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

The influence of silver nanoparticles (AgNPs) 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 AgNPs (i.e., 0, 135, and 1350 mg·L in final concentration) was added to the incubation system containing surface sediments and in-situ bottom water. During six days' incubation, the concentrations of NO and NO, NO, and NO reductases activity, and relative abundances of and genes were measured to explore the effects of AgNPs on denitrification and its mechanism. The results showed that AgNPs significantly inhibited NO and NO reductive capacity, NO and NO reductase activity, and and gene relative abundances, which led to aggravated accumulation of NO. The inhibition of NO reductase was significantly greater than that of NO reductase, and the inhibition of the gene was significantly higher than that of the gene. The inhibition of NO reduction was mainly ascribed to the inhibition of functional genes, but the inhibition of NO reduction was mainly due to the inhibition of reductase activity. The inhibition of NO and NO reductive capacity, NO reductase activity, and and gene relative abundances in the northwest of Jiaozhou Bay was significantly higher than that in the Dagu River estuary.