Element Compositions And Their Spatial Pattern Of Xanthoria Elegans In Taihang-Yanshan Mountains

Lichens,as symbiotic associations between a fungus(mycobiont)and an alga and/or cyanobacterium(photobiont),are highly sensitive to environmental changes especially to air pollution.Lichen can effectively reflect the atmospheric element deposition level in the study area and therefore have been proposed as a good biomonitor for atmospheric pollution.Affected by regional atmospheric transportation and local anthropogenic emission,the atmosphere in Taihang-Yanshan Mountains has been polluted.However,there is a lack of systematic research on the deposition level,spatial distribution pattern,and source apportionment of atmospheric elements in this region.In this study,the lichen Xanthoria elegans and environmental samples(substrate rocks and shallow soil)were collected from 176 sites of Taihang-Yanshan Mountains.The concentrations of 43 elements(Al,As,Ba,Be,Bi,Cd,Ce,Cr,Cs,Cu,Dy,Er,Eu,Fe,Gd,Ge,Ho,La,Li,Lu,Mg,Mn,Mo,Nb,Nd,Ni,Pb,Pr,Rb,Sb,Sc,Se,Sm,Tb,Th,Ti,Tl,Tm,U,V,Y,Yb and Zn)in the samples were determined by ICP-MS,and correlation analysis,cluster analysis and kriging analysis were conducted.By using lichen biomonitoring,our goals were:1)to determine the level,spatial patterns and source of atmospheric pollutants in the region by characterizing element compositions of the samples;and 2)to validate the effectiveness of X.elegans as a biomonitor for atmospheric element depositions in the region.The results show that,29 elements(Al,Ba,Be,Ce,Dy,Er,Eu,Fe,Gd,Ge,Ho,La,Li,Lu,Mn,Nb,Nd,Ni,Pr,Sc,Sm,Tb,Th,Ti,Tm,U,V,Y and Yb)are mainly from the crust,and 13 elements(As,Bi,Cd,Cr,Cs,Cu,Mo,Pb,Rb,Sb,Se,Tl and Zn)are mainly from anthropogenic activities.There is a certain degree of air pollution in the study area,and the content of most elements decreases from the North China Plain and Shanxi Basins to the inner part of the Mountains.It shows that the pattern of atmospheric element depositions in mountains is affected by the long-range transportation of atmospheric pollutants from the North China Plain and Shanxi Basin.The mean bioaccumulation level is light for most elements in Taihang-Yanshan Mountains.The bioaccumulation level are generally higher in eastern part of Taihang Mountains than in western Part,and are higher in southern part of Yanshan Mountains than in northern part.It shows that Xanthoria elegans can effectively monitor the air pollution of Taihang-Yanshan Mountains.