题名：Effects of silver nanoparticles on nitrification and associated nitrous oxide production in aquatic environments
领域：Science & Technology 一区
来源：SCIENCE ADVANCES
发表年代：2017年
作者：Yanling Zheng, Lijun Hou*, Min Liu*, Silvia E. Newell, Guoyu Yin, Chendi Yu, Hongli Zhang, Xiaofei Li, Dengzhou Gao, Juan Gao, Rong Wang, Cheng Liu
Silver nanoparticles (AgNPs) are the most common materials in nanotechnology-based consumer products globally. Because of the wide application of AgNPs, their potential environmental impact is currently a highly topical focus ofconcern. Nitrification is one of the processes in the nitrogen cyclemost susceptible to AgNPs but the specific effects of AgNPs on nitrification in aquatic environments are not well understood. We report the influence of AgNPs on nitrificationand associated nitrous oxide (N2O) production in estuarine sediments. AgNPs inhibited nitrification rates, which decreased exponentially with increasing AgNP concentrations. The response of nitrifier N2O production to AgNPs exhibitedlow-dose stimulation (<534, 1476, and 2473 μg liter−1 for 10-, 30-, and 100-nm AgNPs, respectively) and highdose inhibition (hormesis effect). Compared with controls, N2O production could be enhanced by >100% at low dosesof AgNPs. This result was confirmed by metatranscriptome studies showing up-regulation of nitric oxide reductase (norQ) gene expression in the low-dose treatment. Isotopomer analysis revealed that hydroxylamine oxidationwas themain N2O production pathway, and its contribution to N2O emission was enhanced when exposed to low-dose AgNPs. This study highlights the molecular underpinnings of the effects of AgNPs on nitrification activity and demonstratesthat the release of AgNPs into the environment should be controlled because they interfere with nitrifying communities and stimulate N2O emission.
