Abstract:

Soil pollution remediation has received much attention in recent years. the fragile soil environment combined with oil pollution has caused great harm to the environment in the barren loess areas. It is important to find a suitable remediation method for oil-contaminated soil in loess areas. Immobilized microorganism beans were prepared with straw, biochar, and activated carbon for adsorption carrier respectively and sodium alginate as embedding agent by using highly efficient oil degradation hybrid bacteria screened in early. The effect of soil restoration with different carrier immobilized mixed bacteria and the microbial diversity in the petroleum-contaminated soil after remediation were investigated in the loess region of northern Shaanxi. The degradation effect of immobilized mixed bacteria on crude oil was better than that of free mixed bacteria. the remediation effects of different immobilized carriers were different. After 42-days remediation, the best remediation effect of straw immobilized hybrid bacteria in the sterilized group was 54.92%, which was 20% higher than that of free hybrid bacteria alone. The best remediation effect of biomass charcoal immobilized hybrid bacteria in the unsterilized group was 54.19%, which was nearly 30% higher than that of free hybrid bacteria. It suggested that the immobilized hybrid bacteria were significantly more effective in removing petroleum than the free state hybrid bacteria, and could achieve relatively high removal rate in a relatively short period of time. Soil Shannon-Wiener index and microbial diversity T-RFLP analyses showed that the degradation rate of petroleum hydrocarbons was correlated with the microbial diversity in soils. This might be attributed to the fact that biomass charcoal provided the most suitable environment for the growth of immobilized mixed bacteria, and was the best vehicle to promote the growth of phylum Firmicutes and Proteobacteria, which is more important than straw to improve the nutrients for soil remediation. This study suggested that the immobilized mixed bacteria played an important role in the petroleum biodegradation process.

Key words: loess, petroleum contaminated soil, immobilized microorganisms, microbial community, microbial diversity

摘要：

近些年土壤污染修复问题备受关注,而在贫瘠的黄土地区,本身脆弱的土壤环境加之受石油污染,给环境造成巨大危害,探寻一种适合用于黄土地区石油污染土壤的修复方法尤为重要。利用前期已筛选的高效石油降解菌,分别以小麦秸秆、生物炭和活性炭为吸附载体,海藻酸钠为包埋剂对混合菌进行吸附包埋固定,研究了不同载体固定化混合菌对陕北黄土地区受石油污染土壤的修复效果及修复后土壤中微生物多样性的变化。研究发现固定化混合菌对原油的降解效果比游离态混合菌好,且不同固定化载体修复效果有差异。经过42 d的修复,灭菌组中秸秆固定化混合菌修复效果最好,降解率为54.92%,比单纯的游离混合菌提高了20%;未灭菌组中生物质炭固定化混合菌修复效果最好,降解率为54.19%,比游离态混合菌提高了近30%。与游离态混合菌相比,固定化混合菌对石油的去除效果显著提高,可以在相对短的时间内达到较高的去除率。土壤Shannon-Wiener指数与微生物多样性T-RFLP的分析表明,石油烃降解率和微生物多样性变化相吻合。石油烃降解率高的土壤,其微生物多样性高,这是由于生物质炭为固定化混合菌提供了最适宜的生长环境,同时它是促进厚壁菌门（Firmicutes）和变形菌门（Proteobacteria）生长的最佳载体,对于修复土壤比秸秆提高养分更重要。由此可见,固定化混合菌在石油生物降解过程中起重要作用。

关键词: 黄土, 石油污染土壤, 固定化微生物, 微生物群落, 微生物多样性