Palladium in waste waters and surface waters of north rhine-westfalia

Abstract

Increasing concentrations of platinum group elements (PGE) in several environmental compartments have been reported in a number of recent publications (Helmers et a. 1998, Kmmerer 1999, Laschka and Nachtwey 1997, Pyrzynska 2000, Schfer et al. 1999, Sures et al. 2002a,b). Abundant data on platinum in the environment are available, but there are still important gaps of knowledge concerning the main sources, pathways and sinks of palladium (Pd) in the environment. This is mainly due to the difficulties in the reliable analysis of trace amounts of Pd in real samples, which is hampered by a number of severe interferences. The use of Pd in autocatalysts, dental alloys, electronics and as a catalyst for numerous industrial applications are supposed to be the main sources for Pd in the environment. For the near future, a further increase of the global palladium demand is forecast (Kendall 2004), and thus increasing emissions of palladium into the environment can be expected. Increasing contents of Pd have been reported from sewage sludge (Schfer et al. 1999), and recent investigations on biota have shown that aquatic organisms can accumulate Pd very effectively (Sures et al. 2002b). Thus, Pd input to surface waters by industrial effluents and other waste water sources may be an important link in the biogeochemical cycle of Pd. At present, concentrations of palladium in aquatic systems are usually far below the acutely toxic level. However, long-term effects of Pd-bioaccumulation and its impact on aquatic ecosystems and man as the final link of the foodweb cannot be evalutated with the limited data available today. Pd input from diffuse sources and point sources like road wash-off, sewage treatment plants, and industrial emittents are likely to be significant sources of Pd in surface waters, but little is known about the quantitative relevance of these pathways. Furthermore, only limited data about the level of contamination of surface waters are available. Therefore, the objectives of this study were (i) to investigate the current level of contamination of surface waters with Pd, (ii) to find out relevant sources for Pd in aquatic systems, and (iii) to estimate the Pd fluxes these sources account for.