典型钒矿冶炼厂区域土壤重金属污染及陆生植物富集能力

植物修复是土壤重金属污染修复的重要手段。为了探明南水北调工程中线水源地土壤污染状况并对其进行修复，本研究以湖北省朝北河和典型钒矿冶炼厂为对象，按季节采集该区域土壤（样本量n = 14）和当地优势陆生植物（样本量n = 113），使用微波消解?电感耦合等离子体质谱(ICP?MS)测定V、Cr、As和Cd重金属含量，根据内梅罗指数法综合评价了土壤污染程度，评估了各种植物对四种重金属的富集能力。结果表明，朝北河采样点中排污口与河水交汇处土壤中重金属Cd含量较高；钒矿冶炼厂原矿堆放区V超标近83倍，Cr、As和Cd重金属超标两倍以上，土壤受到严重污染；其他采样点均受到不同程度的重金属污染。植物重金属富集能力和耐受性评价结果表明，鼠麴草、密叶飞蓬、一年蓬对四种重金属耐受性极强，小蓬草、白茅、少花龙葵、野菊、白车轴草、稗是V、Cr和Cd的超富集植物，蜈蚣草、构树对As的富集能力极强，野艾蒿对Cr和Cd的富集能力较强，丁香蓼和日本毛连菜分别对Cr和V具有较强的耐受性和富集特异性，委陵菜和垂序商陆对Cd具有较强的富集能力和特异性。五种优势植物盆栽实验表明，苎麻在复合金属污染条件下耐受性最强，委陵菜富集能力最强。 

Analysis of heavy metal contamination in the soil and enrichment capabilities of terrestrial plants around a typical vanadium smelter area

Phytoremediation is an important means of soil heavy metal pollution remediation. In order to figure out the soil pollution status of the water source in the middle line of the South-to-North Water Transfer Project and repair it, soil samples (n = 14) and local dominant terrestrial plants (n = 113) were collected in typical areas around Chaobei River and the typical vanadium smelter in Hubei Province in four seasons. Microwave digestion–inductively coupled plasma mass spectrometry (ICP?MS) was applied to analyze the concentrations of vanadium (V), chromium (Cr), arsenic (As), and cadmium (Cd) in soils and plants. Soil pollution levels were evaluated on the basis of the Nemerow index method. The enrichment capabilities of plants for the four heavy metals were also analyzed. Results show that the heavy metal content of soil around the junction of the sewage outfall and the river is the highest among the seven sampling sites around Chaobei River. The concentration of V in the raw ore stacking area exceeds the limit by approximately 83 times and the concentrations of Cr, As, and Cd exceed the limit by approximately 2 times, which make the soil in the raw ore stacking area heavily contaminated. The soils in the six other sampling sites in the smelter are polluted in different degrees. The results of the evaluation of the enrichment and tolerance capabilities indicate that Gnaphalium affine, Erigeron multifolius, and Erigeron annuus have the highest tolerance capability for the four heavy metals. Conyza canadensis, Imperata cylindrica, Solanum photeinocarpum, Dendranthema indicum, Trifolium repens, and Echinochloa crusgalli are the hyperaccumulators for V, Cr, and Cd. The enrichment capabilities of Pteris vittata and Broussonetia papyrifera for As are extremely high. Moreover, Artemisia lavandulaefolia has a high enrichment capability for Cr and Cd, Ludwigia prostrata and Picris japonica have prominent tolerance and enrichment specificities for Cr and V, and Potentilla chinensis and Phytolacca americana have obvious enrichment capabilities for Cd specifically. The pot experiments of five local dominant terrestrial plants illustrate that, under the composite heavy metal contaminant conditions, Boehmeria nivea has the highest tolerance capability and Potentilla chinensis has the highest enrichment capability.