香蕉对砷镉铅的富集转运特征及土壤重金属安全阈值

Accumulation and Transformation of Arsenic,Cadmium and Lead in Banana(Musa spp.)and Their Safety Thresholds in Soil

建立土壤重金属安全阈值是保障我国农产品质量安全的一道重要屏障。本研究通过盆栽模拟实验研究香蕉对砷(As)、镉(Cd)、铅(Pb)3种重金属的富集转运特点,进一步通过建立香蕉茎叶与土壤As、Cd、Pb总量和有效态含量的关系,推导香蕉种植系统的土壤As、Cd、Pb的安全阈值。结果显示,Cd、Pb对香蕉生物量表现出“低促高抑”的作用。香蕉各组织对As的富集规律为:根>叶>茎;而对Cd、Pb的富集规律表现为:根>茎>叶。根茎向叶转运As的能力强于转运Cd和Pb。采用回归分析方法,建立香蕉茎叶中重金属与土壤重金属总量和有效态含量之间的回归模型共12个,根据GB 13078—2017《饲料卫生标准》中对原料As、Cd、Pb的限量规定推导出香蕉土壤中As、Cd、Pb总量安全阈值分别为102.40、0.46、15.39 mg/kg,有效态含量安全阈值分别为4.77、0.10、5.27 mg/kg。

Heavy metal safety threshold is important for the control of the quality and safety of agricultural products.In this study,banana(Musa spp.)seedlings were planted in a pot experiment with soils contaminated by different concentrations of arsenic(As),cadmium(Cd)and lead(Pb)to determine the accumulation and transformation characteristics of As,Cd and Pb by banana,and the heavy metal safety thresholds were calculated by the regression models between the concentrations of heavy metals in banana stems and soils.Low concentrations of Cd and Pb showed positive promoting effect on the growth of banana,while high concentrations of Cd and Pb inhibited the growth of banana.Accumulation of As in banana tissues decreased in the order of root>leaf>shoot,while the accumulation of Cd and Pb in banana tissues decreased in the order of root>shoot>leaf.The transportation of As from root and shoot to leaf was higher than Cd and Pb.Twelve regression models between the concentrations of heavy metals in banana stems and the concentrations of total and available heavy metals in soil were built.According to the criterion of Standard of Feed Hygiene(GB 13078—2017)in China,the safety threshold of heavy metals in banana planting soils was calculated as 102.40,0.46 and 15.39 mg/kg respectively for total As,Cd and Pb,and 4.77,0.10,5.27 mg/kg respectively for available As,Cd and Pb.