Temporal and spatial trends of metal contents of Bavarian mosses Hypnum cupressiforme

Since 1981, the Bavarian State Office for Environmental Protection has been operating a biomonitoring network using the epiphytic moss Hypnum cupressiforme, which is located on a regular grid with distances 16 km. Approximately 300 moss specimens are collected yearly (since 1991 every second year) at the end of the growth period, and the concentration of trace metals is measured. In this paper Ti, V, Cr, As, Cd, Sb, Hg, and Pb are treated in detail. The overall 1981-1995 trends of metal contents are described by quantile curves; the spatial distributions and their change over time are visualised by consecutive maps. The Ti, V, and Cr loads did not change substantially since the early 1980s; their spatial distributions show a clear gradient with highest values in north-eastern Bavaria. A similar spatial gradient of the As values diminished, and the quantiles decreased up to 1995. For the rest of the metals, no clear and consistent spatial trends were found. Since the early 1980s, Hg and Sb levels remained constant, whereas Pb and Cd values decreased. The temporal and spatial distributions of metals in Bavarian mosses indicate that the transport of metal-containing particles from adjacent areas in the north-east is the major common source for several metals; other known single emission sources are also reflected in single maps. (C) 1999 Elsevier Science B.V. All rights reserved.