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Examining the evolution of tidal creeks in the Huanghe River delta using multi-temporal Landsat images

Journal of oceanology and Limnology 2024年第4期42卷 1061-1073页

作者： Zhen HAN Kai JIN Quanli ZONG Peng QIN Chunxia LIU Xiuzhi ZHU Xinyue LI college of Resources and environment Qingdao Agricultural UniversityQingdao 266109China

Coastal tidal creeks are important channels for exchanges of material and energy between sea and land,and play an important role in the ecological protection of tidal *** tidal creeks have evolved differently in various regions,the evolutionary process of tidal creeks in the Huanghe(Yellow)River delta of China,one of the most active deltas worldwide,is not entirely ***,the evolution of tidal creeks in the delta from 1981 to 2021 was investigated by quantitatively analysing the tidal creeks and developing a standard for dividing their evolution *** interpretation and supervised classification methods were applied to the Landsat images to extract the tidal creek network,and 17 groups of tidal creek systems were *** indicate that Creek S 1 was the most developed creek for having 113 tidal creeks totaling 65.8 km in length,while Creek E 3 had the fastest growth rate for having average annual increase of 1.9 ***,the level of tidal creeks increased,the average and median lengths of tidal creeks increased,and the number of tidal creeks decreased since *** evolution of the tidal creek system could be divided into four stages,namely,rising,developing,stabilizing,and *** of a representative tidal creek show that there was no degenerated tidal creek during the rising period,with an increase in the number of 50 and a length increase of 57.9 km between 1981 and *** proportion of new tidal creeks in the developing period was more than 50%and the new tidal creeks in the stabilizing period were equal to the degraded tidal *** tidal creeks were greater than 50%during the degrading *** was no fixed order of tidal creek evolution in each period,and there may be a skip in *** findings provided a reference for studying the evolution of tidal creeks.

关键词： tidal creek evolution pattern remote sensing Huanghe(Yellow)River delta

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Alleviated photoinhibition on nitrification in the Indian Sector of the Southern ocean

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Acta oceanologica Sinica 2024年第7期43卷 52-69页

作者： Lingfang Fan Min Chen Zifei Yang Minfang Zheng Yusheng Qiu college of ocean and Earth sciences Xiamen UniversityXiamen 361102China

Nitrification,a central process in the marine nitrogen cycle,produces regenerated nitrate in the euphotic zone and emits N_(2)O,a potent greenhouse gas as a *** regulatory mechanisms of nitrification in the Southern ocean,which is a critical region for CO_(2)sequestration and radiative benefits,remain poorly ***,we investigated the in situ and dark nitrification rates in the upper 500 m and conducted substrate kinetics experiments across the Indian Sector in the Cosmonaut and Cooperation seas in the late austral *** findings indicate that light inhibition of nitrification decreases exponentially with depth,exhibiting a light threshold of 0.53%photosynthetically active radiation.A positive relationship between dark nitrification and apparent oxygen utilization suggests a dependence on substrate availability from primary ***,an increased NH_(4)^(+) supply can act as a buffer against photo-inhibitory ***,substrate affinity(α)increases with depth and transitions from light to dark,decreases with increasing ambient NH_(4)^(+)and exhibits a latitudinal distribution,reflecting substrate utilization *** also reveal that upwelling in Circumpolar Deep Water(CDW)stimulates nitrification through the introduction of potentially higher iron and deep diverse nitrifying microorganisms with higherα.We conclude that although light is the primary limiting factor for nitrification in summer,coupling between substrate availability and CDW upwelling can overcome this limitation,thereby alleviating photoinhibition by up to 45%±5.3%.

关键词： nitrification light inhibition substrate affinity circumpolar deep water(CDW)upwelling the Southern ocean

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Molecular dynamics simulation of the flow mechanism of shear-thinning fluids in a microchannel

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Chinese Physics B 2024年第4期33卷 516-525页

作者：杨刚郑庭程启昊张会臣 Naval Architecture and ocean Engineering college Dalian Maritime UniversityDalian 116026China

Shear-thinning fluids have been widely used in microfluidic systems,but their internal flow mechanism is still ***,in this paper,molecular dynamics simulations are used to study the laminar flow of shear-thinning fluid in a *** validated the feasibility of our simulation method by evaluating the mean square displacement and Reynolds number of the solution *** results show that the change rule of the fluid system's velocity profile and interaction energy can reflect the shear-thinning characteristics of the *** velocity profile resembles a top-hat shape,intensifying as the fluid's power law index *** interaction energy between the wall and the fluid decreases gradually with increasing velocity,and a high concentration of non-Newtonian fluid reaches a plateau ***,the velocity profile of the fluid is related to the molecule number density distribution and their values are inversely *** analyzing the radial distribution function,we found that the hydrogen bonds between solute and water molecules weaken with the increase in *** observation offers an explanation for the shear-thinning phenomenon of the non-Newtonian flow from a micro perspective.

关键词： molecular dynamics simulation non-Newtonian fluid microchannel shear-thinning

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Effect of particle composition and consolidation degree on the wave-induced liquefaction of soil beds

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Acta oceanologica Sinica 2024年第2期43卷 11-22页

作者： Zhiyuan Chen Yupeng Ren Guohui Xu Meng Li Shandong Provincial Key Laboratory of Marine environment and Geological Engineering Ocean University of ChinaQingdao 266100China Marine Ecological Restoration and Smart ocean Engineering Research Center of Hebei Province Qinhuangdao 066000China Key Laboratory of Marine environment and Ecology(ocean University of China) Ministry of EducationQingdao 266100China Key Laboratory of Submarine Geoscience and Prospecting Techniques(ocean University of China) Ministry of EducationQingdao 266100China

The wave-induced liquefaction of seabed is responsible for causing damage to marine *** composition and consolidation degree are the key factors affecting the pore water pressure response and liquefaction behavior of the seabed under wave *** present study conducted wave flume experiments on silt and silty fine sand beds with varying particle ***,a comprehensive analysis of the differences and underlying reasons for liquefaction behavior in two different types of soil was conducted from both macroscopic and microscopic *** experimental results indicate that the silt bed necessitates a lower wave load intensity to attain the liquefaction state in comparison to the silty fine sand ***,the duration and development depth of liquefaction are greater in the silt *** dissimilarity in liquefaction behavior between the two types of soil can be attributed to the variation in their permeability and plastic deformation *** permeability coefficient and compression modulus of silt are lower than those of silty fine ***,silt is more prone to the accumulation of pore pressure and subsequent liquefaction under external *** research has demonstrated that silt beds with varying consolidation degrees exhibit distinct initial failure ***,a dense bed undergoes shear failure,whereas a loose bed experiences initial liquefaction *** study utilized discrete element simulation to examine the microscopic mechanisms that underlie this phenomenon.

关键词： wave flume liquefaction pore water pressure consolidation permeability experiment discrete element simulation

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Distribution of modified Circumpolar Deep Water and its threat in Vincennes Bay,East Antarctica

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Journal of oceanology and Limnology 2024年第5期42卷 1399-1414页

作者： Wenjun YE Lingqiao CHENG Yujiro KITADE Song HU Juncheng ZUO college of oceanography and Ecological science Shanghai Ocean UniversityShanghai 201306China Key Laboratory of Marine Ecological Monitoring and Restoration Technologies Ministry of Natural ResourcesShanghai 201306China Department of ocean sciences Tokyo University of Marine Science and TechnologyTokyo 108-8477Japan

The Antarctic Bottom Water formation site Vincennes Bay,East Antarctica is experiencing a substantial intrusion of modified Circumpolar Deep Water(mCDW),which may inhibit the formation of Dense Shelf Water(DSW)and drive basal melting of the ice *** on hydrographic data obtained from March to November in 2012,we evaluated the spatial spread of mCDW over the continental shelf region of Vincennes Bay and the associated temporal evolution of water properties,as well as the sea ice formation effect on water column in the coastal *** show that two branches of mCDW occupied the deep layers of the continental shelf,distinguished by the potential density(smaller than 27.8 kg/m^(3) or not)when potential temperatureθ=0.5°C in theθ-salinity *** warmer and less dense branch observed on the east plateau,accessed the eastern ice shelves in the coastal polynya to drive basal melting of ice *** contrast,the other colder and denser branch in the mid-depression reached the western Underwood Ice *** formation was detectable in the coastal polynya during September-November,proving the occurrence of deep *** heat loss and brine rejection during the intensive sea ice formation contributed to the destratification of the water column in the coastal *** was estimated that at least 1.11±0.79 TW heat carried by mCDW into the inner part of the polynya.

关键词： modified circumpolar deep water evolution of water properties coastal polynya ice shelf Vincennes Bay

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Defects and morphology engineering for constructing V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S nanotube heterojunction arrays toward efficient bifunctional electrocatalyst for overall water splitting

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Journal of Energy Chemistry 2024年第7期94卷 29-40页

作者： Wenyuan Sun Alan Meng Lei Wang Guicun Li Jinfeng Cui Yongkai Sun Zhenjiang Li college of Materials science and Engineering Qingdao University of Science and TechnologyQingdao 266042ShandongChina Key Laboratory of Optic-electric Sensing and Analytical Chemistryfor Life science MOE College of Chemistry and Molecular EngineeringQingdao Universityof Science and TechnologyQingdao 266042ShandongChina college of environment and Safety Engineering Qingdao University of Science and TechnologyQingdao 266042ShandongChina Qingdao Huanghai University Qingdao 266000ShandongChina college of Electromechanical Engineering Qingdao University of Science and TechnologyQingdao 266061ShandongChina

The development of highly active,stable and inexpensive electrocatalysts for hydrogen production by defects and morphology engineering remains a great ***,S vacancies-rich Ni_(3)S_(2)@Cu_(2)S nan-otube heterojunction arrays were in-situ grown on copper foam(V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S NHAs/CF)for efficient electrocatalytic overall water *** the merits of nanotube arrays and efficient electronic mod-ulation drived by the OD vacancy defect and 2D heterojunction defect,the resultant V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S NHAs/CF electrocatalyst exhibits excellent electrocatalytic activity with a low overpotential of 47 mV for the hydrogen evolution reaction(HER)at 10 mA cm^(-2) current density,and 263 mV for the oxygen evolution reaction(OER)at 50 mA cm^(-2) current density,as well as a cell voltage of 1.48 V at 10 mA cm^(-2).Moreover,the nanotube heterojunction arrays endows V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S NHAs/CF with outstanding stability in long-term catalytic processes,as confirmed by the continuous chronopotentiom-etry tests at current densities of 10 mA cm^(-2) for 100 h.

关键词： Nanotubearrays Heterojunction Vacancy Bifunctional electrocatalyst Overall water splitting

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In-situ sludge reduction based on Mn^(2+)-catalytic ozonation conditioning:Feasibility study and microbial mechanisms

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Journal of environmental sciences 2024年第1期135卷 185-197页

作者： Haozhe Huang Tingting Wei Hui Wang Bing Xue Sisi Chen Xiankai Wang Haibin Wu Bin Dong Zuxin Xu college of environmental science and Engineering Tongji UniversityShanghai 200092China YANGTZE Eco-environment Engineering Research Center China Three Gorges CorporationBeijing 100038China

To improve the sludge conditioning efficiency without increasing the ozone dose,an in-situ sludge reduction process based on Mn^(2+)-catalytic ozonation conditioning was *** ozone conditioning alone as a control,a lab-scale sequencing batch reactor coupled with ozonated sludge recycle was evaluated for its operating performance at an ozone dose of 75 mg O_(3)/g VSS and 1.5 mmol/L Mn^(2+)*** results showed a 39.4%reduction in MLSS and an observed sludge yield of 0.236 kg MLSS/kg COD for the O_(3)+Mn^(2+)group compared to the O_(3)group (15.3%and 0.292 kg MLSS/kg COD),accompanied by better COD,NH_(4)^(+)-N,TN and TP removal,improved effluent SS and limited impact on excess sludge ***,activity tests,BIOLOG ECO microplates and 16S rRNA sequencing were applied to elucidate the changing mechanisms of Mn^(2+)-catalytic ozonation related to microbial action:(1) Dehydrogenase activity reached a higher peak.(2) Microbial utilization of total carbon sources had an elevated effect,up to approximately 18%,and metabolic levels of six carbon sources were also increased,especially for sugars and amino acids most pronounced.(3) The abundance of Defluviicoccus under the phylum Proteobacteria was enhanced to 12.0%and dominated in the sludge,they had strong hydrolytic activity and metabolic *** bacteria of the genus Ferruginibacter also showed an abundance of 7.6%,they contributed to the solubilization and reduction of sludge *** results could guide researchers to further reduce ozonation conditioning costs,improve sludge management and provide theoretical support.

关键词： Activated sludge In-situ reduction Catalytic ozonation conditioning Dehydrogenase activity Carbon source utilization Microbial community

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Using Natural Radionuclides to Trace Sources of Suspended Particles in the Lower Reaches of the Yellow River

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Journal of ocean University of China 2024年第1期23卷 99-108页

作者： ZHANG Han BURNETT CWilliam ZHANG Xiaojie ZHAO Shibin YANG Disong NAN Haiming YU Zhigang XU Bochao Frontiers science Center for Deep ocean Multispheres and Earth System and Key Laboratory of Marine Chemistry Theory and TechnologyMinistry of EducationOcean University of ChinaQingdao 266100China Laboratory for Marine Ecology and environmental science Qingdao National Laboratory for Marine Science and TechnologyQingdao 266071China college of Chemistry and Chemical Engineering Ocean University of ChinaQingdao 266100China Department of Earth Ocean and Atmospheric ScienceFlorida State UniversityTallahasseeFL 32306USA North China Sea environmental Monitoring Center State Oceanic AdministrationKey Laboratory of Ecological Prewarning and Protection of Bohai SeaMNRQingdao 266033China Shandong Provincial Key Laboratory of Marine Ecological environment and Disaster Prevention and Mitigation Qingdao 266033China

Natural radionuclides are powerful tools for understanding the sources and fate of suspended particulate matter(SPM).Particulate matter with different particle sizes behaves differently with respect to adsorption and *** analyzed the activi-ties and distribution characteristics of multiple natural radionuclides(238U,226Ra,40K,228Ra,7Be and 210Pbex)on size-fractionated SPM at the Lijin Hydrographic Station(Huanghe or Yellow River)every month over a one-year *** showed that medium silt(16–32µm)was the main *** expected,the activity of each radionuclide decreased with an increase of particle *** examined the sources of SPM with different particle sizes using activity ratios of 226Ra/238U,228Ra/226Ra,40K/238U and 7Be/210Pbex,and concluded that SPM with different particle sizes originated from different *** results indicate that fine SPM(32µm)was mainly derived from resuspension of riverbed *** high runoff periods,the concentration of SPM increased significantly,and the pro-portion of fine particles originating upstream *** occurring radioactive isotopes,especially on size-fractionated par-ticles,are therefore seen as useful tracers to understand the sources and behaviors of riverine particles transported from land to sea.

关键词： the Yellow River suspended particulate matter size-fractions radionuclides sediment sources water elutriator

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An Innovative Coupled Common-Node Discrete Element Method-Smoothed Particle Hydrodynamics Model Developed with LS-DYNA and Its Applications

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China ocean Engineering 2024年第3期38卷 467-482页

作者： SHEN Zhong-xiang WANG Wen-qing XU Cheng-yue LUO Jia-xin LIU Ren-wei School of Naval Architecture and ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China college of Harbor Coastal and Offshore EngineeringHohai UniversityNanjing 210098China

In this study,a common-node DEM-SPH coupling model based on the shared node method is proposed,and a fluid–structure coupling method using the common-node discrete element method-smoothed particle hydrodynamics(DS-SPH)method is developed using LS-DYNA *** DEM and SPH are established on the same node to create common-node DEM-SPH particles,allowing for fluid–structure *** simulations of various scenarios,including water entry of a rigid sphere,dam-break propagation over wet beds,impact on an ice plate floating on water and ice accumulation on offshore structures,are *** interaction between DS particles and SPH fluid and the crack generation mechanism and expansion characteristics of the ice plate under the interaction of structure and fluid are also *** results are compared with available data to verify the proposed coupling ***,the simulation results demonstrated that controlling the cutoff pressure of internal SPH particles could effectively control particle splashing during ice crushing failure.

关键词： common-node DEM-SPH fluid-structure interaction discrete element method smoothed particle hydrodynamics

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Microseismic observations reveal that internal waves intensify seabed methane release

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science China Earth sciences 2024年第10期67卷 3186-3203页

作者： Zhaoyang TIAN Yonggang JIA Junjiang ZHU Tian CHEN Hui WANG Chunsheng JI Chengyu LIU Longyu LU Manchao HE Shandong Provincial Key Laboratory of Marine environment and Geological Engineering Ocean University of ChinaQingdao 266100China Frontiers science Center for Deep ocean Multispheres and Earth System Key Lab of Submarine Geosciences and Prospecting TechniquesMOE and College of Marine GeosciencesOcean University of ChinaQingdao 266100China Guangzhou Marine Geological Survey China Geological SurveyGuangzhou 511458China Shandong Earthquake Agency Jinan 250014China State Key Laboratory for Tunnel Engineering China University of Mining and Technology(Beijing)Beijing 100083China

Internal waves transport material and energy from the upper water column to the deep ocean, disturbing seabed sediments and resulting in phenomena such as seabed erosion and changes in topography. On the northern slope of the South China Sea and in many coastal margins worldwide, the zones with internal wave action closely overlap with areas where natural gas hydrates are present. However, due to significant differences in the spatial and temporal scales, understanding the influence of internal waves on methane releases from deep seabeds is challenging. In this study, in situ observations of seabed microseismicity and internal waves are conducted at water depths of 655 meters and 1450 meters in the Pearl River Canyon of the South China Sea. The microseismicity caused by internal waves and seabed methane releases is identified, and a method to establish the correlation between internal waves and seabed methane releases through the use of microseismic recordings is proposed, aiming to obtain direct observational evidence of internal waves intensifying seabed methane releases. The results show that internal waves and seabed methane releases generate significant microseismic signals, indicating the continuous influence of internal waves on the deep seabed of the northern slope of the South China Sea and revealing active methane release phenomena on the seabed. At both long and short time scales, internal waves increase the frequency of seabed methane releases by 4.2 times and 2.4 times, respectively, while also enhancing the intensity of these releases. These changes are influenced by the alterations in seabed flow velocity, pressure, and temperature that are induced by internal wave activities. This study emphasizes that microseismic signals are effective carriers of information for multiscale geological processes on seabeds and suggests that internal waves exacerbate marine geological hazards and contribute to global climate change by intensifying seabed methane relea

关键词： Internal waves Seabed methane release Microseismic observation ocean bottom seismometer Northern slope of the South China Sea

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