有机质对典型铜锌污染土壤自然修复过程的影响

为阐明土壤有机质含量对外源铜（Cu）、锌（Zn）自然修复过程的影响，选取红壤、潮土和黑土长期试验中不同有机质含量的土样，分别加入400 mg/kg Cu或500 mg/kg Zn，采用室内培养法研究Cu、Zn污染物的自然修复过程。结果表明：各种土壤有效态Cu、Zn浓度在培养开始的10～20 d内迅速下降，随后变化减缓，培养30～60 d后基本达到平衡。外源Cu、Zn自然修复过程符合二级动力学方程。自然修复90 d后，在红壤和潮土低有机质含量的处理中有效Cu浓度比高有机质含量的处理高24.2%～57.1%；而在黑土和潮土高有机质含量的处理中有效态Zn浓度是有机质含量低的处理的3.44～6.33倍。这说明在3种土壤上增加有机质含量对Cu、Zn的作用效果不同，在红壤上抑制了Cu的有效性，在潮土上抑制有效Cu促进有效Zn，在黑土上则促进Cu、Zn有效性。在3种土壤中，碱性潮土外源Cu、Zn修复速率较快，且有效态Cu、Zn平衡浓度较小，其对Cu、Zn的固定能力最强，酸性红壤则最弱。采用各种措施提高土壤有机质含量可作为修复红壤和潮土重金属Cu污染的有效措施之一，但增加了黑土及潮土Zn的环境风险。

Effects of organic matter on natural-remediation process of typical copper-zinc polluted soils

In order to clarify the effect of soil organic matter (SOM) on natural-remediation of the polluted soils, the remediation processes of copper (Cu) and zinc (Zn) in three kinds of contaminated typical soil of China were studied by incubation under controlled condition. The soils were red soil, fluvo-aquic soil and black soil, taken from 3 long-term fertilization experiments, with different SOM contents. 400 mg/kg Cu, 500 mg/kg Zn were added in soil samples and the incubation time were 90 d. Results showed that, in all soil samples, concentrations of soil available Cu or Zn decreased rapidly within the first 10-20 d, then the rate of decrease slowed down in short time, and dynamic balance were achieved after 30-60 d. The remediation process of Cu or Zn contaminated soils could be simulated by the second-order equation. After 90 days incubation, equilibrium concentrations of Cu in the low SOM content treatments in red soil and fluvo-aquic soil were 24.2%-57.1%, which were higher than those in high SOM content treatments. However, in black soil and fluvo-aquic soil, the equilibrium concentration of Zn in high SOM content treatment was 3.44-6.33 times of those in low SOM content treatment. This result implied different effects of increased SOM in the three kinds of soil. In red soil, the increased SOM repressed the availability of Cu; In fluvo-aquic soil, the increased SOM repressed the available Cu and promoted available Zn; And in black soil, the increase of SOM promoted the availability of both Cu and Zn. In fluvo-aquic soil, the remediation velocity was the largest, dynamic balance time was the shortest, and the equilibrium concentration of Cu and Zn in fluvo-aquic soil was lowest in the three kinds of soil, while such parameters in red soil were opposite. In conclusion, increasing SOM can be one of effective ways to decrease the availability of Cu in red soil and fluvo-aquic soil, whereas might increase the risk of environmental Zn pollution in black soil and fluvo-aquic soil.