Vertical distribution patterns of element concentrations in podetia of cladonia rangiferina from huzhong natural reserve, Heilongjiang, China

Abstract

Lichen element compositions are of a reliable tool for the biomonitoring of atmospheric element deposition. The zoning and patterned accumulation of elements in lichen thallus is one of the important factors influencing lichen element concentrations. We collected an epigenous fruticose lichen Cladonia rangiferina (CR) from a remote site of Huzhong National Natural Reserve, Heilongjiang, NE China. Fifty-five elements (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Gd, Ge, Hg, Ho, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, P, Pb, Pr, Rb, S, Sb, Sc, Se, Si, Sm, Sn, Sr, Tb, Th, Ti, Tl, Tm, U, V, Y, Yb, and Zn) were measured with their differences among 3 parts (upper, middle, and lower) of the podetia compared. The aim of the present study was to examine the vertical patterns of element accumulation in CR. The results display a very low degree of atmospheric element deposition in the study site. Concentrations of most elements of limited metabolic significance generally increase from the upper to lower parts, indicating a continuous bioaccumulation of these elements with exposure time. Concentrations of some nutrients have little vertical difference among parts (Zn), and they are higher in the upper part than in the middle part (K, P, and S), or are similar between the upper and middle parts (B, Cu and Mg). These results suggest a nutrient translocation to the more biologically active young part. Our results highlight the importance of selecting the suitable parts of lichen thallus to increase the comparability of data in lichen biomonitoring studies.