王茹 刘翔麟 周志强 李云云 陈炎辉 陈锦 王果

摘  要：为探讨氯化铵（NH4Cl）和茶皂素（tea saponin， TS）对镉（Cd）赋存形态的影响，以矿区Cd污染农田土壤为试验材料，采用室内土壤培养方法，模拟不同剂量的无机氮肥NH4Cl和TS单施及复合施加对Cd污染农田土壤理化性质及Cd有效性的影响。结果表明：单独施加NH4Cl和TS促进了土壤中残渣态Cd向弱酸提取态及可还原态Cd的转化，提高了土壤中Cd的生物有效性，且高剂量（60 mg/kg）NH4Cl施加要优于低剂量（20 mg/kg）NH4Cl;NH4Cl（40 mg/kg）和TS（4 mg/kg）复合施加同样促进了土壤中残渣态Cd向弱酸提取态Cd的转化，增加Cd的有效性，且增加效果等同于高剂量的NH4Cl和TS单独施加。逐步回归分析表明，pH和Cl是影响土壤中Cd有效性的2个关键因子。因此，在实际植物修复工作中可通过适当的农艺措施提高土壤Cl降低土壤pH以增加植物对Cd的累积量。此外，低剂量的NH4Cl配施TS可显著增加土壤中Cd的生物有效性，避免高施用量NH4Cl引起的土壤环境恶化。

关键词：氯化铵;茶皂素;土壤;镉形态

中图分类号：X53      文献标识码：A

Abstract： In order to investigate the effect of ammonium chloride （NH4Cl） and tea saponin （TS） on cadmium speciations in soil， the Cd-contaminated agricultural soils around mining areas were used as the experimental material. The effects of different doses of NH4Cl， TS and mixed application on the physical chemical properties of the Cd polluted agricultural soil and Cd availability were simulated. The chemical of cadmium speciations was transformed from residual fractions into acid extractable or oxidizable fractions by adding NH4Cl or TS singly. NH4Cl obviously improved available Cd in soil， and high （60 mg/kg） concentration of NH4Cl was better than low （20 mg/kg）. Moreover， the chemical cadmium speciations was transformed from residual fractions into acid extractable fractions and improved available Cd by adding the combination of NH4Cl （40 mg/kg） and TS （4 mg/kg）， and mixed application had the same effect with NH4Cl or TS. Stepwise regression analysis showed that pH and Cl were the two key factors affecting Cd availability in soil. In the actual phytoremediation work， in order to increase the Cd content of plants， we could take appropriate agronomic measures to increase Cl or decrease pH in soil. Low concentration NH4Cl and TS mixed application significantly would improve the Cd bioavailability and avoid soil environment destruction caused by high concentration NH4Cl application.

Keywords： ammonium chloride; tea saponin; soil; cadmium speciation

鎘（cadmium， Cd）是一种有毒重金属元素。2014年环境保护部和国土资源部发布的《全国土壤污染状况调查公报》显示我国土壤Cd的超标率为7.0%[1]。土壤中的Cd可被农作物吸收并通过食物链进入人体，极大的危害着人体健康[2]。对Cd污染土壤的主要修复方法是完全去除和钝化土壤中重金属。植物提取修复是一种环境友好，极具前景的土壤修复技术[3]。植物Cd的含量与土壤Cd的有效性密切相关。研究表明，植物蓄积Cd与土壤中交换态和酸溶态成正相关[4]。而土壤中的Cd主要以残渣态或吸咐在土壤颗粒表面的形式存在，不易被植物吸收富集，这极大的限制了植物提取效率[5-6]。……