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Effects of deep placement of fertilizer on periphytic biofilm development and nitrogen cycling in paddy systems

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Pedosphere 2021年第1期31卷 125-133页

作者： Yanhui ZHAO Xiong XIONG chenxi wu State Key Laboratory of Freshwater Ecology and Biotechnology Institute of HydrobiologyChinese Academy of SciencesWuhan 430072China University of Chinese Academy of Sciences Beijing 100049China

Periphytic biofilms are commonly presented at the water-soil interface in paddy fields. Different fertilization methods can affect the concentration and distribution of nutrients in paddy fields and thus affect the development of periphytic biofilms. In this study, the roles of periphytic biofilms in nitrogen(N) cycling in paddy systems and how they are affected by different fertilization methods were studied using microcosm experiments. Microcosms were prepared using soil samples from a paddy field and treated with surface and deep fertilization under light and dark conditions. Surface fertilization under light condition promoted the development of periphytic biofilms, while deep fertilization under dark condition inhibited their development. The development of periphytic biofilms increased the pH and dissolved oxygen levels in the overlying water. Surface fertilization resulted in high N concentrations in the overlying water and the topsoil layers, which enhanced NH3 volatilization and nitrification-denitrification but inhibited N fixation. The development of periphytic biofilms reduced NH3 volatilization loss but increased nitrification-denitrification loss and the overall N loss in the paddy system. The results from this work suggest that the presence of periphytic biofilms in paddy fields could increase N loss by 3.10%–7.11%. Deep fertilization is an effective method to retard the development of periphytic biofilms in the paddy system and can potentially increase the overall N use efficiency.

关键词： deep fertilization denitrification potential N loss N use efficiency NH3 volatilization paddy field

Experimental Study on Characteristics of NiMnGa Magnetically Controlled Shape Memory Alloy

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Journal of Materials Science & Technology 2006年第1期22卷 55-58页

作者： Fengxiang WANG Wenjun LI Qingxin ZHANG chenxi LI Xinjie wu Shenyang University of Technology Shenyang 110023 China

The static and dynamic magnetic controlling characteristics of NiMnGa magnetically controlled shape memory alloy （MSMA） were experimentally studied. The results show that the characteristics of induced strain with respect to the magnetic field are nonlinear with saturation nature, and dependent on the temperature as well as the load applied to the MSMA. The magnetic shape memory effect can be observed only in complete martensite phase at room temperature. The magnetic permeability of MSMA is not constant and reduces with the increment of magnetic field. The relative saturation magnetic permeability of MSMA is about 1.5.

关键词： NiMnGa Magnetically controlled shape memory alloy Characteristics Experimental study

Surface oxidation of carbon dots enables highly selective and sensitive chemiluminescence detection of hydroxyl radical

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Nano Research 2024年第11期17卷 9275-9283页

作者： Chan Wang Yuan Fang Dongrun Zhou chenxi wu Han Zhu Qijun Song Key Laboratory of Synthetic and Biological Colloids Ministry of Education School of Chemical and Material Engineering Jiangnan University Wuxi 214122 China

The rapid quantification of hydroxyl radical (·OH) in real samples is a great challenge due to its highly reactive nature and the potential interferences from other coexisting reactive oxygen species (ROS). Herein, a chemiluminescence (CL) probe (ox-CDs) was rationally developed for the detection of ·OH through controlled oxidation treatment of original CDs (o-CDs) with H_(2)O_(2). Post-oxidation of CDs can reduce the surface defects or functional groups on the CDs, exposing reactive sites capable of effectively reacting with ·OH. The chemical energy generated from redox reaction between ·OH and the ox-CDs can be efficiently utilized to generate strong and selective CL responses to ·OH without interferences from other ROS. Thus, a highly selective and sensitive CL method with a linear range from 0.01 to 150 μM and a detection limit of 3 nM was developed, which was successfully applied for monitoring the ·OH production from cigarette and mosquito coil smoke.

关键词： carbon dots post-oxidation chemiluminescence probe detection of·OH cigarette and mosquito coil smoke

Effects of herbicide butachlor application on the growth of periphytic biofilms and nitrogen loss in paddy systems

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Pedosphere 2024年第1期34卷 211-221页

作者： Yanhui ZHAO Mingjun LEI Liandong JING Fan XIA Meixia YAN Jiantong LIU Yonghong wu Yunli wu chenxi wu Ecology and Environment Monitoring and Scientific Research Center Yangtze Basin Ecology and Environment AdministrationMinistry of Ecological and EnvironmentWuhan 430010China College of Chemistry and Environmental Protection Engineering Southwest Minzu UniversityChengdu 610041China State Key Laboratory of Freshwater Ecology and Biotechnology Institute of HydrobiologyChinese Academy of SciencesWuhan 430072China State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil SciencesChinese Academy of SciencesNanjing 210008China

The application of butachlor as an herbicide in paddy fields is widely practiced,aiming to increase rice yield by directly or indirectly influencing the paddy *** biofilms,which form at the soil-water interface in paddy fields,are complex bioaggregates that play an important role in nitrogen (N) *** objective of this study was to investigate the effect of butachlor on periphytic biofilm growth and N cycling under both light and dark conditions in the *** results revealed that butachlor application hindered the growth of periphytic biofilms and led to the dominance of Cyanobacteria as the primary prokaryotes,while inhibiting the development of eukaryotic ***,the application of butachlor reduced the richness and diversity of prokaryotes,but increased those of eukaryotes in periphytic *** light treatments exhibited higher total N loss because light favored periphytic biofilm growth and enhanced ammonium (NH_(4)^(+)) assimilation and ***,butachlor application resulted in the increased retention of NH_(4)^(+)-N and nitrate (NO_(3)^(-))-N and an increase in N loss via *** abundances of functional genes encoding enzymes such as ammonia monooxygenase,nitrite reductase,and nitrous oxide reductase were increased by butachlor application,favoring nitrification and denitrification ***,the results suggest that butachlor application leads to an increase in total N loss mainly through denitrification in paddy systems,particularly in the presence of periphytic ***,the results may provide valuable insights into the changes in periphytic biofilm growth and N cycling induced by butachlor,and future studies can further explore the potential implications of these changes in paddy soils.

关键词： ammonia-oxidizing bacteria amoA denitrification denitrifying bacteria nirK nitrification nitrogen cycling nosZ volatilization

Preliminary assessment of heavy metal contamination in surface water and sediments from Honghu Lake, East Central China

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Frontiers of Earth Science 2012年第1期6卷 39-47页

作者： Ying HU Shihua QI chenxi wu Yanping KE Jing CHEN Wei CHEN Xiangyi GONG State Key Laboratory of Biogeology and Environmental Geology Wuhan 430074China School of Environmental Studies China University of GeosciencesWuhan 430074China College of Resources and Environmental Engineering Wuhan University of Science and TechnologyWuhan 430081China

Heavy metal concentrations in surface water and sediments collected from Honghu Lake in Hubei Province, China were analyzed, and ecological risks were evaluated according to the sediment quality guidelines. The results showed that the average concentrations of heavy metals in surface water were ranked as： As 〉 Zn 〉 Cu 〉 Cr 〉 Pb 〉 Ni 〉 Cd 〉 Hg. In comparison with results reported in other rivers and the background values, The Honghu Lake was polluted by As, Cr, Pb, Cu and Ni. Most of metals might be mainly from fertilizers, industrial effluent and domestic wastewater around the lake. Heavy metals concentrations were relatively higher in the inlet area than in other areas. Negative correlations were observed between most heavy metals and pH, while a significant positive correlation was present between Zn, Cd and Pb. In the sediment core, Cu, Zn, Cr and Ni showed a decreasing trend while Cd present an increasing trend. The decrease of As, Cu, Zn, Cr and Ni in the 1990s might due to the flood event in 1998. The analysis of ecological risk assessment based on sediment quality guidelines suggested that heavy metals in most sediments from the Honghu Lake had moderate toxicity, with Cr being the highest priority pollutant.

关键词： Keywords metal distribution sediment core ecologicalrisk assessment wetland

Concentrations and classification of HCHs and DDTs in soil from the lower reaches of the Jiulong River, China

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Frontiers of Environmental Science & Engineering 2012年第2期6卷 177-183页

作者： Jiaquan ZHANG Shihua QI Xinli XING Lingzhi TAN Wei CHEN Ying HU Dan YANG chenxi wu State Key Laboratory of Biogeology and Environmental Geology and School of Environmental StudiesChina University of GeosciencesWuhan 430074China School of Environmental Science and Engineering Huangshi Institute of TechnologyHuangshi 435003China

Soil is an important source to other environ- mental media and organisms for organochlorine pesticides （OCPs） bioaccumulation. Twenty-four representative sur- face soil samples were collected from the lower reaches of the Jiulong River, China, in 2009. The concentrations of hexachlorocyclohexane isomers （HCHs） ranged from 0.38 to 39.52 ng.g~, with a mean value of 9.51 ng.g-~. The concentrations of dichlorodiphenyltrichloroethanes （DDTs） and their metabolites were within the ranges of 0.94-700.99 ng. gl, with a mean value of 71.17 ng. g-1. The concentrations of HCHs and DDTs in the soil were lower than the first grade level （50 ng. g-a） of the Chinese Environmental Quality Standard （GB 15618-1995）. Hier- archical Cluster Analysis （HCA） and Pearson＇s bivariate Correlations Analysis （PCA） were used to analyse the distribution and contamination levels of OCPs in this region. The results showed that DDTs were the major contaminants and there were no significant correlations between various OCPs concentrations and the total organic carbon （TOC） contents. A significant positive correlation was observed between HCHs and DDTs （p 〈 0.01）, which indicates that HCHs and DDTs may have similar sources and fate in the study area.

关键词： Jiulong River hexachlorocyclohexane (HCH)and dichlorodiphenyltrichloroethan (DDT) classification,Hierarchical Cluster Analysis (HCA) Pearson's bivariateCorrelations Analysis (PCA)

Cladophora as ecological engineer:A new test from the largest lake of Qinghai-Tibet plateau with filamentous algal blooms

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Water Biology and Security 2024年第1期3卷 46-52页

作者： Zhihua wu Xigong Yuan Xiong Xiong Hongyi Ao chenxi wu Guoxiang Liu Huan Zhu Institute of Hydrobiology Chinese Academy of SciencesWuhan430072China College of Science Tibet UniversityLhasa850001China Huaihe River Commission of the Ministry of Water Resources Bengbu233001China

Filamentous algae blooms(FABs)have been increasing globally in recent years,and their presence can have both harmful and beneficial effects on aquatic *** one of the most common FABs,Cladophora blooms have been reported in the lakes of the Qinghai-Tibet Plateau during the past few ***,there have been few studies focused on how FABs impact other aquatic organisms,especially in alpine lakes since these are at the forefront of responding to global climate *** this study,the phytoplankton communities in different regions of Qinghai Lake were profiled in different seasons using meta-barcode *** phytoplankton assemblages in areas with Cladophora blooms were compared to those without *** phytoplankton community structure correlated with physicochemical properties including water temperature,electrical conductivity,nitrate,and the presence or absence of Cladophora *** relative abundance of Bacillariophytes was found to be higher in zones with Cladophora blooms than in other *** seasonal changes in phytoplankton biomass andβdiversity were observed in zones with Cladophora *** and microbial degradation of Cladophora can change the pH,dissolved oxygen,secchi depth,and *** with seasonal temperature and electrical conductivity changes,Cladophora growth can significantly impact the phytoplankton biomass,community dissimilarity and assembly *** results showed that Cladophora plays a key role in littoral aquatic ecosystem ecology.

关键词： Filamentous algal blooms Qinghai lake Biodiversity Phytoplankton community Assembly processes Environmental drivers

A review on source,occurrence,and impacts of microplastics in freshwater aquaculture systems in China

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Water Biology and Security 2022年第3期1卷 1-9页

作者： chenxi wu Xiong Xiong Amir Hossein Hamidian Yulan Zhang Xiangrong Xu State Key Laboratory of Freshwater Ecology and Biotechnology Institute of HydrobiologyChinese Academy of SciencesWuhan430072China Department of Environmental Science and Engineering Faculty of Natural ResourcesUniversity of Tehran31587-77878Iran State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou730000China CAS Key Laboratory of Tropical Marine Bio-resources and Ecology Guangdong Provincial Key Laboratory of Applied Marine BiologySouth China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou510301China

Microplastic pollution has become an increasingly important environmental issue worldwide in recent years because of its ubiquitous presence in different environmental media and its potential to affect the health of organisms and *** contributes significantly to the world's food production and nutritional supply,especially in developing *** occurrence of microplastics in aquaculture systems has raised great concern regarding aquaculture production and food safety issues of aquaculture *** is a world leader in aquaculture production,with freshwater aquaculture accounting for 59.1%of total aquaculture production of the world in ***,this review mainly focuses on recent research progress related to microplastic pollution in freshwater aquaculture systems in *** from the literature show that microplastics are present in freshwater aquaculture systems at abundances comparable to natural waterbodies in *** can be ingested and remain in the body of aquaculture *** to microplastics can adversely affect the health of aquatic organisms and aquatic ecosystem ***,risks of microplastics in real world environment remain *** of freshwater aquaculture products is not a major pathway for human exposure to *** provide scientific guidance for governmental decision-making and pollution control,future work should focus on progress in toxicological methodology and understanding the impacts of microplastics at community and ecosystem levels.

关键词： Pond aquaculture Pollution characteristics Aquatic product Exposure risks Microplastics

Characteristics of microbial communities and antibiotic resistance genes in typical rivers of the western Qinghai Lake basin

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Water Biology and Security

Water Biology and Security 2024年第2期3卷 46-54页

作者： Jia Jia Xiaoyan Xi Xin Li Hongjuan Hu Kelong Chen chenxi wu State Key Laboratory of Freshwater Ecology and Biotechnology Institute of HydrobiologyChinese Academy of SciencesWuhan430072China School of Geographical Sciences Qinghai Normal UniversityXining810008QinghaiChina Qinghai Province Key Laboratory of Physical Geography and Environmental Process College of Geographical ScienceQinghai Normal UniversityXining810008China Key Laboratory of Tibetan Plateau Land Surface Processes and Ecological Conservation(Ministry of Education) Qinghai Normal UniversityXining810008China National Positioning Observation and Research Station of Qinghai Lake Wetland Ecosystem in Qinghai National Forestry and Grassland AdministrationHaibei812300China Qinghai Lake Comprehensive Observation and Research Station Chinese Academy of SciencesGonghe813099China

Environmental factors and anthropogenic activity are key factors that shape the distribution of bacteria and antibiotic resistance genes(ARGs)in natural ***,few studies have focused on the occurrence of bacteria and ARGs in remote and pristine *** this study,the distribution of bacteria and ARGs in two typical rivers of the western Qinghai Lake basin was *** showed that cold-resistant Planomicrobium *** the predominant genus due to the low temperature,followed by unclassified_f_*** nitrogen nutrients increased the abundance and diversity of the bacteria community and denitrification was the dominant means of bacterial nitrate *** resistance genes including tetA,tetB,and tetC were the dominant ARGs in the western Qinghai Lake basin,ranging from 2.30×10^(3)to 1.91×10^(8)copies/L,while the low abundances of intI1,and ARGs such as sul1 indicated low anthropogenic activity in the western Qinghai Lake ***,the strong positive correlation between ARGs and intI1 highlights the potential transmission risk of ARGs through cross-or co-selection by horizontal gene *** study emphasized the adaptation of bacteria to the environment and the facilitation of anthropogenic activity in the propagation of ARGs in natural environments.

关键词： Bacteria Antibiotic resistance gene Environmental factor Anthropogenic activity Qinghai lake