An Ecological Survey On Vegetation And Screening Of Heavy Metal Hyperaccumulator At Ganluo Lead/Zinc Mine Area In Sichuan Province

As one of the main environmental problems,Soil contamination is hard to handle and dispose,therefore,phytoremediation-a new green technique was proposed. Hyperaccumulator or tolerant plants was the key to apply the technique to heavy metal contaminated soil,so the author investigated to screening out of such plant species.A survey was conducted on plant vegetation in two mine area of Chipugou and Aidai in Ganluo County,Liangshan State,Sichuan Province,respectively in April, 2006 and April,2007.By analyzed the soil properties and heavy metal concentrations in both collected plant and soil samples,the major results were revealed as following:(1) The mine soil was slightly acali,and the contents of organic matter were quite high at large.Soil there was highly contaminated by Pb,Zn and Cd.The heavy metal concentrations in soils were in an order of:Pb＞Zn＞Cu＞Cr＞Cd,which approximately accorded with that of the plants.(2) The original subtropical evergreen broad-leaved forest was destroyed due to the exploitation of mine,formed secondary bush land,the coverage of which was about 65%.In plant vegetation,the representative plants were Machilus microcarpa Hemsl.for tree layer;Solanum indicum L.,Cynanchum auriculatum Royle ex Wight, Buddleja albiflora Hemsl.,Debregeasia orientalis C.J.Chen,Rumex hastatus D.Don for brushwood layer;Chenopodium ambrosioides L.,Pteris vittata L.,Artemisia argyi Levi.Et Vant.,Boehmeria clidemioides Miq.var.diffusa(Wedd.) Hand.-Mazz., Girardinia palmate(Forsk.) Gaud.,Erianthus rufipilus(Steud.) Griseb.,Bidens pilosa L.for herbaceous layer.There were 67 plants which were mostly herbs,belonged to 31 families and 53 genuses.The dominant plant species included Artemisia argyi,Bidens pilosa, Chenopodium ambrosioides,Boehmeria clidemioides Miq.var.diffusa,Pteris vittata, Erianthus rufipilus,Senecio scandens,Elsholtzia cypriani and Solanum indicum,and Ricinus communis,Ainaslisea hanryi,Chamaenerion angustifolium and Rumex hastatus in some special places.(3) Pb and Zn concentrations were obviously higher than that of the other heavy metals in plant communities,but there were no relationships between Pb and Zn concentrations in communities and the total and extracble ones of soils.(4) The correlation analyses between heavy metal concentrations of soils and plants suggested that there were certain positive correlations between heavy metal concentrations in plants and associated soils,except Pb and Cu.Additionally,there was no relationship between heavy metal concentrations in plant communities and value of pH in soils,but there was obvious positive correlation between Cr concentrations in plant communities and contents of organic matter in soils.(5) The accumulation and absorption abilities of heavy metals were so different in plants of different species or different conditions.Several potential hyperaccumulators or hyperaccumulator and tolerant plants were identified:plant 1 as Pb hyperaccumulator,Dumasia villosa,Elsholtzia cypriani,Anemone tomentosa, Clinopodium gracile,Senecio scandens,Ainaslisea hanryi,Artemisia apiacea, Oreocnide frutescens,Pteris nervosa and Anemone hupehensis as potential Pb hyperaccumulators,Comnyza Canadensis,Ficus tikoua,Boehmeria clidemioides Miq.var.diffusa,Bidens pilosa,Artemisia hedinii,Isoden serra,Woodwardia.japonica, Streptolirion volubile,Erianthus rufipilus,Senecio wightii,Verhena officinalis, Eupatorium Adenophorum,Nicandra physaloides,Girardinia palmate,Carex souliei, Artemisia argyi,Solanum indicum,Rumex hastatus,Solanum nigrum,Hypericum patulum and Sambucus chinensis as tolerant plants of Pb.The root of Carex souliei had ability to hyperaccumulate Zn.Cd concentrations in aboveground part of Senecio wightii approaching the standard of Cd hyperaccumulator,showed its strong ability to bioaccumulate and transfer Cd...