| The paper selects Datong wetland ecological zone, Panyi reclaimed soil and Xinzhuangzi mine as survey region. Collect plant samples and rhizosphere soil from this researching area, analyse contents of heavy metal in samples, evaluate the contaminative status of heavy metal. For the sake of providing a theoretical basis and scientific proof to crop food safety, the paper evaluates the contaminative status of heavy metal in crops, respectively using pollution load index method and health risk model. Analyse enrichment transport capacity of weeds, and screen high enrichment plant, which having reparative potential. Meanwhile, conduct the correlation analysis of heavy metal to crop rhizosphere soil and weeds. The main conclusions of this paper are as follows:1. Expect for Cd, seven kinds of heavy metal contents meet requirements of agriculture utilization, which reaching classâ…¡of soil environmental quality. In comparison with the backgroud values of Huainan soil, the content of As in weeds rhizosphere soil is lower, at a safety level, the others is higher, higher values decrease in the order:Cd>Cr>Pb>Ni>Hg>Cu>Zn.2. According to the correlation analysis of heavy metal in crop rhizosphere soil, Zn and Cu, Ni and Cr, As and Cu, Zn, Cr, Cd and Cr, Pb, Ni have significant correlation, the source maybe the same. In weeds shoot, the correlation of Ni and Cr, As and Cd respectively is 1%,5%. In weeds root, the correlation of Ni and Cu is 1%, but the correlation of Ni and Cr, Cr and Cu, Cd and Zn, Ni is 5%. The content of Ni, Cr and Pb in weeds shoot have good correlation with weeds root.3.In comparison with limited standard, the worst elements are Hg, As and Pb in contaminated crops, and they mainly accumulate the edible part. For the ske of shrinkaging heavy metal harm to human health by means of food chain, we must take appropriate measures to decrease the accumulation in crop edible part. Expect for radish and chilli, other crops don't suffer from Cd pollution.4. At the base of pollution load index method and health risk model, crops are suffered from heavy metal contamination. Hg is main contaminated element, and potherb mustard, radish, sweet potato is worst, which have serious threaten to human health. 5. In comparison with heavy metal in general plant, the heavy metal contents of Cr and Cd are more than 10 times, but Zn is lower.6. The ability of heavy metal enrichment in different weeds is different. The enrichment coefficient decrease in the order:Cu>Cd>Zn>Ni>Pb>As>Cr, which suggesting different mechanism impact enrichment transport characteristics of heavy metal in plant. The total enrichment coefficient of heavy metal in different weeds decrease in the order:wild cowpea>xanthium sibiricum patrin>jerusalem artichoke> bidens pilosa> ophiopogon japonicus> endive> mugwort> aster subulatus> green bristle grass>solidago canadensis>lris confuse>phragmites australis.7. Twelve kinds of weeds are belong to 5 families and 12 genera, mainly composite and poaceae. According to screening standard, the paper finds that wild cowpea, Jerusalem artichoke and xanthium sibiricum patrin are copper high enrichment plant, wild cowpea is also zinc and arsenic high enrichment plant, jerusalem artichoke and xanthium sibiricum patrin are also cadmium high enrichment plant, but not find nickel, lead and chromium high enrichment plant.8. Wild cowpea is Cu/Zn/As high enrichment plant, jerusalem artichoke and xanthium sibiricum patrin are Cu/Cd high enrichment plant.Figure [25] Table [25] Reference [109]... |
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