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Acta Prataculturae Sinica ›› 2017, Vol. 26 ›› Issue (10): 237-244.DOI: 10.11686/cyxb2016499

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Heavy metal absorption and enrichment characteristics of dominant weed species naturally growing on farmland in Northern Guizhou

YAN Lian-Ying1, 2, FAN Cheng-Wu1, 3, ZHAO Zhen-Yu4, LIU Gui-Hua1, 3, HU Gang1, 3, QIN Song1, 3, *   

  1. 1.Guizhou Institute of Soil and Fertilizer, Guiyang 550006, China;
    2.College of Agriculture, Guizhou University, Guiyang 550025, China;
    3.Guizhou Province Engineering Research Center for Agricultural Resources and Environment, Guiyang 550006, China;
    4.Kweichow Moutai Company Limited, Renhuai 564500, China
  • Received:2016-12-28 Online:2017-10-20 Published:2017-10-20

Abstract: The aim of this research was to provide reference data for the remediation of sites contaminated by heavy metals in Guizhou Province, a mountain-and-hill area. The heavy metal absorption and enrichment characteristics of 12 dominant weeds naturally growing in farmland in northern Guizhou and their root soils were analyzed. The weeds were sampled from the field, and the soils were analyzed to determine the background concentrations of heavy metals. The quality of the soil environment with reference to heavy metal pollution was judged against the Agricultural Environment Quality Evaluation Standards, and on the basis of the single factor pollution index and the Nemerow pollution index. The bioconcentration factor and transfer factor were calculated to evaluate the enrichment characteristics of the dominant weeds. The soil had single factor pollution indexes for Cu, Zn, Cd, and Pb ranging from 0.30 to 1.71 and a Nemerow comprehensive pollution index of 1.31. Therefore, the soil was judged as lightly polluted, and Cd was the main contributor. The dominant weeds in the study area were Acalypha australis, Solanum nigrum, Artemisia argyi, Lapsana apogonoides, Digitaria sanguinalis, Abelmoschus esculentus, Viola verecunda, Amaranthus spinosus, Gynura crepidioides, Youngia heterophylla, Clinopodium chinensis, and Allium fistulosum. The ranges of heavy metal contents in these weeds were as follows: Cu, 42.15-110.27 mg/kg; Zn, 35.89-157.87 mg/kg; Cd, 0.29-6.08 mg/kg; and Pb, 2.99-37.19 mg/kg. These values were within the normal range and were not indicative of hyperaccumulating plants. The bioconcentration factors and transfer factors were greater than 1 in A. australis, A. esculentus, and G. crepidioides for Cu, Zn, and Cd; in L. apogonoides for Cu and Zn, and in V. verecunda, A. spinosus, and Y. heterophylla for Cd. These species showed some characteristics of hyperaccumulation plants. The contents of heavy metals in lightly polluted farmland soil did not significantly affect the heavy metals contents in weeds. The absorption of Pb by the roots of weeds promoted Pb accumulation. In conclusion, the contents of heavy metals in the dominant weeds were in the normal range, but some dominant weeds possessed some important characteristics of hyperaccumulation plants, and have the potential to be hyperaccumulation plants.