Immobilising of Cd, Pb, and Zn contaminated arable soils close to a former Pb/Zn smelter: a field study in Austria over 5 years.

Numerous smelter sites are surrounded by rural land. The entrance of non-essential metals such as lead or cadmium into the food chain is very likely as well as phytotoxicity effects of zinc. Finding a realistic solution for these large-scale contaminations was one aim of this study. Previous results from pot experiments showed a high potential for the reduction of metals entering the food chain via crops grown on smelter-contaminated soils from Arnoldstein, Austria, by the use of amendments for immobilisation. A further aim was to optimise a field experiment for overcoming the gap between pot and field experiments and to look for long-term efficiency of the treatments [lime (CA), red mud (RM), gravel sludge + red mud (GS + RM)]. Field experiment results were obtained for 5 years. Besides soil and soil pore water samples, the following harvests were yielded: spring barley (Hordeum distichon ssp. L.) (2004-2005), narrowleaf plantain (Plantago lanceolata L.) (2006-2007) and velvet grass (Holcus lanatus L.) (2007-2008). The long-term efficiency of GS + RM led us to conclude that their application seems to be a realistic and practical measure for extensively contaminated land, best in combination with metal excluding cultivars.