An extended study of heavy metal deposition in Galicia (NW Spain) based on moss analysis

This paper describes the first attempt to determine the levels of heavy metal contamination in Galicia (NW Spain) by analysis of moss species. Samples of Scleropodium purum and Hypnum cupressiforme were collected from 75 sites, in 1995 and 1997, and analysed by atomic absorption spectrophotometry and atomic fluorescence for Al, As, Co, Cr, Cu, Fe, Hg, Ni, Pb and Zn. Comparisons were made between the two moss species used and, for those elements present at different concentrations in the two species, regression lines were made for interspecies calibration. Distribution maps were drawn up for each of the elements according to their concentration in the moss. In certain areas it was possible to relate deposition to the existence of known sources of contamination. The study demonstrates that the highest levels of elements were found in the most heavily industrialised and populated areas. Concentrations of As, Cu, Hg and Ni, recorded during the 1997 sampling were significantly higher than those found in 1995, possibly due to agricultural and industrial activities.