采用温室盆栽试验，在种植紫花苜蓿的同时，分别施加木霉菌剂、根瘤菌菌剂以及木霉与根瘤菌复合菌剂，并采用离心分级法将处理后土壤分为 4 个粒径团聚体，即细黏粒(0.1 ~ 1 μm)、粗黏粒(1 ~ 5 μm)、粉粒(5~50 μm)以及细砂粒(50 ~ 250 μm)，分析了植物–微生物联合作用对不同粒径土壤中 PAHs 的去除效应。研究结果表明：紫花苜蓿–根瘤菌联合作用对 PAHs 污染土壤的修复效果最优，其降解率达 60% 以上。不同粒径组分中 PAHs 含量的分布表现为细砂粒＞粉粒＞粗黏粒＞细黏粒，且 PAHs 在不同粒径团聚体中去除率差异性较大。低环(2、3环)PAHs 在各粒径组分中去除率较低(20% 以下)，并在不同粒径组分间呈非均衡分配状态；4 环PAHs 的去除主要集中在粉粒和细砂粒中，而 5 环 PAHs 的去除主要发生在细黏粒上。可见，PAHs 在土壤不同粒径组分中分布特征及降解效应为进一步阐明 PAHs 污染土壤的生物修复机制提供了科学依据。

A pot experiment was conducted to explore the combined remediation of microorganisms (Trichoderma reesei and Rhizobium meliloti) and alfalfa stimulated the degradation of PAHs by rhizosphere microflora in different particle-size fractions of soil aggregates. Soil aggregates were partitioned into 4 particle-size fractions (clay: 0.1 – 1 μm, fine silt: 1 – 5 μm, silt: 5 – 50 μm and fine sand: 50 – 250 μm) by using the method of centrifugation in five treatments. The results showed that the degradation rate of PAHs in soil treated with Rhizobium meliloti with alfalfa was 60%. The distribution of 16 PAHs concentrations in different soil particle size composition was in the order of fine sand ＞ silt ＞ fine sand ＞ clay, besides, low-molecular (2, 3-ring) PAHs was not degraded and but transferred in different size of particles (degradation rate less than 20%). The degradation of 4-ring PAHs occurred mainly on silt and fine sand soil particles and 5-ring PAHs degradation on the clay. Hence, the distribution and degradation of PAHs in different size of particles has a great significance on remediation of PAHs polluted soil.

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国家自然科学(41230858, 41271329)资助