TIME-AND-SITE INTEGRATED LONG-TERM BIOMONITORING OF CHEMICAL-ELEMENTS BY MEANS OF MOSSES

Abstract

To use Polytrichum formosum for biomonitoring the heavy metal status of the environment and to obtain further information on the long-term behaviour of Polytrichum concerning chemical substances, 12 chemical elements (Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Ni, Pb, Sr, and Zn) were quantitatively determined by AAS and AES/ICP measurements after sampling over regular intervals from 1985 to 1991. As already found in previous studies, all chemical elements are characterized by typical seasonal variations with maximum concentrations in the winter and lowest concentrations in the summer month due to the dilution effect of chemical elements caused by the higher biomass production of Polytrichum formosum in spring. An exception is the element K, showing contrary behaviour throughout all the years with highest concentrations in the summer month which can be explained by the important physiological and osmolytical function of this element (e.g. for movement of the leaves). According to lower emission rates the concentrations of Cd, Cr, Fe, and Ni decrease from 1985 to 1991 and a reduction of the amplitude of the seasonal variations is observable. After reduction of the Pb concentration from 1985 to 1988, it increases in 1989 and a decreasing trend is now again observable. The increased west-east traffic between Amsterdam and Berlin after the opening of the Berlin wall in 1989 may be the reason, because the sampling area is relatively close to the A30 motorway. Besides the decrease in these heavy metals the concentration of the nutritional elements Ca and Mg increases from 1985 to 1991, which is in good agreement with results of the behaviour of these elements in different polluted areas. Lower concentrations of these elements were found in polluted regions and higher concentrations in unpolluted areas. The other earth-alkaline elements represent constant concentrations (Sr) or decreasing concentrations (Ba), possibly a competition effect by Ca and Mg on the uptake mechanism for Sr and Ba. The element Cu is characterized by decreasing concentration levels but from 1990 a new increase of Cu in Polytrichum formosum is observable. The Zn content is nearly constant from 1988 on. Polytrichum formosum has been tested as an acceptable bioindicator for different chemical elements. In order to extend this plant into a biomonitoring system it is proposed to test Polytrichum formosum at about 20 different sites in Europe with different degrees of pollution.