以陕北地区常见的10种灌草植物凋落物组成9种混合物，分别将单种或混合凋落物以2%的比例（质量分数）混入15 g/kg原油污染土壤，在室温（20-25℃）恒湿条件下进行150 d的室内模拟修复试验，分析凋落物混合添加对其修复油污土壤能力的影响。结果表明：（1）较之自然衰减，单种凋落物处理普遍显著提高了污染物降解率（原油降解率提高35%-85%）以及土壤硝态氮、有效磷和速效钾含量（提高0.36-56倍），且多数处理显著提高了污染土壤中蔗糖酶、脲酶、碱性磷酸酶和脱氢酶的活性（提高0.4-6.8倍）。（2）白羊草+杠柳+狼牙刺、胡枝子+铁杆蒿、胡枝子+狗娃花+黄蒿或铁杆蒿+杠柳凋落物混合在促进原油及其组分降解时呈协同作用，使其降解率较单种处理再提高5%-28%，或较基于单种处理结果的预测值提高5%-17%，但其同时拮抗削弱凋落物对土壤速效氮（特别是硝态氮）的补充作用（较预测值降低6%-78%）及（或）酶活性（特别是蔗糖酶和脱氢酶）的刺激作用（较预测值降低14%-67%）。在实际使用中可通过上述混合强化凋落物对污染物的降解能力，但需配合其他修复手段改善污染土壤生化性质。白羊草+狼牙刺、铁杆蒿+狼牙刺、杠柳+狼牙刺凋落物混合使各种污染物降解率较单种处理或预测值显著降低，在使用时应对不同凋落物进行分离，以避免削弱其修复效果。（3）总体而言，添加多酚、黄酮、有机酸和磷含量高，碳含量和碳磷比低且化学多样性更高的混合凋落物更有利于降解原油污染物，但同时其含有的上述次生代谢物可能不利于土壤养分状况和酶活性的恢复。
To investigate the effects of the mixed addition of shrub and grass litters on the remediation of crude oil contaminated soil, a total of 9 types of mixture litters that mixed from 10 common shrub and grass species in northern Shaanxi were selected. The single-specific litter or litter mixtures were added into 15 g/kg crude oil contaminated soil at a proportion of 2% (litter:soil, w/w), and then a 150-day simulated necrophytoremediation experiment was conducted at the room temperature (20-25℃) with constant humidity. The results indicated that single-litter treatments significantly increased the degradation rate of the contaminants (the degradation rate of crude oil increased by 35%-58%) and the contents of nitrate nitrogen, available P and available K (36%-5600%), and most of the treatments significantly increased the activities of sucrase, urease, alkaline phosphatase and dehydrogenase by 40%-680% in the contaminated soil. In addition, the mixture of litters of Bothriochloa ischaemum with Periploca sepium and Sophora davidii, Lespedeza davurica with Artemisia gmelinii, L. davurica with Heteropappus altaicus and Artemisia annua or A. gmelinii with P. sepium could promote the degradation of crude oil and its components as well as the significant synergistic effects. As compared with the single-litter treatments, the degradation rates and the predicted values in these mixture treatments increased by 5%-28% and 5%-17%, respectively. At the same time, the antagonistic effects in these mixture treatments could weaken the supplement ability of soil available N (especially the nitrate N) and the stimulation effect of soil enzymatic activity (especially the activities of sucrase and dehydrogenase), which decreased by 6%-78% and 14%-67% as compared with the predicted values, respectively. In practice, the above mentioned mixture treatments could enhance degradation capacity of litter to contaminants, which still need to combine with other remediation methods to improve the biochemical properties of the contaminated soil. However, compared with the single-litter treatments, the mixing of litters of B. ischaemum with S. davidii, A. gmelinii with S. davidii or P. sepium with S. davidii significantly decreased the degradation rate of contaminants. Thus, to avoid their antagonistic effects in the remediation of crude oil contaminated soil, different litters should be separated. In general, adding mixed litters with high polyphenols, flavonoids, organic acids and P contents, low C content and C/P ratio, and high chemical diversity were more favorable to remove the petroleum contaminants in soil. However, the mentioned secondary metabolites from litters might be adverse to recovery of the nutritional conditions and enzymatic activities of the contaminated soil.