Stronger Phytotoxicity of Nickel than Copper in Acidic Soils but Not in Alkaline Soils in China

摘要

Copper and nickel phytotoxicity are affected by the pH of different media,?especially field soil, but the mechanism and extent of these pH effects are unclear, and an understanding is required to develop environmental soil quality standards. In the?present study, it was found soil pH, as a single factor, explained &63% of the variance?of Ni phytotoxicity. In addition, Ni phytotoxicity decreased, or substantially removed, by?leaching after spiking into alkaline laboratory soils and field soils. Compared with Ni,?soil pH had a significantly weaker effect on Cu phytotoxicity in soils, which was also decreased by leaching after Cu spiking. When pH increased by 1 unit, the Cu and Ni?phytotoxicity decreased by 1.48-fold (1.34–1.78) and 2.60-fold (1.86–3.72), respectively,?indicating Ni phytotoxicity was serious than Cu in acidic soils, but not in alkaline soils, probably due to the easier formation of Ni precipitates on solid surfaces. The results also?showed that leaching was a necessary treatment in laboratory experiments to predict the?Cu and Ni phytotoxicity in field soils, especially for Ni.