Chaney Rufus L, Angle J Scott, McIntosh Marla S, Reeves Roger D, Li Yin-Ming, Brewer Eric P, Chen Kuang-Yu, Roseberg Richard J, Perner Henrike, Synkowski Eva Claire, Broadhurst C Leigh, Wang S, Baker Alan J M
USDA-Agricultural Research Service, Animal Manure and By-Products Lab, Beltsville, Maryland 20705, USA.
Z Naturforsch C J Biosci. 2005 Mar-Apr;60(3-4):190-8.
Two strategies of phytoextraction have been shown to have promise for practical soil remediation: domestication of natural hyperaccumulators and bioengineering plants with the genes that allow natural hyperaccumulators to achieve useful phytoextraction. Because different elements have different value, some can be phytomined for profit and others can be phytoremediated at lower cost than soil removal and replacement. Ni phytoextraction from contaminated or mineralized soils offers economic return greater than producing most crops, especially when considering the low fertility or phytotoxicity of Ni rich soils. Only soils that require remediation based on risk assessment will comprise the market for phytoremediation. Improved risk assessment has indicated that most Zn + Cd contaminated soils will not require Cd phytoextraction because the Zn limits practical risk from soil Cd. But rice and tobacco, and foods grown on soils with Cd contamination without corresponding 100-fold greater Zn contamination, allow Cd to readily enter food plants and diets. Clear evidence of human renal tubular dysfunction from soil Cd has only been obtained for subsistence rice farm families in Asia. Because of historic metal mining and smelting, Zn + Cd contaminated rice soils have been found in Japan, China, Korea, Vietnam and Thailand. Phytoextraction using southern France populations of Thlaspi caerulescens appears to be the only practical method to alleviate Cd risk without soil removal and replacement. The southern France plants accumulate 10-20-fold higher Cd in shoots than most T. caerulescens populations such as those from Belgium and the UK. Addition of fertilizers to maximize yield does not reduce Cd concentration in shoots; and soil management promotes annual Cd removal. The value of Cd in the plants is low, so the remediation service must pay the costs of Cd phytoextraction plus profits to the parties who conduct phytoextraction. Some other plants have been studied for Cd phytoextraction, but annual removals are much lower than the best T. caerulescens. Improved cultivars with higher yields and retaining this remarkable Cd phytoextraction potential are being bred using normal plant breeding techniques.
驯化天然超积累植物以及利用使天然超积累植物实现有效植物提取的基因对植物进行生物工程改造。由于不同元素具有不同价值，一些元素可进行植物采矿以获取利润，而另一些元素则可通过植物修复以低于土壤移除和替换的成本进行处理。从受污染或矿化土壤中进行镍的植物提取所带来的经济回报高于种植大多数作物，尤其是考虑到富镍土壤的低肥力或植物毒性时。只有基于风险评估需要修复的土壤才会构成植物修复的市场。改进后的风险评估表明，大多数锌 + 镉污染土壤不需要进行镉的植物提取，因为锌限制了土壤镉带来的实际风险。但是水稻和烟草，以及在镉污染土壤上种植而锌污染没有相应高出100倍的食物，会使镉很容易进入食用植物和饮食中。仅在亚洲以种植水稻为生的农户中获得了土壤镉导致人体肾小管功能障碍的明确证据。由于历史上的金属开采和冶炼，在日本、中国、韩国、越南和泰国都发现了锌 + 镉污染的稻田土壤。使用法国南部的天蓝遏蓝菜种群进行植物提取似乎是在不进行土壤移除和替换的情况下减轻镉风险的唯一实用方法。法国南部的植物地上部分积累的镉比大多数天蓝遏蓝菜种群（如来自比利时和英国的种群）高出10至20倍。添加肥料以实现产量最大化并不会降低地上部分的镉浓度；而土壤管理则促进了每年镉的去除。植物中镉的价值较低，因此修复服务必须支付镉植物提取的成本以及向进行植物提取的各方支付利润。已经对其他一些植物进行了镉植物提取的研究，但每年的去除量远低于最佳的天蓝遏蓝菜。正在使用常规植物育种技术培育产量更高且保留这种显著镉植物提取潜力的改良品种。
