碳酸钙和海泡石组配对水稻中Pb和Cd迁移转运的影响

为研究组配改良剂LS(碳酸钙+海泡石)对农田土壤重金属Pb和Cd的固化效果以及水稻各部位吸收累积Pb和Cd的影响,在湘南2个矿区(矿区A和矿区B)附近污染稻田中施用了不同添加量的LS (0、2、4和8 g/kg),并进行了水稻种植的田间实验。结果表明,(1)施用2~8 g/kg的LS能使矿区A和矿区B土壤pH值分别增加1.11~1.95和1.61~2.31个单位,能使矿区A和矿区B土壤中Pb和Cd的TCLP提取态含量分别降低18.6%~62.7%、15.7%~37.1%和38.6%~66.7%、0~76.6%。(2)LS能不同程度地降低水稻各部位重金属含量。矿区A糙米中Pb和Cd含量降低9.4%~35.6%、56.1%~66.8%;矿区B糙米中Pb含量降低14.4%~36.6%,而Cd含量变化不明显。(3)LS对水稻中Pb和Cd在各部位之间的转运系数均有不同程度的影响,其中Pb和Cd从茎叶到谷壳的转运系数最大,说明水稻茎叶对重金属的转运能力最强。(4)LS添加量为8 g/kg时,Pb和Cd从谷壳到糙米的转运系数最小,且糙米中Pb和Cd含量最低。

Effects of combined amendment (limestone + sepiolite) on translocation of Pb and Cd in rice

In order to study the effects of a combined amendment (LS, limestone + sepiolite) on stabilization of heavy metals (Pb and Cd) in soil and on accumulation of heavy metals in different rice organs, a field experiment was conducted in paddy soils near two mining areas, marked as Area A and Area B, respectively, in southern Hunan, in which LS was applied in situ with ratios of 0, 2, 4, and 8 g/kg and rice was planted. The results indicated that: (1) Applying 2~8 g/kg of LS resulted in increasing soil pH values, ranged 1.11~1.95 units for Area A and 1.61~2.31 units for Area B. In addition, LS led to a reduction in TCLP (toxicity characteristic leaching procedures) extractable contents of soil Pb and Cd by 18.6%~62.7% and 15.7%~37.1% in Area A and by 38.6%~66.7% and 0~76.6% in Area B, respectively. (2) Contents of Pb and Cd in different rice organs decreased in different degrees after LS applying. Compared with the control group, contents of Pb and Cd in brown rice were decreased by 9.4%~35.6% and 56.1%~66.8%, respectively, as a result of LS applying with 2~8 g/kg to Area A soil. For Area B soil with the same ratios of LS applying, Pb contents in brown rice reduced 14.4%~36.6%, but no apparent changes were observed for Cd contents. (3) Effects of LS applying on the translocation factors of Pb and Cd were quite different within different rice organs. The greatest translocation factors of Pb and Cd were from rice straw to husk, implying that rice straw was of the greatest ability to transfer heavy metals. (4) When LS applying amount was 8 g/kg, the minimum translocation factors of Pb and Cd were obtained from rice husk to brown rice and the lowest contents of Pb and Cd in brown rice were observed.