Distribution and heavy metal accumulation of pioneer plants in lead-zinc tailings ponds in southern Guizhou
Ecological restoration of tailings ponds is crucial for improving biodiversity and reducing pollution from heavy metal sources in mining regions.To screen the pioneer plant species that can be used for ecological restoration of lead-zinc tailings in karst areas,we measured the diversity index and distribution characteristics of plant species in a new tailings pond and an old tailings pond in the centralized area of Niujiaotang lead-zinc tailings pond in southern Guizhou were selected as the study area.Seven pioneer plant species were evaluated and screened,and their bioconcentration factors(BCF)and translocation factors(TF)of Zn,Pb,Cd,Cu,As,and Sb in tailings were analyzed to explore their accumulation characteristics and ecological restoration potential.The results showed that the tailings in the study area were alkaline.Cd and Zn contents exceeded soil background values of Guizhou Province and local soil heavy metal contents by several times,and the contents of bioavailable Cd and Zn were the highest.A total of eight plant species belonging to eight genera and four families(Ilex crenata,Arundinella hirla,Eremochloa ciliaris,Imperata cylindrica,Saccharum arundinaceum,Equisetum hyemale,Miscanthus floridulus,and Bidens pilosa)were distributed in the study area,which were mainly from Gramineae.Seven pioneer species screened(except I.crenata)were herbs and the contents of Zn,Cd,Cu,and As exceeded the normal levels in plants.The BCF and TF of E.ciliaris,I.cylindrica,and E.hyemale were greater than one for Cu,the BCF and TF of M.floridulus and B.pilosa were greater than one for As.Similarly,the BCF and TF of S.arundinaceum were greater than one for Cu and As.The abovementioned species are Cu and As accumulator,respectively.The BCF of A.hirla was greater than one for Cu,but the TF was less than one,indicating it is a root hoarding plant.In conclu-sion,seven pioneer plant species in the study area showed strong tolerance and accumulation ability to Cu,As,and other heavy metals,and had certain potential to be used in ecological restoration.
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