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摘要
This study aimed at analyzing the metal accumulation in mosses sampled in forests across Germany. The data that were used to this end were collected in the framework of the European Heavy Metals in Mosses Surveys conducted every 5 years since 1990 in at least 21 European countries. The moss surveys aim at uncovering the accumulation of up to 40 metals and, since 2005, nitrogen in mosses. Germany took part in the moss-monitoring campaigns 1990, 1995, 2000 and 2005. The sampling at up to 1,028 forest sites and the chemical measurements of the concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), nickel (Ni), lead (Pb), antimony (Sb), titanium (Ti), vanadium (V) and zinc (Zn) followed a European guideline. The measurement data and the detailed sites descriptions were integrated into a geographical information system. The site and element-specific measurement data as well as their geostatistical surface estimations were analyzed by means of descriptive statistics and they were aggregated to multi-metal indices (MMI). The MMI represents the mean rank of each monitoring site or geostatistically estimated raster cell regarding all elements referred to. Hence, the metal bioaccumulation in German forests could be assessed as a whole over the period 1990-2005. The MMI was calculated for two sets of elements: Cr, Cu, Fe, Ni, Pb, Ti, V and Zn (MMI(1990-2005)) and As, Cd, Cr, Cu, Fe, Ni, Pb, Ti, V and Zn (MMI(1995-2005)). Element-specific percentile statistics and correlation analyses were performed to uncover element-specific developments over time. Furthermore, correlations between metal concentrations in mosses and depositions were calculated. In terms of the MMI(1990-2005) and the MMI(1995-2005), respectively, the metal bioaccumulation in the forests of Germany clearly decreased continuously between 1990 and 2000. Contrary to this, the MMI increased from 2000 to 2005. This also holds true for the medians of the element loads of As, Cr, Cu, Fe, Ni, Sb, Ti and Zn. The median bioaccumulation of Cd, Pb and V in the German forests do not follow this trend after they have been decreasing continuously since 1990 together with all other elements. Many of the elements show moderate correlations (r > 0.5) but these correlations could not be corroborated to be stable over time. Moderate to high correlations could be proven for the metal concentrations in mosses and depositions. The European moss monitoring allows for a long-term monitoring of the metal bioaccumulation in forests. The moss surveys complement and detail the deposition measurements in forest ecosystems in terms of high spatial resolution and a broad range of elements. No other Germany monitoring network allows for combination of measurement data with topographical, land use and ecological information describing the sampling sites and their surroundings to evaluate whether the measurements are influenced by site-specific or regional land characteristics. Other investigations would profit from such a comprehensive data base since factors could be detected which, besides the deposition rates, influence the metal bioaccumulation in forests: moss species-specific accumulation rates, canopy drip effects and the growth patterns of the sampled mosses. The investigation gives the latest comprehensive overview of the metal bioaccumulation in the German forests. The MMI approach allows summarising the temporal trends of element loads in mosses. The moss monitoring is a significant part of forest monitoring and unique rgarding spatial resolution, elements covered, and consideration of site-specific and regional confounding factors in the statistical analyses and transparency and performance of data management.
- 出版日期2010-5
