东南景天是一种镉和锌的超积累植物，改变土壤pH能否有效提高其吸收镉的效率，需要进一步验证。采用盆栽实验研究不同土壤pH下东南景天吸收和积累Cd的差异以及对CaCl2提取有效态镉的影响。结果表明，降低土壤pH值显著提高了土壤镉的有效态含量。弱酸性土壤即pH接近5.5时东南景天生物量及累积镉的量最大，土壤镉去除率也最高，达6.6%。强酸性即当pH接近4时，虽然植物地上与地下镉含量均最高，但生物量最小，植物去除率较其他处理低。研究证实降低土壤pH是提高植物提取效率的有效办法，这为进一步利用东南景天修复镉污染土壤，提高修复效率提供了科学依据。%Sedum alfredii Hance is an important hyperaccumulator of Cd and Zn , whether adjusting soil pH is an efficient way to enhance metal uptake must by clarified. Different pH levels were designed to measure the CaCl2 extractable soil Cd concentrations and metal concentrations in Sedum alfredii Hance tissue . Results showed that the available metal form of Cd was greatly increased with decreasing pH . Lowering pH significantly influenced plant metal uptake . Highest plant biomass and accumulation of Cd in plant existed at the second lowest soil pH ( 5 . 5 ) , while plant also extract the most total Cd in soil as to 6 . 6% . The highest shoot and root metal concen-tration were at the lowest pH ( 4 . 0 ) , but due to smallest biomass , plant extracted the smallest Cd . Overall , decreasing pH was a useful approach to enhancing the phytoremediation efficiency of Cd contaminated soils by Sedum alfredii Hance .
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