纳米银对胶州湾西北部海区及河口区沉积物反硝化能力和功能基因丰度的影响

Effect of Silver Nanoparticles on Denitrification and Functional Gene Abundances of Sediment in Dagu River Estuary and Northwest of Jiaozhou Bay

在胶州湾西北部海区和大沽河河口区选择S站和E站2个研究站位,现场采样带回实验室进行模拟培养,研究纳米银对沉积物反硝化能力、反硝化酶活性及功能基因丰度的影响.将不同剂量(0、135、1 350 mg·L^(-1))的纳米银添加至由表层沉积物和原位底层海水组成的培养体系中培养6 d,测定其在不同时间内NO_3^-和NO_2^-含量、NO_3^-还原酶和NO_2^-还原酶活性、反硝化功能基因narG和nirS相对丰度的变化,探讨纳米银对不同区域沉积物反硝化过程的影响和可能的作用途径.结果表明,纳米银胁迫对2个站位沉积物NO_3^-和NO_2^-的还原能力、NO_3^-和NO_2^-还原酶活性及narG和nirS的基因丰度均具有明显的抑制效应,纳米银浓度越高,抑制程度越强,并会导致NO_2^-累积量的增加;纳米银对NO_2^-还原酶的抑制程度明显大于NO_3^-还原酶,对功能基因nirS的抑制程度明显大于narG;纳米银胁迫对NO_3^-还原过程的影响主要通过对功能基因的抑制作用,而对NO_2^-还原过程的影响主要是通过对还原酶活性的抑制作用;纳米银对胶州湾西北部海域反硝化能力、NO_3^-还原酶和基因丰度的抑制程度大于大沽河河口区.

The influence of silver nanoparticles（ Ag NPs） on the denitrification performance,enzyme activity,and functional gene relative abundances of sediment was investigated based on the methods of laboratory simulation incubation in the Dagu River estuary and bay area in the northwest of Jiaozhou Bay. The different dosages of Ag NPs（ i. e.,0,135,and 1 350 mg·L^-1 in final concentration）was added to the incubation system containing surface sediments and in-situ bottom water. During six days＇ incubation, the concentrations of NO3^- and NO2^-,NO3^-,and NO2^- reductases activity,and relative abundances of narG and nirS genes were measured to explore the effects of Ag NPs on denitrification and its mechanism. The results showed that Ag NPs significantly inhibited NO3^- and NO2^- reductive capacity,NO3^- and NO2^- reductase activity,and narG and nirS gene relative abundances,which led to aggravated accumulation of NO2^-. The inhibition of NO2^- reductase was significantly greater than that of NO3^- reductase,and the inhibition of the nirS gene was significantly higher than that of the narG gene. The inhibition of NO3^- reduction was mainly ascribed to the inhibition of functional genes,but the inhibition of NO2^- reduction was mainly due to the inhibition of reductase activity. The inhibition of NO3^- and NO2^- reductive capacity,NO3^- reductase activity,and narG and nirS gene relative abundances in the northwest of Jiaozhou Bay was significantly higher than that in the Dagu River estuary.