Relationships between soil properties and toxicity of copper and nickel to bok choy and tomato in Chinese soils.
ABSTRACT The toxicity of copper (Cu) and nickel (Ni) to bok choy and tomato shoot growth was investigated in a wide range of Chinese soils with and without leaching with artificial rainwater. The results showed that the variations of Ni toxicity induced by soil properties were wider than that of Cu toxicity to both tomato and bok choy plant growth. Leaching generally decreased the toxicity of Cu and Ni added to soils, which also depended on soils, metals and test plant species. Soil factors controlling metal phytotoxicity were found to be soil pH and soil organic carbon content for Cu, and soil pH for Ni. It was also found that soil pH had stronger effects on Ni toxicity, compared to Cu toxicity. Predictive toxicity models based on these soil factors were developed. These toxicity models for Cu and Ni toxicity to tomato plant growth were validated using an independent dataset using European soils. These models could be applied to predict the Cu and Ni phytotoxicity in not only Chinese, but also European soils. Environ Toxicol Chem © 2013 SETAC.
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ABSTRACT: The effect of pH on the bioaccumulation of nickel (Ni) by plants is opposite when using a nutrient solution or a soil as a growing medium. This paradox can be understood if the pH effect on the bioaccumulation, on the chemical speciation in the soil solution, and on the binding to the soil of Ni are all taken into account. Using simple equations to describe the individual relationships, it is possible to quantify these effects once the relationships have been established. Increased Ni uptake leads to reduced plant dry weight production for a certain growing period. The median effective concentration (EC50) decreased from 23 to 1.7 microM Ni in the nutrient solution for pH 4.0 to 7.0, whereas the EC50 of added Ni in a sandy soil increased from 0.72 to 9.95 mmol Ni/kg soil for pH 4.7 to 6.8. Bioaccumulation, binding to the soil solid phase, and binding to the dissolved organic matter all increase with increasing pH. However, the magnitude of the effect is the least for bioaccumulation as a function of pH, causing the apparent paradox.Environmental Toxicology and Chemistry 10/2003; 22(9):2180-7. · 2.62 Impact Factor