Article
Environmental Sciences
Jie Huang, Simin Wang, Xinran Li, Rongyao Xie, Jianxiong Sun, Benwei Shi, Feng Liu, Huayang Cai, Qingshu Yang, Zhaoyong Zheng
Summary: This study investigates the influences of shear stress and salinity stratification on the floc size distribution of fine cohesive sediments in an estuary. The results show that strong turbulent shear rates lead to smaller flocs dominating in the bottom layer, while salinity stratification results in larger flocs dominating in the upper or middle layers. The study provides insights into the flocculation process in complex estuarine environments.
FRONTIERS IN MARINE SCIENCE
(2022)
Article
Geosciences, Multidisciplinary
Zhirui Deng, Qing He, Claire Chassagne, Zheng Bing Wang
Summary: The variation of floc population in the Changjiang Estuary has been studied for both winter and summer seasons, with the presence of living algae characterized through the chlorophyll-a concentration to suspended sediment concentration ratio. The floc population consists of three particle classes and remains at a steady state due to limited flocculation ability between classes. Macroflocs and microflocs coexist in the water column, with macroflocs found mainly at the top during winter and abundant in the presence of algae during summer.
Article
Marine & Freshwater Biology
Sifat Sarwar, Alistair G. L. Borthwick
Summary: This article examines the uncertainty propagation from input floc size to output sedimentation rate in the Meghna estuary, Bangladesh. The results show that the coefficient of variation ranges from 20% to 38% across three locations. Planners need to consider substantial uncertainty in cohesive sediment transport estimates, especially in deposition-prone areas with increased flooding risk.
ESTUARINE COASTAL AND SHELF SCIENCE
(2023)
Article
Environmental Sciences
Chao Guo, Leicheng Guo, Sarah Bass, Andrew J. Manning, Zhongwu Jin, Yinjun Zhou
Summary: The effects of different types of organic matter on fine sediment flocculation were investigated through laboratory tank experiments. Results demonstrated that the introduction of organic polymers (such as xanthan gum and guar gum) significantly enhanced flocculation, while the addition of humic acid had minimal influence. The nonionic polymer guar gum showed greater efficacy in promoting larger and more fractal flocs compared to the anionic polymer, xanthan gum. Non-linear trends were observed in the evolution of floc size and structure with increasing ratios of organic polymer concentration to kaolinite concentration.
JOURNAL OF ENVIRONMENTAL MANAGEMENT
(2023)
Article
Geosciences, Multidisciplinary
Andres Garcia-Ruiz, Manuel Carpio, Ricardo Giesecke, Maria Bermudez, Manuel Diez-Minguito
Summary: This study focuses on the estuarine regimes and subtidal circulation in the Valdivia River Estuary in southern Chile, and how they impact the distribution of Suspended Meso-Zooplankton Carcasses (SMZC). Field campaigns were conducted in 2014 and 2015, and time series of metocean forcings span from 2012 to 2018. The research highlights the importance of circulation-stratification relationships in controlling SMZC trapping mechanisms and identifying hotspots of benthic biomass in mid-latitude estuaries.
JOURNAL OF MARINE SYSTEMS
(2022)
Article
Chemistry, Multidisciplinary
Gabriela Adriana Bastida, Quim Tarres, Roberto Aguado, Marc Delgado-Aguilar, Miguel Angel Zanuttini, Maria Veronica Galvan
Summary: This study aims to understand the key factors influencing the rheological behavior and mechanism of natural PECs as flocculation agents for CMFs and CNFs. The results showed that lower xylan mass ratios led to higher intrinsic viscosity, hydrodynamic size, z-potential, and lower critical concentration. Under dynamic conditions, a very low dosage of PEC was sufficient for flocculation, while higher doses were required for CNF suspensions compared to CMF suspensions. Under static conditions, maximum floc sizes were observed at the same PEC dosage where minimum gel points were reached.
Article
Environmental Sciences
Lijie Zhou, Nan Dong, Biao Ye, Wei-Qin Zhuang, Siqing Xia
Summary: Calcium ions can trigger the coagulation-flocculation process to form macro-flocculated sludge, where an elevated Ca2+ concentration in MBRs can lead to the formation of granular sludge with diameters up to 900 μm. The addition of Ca2+ can flocculate and precipitate soluble proteins and polysaccharides, resulting in a negative correlation between extracellular polymeric substances concentrations and the formation of MFS. The microbial communities in the MBRs undergo significant changes with the addition of Ca2+, affecting total nitrogen removal due to the formation of diffusion barriers by the enlarging MFS.
SCIENCE OF THE TOTAL ENVIRONMENT
(2021)
Article
Environmental Sciences
Krishnamoorthy Lakshmi Ammal Priya, Soufiane Haddout, Joan Cecilia Catubig Casila
Summary: This study measured water depth, salinity, current, and suspended sediment concentration in an estuarine longitudinal section to investigate their effects on floc size. The results showed that floc size increased with the increase in clay and silt content, but decreased with the increase in sand content of bed sediment. The turbulent shear had a direct effect on floc size, with its value increasing up to a certain point and then decreasing. The study developed a new model that incorporated the additional shear imparted by sand and improved the predictability of floc size. Furthermore, the study highlighted the influence of sand in causing the break-up of flocs in mixed sediment estuarine environments.
INTERNATIONAL JOURNAL OF SEDIMENT RESEARCH
(2022)
Article
Geochemistry & Geophysics
Yuping Fan, Yangyang Zhang, Xianshu Dong, Xiaomin Ma, Na Li, Wei Jin
Summary: This study investigated the impact of coagulant type and dosage on the clarity, zeta potential, floc size, and floc structure of a coal slurry suspension. The findings showed that trivalent ions had lower critical coagulation concentrations and AlCl3 and FeCl3 had a greater effect on initial settling. Additionally, trivalent ions significantly decreased the supernatant turbidity at lower dosages, enhancing the coagulation effect.
Article
Environmental Sciences
Zhenzhen Jia, Shiyu Li, Qiuxin Liu, Feng Jiang, Jiatang Hu
Summary: The study found significant salinity variations in the Modaomen estuary, with higher heavy metal concentrations in bottom water likely due to elevated salinity and water stratification causing restricted mixing. Sediment heavy metal distribution was influenced by various factors, with internal release potentially contributing significantly to higher levels in bottom water. Saltwater intrusion facilitated the mobility and repartitioning of metals in the estuarine ecosystem.
ENVIRONMENTAL POLLUTION
(2021)
Article
Marine & Freshwater Biology
Matteo Postacchini, Andrew J. Manning, Joseph Calantoni, Joseph P. Smith, Maurizio Brocchini
Summary: Many macro- and mesotidal estuaries have TMZs, which are regions with higher suspended solid concentrations compared to the rest of the estuary. These zones are modulated by tidal oscillations and are not typically found in micro-tidal estuaries.
ESTUARINE COASTAL AND SHELF SCIENCE
(2023)
Review
Engineering, Environmental
Robert P. Chapuis
Summary: This article presents various models for fitting grain size distribution curves and provides a list of comparative studies. It demonstrates how to extract and verify the internal structure of data. The extraction is crucial for determining soil hydraulic properties and behavior. The article introduces new equations that link different metrics to assess goodness-of-fit. The MDM model is proven to be excellent and applicable to any soil.
BULLETIN OF ENGINEERING GEOLOGY AND THE ENVIRONMENT
(2023)
Article
Environmental Sciences
Hao Wu, Jieping Tang, Weihua Li, Fei Xing, Haifei Yang, Fan Zhang, Ya Ping Wang
Summary: This study presents in-situ observations of fluid mud in the Yangtze Estuary and provides valuable insights into its formation and breakdown process. The thickness and turbulence kinetic energy of the fluid mud were found to be influenced by external factors such as advection and tidal pumping. The increased cross-channel current velocity during flood facilitated the lateral transport of eroded sediment. These findings contribute to estuarine hydrodynamic modeling studies and enhance the understanding of estuary dynamics.
FRONTIERS IN MARINE SCIENCE
(2023)
Article
Engineering, Chemical
Ploypailin Romphophak, Carole Coufort-Saudejaud, Claude Le Men, Pisut Painmanakul, Alain Line
Summary: A quasi-two-dimensional apparatus was designed to visualize the interaction between floc size distribution and hydrodynamics in the flocculation zone of a jet clarifier. Measurements were performed using shadowgraphy method and image analysis, revealing a direct correlation between the evolution of aggregate number along the jet and the recirculation loop in the flocculation zone. The independence of floc size distributions on flow rate, as discussed in light of the constant Camp number Gt for different flow rates, contributes to the efficiency of the jet clarifier in terms of flocculation.
CHEMICAL ENGINEERING RESEARCH & DESIGN
(2021)
Article
Ecology
Yin Liu, Lun Song, GuangJun Song, JinHao Wu, Kun Wang, ZaoHui Wang, SuXuan Liu
Summary: The grain size structure of phytoplankton has a significant impact on shellfish culture. This study assessed the spatial and temporal variation in the phytoplankton community structure in the Yalu River Estuary and explored the relationship between the phytoplankton community structure and various environmental parameters. High-throughput sequencing was used to analyze the data. The results showed that nanophytoplankton, especially Karlodinium veneficum, dominated the estuary throughout the year. The biomass ratio of different size classes varied across seasons. Additionally, environmental factors such as COD, T, SST, and Dep influenced the phytoplankton community structure in the estuary.
ECOSYSTEM HEALTH AND SUSTAINABILITY
(2022)
Article
Geosciences, Multidisciplinary
Joshua Williams, Guan-hong Lee, Hyun-Jung Shin, Timothy Dellapenna
Article
Marine & Freshwater Biology
Sun Min Choi, Jun Young Seo, Ho Kyung Ha, Guan-hong Lee
ESTUARINE COASTAL AND SHELF SCIENCE
(2018)
Article
Oceanography
Guan-hong Lee, Hyun-Jung Shin, Young Taeg Kim, Timothy M. Dellapenna, Kuk Jin Kim, Joshua Williams, Seok-Yun Kim, Steven Miguel Figueroa
Article
Marine & Freshwater Biology
Steven Miguel Figueroa, Guan-hong Lee, Hyun-Jung Shin
ESTUARINE COASTAL AND SHELF SCIENCE
(2020)
Article
Environmental Sciences
KiRyong Kang, Guan-hong Lee
Article
Environmental Sciences
Nathalie W. Jung, Guan-hong Lee, Yoonho Jung, Steven M. Figueroa, Kenneth D. Lagamayo, Tae-Chang Jo, Jongwi Chang
Summary: The study introduces MorphEst, a MATLAB-based tool that automatically measures estuarine planform geometry by extracting information from channel masks and comparing it with independent measurements. The results show a high level of accuracy and applicability, making it helpful for solving research questions related to estuarine evolution.
Article
Oceanography
Steven M. Figueroa, Guan-hong Lee, Jongwi Chang, Nathalie W. Jung
Summary: Estuarine dams can amplify the tidal range and reduce tidal currents, leading to changes in estuarine types and affecting river runoff and tidal pumping.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Environmental Sciences
Steven M. Figueroa, Minwoo Son, Guan-hong Lee
Summary: The effect of an estuarine dam located near the mouth on different estuarine types was studied using a numerical model. The results showed that the dam altered the tide and river forcing, affecting the stratification, circulation, sediment fluxes, and depths. The dam location primarily affected tide-dominated estuaries, while the discharge interval primarily affected river-dominated estuaries.
FRONTIERS IN MARINE SCIENCE
(2022)
Article
Geosciences, Multidisciplinary
Steven Miguel Figueroa, Guan-hong Lee, Jongwi Chang, Nathalie W. Schieder, Kyeongman Kim, Seok-Yun Kim