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CALCULATION MODELS FOR THE SUSPENDED SEDIMENT TRANSPORT RATE

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Journal of Hydrodynamics 1993年第1期5卷 10-21页

作者： ni, jinren Peking Univ Beijing China

The calculation accuracy of the suspended sediment transport rate relies on that of the vertical distribution of the particle concentration,the particle velocity distribution and the reference *** view of the limitations of the previons formulas for both the velocity and the concentration distributions,general expressions are introduced to the calculation of sus- pended sediment transport *** on these analyses,a simple and practical calculation model is given in the present paper.

关键词： suspended sediment transport rate concentration profile

MIXING MODEL EXTENDED TO TURBULENT FLOW IN NARROW SMOOTH OPEN CHANNELS

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Journal of Hydrodynamics 1996年第4期8卷 40-48页

作者： ni, jinren Peking Univ Beijing China

On the basis of systematic analyses of the relation among the width-depth ratios, the locations of maximum velocity in the cross section and boundary shear stress distributions, a simple model for the velocity distribution in smooth rectangular open channels has been presented. it became possible to reasonably predict the velocity value at every point of a rectangular cross section. As a good approximation, the model was then suggested to be used for turbulent flow in open channel with any given symmetrical shape.

关键词： Approximation theory Flow of water Mathematical models Turbulent flow Velocity Viscous flow

Structural characteristics of river networks and their relations to basin factors in the Yangtze and Yellow River basins

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Science China(Technological Sciences) 2019年第11期62卷 1885-1895页

作者： CHEN XiaBin WANG YiChu ni jinren The Key Laboratory of Water and Sediment Sciences Ministry of EducationCollege of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China Beijing Innovation Center for Engineering Science and Advanced Technology(BIC-ESAT) Peking UniversityBeijing 100871China

The integration of rivers and basins highly implies the possible existence of certain relationships between hierarchical characteristics of river networks and primary basin *** we investigated river networks in two large basins,the Yangtze River and the Yellow River,characterized with basic factors such as annual precipitation,slope,soil erodibility and *** analysis demonstrated a fair self-similarity of river networks at the stream-order 1-5 in both rivers,described by the structural parameters including bifurcation ratio,side-branching ratio,drainage density,and length of *** precipitation,basin slope was essential in shaping river networks in both basins,showing a significant positive correlation(R^2=0.39-0.85)to bifurcation ratio,side-branching ratio,and drainage *** the same basin slope(5°-15°),the higher soil erodibility and sparse vegetation would promote greater side-branching ratio and drainage density in the Yellow River,which were estimated 11.97%and 63.70%larger,respectively than those in the Yangtze *** study highlights the importance to formulate basin-specific strategies for water and soil conservation in terms of different structures of river networks.

关键词： river network structural characteristics basin factor Yangtze River Yellow River

Sorption of Triton X-100 on soil organic matter fractions:Kinetics and isotherms

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Journal of Environmental Sciences 2009年第6期21卷 795-800页

作者： ZHANG Guangzhi HU Hao SUN Weiling ni jinren Department of Environmental Engineering Peking University The Key Laboratory of Water and Sediment Sciences Ministry of Education Beijing 100871 China Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences Beijing 100081 China

Kinetics and isotherms of Triton X-100 sorption on soil,base-extracted soil（BE）,humic acid（HA） and humin（HM） were investigated respectively to get better understanding on characteristics of the surfactant sorption onto different soil organic matters（SOMs）.It was demonstrated that the kinetics results could be satisfactorily described by the pseudo-second order *** half of the time to reach equilibrium（t1/2） for different sorbents followed the sequence of soil 〉 HA 〉 BE 〉 ***,the calculated equilibrium sorption capacity（Ceq） was found in the sequence of HA 〉 BE 〉 HM 〉 soil,which agreed well with the experimental *** isotherms of Triton X-100 sorption on soil and HA could be well described by the S-type isotherm,but BE and HM by the *** isotherms of all the four sorbents were found reasonably fitted to the Langmuir *** Kd value,defined as the ratio of Triton X-100 in sorbent and in the equilibrium solution for given concentrations,generally followed the order of HM 〉 HA 〉 soil 〉 *** HM and HA showed high affnity for Triton X-100,but the HA and HM in soil and BE were tightly bounded by the ***,the HA on the soil surface might dominate the sorption,whereas the bounded HM would play a key role upon the surfactants being penetrated inside the soil.

关键词： Triton X-100 sorption soil organic matters nonionic surfactant kinetics isotherms

Microscopic view of phytoplankton along the Yangtze River

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Science China(Technological Sciences) 2019年第11期62卷 1873-1884页

作者： LIU YuXin XU XuMing WANG Ting ni jinren Key Laboratory of Water and Sediment Sciences Ministry of EducationCollege of Environmental Sciences and EngineeringPeking University

Phytoplankton play an important role in nutrient cycling and energy conversion. However, phytoplankton community is poorly understood in large river ecosystems. Based on the large-scale samplings conducted in spring and autumn of 2017, a systematic study has been made on seasonal and spatial distributions of phytoplankton community along the mainstream of the Yangtze River. As results, 6 phyla were identified and 59 phytoplankton species were detected using microscopy, including Bacillariophyta(29 species), Chlorophyta(13 species) and Cyanophyta(8 species) as the dominant group. Moreover, the density of phytoplankton was ranged 0.05×10^6–1.90×10^6 cells/L and the biomass was 0.01–1.01 mg/L, both reaching their maximum in the middle reach from Yichang to Wuhan. Significant seasonal difference of phytoplankton community was observed and spatial dissimilarity in spring was revealed. The cell abundance and biomass of phytoplankton could be fairly estimated by chlorophylla, and redundancy analysis indicated that water temperature, dissolved oxygen, biochemical oxygen demand, nitrite, and ammonia nitrogen were the most important explanatory environmental factors for phytoplankton compositions in the Yangtze River.

关键词： microscopic view phytoplankton community spatiotemporal distribution Yangtze River environmental factor

Treatment of landfill leachate by immobilized microorganisms

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Science China Chemistry 2008年第10期51卷 1014-1020页

作者： YE ZhengFang YU HongYan WEN LiLi ni jinren Key Laboratory of Water and Sediment Sciences of Ministry of Education Department of Environmental EngineeringPeking UniversityBeijing 100871China Key Laboratory of Environmental and Urban Sciences Shenzhen Graduate SchoolPeking UniversityShenzhen 518055China

This paper focuses on the outcome and the main performance of the immobilized microbial that treats landfill leachate. Based on the analysis of COD and ammonia-nitrogen of the influent and effluent, research was done on the high removal efficiency of COD and ammonium nitrogen by immobilized microbial. The leachate composition was analyzed qualitatively using GC-MS before and after being treated. Biological loading of efficient microbial flora on the carrier was measured by Kjeldahl’s method. Finally, the patterns of immobilized microbe were observed through scanning electron microscopy (SEM). The results showed that in immobilized microorganisms system, the efficiencies of COD and nitrogen were 98.3% and 99.9%, respectively. There was a great reduction of organic components in effluent. When the immobilized biomass on the carrier was 38 g·L?1 (H2O), the filamentous microorganism was highly developed. There was no inhibitory effect on the nitrobacteria and nitrococcus, when ammonia was over 200 mg·L?1 and NH3 over 150 mg·L?1. At a high organic loading, it still had good nitrification. This paper also compares the performance of immobilized microbial with free microbial under the same condition. The immobilized microbial technology demonstrated better than the latter in all aspects.

关键词： immobilization microbial performance treatment landfill leachate

Mechanism of combination membrane and electro-winning process on treatment and remediation of Cu^(2+) polluted water body

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Journal of Environmental Sciences 2009年第6期21卷 764-769页

作者： ZHANG Linnan WU Yanjun QU Xiaoyan LI Zhenshan ni jinren Department of Environmental Engineering Peking University The Key Laboratory of Water and Sediment Sciences Ministry of Education of China Beijing 100871 China Shenzhen Graduate School Peking University Shenzhen 518055 China

Mechanism of treatment and remediation of synthetic Cu^2＋ polluted water body by membrane and electro-winning combination process was *** influences of electrolysis voltage,pH,and electrolysis time on the metal recovery effciencies were *** between trans-membrane pressure drop（△P）,additions ratio,initial Cu^2＋ concentration on operating effciency,stability of membrane and the possibility of water reuse were also *** morphology of membrane and electrodes were observed using scanning electron microscopy（SEM）,the composition of surface deposits was ascertained using combined energy dispersive X-ray spectroscopy（EDX） and atomic absorption *** results showed that using low pressure reverse osmosis（LPRO）,Cu^2＋ concentration could increase from 20 to 100 mg/L or even higher in concentrated solutions and permeate water conductivity could be less than 20 μS/*** addition of sodium dodecy/sulfate sodium dodecyl sulfate improved Cu^2＋ removal effciency,while EDTA had little side *** electro-reduction process,using plante electrode cell,Cu^2＋ concentration could be further reduced to 5 mg/L,and the average current effciency ranged from 9% to 40%.Using 3D electrolysis treatment,Cu^2＋ concentration could be reduced to 0.5 mg/L with a current effciency range 60%-70%.

关键词： heavy metal water body membranes electro-winning remediation

Characteristics of Pb^(2+) biosorption with aerobic granular biomass

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Chinese Science Bulletin 2008年第6期53卷 948-953页

作者： YAO Lei YE ZhengFang WANG ZhongYou ni jinren Key Laboratory of Water and Sediment Sciences Department of Environmental Engineering Peking University Beijing 100871China

Experimental studies were conducted on the feasibility of aerobic granular biomass as a novel type of biosorbent for Pb2+ removal. The results show that the initial pH, Pb2+ concentration (C0) and biomass concentration (X0) affected the biosorption process significantly. Both the Freundlich and Langmuir isotherm models describe the biosorption process accurately, with correlation coefficients of 0.932 and 0.959 respectively. The Pb2+ biosorption kinetics is interpreted as having two stages, with the second stage described reasonably well by a Lagergren pseudo-second order model. Moreover, the surface change of granular biomass after the Pb2+ biosorption process appears to be caused by ion exchange and metal chelation according to the analysis results of Environmental Scanning Electron Microscopy (ESEM) and Energy Dispersive X-ray Spectroscopy (EDX).

关键词：需氧颗粒生物量铅离子生物吸附环境生物学

水电梯级开发真的破坏下游河段营养盐情势吗?

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Science Bulletin 2024年第5期69卷 661-670页

作者：陈求稳陈宇琛林育青张建云倪晋仁夏军肖琳冯韬马宏海 State Key Laboratory of Hydrology-Water Resources&Hydraulic Engineering Nanjing Hydraulic Research InstituteNanjing 210029China Center for Eco-Environment Research Nanjing Hydraulic Research InstituteNanjing 210029China Yangtze Institute for Conservation and Green Development Nanjing 210024China School of the Environment Nanjing UniversityNanjing 210008China The Key Laboratory of Water and Sediment Sciences Ministry of EducationPeking UniversityBeijing 100091China State Key Laboratory of Water Resources and Hydropower Engineering Sciences Wuhan UniversityWuhan 430072China

River damming is believed to largely intercept nutrients,particularly retain more phosphorus(P)than nitrogen(N),and thus harm primary productivity,fishery catches,and food security downstream,which seriously constrain global hydropower development and poverty relief in undeveloped regions and can drive geo-political disputes between nations along trans-boundary *** this study,we investigated whether reservoirs can instead improve nutrient regimes *** measured different species of N and P as well as microbial functions in water and sediment of cascade reservoirs in the upper Mekong River over 5 years and modelled the influx and outflux of N and P species in each *** partially retaining total N and total P,reservoirs increased the downstream flux of ammonium and soluble reactive phosphorus(SRP).The increase in ammonium and SRP between outflux and influx showed positive linear relationships with the hydraulic residence time of the cascade reservoirs;and the ratio of SRP to dissolved inorganic nitrogen increased along the reservoir *** lentic environment of reservoirs stimulated algae-mediated conversion of nitrate into ammonium in surface water;the hypoxic condition and the priming effect of algae-induced organic matter enhanced release of ammonium from sediment;the synergy of microbial phosphorylation,reductive condition and sediment geochemical properties increased release of *** study is the first to provide solid evidence that hydropower reservoirs improve downstream nutrient bioavailability and N-P balance through a process of retention-transformation-transport,which may benefit primary *** findings could advance our understanding of the eco-environmental impacts of river damming.

关键词： River damming Biogeochemical cycle nitrogen Phosphorus Ecological impacts