中文摘要：

选取了6种不同性质土壤，添加7个浓度水平的Zn，研究了不同老化时间（14、90、180、360和540d）对土壤中外源性Zn有效形态及毒性阈值（ECx）的影响，并对Zn老化过程的主要影响因子进行分析．结果表明：土壤中0．01mol·L—CaCl2提取态Zn含量随着老化时间的增加先快速下降，随后变化减缓，到540d时基本达到平衡．随着老化时间的增加，土壤中Zn对小白菜生长的毒性阈值（ECx，x=10、50）逐渐增加，毒性显著降低（P〈0．05）．Zn老化因子（AF）AF10和AF50分别为1．077～1．743和1．174～1．441，老化因子随老化时间增加而增大．土壤中Zn的平衡浓度（C∞）与土壤pH、阳离子交换量（CEC）、有机碳含量呈显著负相关关系，其中pH是决定Zn老化速率最重要的因素，其次是CEC和有机碳含量，高pH下土壤中Zn达到平衡所需的时间较短．基于土壤老化因子与主控因子建立土壤中Zn的毒性阈值预测模型，所得预测值与实测值之间有较好的相关性．研究结果将为不同土壤中外源性Zn毒性阈值的归一化处理及生态风险基准值的制定提供理论依据．

英文摘要：

Six typical China soils with different properties were selected and added with seven concentrations of ZnCl2 to study the effects of different aging time （ 14, 90, 180, 360, and 540 days） on the form transformation and eco-toxicity threshold （ ECx ） of added Zn in the soils, with the main affecting factors analyzed. The results indicated that with the increase of aging time, the fraction of 0.01 mol·L-1 CaCl2-extracted Zn in the soils decreased sharply initially, then slowed down, and reached the dynamic balance after 540 d incubation. The eco-toxicity thresholds （ECx, x = 10, 50） of Zn to bok choy increased significantly with aging time （P〈0.05） , which implied the marked decrease of the phyto-toxicity of Zn. The measured aging factors AF10 and AF50 of Zn ranged from 1. 077-1. 743 and 1. 174-1. 441, respectively, and increased with aging time. The balanced concentration of Zn in the soils was significantly negatively correlated with soil pH, CEC, and organic carbon （Org-C） content, and soil pH was the most important controlling factor, followed by CEC and Org-C. It took shorter time to reach Zn balance in the soils with higher pH. The prediction model of the ECx of Zn was developed based on the aging factors and the main soil properties, and could be well validated by the measured ECx under field condition. This study would provide theoretical basis for the normalization of the eco-toxicity thresholds of added Zn in different soils and the formulation of the environmental criterion of Zn in China soils.