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| 1 | Effects of Silver Nanoparticles on Soil Microbial Communities and Bacterial Nitrification in Suburban Vegetable Soils显示文摘Silver nanoparticles(AgNPs) are widely used antimicrobial compounds; however, they may pose a threat to non-targeted bacteria in the environment. In this study high-throughput sequencing was used to investigate the effects of different concentrations of AgNPs(10, 50, and 100 mg kg-1) on soil microbial community structure during short-term(7 d) exposure. The amounts of Acidobacteria,Actinobacteria, Cyanobacteria, and Nitrospirae significantly decreased with increasing AgNP concentration; meanwhile, several other phyla(e.g., Proteobacteria and Planctomycetes) increased and dominated. Nitrosomonas europaea, a well-characterized ammoniaoxidizing bacterium, was used to study the sensitivity of bacteria to Ag NPs and ionic silver(Ag^+). Flow cytometry was used to monitor the toxicity of low(1 mg L^(-1)), middle(10 mg L^(-1)), and high concentrations(20 mg L^(-1)) of AgNPs, as well as Ag^+(1 mg L^(-1)) released into the medium from 20 mg L^(-1) concentration of AgNPs, towards N. europaea. After 12 h of exposure, the survival rate of N. europaea treated with 1 mg L^(-1)Ag^+ was significantly lower than those treated with low(1 mg L^(-1)) and middle concentrations(10 mg L^(-1)) of AgNPs, but the survival rate in the treatment with high concentration(20 mg L^(-1)) of AgNPs was much lower. Additionally, necrosis rates were higher in the treatment with 20 mg L^(-1) AgNPs. Electron microscopy showed that Ag+caused serious damage to the cell wall of N. europaea, disintegrated the nucleoids, and condensed next to the cell membrane; however,dissolved Ag^+ is only one of the antibacterial mechanisms of AgNPs. | WANG Juan SHU Kunhui ZHANG Li SI Youbin | 2017 | Pedosphere2017，27，3： | 5 |
| 2 | Adsorption of SeO_3^(2-) by Soils at Different S Levels显示文摘 | MA YOUHUA, E. SCHNUG, SI YOUBIN, ZHANG LIGAN, DING RUIXING and ZHANG JIZHENG Department of Soil and Agrochemistry, Anhui Agricultural University, Hefei 230036 (China) Institute of Plant Nutrition and Soil Science, Federal Agricultural Research Centre, 3 | 2002 | Pedosphere2002，12，1： | 2 |
| 3 | Reductive transformation of 2,4-dichlorophenoxyacetic acid by nanoscale and microscale Fe304 particles显示文摘 | Si Youbin Fang Guodong Zhou Jing | 2010 | Journal of Environmental Science and Health Part B: Pesticides Food Contaminants and Agricultural Wastes2010，45，3： | 1 |
| 4 | Degradatin of 2,4-D in soils by Fe3 04 nanoparticles combined with stimulating indige- nous microbes显示文摘 | FANG Guodong SI Youbin TIAN Chao | 2012 | Environmental Science and Pollutiort Research2012，19，3： | 1 |
| 5 | Leaching and degradation ofethametsulfuron-methylinsoil显示文摘 | Youbin Si Shanqiang Wang Jing Zhou | 2005 | Chemosphere2005，60，： | 1 |
| 6 | Photostabilization of the herbicide bensulfuron-methyl by using organoclays显示文摘 | Youbin Si Jing Zhou Huaiman Chen Dongmei Zhou | 2003 | Chemosphere2003，，7： | 1 |
| 7 | Impacts of silver nanoparticles on enzymatic activities,nitrifying bacteria,and nitrogen transformation in soil amended with ammonium and nitrate显示文摘Silver nanoparticles(AgNPs)are effective antimicrobial compounds that are used in a myriad of applications.Soil microorganisms play crucial roles in nitrogen cycling,but there is a lack of comprehensive understanding of the effects of Ag NPs on enzymatic activity in the nitrogen cycle,nitrifying bacteria,and nitrogen transformation in soil.Herein,enzyme activities were determined following the addition of different forms of nitrogen,ammonium nitrogen((NH_(4))_(2)SO_(4)),nitrate nitrogen(KNO_(3)),and amide nitrogen(urea,CO(NH_(2))_(2))at 200 mg N kg^(-1),into the soil amended with AgNPs at 0,10,50,and 100 mg kg^(-1).After 7 d of incubation with 10 mg kg^(-1) Ag NPs,the activities of urease,nitrite reductase(NiR),nitrate reductase(NaR),and hydroxylamine reductase(HyR)were reduced by 12.5%,25.0%,12.2%,and 24.2%,respectively.Of particular note,more than 53.5%,61.7%,and 34.7% of Na R,NiR,and HyR activities,respectively,were inhibited at 100 mg kg^(-1) Ag NPs.The abundance(most probable number)of ammonia-and nitrite-oxidizing bacteria(AOB and NOB,respectively)was measured using real-time quantitative polymerase chain reaction(qPCR)and the Cochran method.The abundance of AOB and NOB decreased when Ag NPs were present in the soil.The NH_(4)NO_(3) amendment increased copy numbers of bacterial and archaeal amo A nitrification functional genes,by 38.3% and 12.4%,respectively,but AgNPs at 50 mg kg^(-1) decreased these values by 70% and 56.4%,respectively.The results of ^(15)N enrichment(atom% excess)of NH_(4)^(+) and NO_(3)^(-) experiments illustrated the influence of AgNPs on soil nitrogen transformation.According to the ^(15)N atom% excess detected,the conversion of ^(15)N-labeled NH_(4)^(+) to NO_(3)^(-) was significantly inhibited by the different levels of Ag NPs in soil.The reduced gross nitrification rate further confirmed this finding.Overall,this study revealed considerable evidence that AgNPs inhibited nitrogen cycle enzyme activity,the number of nitrifying bacteria,the abundance of the amo A gene,and the gross nitrification rate.Silver nanoparticles inhibited nitrogen transformation,and the rate of nitrification was also negatively correlated with AgNP levels. | Xiaohong LIU Juan WANG Lingli WU Li ZHANG Youbin SI | 2021 | Pedosphere2021，31，6： | 0 |
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