Reliability of moss ( Hylocomium splendens and Pleurozium schreberi) as a bioindicator of atmospheric chemistry in the Barents region: Interspecies and field duplicate variability

Abstract

As part of a collaborative ecogeochemical mapping project in the European Arctic, the terrestrial mosses Hylocomium splendens ( Hs) and Pleurozium schreberi ( Pl) have been used to document atmospheric chemistry. The regional importance of the variability of interspecies and field duplicate samples on the element distribution in the central Barents region has been calculated. Of the 36 elements studied, 17 have significantly different concentrations in the two species. Except for K, in which all Pl samples are significantly enriched compared to Hs samples, all elements showed at least one pair that displayed the opposite behaviour to the overall trend. For the regional data set of the central Barents region, the interspecies results for (B), Bi, Cd, Co, Fe, Mn, (Na), Ni, P, Pb, S, Si, Sr, Th, U, V and Zn are directly comparable without calibration, due to lack of significant interspecies differences or a higher field duplicate uncertainty. The regional distribution of Ag, Ba, Hg, K and Sb must be interpreted cautiously in background areas, since these elements lack interspecies correlation and show significant differences between the species. Furthermore, calibration may be advisable for Al, As, Co, Cr, Cu, Fe, Mo, Tl and V for which the interspecies ratio ( Pl: Hs) varies from 0.56 to 0.91, and Ca, Cd, Mg, Pb and Rb for which the ratio varies from 1.10 to 1.38. However, as a result of our study we recommend that the original data be used without undertaking calibration, but interspecies ratios need to be quantified in all multispecies datasets. Calibrated maps of the latter elements gave no striking changes in the patterns, and a new uncertainty is introduced by calibrating the original data sets. Striking differences between interspecies ratios from six comparable studies are found, especially for As, Ni, Pb and V, which underline the fact that interspecies variations depend greatly on deposition levels and living conditions for the moss.