Temporal trends in the concentration of arsenic, chromium, copper, iron, nickel, vanadium and zinc in mosses across Europe between 1990 and 2000

The European heavy metals in mosses biomonitoring network provides data on the concentration of 10 heavy metals in naturally growing mosses and is currently coordinated by the UNECE ICP Vegetation (United Nations Economic Commission for Europe International Co-operative Programme on Effects of Air Pollution on Natural Vegetation and Crops). The technique of moss analysis provides a surrogate, time-integrated measure of metal deposition from the atmosphere to terrestrial systems. It is easier and cheaper, less prone to contamination and allows a much higher sampling density than conventional precipitation analysis. Moss surveys have been repeated at five-yearly intervals and in this paper we report on the temporal trends in the concentration of arsenic, chromium, copper, iron, nickel, vanadium and zinc between 1990 and 2000. Maps were produced of the metal concentration in mosses for 1990, 1995 and 2000, showing the mean concentration per metal per EMEP grid square. Metal- and country-specific temporal trends were observed. Although the metal concentration in mosses generally decreased with time for all metals, only the decreases for arsenic, copper, vanadium and zinc were statistically significant. The observed temporal trends were compared with emission trends for Europe reported by EMEP (Co-operative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutant in Europe).