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大气沉降对烟叶重金属含量的影响及溯源分析

Effects of atmospheric deposition on heavy metal contents in tobacco leaves and traceability analysis

  • 摘要: 为加强大气沉降对烟叶重金属富集风险的评估,明确烟叶重金属的主要来源,以黄淮烟区某地具有不同大气污染代表性的生态环境类型烟田(一般农区、公路两侧、厂矿周边)为研究对象,采用薄膜覆盖覆膜(M)、不覆膜(CK)及Ti元素关联分析法,研究了不同污染特征环境下大气沉降对烟叶6种重金属积累的影响。结果表明:①不同重金属元素在各生态类型区上部烟叶中含量差异显著,厂矿周边环境下Cr、As及Pb 3种元素对烟叶污染风险较高,且风险程度依次为Pb > As > Cr;公路两侧环境下烟叶中Ni、Cd均显著高于厂矿周边及一般农区环境(P < 0.05)。②薄膜覆盖均能明显降低大气沉降对上部烟叶的重金属污染风险,M处理上部烟叶6种重金属含量均明显低于CK,厂矿周边、公路两侧及一般农区M处理上部烟叶6种重金属含量分别较CK降低37.2%、24.8%和41.4%。③不同类型烟田中部烟叶重金属含量明显高于上部烟叶,CK中部烟叶各重金属含量较上部烟叶平均提高为29.7%~49.5%。④大气沉降对上部烟叶样品Cr、As和Pb的平均贡献率分别为80.82%、72.92%和73.09%。因此,选取适宜的生态环境区进行烟叶种植对防护大气沉降影响烟叶重金属含量十分必要。

     

    Abstract: In order to assess the risks of atmospheric metal deposition in tobacco heavy metal enrichment and clarify the main sources of heavy metals in tobacco leaves, film mulching (M:mulching, CK:non-mulching) and Ti element correlation analysis was used to study the effects of atmospheric deposition and the accumulation of six heavy metals in tobacco leaves from typical tobacco fields (general farmlands, farmlands near a highway, and farmlands near a factory or a mine) with different environmental pollution and ecological types in Huanghuai tobacco-planting areas. The results showed that:1) Heavy metal contents in upper leaves from different ecological areas significantly differed. In the fields near a factory or a mine, the levels of Cr, As and Pb in tobacco were higher, and the risk degree was in the order of Pb > As > Cr. The contents of Ni and Cd in upper leaves from the fields near a highway were significantly higher than those near a factory or a mine and general farmlands (P < 0.05). 2) Film mulching could significantly reduce the risk of heavy metal pollution in upper leaves. Under M treatment, the contents of the six heavy metals in upper leaves from general farmlands, farmlands near a highway and farmlands near a factory or a mine were lower than CK with an average decrease extent of 37.2%, 24.8% and 41.4%, respectively. 3) The contents of the heavy metals in middle leaves were significantly higher than those in upper leaves. Under the CK treatment, the contents of the six heavy metals in middle leaves averagely increased by 29.7%-49.5% comparing with those in upper leaves. 4) The average contribution rates of atmospheric deposition to Cr, As and Pb in upper leaves were 80.82%, 72.92% and 73.09%, respectively. Therefore, it is necessary to select suitable ecological areas for tobacco planting to reduce the effects of atmospheric deposition of heavy metals in tobacco leaves.

     

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