土壤溶液性质对水溶性镍的西红柿毒害的影响

选取17种具有代表性的中国土壤，研究土壤溶液性质对土壤孔隙水以及0.01 mol/L CaCl2浸提液中镍(Ni)植物毒害的影响。结果发现，孔隙水中Ni(PW-Ni)对西红柿地上部分生物量50% 抑制的毒性阈值(EC50)变化范围为1.02 ~ 8.91 mg/L，最大值是最小值的 8.7倍；CaCl2-Ni的毒性阈值EC50变化范围为 0.77 ~ 20.40 mg/kg，最大值是最小值的26.5倍，表明土壤溶液性质对水溶性Ni的毒性阈值影响很大。土壤PW-Ni毒性主要受到K+、Mg2+、S的影响，基于这3个因子的回归方程可以较好预测PW-Ni对西红柿毒性阈值EC50，决定系数为0.71。当回归方程包括土壤溶液中溶解性有机碳(DOC)、pH、电导率(EC)、Ca2+、Na+ 时，其决定系数提高到0.84，说明其他因子对PW-Ni的毒性也存在一定的影响，利用这些土壤溶液性质可以较好预测PW-Ni的植物毒性阈值。

The Influence of Soil Solution Properties on Soluble Nickel Toxicity to Tomato Shoot

The influence of soil pore water properties on soluble nickel (Ni) phyto-toxicity based on soil pore water and 0.01 mol/L CaCl2 extraction was investigated using 17 Chinese soils. Results showed that the effective concentrations of Ni in soil pore water (PW-Ni) that caused 50% inhibition (EC50) varied widely from 1.02 to 8.91 mg/L, represented 8.7 folds differences between the maximum and minimum values. Similarly, the EC50 of CaCl2-Ni varied widely from 0.77 to 20.40 mg/L, represented 26.5 folds differences. These results indicated that soil solution properties greatly influenced the toxicity thresholds of soluble Ni in a wide range of soils. The K+, Mg2+ and S were three important factors controlling the influence of PW-Ni toxicity and multiple regression results showed that they could better predict the toxicity threshold with the coefficient of determination (R2) of 0.71. When incorporating other parameters (dissolved organic carbon (DOC), pH, electrical conductivity (EC), Ca2+ and Na+) into the regression models, the R2 for EC50 increased to 0.84, which implied that other factors also influenced the PW-Ni toxicity and these soil pore water chemistry could predict PW-Ni toxicity on tomato shoot.