Abstract:

In order to study the physical and chemical properties and remediation effect of passivating agent on Cd contaminated soil, and provide basis for the safe utilization of lightly and moderately polluted farmland in north China. Pot culture experiment was conducted to study the effects of 8 kinds of passivators on physical and chemical properties, main nutrient accumulation, Cd availability and Cd content in Chinese cabbage in different Cd contaminated soil. The results showed that compared with CK, the addition of 1% and 5% of six other passivators, except P6 and P7, could significantly reduce the soil available Cd content, the range of 9.09%-56.73% on the soil Cd content of 1 mg∙kg^-1. The Cd passivating effect of P3 treatment was the most obvious, the soil available Cd content decreased by 54.90% and that of Cd content in Chinese cabbage was 54.04% with the addition of 5% of P3. The Cd content of all treatments was lower than 0.2 mg∙kg^-1, which was in accordance with the National Food Contaminant Limit Standard (GB 2762—2017). On the soil Cd content of 5 mg∙kg^-1, 8 kinds of passivators (1% and 5%) could significantly reduce the soil available Cd content by 11.14%-81.08%. The Cd passivating effect of P3 passivator was the most obvious, the reducing rate of soil available Cd was 81.08%, and that of Cd content in Chinese cabbage was 72.16%, and the Cd content of Chinese cabbage (0.22 mg∙kg^-1) was close to the national food limit (GB 2762—2017), the Cd content of Chinese cabbage treated with other 7 kinds of passivators exceeded the standard in different degrees. The application of passivators increased soil pH, organic matter and available N, P, K contents in different degrees. Correlation analysis showed that soil available Cd content and Cd content in Chinese cabbage were negatively correlated with soil pH, organic matter, available P and available K content, and reached significant or extremely significant levels. It can be seen that the soil nutrient status can be improved by applying suitable passivator products to the alkaline Cd polluted farmland in the north of China, so as to reduce the availability of soil Cd and achieve the goal of safe production of agricultural products.

Key words: passivator, cadmium pollution, alkaline soil, physical and chemical properties, Cd availability

摘要：

探讨施用钝化剂对Cd污染土壤理化性质和修复效果,可为北方轻中度Cd污染农田安全利用提供依据。采用盆栽培养试验,研究不同Cd污染程度下,施用8种钝化剂产品对土壤理化性质、主要养分积累、Cd有效性和小白菜吸收Cd的影响。结果表明,与对照相比,土壤加入1 mg∙kg^-1 Cd时,除P6和P7钝化剂外,其他6种钝化剂可显著降低土壤有效态Cd含量,降幅为9.09%—56.73%;P3钝化剂的Cd钝化效果最佳,添加量为5%时土壤有效态Cd降低率为54.90%,小白菜降Cd率为54.04%;所有处理小白菜Cd质量分数均低于0.2 mg∙kg^-1,符合国家食品污染物限量标准。土壤加入5 mg∙kg^-1 Cd时,添加8种钝化剂处理均可显著降低土壤有效态Cd含量,降幅为11.14%—81.08%;其中P3钝化剂的Cd钝化效果最佳,添加量为5%处理下土壤有效态Cd降低率81.08%,小白菜降Cd率为72.16%,小白菜Cd含量（0.22 mg∙kg^-1）基本上接近国家食品中污染物限值,而其他7种钝化剂处理小白菜Cd含量均不同程度超标。相关性分析表明,土壤有效态Cd含量、小白菜Cd含量分别与土壤pH、有机质、速效磷和有效钾含量呈显著或极显著的负相关关系。由此可见,对于北方轻中度Cd污染农田,可通过施用合适的钝化剂产品来改善土壤养分状况,降低土壤Cd的有效性,从而达到农产品安全生产的目的。

关键词: 钝化剂, Cd污染, 碱性土壤, 理化性质, Cd有效性