Mapping atmospheric depositions of cadmium and lead in Germany based on EMEP deposition data and the European Moss Survey 2005

Winfried Schröder, Marcel Holy, Roland Pesch, Harald Zechmeister, Harry Harmens, Ilia Ilyin
2011 Environmental Sciences Europe  
Every ve years since 1990, the European Heavy Metals in Mosses Survey provided data on atmospheric heavy metal bioaccumulations in mosses throughout Europe at a high spatial resolution. The moss data show the e ectiveness of air quality control policies: for Germany the metal bioaccumulations decreased between 1990 and 2000, whilst they increased from 2000 to 2005. This investigation is intended to show how the moss data could be used to map atmospheric depositions of Cd and Pb, which later on
more » ... Pb, which later on might serve for the calculation of Critical Loads Exceedances. In addition, we compared how much heavy metal concentrations in mosses in Germany deviate from background data observed in Greenland. Methods Mapping heavy metals with a high spatial resolution for the German territory was conducted according to the following methodology: EMEP deposition maps (50 km by 50 km spatial resolution) were intersected within a GIS with Kriging maps on Cd and Pb accumulations in mosses (EMEP (European Monitoring and Evaluation Programme) is a scienti cally based and politically driven programme under the Convention on Long-range Transboundary Air Pollution for international co-operation to solve transboundary air pollution problems). Subsequently, the statistical relations between the EMEP modelled depositions and the bioaccumulations in mosses were quanti ed by using regression analysis. The regression functions were used to transform the moss concentration maps into deposition maps. The resulting maps on Cd and Pb depositions have a spatial resolution of 5 km by 5 km and were added to the respective map on the residuals of the regression functions (Regression Kriging). Finally, the territory of Germany was extracted from the European maps on Cd and Pb depositions and the legends were adjusted accordingly in terms of n standard deviations from the German mean value. The concentrations of Al, As, Cd, Cr, Cu, Mo, Pb, Sb, Sn, and Zn in the mosses sampled in 1990, 1995, 2000 and 2005 in Germany were compared with background values derived from mosses sampled in north-eastern Greenland (Zackenberg Background Values). The di erences between heavy metal concentrations in mosses in Germany and Greenland were calculated for the 16 federal states of Germany and mapped for Pb. Results and discussion The regression models corroborate that the Cd concentration in mosses is correlated with the EMEP modelled total Cd deposition across Europe (regression coefficient according to Pearson, r p = 0.67; regression coefficient according to Spearman, r s = 0.69). The coefficient of determination is r 2 = 0.44. The same is true for Pb with r p = 0.76 and r s = 0.77 and r 2 = 0.58. Based on the regression models and the respective residuals, maps on the total deposition of Cd and Pb were calculated for the year 2005. The German mean value of total Cd and Pb deposition was 0.342 g / ha / a (standard deviation 0.08 g / ha / a and 8.6 g / ha / a (standard deviation 2.1 g / ha / a) respectively. The maps depict the spatial patterns of the total Cd and Pb deposition in terms of n standard deviations from the respective German wide mean value. The spatial resolution of the maps is 5 km x 5 km and reflects the mesh size of the moss monitoring net. Even today, the bioaccumulation of several metals in Germany still exceeds the background values observed in Greenland. This is true especially for Cd, Cr, Cu, Mo, Pb, Sb, Sn and Zn. Comparing the results of this investigation with those from other methods it can be concluded that the mean values calculated for the total Cd and Pb deposition for Germany differ from such assessed by deposition measurements and models. The latter are used to calculate Critical Loads Exceedances, which complement the ecotoxicological endpoint ´accumulation´. The deposition measurements in Germany are mainly based on monitoring systems conducted by the federal states. When trying to use deposition measurements from the ICP Forests level II programme for the validation of the EMEP deposition modelling, problems arose due to a lack of methodical harmonization and the quality of the depositions measurements. That is why in this investigation the quality controlled and spatially high resolved moss data were used to empirically validate EMEP modelled deposition maps. Conclusions In Germany, the moss measurement data provide a valuable tool at a high spatial resolution for the validation of modelling and mapping of atmospheric heavy metal deposition and should as such be used for this purpose. The comparison of the metal concentrations in mosses in Germany with the values found in Greenland indicate that atmospheric deposition of heavy metals in Germany is still considerably higher than the natural background deposition. Keywords EMEP deposition network and modelling; European Moss Survey as part of UNECE ICP Vegetation; Mapping atmospheric depositions of Cd and Pb; Zackenberg Background Values Zusammenfassung Hintergrund Das Moos-Monitoring liefert seit 1990 alle fünf Jahre flächendeckende, qualitätskontrollierte Daten über die Bioakkumulation von Schwermetallen und Stickstoff (seit 2005) in Europa. Die Monitoring-Daten belegen eindrücklich, wie sich Luftreinhaltepolitik auf die Anreicherung atmosphärischer Depositionen auswirkt. Das Moos-Monitoring reagiert auch sensibel auf eine Trendumkehr: Nachdem die Metallanreicherungen von 1990 bis 2000 deutlich sanken, stiegen die Gehalte einiger Metalle bis 2005 wieder an. Depositionsmessungen konnten diesen Trend, der auch in anderen europäischen Staaten nur durch das Moos-Monitoring entdeckt wurde, nicht detektieren. Ziel dieser Untersuchungen ist es zu zeigen, dass die Daten des Moos-Monitoring nicht nur zur Kartierung der Bioakkumulation atmosphärischer Depositionen verwendet werden können, sondern auch zur räumlich hochauflösenden Kartierung von Schwermetall-Gesamtdepositionen als Grundlage für die Berechnung von Critical Loads Exceedances. Wie weit die Bioakkumulation von Metallen in Deutschland von einem quasi-natürlichen Zustand abweicht, soll anhand geeigneter Referenzwerte bestimmt werden. Methoden Die räumlich hoch auflösende Kartierung atmosphärischer Schwermetall-Gesamtdepositionen für das Gebiet der Bundesrepublik Deutschland basiert auf folgenden methodischen Fundamenten: Die auf der Grundlage europaweit harmonisierter Messungen atmosphärischer Depositionen von Cd und Pb (Jahr 2005) an 70 Orten Europas berechneten flächendeckenden EMEP-Depositionskarten (räumliche Auflösung 50 km mal 50 km) wurden mit geostatistich validen Kriging-Karten über die Anreicherung von Cd und Pb in europaweit gesammelten Moosen in einem geografischen Informationssystem (GIS) verschnitten (EMEP (European Monitoring and Evaluation Programme) is a scientifically based and politically driven programme under the Convention on Long-range Transboundary Air Pollution for international co-operation to solve transboundary air pollution problems). Sodann wurden die statistischen Beziehungen zwischen den im EMEP-Depositionsnetz und im ICP Vegetation Moosmessnetz erhobenen Cd-und Pb-Depositionen sowie den Anreicherungen dieser beiden Metalle regressionsanalytisch quantifiziert. Mit den Regressionsfunktionen wurden anschließend die hoch aufgelösten Kriging-Karten der Cd-bzw. Pb-Gehalte der Moose in räumlich hoch aufgelöste Depositionskarten umgerechnet. Die dadurch entstandenen Cd-Schröder et al. Environmental Sciences Europe 2011, 23:19
doi:10.1186/2190-4715-23-19 fatcat:i6teyfvzqzdjvppmccpanyfkoy