In Situ Stabilization of Trace Metals in a Copper-Contaminated Soil using P-Spiked Linz-Donawitz Slag

P-spiked Linz-Donawitz (LD) slag was used as a soil additive to improve physico-chemical soil properties and in situ stabilize Cu and other trace metals in a sandy Cu-contaminated soil (630 mg kg-1 soil) from a former wood preservation site. The LD slag was incorporated into the contaminated soil to consist four treatments: 0 % (T1), 1 % (T2), 2 % (T3), and 4 % (T4) per air-dried soil weight. A similar uncontaminated soil was used as a control (CTRL). After a one-month reaction period, potted soils (1kg) were used for a 2-week growth experiment with dwarf beans (Phaseolus vulgaris L.). Soil pH increased with the incorporation rate of LD slag from 5.7 in the T1 soil up to 7.9 in the T4 soil. Similarly the soil electrical conductivity (EC, in mS cm- 1) rose from 0.15 (T1 soil) up to 1.17 (T4 soil). Bean plants grown on the T1 soil showed a high phytotoxicity. All incorporation rates of LD slag increased the root and shoot dry weight yields compared to the untreated soil (T1). The foliar Ca concentration of beans was enhanced for all LD slag-amended soils, while the foliar Mg, K, and P concentrations were not increased. Foliar Cu, Zn, and Cr concentrations of beans decreased with the LD slag incorporation rate. The 2% incorporation rate was sufficient to obtain the highest bean growth and foliar Ca concentration, to reduce foliar Cu concentration below its upper critical value, and to avoid an excessive soil EC and Zn deficiency