Leaching and distribution of nitrogen and nickel in nickel-perturbed jack pine forest microcosms

Abstract

The effects of NiSO₄, additions of 100 and 500 μg Ni g ⁻¹soil, and of stack-dust from a Ni smelter in Sudbury Ontario, on the accumulation and leaching of N and Ni in a boreal jack pine (Pinus banksiana Lamb.) ecosystem were studied using microcosms in the greenhouse. NiSO₄ was found to significantly increase leaching losses of NH₄ ⁺ and NO₃ ⁻ at some sampling times. Stack-dust added in a single large dose produced much more dramatic leaching losses of N than did the NiSO₄, while gradual additions of stack-dust produced no excess leaching losses relative to controls. At the end of 11 mo there were no significant differences in N concentrations of plants in microcosms receiving different treatments, nor were there differences in inorganic N concentrations in soil. Significant leaching of Ni occurred from all microcosms except those treated weekly with stack-dust. Nickel retained by the microcosms was found to accumulate primarily in the organic soil layers. Nickel concentrations of plants were also increased by the treatments, especially in the moss layer. The 500 μ g g⁻¹ NiSO₄ treatment produced the highest increases in plant concentrations of Ni.