Bedform segregation and locking increase storage of natural and synthetic particles in rivers

AbstractWhile the ecological significance of hyporheic exchange and fine particle transport in rivers is well established, these processes are generally considered irrelevant to riverbed morphodynamics. We show that coupling between hyporheic exchange, suspended sediment deposition, and sand bedform motion strongly modulates morphodynamics and sorts bed sediments. Hyporheic exchange focuses fine-particle deposition within and below mobile bedforms, which suppresses bed mobility. However, deposited fines are also remobilized by bedform motion, providing a mechanism for segregating coarse and fine particles in the bed. Surprisingly, two distinct end states emerge from the competing interplay of bed stabilization and remobilization: a locked state in which fine particle deposition completely stabilizes the bed, and a dynamic equilibrium in which frequent remobilization sorts the bed and restores mobility. These findings demonstrate the significance of hyporheic exchange to riverbed morphodynamics and clarify how dynamic interactions between coarse and fine particles produce sedimentary patterns commonly found in rivers.

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Bedform segregation and locking increase storage of natural and synthetic particles in rivers

10.31223/x5jc9k ◽

2021 ◽

Author(s):

Jonathan Dallmann ◽

Colin Phillips ◽

Yoni Teitelbaum ◽

Edwin Saavedra Cifuentes ◽

Nicole Sund ◽

...

Keyword(s):

Suspended Sediment ◽

Fine Particle ◽

Particle Deposition ◽

Fine Particles ◽

Dynamic Equilibrium ◽

Hyporheic Exchange ◽

Ecological Significance ◽

Dynamic Interactions ◽

Bed Sediments ◽

Bed Mobility

While the ecological significance of hyporheic exchange and fine particle transport in rivers is well established, these processes are generally considered irrelevant to riverbed morphodynamics. We show that coupling between hyporheic exchange, suspended sediment deposition, and sand bedform motion strongly modulates morphodynamics and sorts bed sediments. Hyporheic exchange focuses fine-particle deposition within and below mobile bedforms, which suppresses bed mobility. However, deposited fines are also remobilized by bedform motion, providing a mechanism for segregating coarse and fine particles in the bed. Surprisingly, two distinct end states emerge from the competing interplay of bed stabilization and remobilization: a locked state in which fine particle deposition completely stabilizes the bed, and a dynamic equilibrium in which frequent remobilization sorts the bed and restores mobility. These findings demonstrate the significance of hyporheic exchange to riverbed morphodynamics and clarify how dynamic interactions between coarse and fine particles produce sedimentary patterns commonly found in rivers

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Dynamics of Hyporheic Exchange Flux and Fine Particle Deposition Under Moving Bedforms

Water Resources Research ◽

10.1029/2020wr028541 ◽

2021 ◽

Vol 57 (4) ◽

Author(s):

Yoni Teitelbaum ◽

Jonathan Dallmann ◽

Colin B. Phillips ◽

Aaron I. Packman ◽

Rina Schumer ◽

...

Keyword(s):

Fine Particle ◽

Particle Deposition ◽

Hyporheic Exchange ◽

Exchange Flux

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Landscape and river self-organization limit the flux of fine particles

10.5194/egusphere-egu2020-12885 ◽

2020 ◽

Author(s):

Colin Phillips ◽

Carlos Rogéliz ◽

Daniel Horton ◽

Jonathan Higgins ◽

Aaron Packman

Keyword(s):

Suspended Sediment ◽

Fine Particle ◽

River Flow ◽

Fine Particles ◽

Strong Support ◽

Sediment Concentration ◽

Sediment Flux ◽

Suspended Sediment Transport ◽

Erosion Rates ◽

Suspended Sediment Flux

<p>Fine particles in rivers comprise a substantial fraction (>50%) of the mass leaving a landscape, while at shorter timescales they represent significant carriers of nutrients and contaminants with the potential to both degrade and enhance aquatic habitats. Predicting fine particle dynamics within rivers remains challenging due to a complex relationship between sediment and water availability from the landscape. This inherent complexity results in watershed-specific understandings of suspended sediment dynamics, typically parameterized as empirical functions of catchment land use, geology, and climate. However, observations of significant fine particle storage within river corridors may indicate that the flux of suspended sediment depends on reach-scale hydraulics. To better understand these dynamics, we synthesized over 40 years of suspended sediment concentration (SSC), hydraulic geometry, river flow, and grainsize data collected by the US Geological Survey from hundreds of rivers spanning a large variety of environments across the continental United States. This data synthesis reveals a strong nonlinear trend between reach-scale hydraulics and the suspended sediment flux, with a secondary dependence on particle properties. The multi-site synthesis reveals that by normalizing the suspended sediment flux by the bankfull shear stress and flux results in a collapse of the observed data onto a single function that describes a self-organizing structure for suspended sediment transport in watersheds. This general relationship indicates strong support for the role of autogenic processes in setting the flux of fine particles and erosion rates of watersheds.</p>

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Interplay of hyporheic exchange and fine particle deposition in a riverbed

Advances in Water Resources ◽

10.1016/j.advwatres.2019.04.014 ◽

2019 ◽

Vol 128 ◽

pp. 145-157 ◽

Cited By ~ 3

Author(s):

Guangqiu Jin ◽

Yilin Chen ◽

Hongwu Tang ◽

Pei Zhang ◽

Ling Li ◽

...

Keyword(s):

Fine Particle ◽

Particle Deposition ◽

Hyporheic Exchange

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Effect of body size on breathing pattern and fine-particle deposition in children

Journal of Applied Physiology ◽

10.1152/japplphysiol.01403.2003 ◽

2004 ◽

Vol 97 (3) ◽

pp. 821-826 ◽

Cited By ~ 64

Author(s):

William D. Bennett ◽

Kirby L. Zeman

Keyword(s):

Fine Particle ◽

Particle Deposition ◽

Breathing Pattern ◽

Fine Particles ◽

Minute Ventilation ◽

Ambient Air ◽

Healthy Children ◽

Overweight Children ◽

Breathing Patterns ◽

Increased Risk

Interchild variability in breathing patterns may contribute to variability in fine particle lung deposition and morbidity in children associated with those particles. Fractional deposition (DF) of fine particles (2-μm monodisperse, carnauba wax particles) was measured in healthy children, age 6–13 yr ( n = 36), while they followed a resting breathing pattern previously determined by respiratory inductance plethysmography. Interchild variation in DF, measured by photometry at the mouth, was most strongly predicted by their tidal volume (Vt) ( r =0.79, P < 0.001). Multiple regression analysis further showed that, for any given height and age, Vt increased with increasing body mass index (BMI) ( P < 0.001). The overweight children (≥95th percentile BMI) ( n = 8) had twice the DF of those in the lowest BMI quartile (<25th percentile) ( n = 9; 0.28 ± 0.13 vs. 0.15 ± 0.06, respectively; P < 0.02). In the same groups, resting minute ventilation was also significantly higher in the overweight children (8.5 ± 2.2 vs. 5.9 ± 1.1 l/min; P < 0.01). Consequently, the rate of deposition (i.e., particles depositing/time) in the overweight children was 2.8 times that of the leanest children ( P < 0.02). Among all children, the rate of deposition was significantly correlated with BMI ( r = 0.46, P = 0.004). These results suggest that increased weight in children may be associated with increased risk from inhalation of pollutant particles in ambient air.

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Application of Ceramic Membrane Technology in Tungsten Fine Particle Concentration Process

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.692.191 ◽

2014 ◽

Vol 692 ◽

pp. 191-199

Author(s):

Wan Fu Huang ◽

Xiao Feng Wang ◽

Xin Dong Li ◽

Si Ming Yan

Keyword(s):

Fine Particle ◽

Particle Concentration ◽

Fine Particles ◽

Ceramic Membrane ◽

Membrane Technology ◽

Factors Affecting ◽

Membrane Flux ◽

Concentration Test ◽

Optimal Effect ◽

Membrane Concentration

This study used ceramic membrane technology to concentrate tungsten fine particles for its inefficient recycling issue. Factors affecting the membrane concentration test were discussed, and the results show that: under the feed flow of 7000 mL/min, concentration time of 3 hours, and concentration liquid flow of 500 mL/min, it is the optimal effect of ceramic membrane concentration tungsten fine particle, which the interception rate reaches more than 99%, the membrane permeation flux can be nearly reach 470mL/(min×1099cm2) above, and concentrate concentration can be basically stable at around 29% . Ceramic membrane flux recovery rate can be as high as 93% by 7 minutes backwashing firstly and then 2 minutes forward cleaning.

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Numerical Simulation of Powder Dispersion Performance by Different Mesh Types

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.680.82 ◽

2016 ◽

Vol 680 ◽

pp. 82-85

Author(s):

Jian Cai ◽

Lan Chen ◽

Umezuruike Linus Opara

Keyword(s):

Numerical Simulation ◽

Flow Field ◽

Fine Particle ◽

Particle Deposition ◽

Tetrahedral Mesh ◽

Computational Time ◽

Kinetic Characteristics ◽

Powder Dispersion ◽

Simulation Results ◽

Time Accuracy

OBJECTIVE To investigate the influence of mesh type on numerical simulating the dispersion performance of micro-powders through a home-made tube. METHODS With the computational fluid dynamics (CFD) method, a powder dispersion tube was meshed in three different types, namely, tetrahedral, unstructured hexahedral and prismatic-tetrahedral hybrid meshes. The inner flow field and the kinetic characteristics of the particles were investigated. Results of the numerical simulation were compared with literature evidences. RESULTS The results showed that using tetrahedral mesh had the highest computational efficiency, while employing the unstructured hexahedral mesh obtained more accurate outlet velocity. The simulation results of the inner flow field and the kinetic characteristics of the particles were slightly different among the three mesh types. The calculated particle velocity using the tetrahedral mesh had the best correlation with the changing trend of the fine particle mass in the first 4 stages of the new generation impactor (NGI) (R2 = 0.91 and 0.89 for powder A and B, respectively). Conclusions Mesh type affected computational time, accuracy of simulation results and the prediction abilities of fine particle deposition.

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Study of pressurised metered dose inhalers for the purpose of standardization of quality attributes characterizing uniformity of dosing

ScienceRise Pharmaceutical Science ◽

10.15587/2519-4852.2021.238294 ◽

2021 ◽

pp. 11-23

Author(s):

Elena Bezuglaya ◽

Nikolay Lyapunov ◽

Vladimir Bovtenko ◽

Igor Zinchenko ◽

Yurij Stolper

Keyword(s):

Particle Size ◽

Fine Particle ◽

Fine Particles ◽

Average Dose ◽

Metered Dose Inhalers ◽

Fine Particle Dose ◽

Particle Dose ◽

Metered Dose ◽

Delivered Dose

Aim. The purpose was to provide the rationale of test in regard to uniformity of fine particles dose for pressurised metered dose inhalers (pMDIs). Materials and methods. The pMDIs containing suspensions of salbutamol sulfate (SS) or solutions of beclometasone dipropionate (BD) were studied by laser diffraction and high performance liquid chromatography (HPLC). The particle size distribution of SS, the average dose mass and uniformity of dose mass, the average delivered dose and the uniformity of delivered dose, the average fine particles dose and uniformity of fine particles dose were determined. Apparatus A was used for assessment of fine particles dose. Results. The two analytical procedures for the quantitative determination of SS and BD by HPLC were validated in the ranges with low concentrations of these substances. The 5 medicinal products in pMDI dosage form were studied: 3 preparations were with SS and 2 ones contained BD. It was shown that three products with SS were very similar in regard to particle size distribution in containers and the average values of delivered dose were almost the same, but these products were different in the average dose mass and fine particle dose. According to the research results, the expediency of determining the average dose mass and the tests concerning uniformity of dosing of preparations by dose mass and by fine particle dose was substantiated. It was shown that in the case of pMDI the dosing of solutions of BD was more uniform compared to suspensions of SS. The approaches of leading and other pharmacopoeias concerning uniformity of dosing for pMDIs were critically discussed. The expediency of determination of uniformity of fine particle dose at the stage of pharmaceutical development was substantiated, as the therapeutic effect depends on fine particle dose. Issues concerning standardization pMDIs in regard to uniformity of fine particle dose were discussed. Conclusions. The expediency of standardization and quality control of pMDIs in regard to such attributes as the average dose mass, which characterizes the volume of the metering chamber of the valve as well as the uniformity of the dose mass and the uniformity of fine particle dose, which assure the therapeutic effect of each dose of the product was substantiated

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Atmospheric oxidation capacity in Chinese megacities during photochemical polluted season: radical budget and secondary pollutants formation

10.5194/acp-2018-959 ◽

2018 ◽

Cited By ~ 1

Author(s):

Zhaofeng Tan ◽

Keding Lu ◽

Meiqing Jiang ◽

Rong Su ◽

Hongli Wang ◽

...

Keyword(s):

Fine Particle ◽

Fine Particles ◽

Nox Reduction ◽

Ozone Production ◽

Atmospheric Oxidation ◽

Ozone Pollution ◽

Oxidation Capacity ◽

Radical Chemistry ◽

Budget Analysis ◽

Secondary Pollutants

Abstract. Atmospheric oxidation capacity is the core of converting fresh-emitted substances to secondary pollutants. In this study, we present the in-situ measurements at four Chinese megacities (Beijing, Shanghai, Guangzhou, and Chongqing) in China during photochemical polluted seasons. The atmospheric oxidation capacity is evaluated using an observational-based model with the input of radical chemistry precursor measurements. The radical budget analysis illustrates the importance of HONO and HCHO photolysis, which contribute nearly half of the total radical primary sources. The radical propagation is efficient due to abundant of NO in the urban environments. Hence, the production rate of secondary pollutants, i.e. ozone and fine particle precursors (H2SO4, HNO3, and ELVOCs) is fast resulting in secondary air pollution. The ozone budget demonstrates that strong ozone production occurs in the urban area which results in fast ozone concentration increase locally and further transported to downwind areas. On the other hand, the O3-NOx-VOC sensitivity tests show that ozone production is VOC-limited, among which alkenes and aromatics should be first mitigated for ozone pollution control in the presented four megacities. However, NOx emission control will lead to more server ozone pollution due to the drawback-effect of NOx reduction. For fine particle pollution, the role of HNO3−NO3− partitioning system is investigated with a thermal dynamic model (ISORROPIA2) due to the importance of particulate nitrate during photochemical polluted seasons. The strong nitrate acid production converts efficiently to nitrate particles due to high RH and ammonium-rich conditions during photochemical polluted seasons. This study highlights the efficient radical chemistry maintains the atmospheric oxidation capacity in Chinese megacities, which results in secondary pollutions characterized by ozone and fine particles.

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