沉积物中多环芳烃对反硝化功能基因垂直分布的影响

研究了沉积物中PAHs对特定反硝化功能基因垂直分布的影响,以建立反硝化条件下PAHs和各阶段反硝化反应之间的关系.2011年3月,对珠江广州河段珠江大桥、黄沙码头和二沙岛三处具有代表性的区域沉积物进行采集,对沉积物PAHs污染和特定反硝化功能基因(narG、nirS、nosZ和nrfA)的垂直分布特征进行了研究,并通过多变量技术建立了反硝化条件下PAHs和特定反硝化功能基因之间的关系.典范对应分析(CCA)表明,硝酸盐异化还原反应和高环PAHs之间联系密切.PAHs对nosZ编码基因影响最为明显,即对反硝化作用氧化亚氮还原阶段抑制作用最强.除氧化亚氮还原阶段外,其他各阶段反硝化细菌普遍体现出对高环PAHs的适应性,特别是含有异化亚硝酸盐还原酶编码基因(nrfA)的微生物可能具有潜在的高环PAHs厌氧降解能力.亚硝态氮还原酶编码基因(nirS)表现出特异性,需要进一步深入研究.

Effect of Polycyclic Aromatic Hydrocarbons on the Vertical Distribution of Denitrifying Genes in River Sediments

To establish the relationship between polycyclic aromatic hydrocarbons (PAHs) and various stages of denitrification under denitrifying conditions in sediments, we examined the impact of PAHs on the vertical distribution of special denitrifying genes. In March of 2011, sediment samples were collected from three representative locations along the Pearl River. The characteristics of vertical distribution of PAHs as well as denitrifying genes in the sediment samples were analyzed. Based on these vertical characteristics, relationships between PAHs and special denitrifying genes(narG, nirS, nosZ and nrfA) were established using the multivariate method. Results of canonical correspondence analysis (CCA) showed a close correlation between high ring PAHs and dissimilatory nitrate reduction. The impact of PAHs on nosZ was the most significant, namely PAHs imposed strong inhibition on the nitrite reduction stage. Except for the nitrite reduction stage, denitrifying bacteria from other stages of denitrification acclimatized themselves to the high ring PAHs. Especially, bacteria containing nrfA may have the potential to anaerobically degrade high ring PAHs. Besides this, the special role of nirS remains to be studied further.