Long-Term Effects of Liming on Soil Chemistry in Stable and Eroded Upland Areas in a Mining Region

Knowledge of the levels of both total metal content and metal bioavailability is critical for understanding the long-term effects of liming on soil chemistry and potential metal uptake by biota. In the present study, the long-term effects of liming on metal bioavailability in soils contaminated by smelter emissions were assessed in eroded and stable uplands in the Sudbury region, Ontario, Canada. Analytical results revealed that total metal and nutrient contents of the soil matrix are not dominantly in forms available for plant uptake for these soils. On average, only 1 and 1.1 % of total copper and nickel, respectively, were phytoavailable. Landscape topography, site stability, and smelter proximity all play an important role in metal accumulation in the surface organic and mineral horizons of regional soils. The levels of total and bioavailable elements for eroded sites were always smaller for stable and reference sites. The pH in limed sites was significantly higher, ranging from 4.12 to 6.75, in the humus form compared to unlimed areas, even 20 to 30 years following applications of the crushed dolostone (liming). No significant differences between limed and unlimed areas were found for total metal and nutrient contents. Interestingly, in the higher pH limed areas, the levels of bioavailable Al, Co, Cu, Fe, K, Mn, Ni, and Sr were lower than on unlimed areas.