Flora And Biogeochemical Characteristics Of Karst Bauxite Area

Study on the flora geography and biogeochemistry can provide valuable scientific data for ecological restoration of environmental pollution and protection and utilization of biological resources in mining areas.Research of the relationship between complete floristic geography and geochemical characteristics of karst bauxite area in China were not clear.In this paper,study on the plants of four typical karst bauxite areas in Guizhou province,China.Adopting the theories and methods of bryology,phytogeography and biogeochemistry,establishing the plant list of karst bauxite area,and analyzing the geographical characteristics and properties of the flora.The concentrations of metal elements in plants and soil were analyzed by ICP-MS and assessment soil metal contamination levels.Transfer characteristics of soil metals in plants were analyzed.Comprehensive analysis showed that the flora geography had obvious characteristics of transition from tropical to subtropical and temperate zone.Barbula rigidula and Pteris vittata were suited species for pollution monitoring and ecological restoration of karst bauxite area.The main research as follows:1.The characteristics of the floristic composition(1)The species of the study area were rich.The flora consists of81 families and 285 species belonging to 176 genera.There were 124species of bryophytes belonging to 20 families and 47 genera.There were161 species of vascular plants belonging to 61 families and 129 genera.The dominance family and genus of plant were comparatively strong,and characteristics of genus and species were comparatively poor.(2)The life forms types of plant were monotonous.The life forms of bryophytes included Short turfs,Tall turfs,Mats and Wefts and Turfs were the main.The life forms of vascular plants were dominated by herbaceous plants.Turfs bryophytes and herbaceous plants were suited for growing in arid and barren soil environment of mining area.2.The characteristics of the floristic areal types(1)The floristic elements were comparatively complicated and diverse.Floristic elements of bryophytes contained 9 types,North temperate and Tropical asia were the main.Floristic elements of vascular plants family included 7 types,floristic elements of vascular plants genus contained 11 types and species contained 12 types,Pantropical and North temperate were the dominant.(2)The flora had obvious characteristics of transition from tropical to subtropical and temperate zone.The floristic composition were rich.Results showed that the natural history evolution of floristic geographical components were related to the origin of Subtropical,Tropical and Temperate regions.3.Variation characteristics of metals element content in plants(1)Contents of Al and Fe in plants were positively correlated.Al and Fe in Barbula rigidula were strong positive correlation(r=0.910),there may be obvious synergistic effect.It was a pioneer plant with good indicators of soil pollution.(2)Pteris vittata was easy to adsorb and accumulate Al and Fe elements.There was a strong positive correlation between Al and Fe in Pteris vittata root(r=0.921),a very significant positive correlation between Al and Fe in Pteris vittata stem(r=0.958),and a significant positive correlation between Al and Fe in Pteris vittata leaf(r=0.984).It was a dominant plant for vegetation restoration and reconstruction.4.Differential characteristics of metals element concentration in soils(1)Concentrations of Al in topsoils of bryophytes were relatively high,Ti contents were relatively low.Concentrations of Al and Fe in topsoil of Barbula rigidula were higher and positively correlated(r=0.503).Principal component analysis(PCA)showed that there were a significant positive correlation between Al and Fe in Barbula rigidula and the topsoil.Results showed that the tolerance and enrichment ability of Barbula rigidula and was suited for monitoring soil environmental pollution.(2)Contents of Al and Fe in rhizosphere soils of vascular plants were relatively high,Ti concentrations were relatively low.The concentrations of Al and Fe in rhizosphere soil of Pteris vittata were higher and positively correlated.Principal component analysis showed that there were a strong positive correlation between Al and Fe elements in Pteris vittata and was suited for ecological restorer of metal pollution treatment.5.Plant metals enrichment characteristics and soil contamination assessment(1)Bioconcentration factor(BCF)analysis showed that there we-re the differences in bioaccumulation capacity of elements in plants and organs.The enrichment capacity of Al and Fe in Barbula rigidula and Pteris vittata root were relatively high(BCF>1)and were the relative enrichment.Transfer factor(TF)analysis showed the transfer coefficient of Al and Fe in Pteris vittata were the lowest(TF<1).Al and Fe were mainly enriched in roots,and accumulation capacity of roots were significantly higher than that of stems and leaves.Analysis showed that Barbula rigidula and Pteris vittata play an important role in ecological monitoring and restoration.(2)Using pollution index to evaluate metal pollution.The single factor pollution(P_i)index and nemero comprehensive pollution index(P_c)of the six metal elements were all greater than 3,and index of geo-accumulation(I_geo)was at moderate to severe pollution level.Revealed that the soil in the mining area was at moderate to severe pollution level.