Abstract:
In order to analyze and compare the differences in heavy metal absorption and ecological restoration between
Phragmites australis (the reed) and
Typha angustifolia L. (the typha) in the Xiaobai River ecological restoration area, a river polluted by heavy metals in the mining area of Southeast Yunnan, we collected soil and plant samples on the west bank (wild plant area) and the east bank (ecological restoration area). The lead (Pb), zinc (Zn), chromium (Cr), nickel (Ni) in the soil and plant samples were analyzed by ICP-OES, and arsenic (As) was analyzed by AFS. The results showed that: (1) The
w(As) and
w(Ni) contents in the sediments of the reed planting area on the east bank were 38.82% and 50.53% lower than those in the west bank, while the contents of
w(As) and
w(Ni) in the sediment of the typha area were 13.54% and 21.95% lower than those in the west bank, and the wetland sediment in the ecological restoration area was seriously polluted by As and Zn. (2) There was a synergetic relationship among the enrichment of heavy metals by plants. This characteristics manifested among As-Pb-Zn, Pb-Cr and Cr-Ni in the reed, and in typha this characteristic was shown among As-Zn-Ni and Pb-Cr, being more pronounced in the reed than the typha. (3) The higher bioenrichment factor (BCF) of Cr and the transfer factor (TF) in the reed indicated that the characteristics of enrichment tolerance, while the tolerance strategy for Zn and Ni was root hoarding in reed. The results in the typha showed that higher BCF and the TF (about 1) in Pb, Zn, Ni and Cr, showing the characteristics of enrichment and tolerance, and the tolerance model for As was root hoarding. Based on our data, it could concluded that reed with large biomass and high coverage can be used as the pioneer plant in river ecological restoration area polluted by heavy metals. Moreover, the typha shows a high bioaccumulation factor and a strong ability to bioaccumulate heavy metals in the upper part of the ground, and therefore could be considered to change the planting mode of the two plants into intercropping, and harvest the upper part of typha regularly, in order to seek a better effect of heavy metals restoration in the ecological restoration area.