABD的地上部(可食部位) As含量均低于国家标准(GB 2762—2017)(新鲜蔬菜As≤0.5 mg/kg);处理AB、AC和ABC均不同程度地抑制白菜向地上部迁移As的能力。【结论】施用复合钝化剂2.5%铁矿粉+1.0%钢渣+2.0%煤渣,既可有效降低土壤As有效态含量,又能最大限度减少As在白菜地上部(可食部位)中的累积,有效促进白菜生长。

     

    Abstract: 【Objective】To explore the effects of applying different compound passivation materials on soil As speciation and cabbage growth in karst mountainous areas in Guizhou, and to screen passivation material which were able to reduce heavy metal content in crops, so as to provide a theoretical basis for the remediation of arsenic-polluted soil.【Method】Pot experiment was carried out. Taking the soil with no passivation as control(CK), and different compound passivation iron ore powder+steel slag(AB), iron ore powder+cinder(AC), iron ore powder+steel slag+cinder(ABC), iron ore powder+steel slag+humus(ABD), iron ore powder+steel slag+cinder+humus(ABCD) were applied in contaminated soil, and As content in soil and cabbage was determined by atomic fluorescence spectrometer to analyze passivation effects of different compound passivation materials.【Result】Compared with CK, adding four kinds of compound passivation materials, AB, AC, ABC and ABCD could significantly reduce the effective content of As in the soil (P<0.05, the same below), while the passivation effect of ABD was not significant(P>0.05), and treatment ABC had the highest passivation rate of 60.91%. The proportions of O-As and Al-As in the tested soil showed a gradually increasing trend, and the proportions ranged from 32.52% to 34.88%, 16.44% to 28.17%; and the proportions of AE-As, Fe-As and Ca-As showed a downward trend, and the proportions ranged from 0.66% to 1.50%, 19.63% to 31.28%, and 16.64% to 17.15%. After the applying compound passivation agents, the biomass of cabbage was significantly increased, and the highest increase of 91.46% was witnessed in treatment ABC, and the plant height and plant width also increased correspondingly, reaching a significant level(except for plant width in treatment AC). The variation range of arsenic content in the above-ground and underground parts was 0.306-0.588 mg/kg, 0.622-1.592 mg/kg, which indicated the materials effectively inhibitedarsenic accumulation in the above-ground and under-ground parts of cabbage. The arsenic content of the above-ground parts(edible parts) treated by AB, AC, ABC and ABD were all lower than the national standard(GB 2762-2017) (fresh vegetables As ≤ 0.5 mg/kg); treatments AB, AC, and ABC inhibited the ability of cabbage to transport arsenic to the above-ground to different degrees.【Conclusion】Applying 2.5% iron ore powder+1.0% steel slag+2.0% cinder can not only effectively reduce the effective content of arsenic in the soil, but also minimize arsenic accumulation of in the above-ground of the cabbage (edible part) to promote the growth and development of cabbage.

     

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