矿区农田蔬菜重金属污染评价和富集特征研究

Pollution assessment and enrichment characteristics of heavy metals in farmland vegetables near a mining area

为明确南丹矿区周边农田不同种类蔬菜污染情况,筛选适宜本区域种植的蔬菜品种,降低生态风险,通过实地采样调查,运用单因子污染指数、综合污染指数、富集系数及系统聚类分析法,评价及比较不同蔬菜可食部位中Cd、As、Pb污染状况及富集特征,同时选取叶菜类及萝卜进行不同部位重金属累积情况分析。结果表明,研究区域农田土壤为Cd、As重度污染,Cd是蔬菜的主要污染因子,不同种类蔬菜对Cd的富集能力大小表现为叶菜类>茄科类>块根类>瓠果类>豇豆类。叶菜类、豇豆类及茄科类蔬菜对3种重金属的富集能力大小为Cd>Pb>As,块根类和瓠果类的大体趋势为Cd>As>Pb,其中抗热尖叶油麦菜对Cd、Pb的富集能力最强,生姜对As富集能力最强。通过对叶菜类及萝卜不同部位重金属浓度分析,Cd、As、Pb浓度表现为可食部位<不可食部位。研究表明,不同种类蔬菜的重金属富集能力不同,大部分易受Cd污染,其中叶菜类对Cd的富集能力基本强于其他类蔬菜,为保障村民蔬菜食用安全,建议规避叶菜类蔬菜种植,推荐种植苦瓜、香芋南瓜、七寸人参红萝卜、紫薯等瓠果及块根类蔬菜。

To clarify the pollution of different vegetables in a farmland near the Nandan mining area in China, varieties of vegetables suitable for planting in the area were selected to reduce ecological risks. Based on in situ sampling, the Cd, As, and Pb pollution status and enrichment characteristics in the edible parts of these vegetables were evaluated and compared using a single-factor pollution index,comprehensive pollution index, bioconcentration factor, and systematic cluster analysis. Leaf vegetables and radishes were also selected to analyze heavy metal enrichment in different plant parts. The results showed that the farmland soil in this area was heavily polluted with Cd and As, and the edible parts of the vegetables were mainly polluted with Cd. The Cd-enrichment capacity of different vegetables followed the order of:leafy vegetables > solanaceous vegetables > root vegetables > gourds > cowpea vegetables. The order of the enrichment capacity of similar species, namely leafy, cowpea, and solanaceous vegetables, for the three heavy metals studied was Cd > Pb > As, and the general trend of the enrichment capacity of root vegetables and gourd vegetables for heavy metals was Cd>As>Pb. Among these vegetables,the heat-resistant sharp-leaf lettuce exhibited the strongest capacity for Cd and Pb enrichment, while ginger had the strongest capacity for As-enrichment. Based on an analysis of the accumulation of heavy metals in different parts of leafy vegetables and radishes, the trends of Cd, As, and Pb concentrations showed that heavy metal concentrations in the edible parts of the plants were lower than those within the inedible parts. Overall, different species of vegetables had different enrichment capacities for heavy metals, and vegetables were more susceptible to Cd contamination. Among the analyzed vegetables, leafy vegetables had the strongest capacity to accumulate Cd. Therefore,to ensure the safety of those consuming vegetables grown in this area, leafy vegetables should not be planted. Furthermore, the study recommend the growing of momordica charantia, taro pumpkins, seven-inch ginseng carrots, purple sweet potatoes, and other gourd or root vegetables.