土壤重金属Cd在木薯中累积特征及产地环境安全临界值

【目的】研究土壤重金属Cd在木薯中累积与分配特性，探讨木薯在Cd污染土壤环境中的安全临界值。【方法】采用土壤盆栽试验，设6个土壤Cd浓度水平，测定不同土壤Cd浓度处理下木薯块根、茎叶的Cd含量，建立线性回归模型，并依据GB 2762-2005标准模拟求出木薯在Cd污染土壤环境中的安全临界值。【结果】木薯根、茎、叶的Cd含量与土壤Cd浓度呈极显著正相关，整体分布特征为茎>叶>根。当土壤Cd添加量为25 mg/kg时，木薯块根Cd含量达到0.22 mg/kg，超过国家薯类作物的限量标准0.1 mg/kg。模拟求出种植木薯的土壤Cd安全临界值为1.28 mg/kg，以木薯块根为收获目标的土壤Cd安全临界值为13.23 mg/kg。【结论】木薯对Cd累积规律为茎>叶>根，拟合求出以木薯块根为收获目标的土壤Cd安全临界值为13.23 mg/kg。

Cd accumulation characteristics of cassava and its safe critical value in soil

Result]Cd content in root,stem and leaf showed significantly positive correlation with Cd concentration in soil.The Cd accumulation in different parts of cassava presented shoot>leaf>root.Stems accumulated the highest Cd content,followed by leaves and roots.At 25 mg/kg Cd concentration in the soil,to the roots showed 0.22 mg/kg Cd content,violating the food safety standard(GB 2762-2005,Cd≤0.1 mg/kg).Safe critical value Cd was identified as 1.28 mg/kg for cassava plantation soils.At the concentration of 13.23 mg/kg Cd in soil,tuberous root of cassava were found safe for eating purpose.Conclusion]The Cd accumulation in cassava presented shoot>leaf>root.At the concentration of 13.23 mg/kg Cd in soil,tuberous root of cassava was found safe for eating purpose.