期刊
JOURNAL OF HAZARDOUS MATERIALS
卷 389, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.jhazmat.2020.122130
关键词
Isotopic tracer method; Silver nanoparticles; Nitrogen cycle; Environmental risk; Water-sediment systems
资金
- National Natural Science Funds for Excellent Young Scholars [51722902]
- National Science Funds for Creative Research Groups of China [51421006]
- Fundamental Research Funds for the Central Universities [2019B63414]
- National Natural Science Foundation of China [51709081]
- Outstanding Youth Fund of the National Natural Science Foundation of Jiangsu, China [BK20160038]
- Postgraduate Research and Practice Innovation Program of Jiangsu Province [SJKY19_0533]
- PAPD
The effects of varying concentrations of Ag NPs on coupled nitrification and denitrification (CND) in two suspended sediments (SPSs) sizes were investigated using isotopic tracer method. In general, 0.5 and 5 mg/L Ag NPs had less effect on CND, while 2 and 10 mg/L Ag NPs exhibited the improvement and inhibition effect, respectively. The CND improvement by 2 mg/L NPs was mainly due to the enhanced nitrifying and denitrifying enzyme activity. However, 10 mg/L Ag NPs inhibited NH4+ oxidation by directly reducing the AMO activity and AOB abundance. The inhibition on NAR and NIR activity and their encoding narG and nirK gene abundance further inhibited NO3- and NO2- reduction, leading to a dramatic decrease in the N-15-N-2 production. The above inhibition effects were attributed to the nano-effects of Ag NPs, which led to the excessive ROS amount and the decreased T-AOC level in microbial systems. But the connection between nitrification and denitrification was not broken after Ag NPs exposure. Moreover, the results indicated that N-cycling in clay and silt-type SPS systems could be more sensitive than sand-type SPS systems to NP exposure. The findings provide a basis for evaluating the environmental risks of Ag NPs in water-sediment systems.
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