4种蔬菜对土壤Mn转运累积特征及食用安全性研究

为探究土壤中锰(Mn)污染对蔬菜食用安全性的影响,以上海市常见的4种蔬菜(青椒,CA;黄瓜,CS;豇豆,VU;菠菜,SO)为试验材料,采用温室盆栽土培试验方法研究了不同土壤Mn含量梯度下的蔬菜生物量变化以及各部位Mn转运累积特征,并基于各蔬菜食用安全分析了土壤中Mn的安全阈值。研究结果表明,Mn对4种蔬菜的生长均表现出低含量促进、高含量抑制现象,SO和VU对Mn的耐受度强于CA和CS。Mn主要富集在SO的茎叶,以及CA、CS和VU的茎叶和根部,可食部分中Mn含量大小排序为SO>VU>CS>CA。SO可食部分Mn含量与土壤Mn含量呈显著对数相关(P<0.01),其他3种蔬菜的可食部分Mn含量与土壤Mn含量均呈显著指数相关(P<0.01)。依据新鲜蔬菜中Mn食用安全限量值,推导出各蔬菜对应的土壤Mn安全阈值预测区间为:SO 992.5～1 097.3 mg·kg~(-1),VU 2 607.5～2 910.0 mg·kg~(-1),CS 3 147.5～3 494.6 mg·kg~(-1),CA3 618.0～3 921.5 mg·kg~(-1)。Mn污染土壤的安全利用应优先选择种植CA、CS和VU等低累积品种。

Study on Accumulation and Transport of Mn in Four Vegetables and Their Edible Safety

Four kinds of common vegetables (Capsicum annuum, CA; Cucumis sativus L., CS; Vigna unguiculata, VU; Spinacia oleracea L., SO) in Shanghai were chosen as experimental materials to study the impact of manganese (Mn) pollution in soil on food safety for vegetables. Pot experiments were conducted to investigate the variation of vegetable biomass and Mn transfer/accumulation in different tissues of four vegetables under different Mn concentration gradients in soil, and calculate the threshold value for Mn in soil based on food safety for different vegetables. The results showed that the growth of four vegetables was promoted at low doses of Mn and inhibited at high doses. VU and SO had stronger tolerance to soil Mn than CA and CS. The contents of Mn in four vegetables increased with the increase of the Mn concentration in soil. Mn pollutants were concentrated mainly in the edible part of SO, and non-edible parts (roots, stems and leaves) of the other three kinds of vegetables. The order of Mn contents in the edible parts of vegetables was as follows: SO > VU > CS > CA. Significant logarithmic correlation was observed between Mn content in the edible part of SO and that in soil, while significant exponential correlation existed between Mn content in the edible part of the other vegetables and that in soil. According to oral reference dose (RfD) value of Mn recommended by US EPA, the prediction intervals of Mn threshold values in soil were deduced as 3 618.0~3 921.5 mg kg^?1 for CA, 3 147.5~3 494.6 mg kg^?1 for CS, 2 607.5~2 910.0 mg kg^?1 for VU, and 992.5~1 097.3 mg kg^?1 for SO, respectively. Mn contaminated soil is suitable for planting vegetables of low Mn accumulation, such as CA, CS and VU.