Sedimentation Stability Research Articles

Interpreting monitoring data for shoreline and geohazard mapping

The demand for marine-related spatial information has become increasingly apparent in recent years at a European and national scale, due to the increased pressures on the sea-floor environments and marine resources of UK territorial waters. The advent of economically viable swath bathymetry data acquisition in the coastal zone and effective collaborative partnerships between the Channel Coastal Observatory, Maritime and Coastguard Agency, UK Hydrographic Office, British Geological Survey and academic institutions, have opened up new opportunities to produce a robust scientific evidence base to inform integrated coastal zone management objectives and contribute to wider scientific initiatives. Interpretation of high-quality bathymetric data, acoustic backscatter and ground-truthing data allows zones of exposed bedrock, rock outcrops and pinnacles to be identified, along with areas of mobility or stability of surficial sediments. Temporal and spatial analyses of coastal and marine monitoring datasets also contribute to improved understanding of interactions between natural coastal process and coastal-defence and beach-management operations. Furthermore, developments in three-dimensional mapping techniques and visualisation technologies have enabled seamless high-resolution coastal geology maps to be re-interpreted and extended offshore, providing a more complete picture of the baseline geology, physical properties, structure and geohazards in the coastal and nearshore zone. The full paper details the methodology developed to produce a range of indicative marine mapping layers, and presents examples from eastern and southern England where marine-related spatial data has contributed to the multi-disciplinary scientific evidence base to inform development of UK marine policy and planning, coastal management and coastal zone geological mapping.

Magnetorheological behaviour and electrospinning of poly(ethylene oxide) suspensions with magnetic nanoparticles

The properties of poly(ethylene oxide) aqueous suspensions with magnetic nanoparticles synthesized under microwave-assisted radiation are studied. The magnetic nanoparticles are formed by iron (III) chloride hexahydrate (FeCl3·6H2O) dissolved in ethylene glycol (C2H4(OH)2) and subsequently in aqueous ammonia solution (approx. 25 wt% aq.). The polymer suspension exhibits substantial advantages over a suspension when ‘classical’ carrier fluids (water and silicone oil) are used. First, the presence of poly(ethylene oxide) significantly contributes to a fabrication of nanofibrous webs, the morphology of which is documented by scanning electron microscopy technique. Second, better sedimentation stability of the processed suspension during electrospinning reflects in a uniform distribution of magnetic nanoparticles along the nanofibres, thus ensuring even magnetic performance of the resulting membranes.

Comprehensive Seagrass Restoration Planning in Southwest Florida: Science, Law and Management

In coastal Florida, the development and maintenance of docks, marinas, and channels frequently cause destruction of seagrass beds. Seagrass loss is accompanied by a loss of the ecosystem services the beds provide, such as sediment stabilization, water filtration, protection from storms, and habitat and nursery grounds for fish species. The current legal framework for seagrass protection and the implementation of mitigation for seagrass loss could be improved. In this Article, the authors argue that policymakers could revise the Uniform Mitigation Assessment Method to include more assessments related specifically to the ecology of seagrass beds and their ecosystem services. Seagrass mitigation is currently carried out by the permittee that applied to create or maintain the seagrass-impacting development. In comparison, wetland mitigation is typically carried out by publicly or privately operated mitigation banks. The creation of mitigation banks for seagrass restoration would streamline the process of seagrass mitigation and promote the public's interest in seagrass restoration.

ВСТАНОВЛЕННЯ УМОВ СТАБІЛІЗАЦІЇ МАГНІТНИХ НАНОЧАСТИНОК У СКЛАДІ СИСТЕМ МАГНІТОКЕРОВАНОГО ТАРГЕТІНГУ ЛІКАРСЬКИХ РЕЧОВИН

ВСТАНОВЛЕННЯ УМОВ СТАБІЛІЗАЦІЇ МАГНІТНИХ НАНОЧАСТИНОК У СКЛАДІ СИСТЕМ МАГНІТОКЕРОВАНОГО ТАРГЕТІНГУ ЛІКАРСЬКИХ РЕЧОВИН

ANSYS finite element design of an energy saving magneto-rheological damper with improved dispersion stability

The magnetorheological (MR) damper is one of the utmost progressive applications of asemi-active damper. Uninterrupted controllability in both on and off state is an important factor of its plenitude application. Current research is attempting to make the damper more effective and efficient by minimizing the existing limitations such as MR fluid’s sedimentation, power consumption and temperature rising, and design optimization. We have broadly analyzed the optimization of MR dampers design with finite element simulation where various parameters of the MR damper have been considered for more accurate results. A prototype MR fluid has been prepared by coating the carbonyl iron particles with xanthan gum to reduce sedimentation. The SEM and Turbiscan results noticeably verify the improved sedimentation stability. In addition, a power-saving MR damper model has been developed by finite element analysis using ANSYS software. Prolonged operation raises the damper’s body temperature and degrades the performance. However, in this energy-saving MR damper model the temperature is not rising to a higher value compared to the conventional dampers, and consequently promotes damper efficiency.

Phenology, biomass and productivity of sub-Antarctic Ruppia filifolia

Seagrasses play important ecological roles in shallow coastal ecosystems from tropical to sub-polar seas. Ruppia filifolia (Phil.) Skottsberg is the seagrass with the world’s southernmost distribution but with virtually unknown biology and ecology. The goal of this study was to identify the ecological roles that R. filifolia might play in sub-Antarctic environments through the assessment of the development and primary productivity of this aquatic flowering plant. We monitored biomass and shoot density, rhizome growth and the presence of reproductive structures during 1 year in Skyring Sound, sub-Antarctic Chile. Ruppia filifolia forms perennial meadows with high biomass (124–293 g DW m−2) and shoot density (1800–5300 shoot m−2), a continuous presence of vertical stems and a rhizome plus root to shoot biomass ratio >1. Plant development shows a unimodal seasonal pattern with flowering in spring, and fruiting and maximum growth during summer. An average rhizome plastochrone of 37 days and median rhizome elongation of 27.5 cm plant−1 year−1 rank R. filifolia as a slow-growing seagrass. Primary productivity varied from 0.5 to 4.2 g DW m−2 day−1, resulting in an annual primary production of 700 g DW m−2. Ruppia filifolia in sub-Antarctic environments might play ecosystem roles (carbon sequestration, sediment stabilization, structural habitat, nutrition sources) as important as those played by seagrasses in tropical or temperate coastal environments.

Stabilization of bottom sediments from Rzeszowski Reservoir

Abstract The paper presents results of stabilization of bottom sediments from Rzeszowski Reservoir. Based on the geotechnical characteristics of the tested sediments it was stated they do not fulfill all the criteria set for soils in earth embankments. Therefore, an attempt to improve their parameters was made by using two additives – cement and lime. An unconfined compressive strength, shear strength, bearing ratio and pH reaction were determined on samples after different time of curing. Based on the carried out tests it was stated that the obtained values of unconfined compressive strength of sediments stabilized with cement were relatively low and they did not fulfill the requirements set by the Polish standard, which concerns materials in road engineering. In case of lime stabilization it was stated that the tested sediments with 6% addition of the additive can be used for the bottom layers of the improved road base.

Effects Of Environmental Factors On The Dispersion Behavior Of Iron Oxide In Aqueous Solutions With Poly Acrylic Acid

Abstract After preparing aqueous suspensions from magnetite particles with a poly-acrylic acid, we investigated the effects of several experimental parameters. We characterized the stability of the suspensions using visual inspection, sedimentation, adsorption, and thermal stability of the dispersant. The dispersion stability is affected by the solution pH, the concentrations of magnetite particles, the molecular weight, the concentration of the dispersants, and the temperature. The stability of the suspensions increased as the concentration of the dispersant and the temperature increased. In terms of the molecular weights of the dispersant, the suspensions with dispersant of low-molecular weight (1800) were more stable than those of high-molecular weight (250000) at room temperature. However, at high temperature the suspensions with high-molecular weight showed stability. The adsorption efficiency of the dispersant was very low. The dispersant of high-molecular weight showed a higher thermal integrity than that of low-molecular weight. From this work, we obtained the optimum conditions for stable aqueous suspensions of magnetite particles.

Effect of coupling agent on nano-ZnO modification and antibacterial activity of ZnO/HDPE nanocomposite films

Commercial zinc oxide nanoparticles were modified by silane coupling agent of KH550 and KH560, respectively. The obtained nanocomposite was characterized by scanning electron microscopy (SEM), Thermogravimetric analyses (TGA) and apparent sedimentation stability (Sapp). Then, nano-ZnO/high-density polyethylene (HDPE) composite films were prepared via melt blending and a hot compression-molding process. The antibacterial testing of the films against E. coli and S. aureus was carried out via plate counting. SEM, TGA and Sapp suggest the modifier of silane changed the surface hydrophilicity and effectively broke the agglomerations of nanoparticles. Antibacterial testing results indicated the antibacterial rate of the films increased with increasing nano-ZnO content. At a low doped content of 0.2 wt%, the types of coupling agent influenced the antibacterial property with that of KH560-modified nano-ZnO/HDPE KH550-modified nano-ZnO/HDPE unmodified nano-ZnO/HDPE films. When the dosage nano-ZnO was over 0.2 wt%, the differences of antibacterial activity resulted by modification was concealed by the strong antibacterial activity with near 100% of the nano- ZnO/HDPE composite films.

RESEARCH OF INFLUENCE OF ASPHALTENE-RESIN SUBSTANCES INTO OIL ON THE FORMATION OF ASPHALTENE-PARAFFIN-RESIN DEPOSITION

The completion phase of an oil field development is characterized by increased water cutting of well production, reservoir and bottom-hole pressures decline, growth of high molecular weight (HMW) components content in crude oil. These aspects make field operations more hazardous as they lead to formation of asphaltene-paraffin-resin deposition (APRD) on borehole walls and equipment. The impact of HMW components in crude oil and water-cut on pressure and temperature conditions of APRD and on its rate needs detailed study. This paper presents some results of the analysis of oil paraffin saturation point depending on asphaltene-resin substances (ARS) content under reservoir conditions. Dependence of the rate of APRD on a cold well walls and resin substances content in oil is studied. The results of experiments with low-resin and high-paraffin crude oil show that asphaltenes and resins in oil dispersion system can result in depressive effects. According to the results, asphaltene-resin substances are natural depressants, making the temperature of paraffin appearance in oil lower, and their properties depend on the base of oil. The results of the rate of APRD show that sedimentation stability of dry crude oil with increasing of ARS content remains almost stable and does not have any impact on deposition, whereas in experiments with wet crude oil increased ARS content leads to significantly higher deposition.

Sticky stuff: Redefining bedform prediction in modern and ancient environments

The dimensions and dynamics of subaqueous bedforms are well known for cohesionless sediments. However, the effect of physical cohesion imparted by cohesive clay within mixed sand-mud substrates has not been examined, despite its recognized influence on sediment stability. Here we present a series of controlled laboratory experiments to establish the influence of substrate clay content on subaqueous bedform dynamics within mixtures of sand and clay exposed to unidirectional flow. The results show that bedform dimensions and steepness decrease linearly with clay content, and comparison with existing predictors of bedform dimensions, established within cohesionless sediments, reveals significant over-prediction of bedform size for all but the lowermost clay contents examined. The profound effect substrate clay content has on bedform dimensions has a number of important implications for interpretation in a range of modern and ancient environments, including reduced roughness and bedform heights in estuarine systems and the often cited lack of large dune cross-sets in turbidites. The results therefore offer a step change in our understanding of bedform formation and dynamics in these, and many other, sedimentary environments.

Characterization of stratification for an opaque highly stable magnetorheological fluid using vertical axis inductance monitoring system

A key requirement for the commercialization of various magnetorheological fluid (MRF)-based applications is sedimentation stability. In this study, a high viscosity linear polysiloxane (HVLP), which has been used for shock absorbers in heavy equipment, is proposed as a new carrier fluid in highly stable MRFs. The HVLP is known to be a thixotropic (i.e., shear thinning) fluid that shows very high viscosity at very low shear rate and low viscosity at higher shear rate. In this study, using the shear rheometer, the significant thixotropic behavior of the HVLP was experimentally confirmed. In addition, a HVLP carrier fluid-based MRF (HVLP MRF) with 26 vol. % was synthesized and its sedimentation characteristics were experimentally investigated. But, because of the opacity of the HVLP MRF, no mudline can be visually observed. Hence, a vertical axis inductance monitoring system (VAIMS) applied to a circular column of fluid was used to evaluate sedimentation behavior by correlating measured inductance with the volume fraction of dispersed particles (i.e., Fe). Using the VAIMS, Fe concentration (i.e., volume fraction) was monitored for 28 days with a measurement taken every four days, as well as one measurement after 96 days to characterize long-term sedimentation stability. Finally, the concentration of the HVLP MRF as a function of the depth in the column and time, as well as the concentration change versus the depth in the column, are presented and compared with those of a commercially available MRF (i.e., Lord MRF-126CD).

ИССЛЕДОВАНИЕ СВОЙСТВ ГРАФИТООКСИДНЫХ КОМПОЗИЦИЙ ДЛЯ ЛИТЕЙНОГО ПРОИЗВОДСТВА

The research aimed at figuring out dependence of the technological properties (density, thickness of the coating, reduced strength and sedimentation stability) of the suspensions for nonstick coatings on the for activation time powder quartz graphite filler. It is shown that with increasing activation time to 10 minutes all the basic properties of graphite suspension powder quartz were improved. The paper presents the results of comparative studies of technological properties of suspensions of activated graphite oxide compositions prepared on the basis of activated aluminum oxide and periclase. The resulting suspension may be recommended for cast iron and non-ferrous castings.

Invasion chronosequence of Spartina alterniflora on methane emission and organic carbon sequestration in a coastal salt marsh

Spartina alterniflora was intentionally introduced to China in 1979 for the purpose of sediment stabilization and dike protection, and has continuously replaced native plants or invaded bare mudflats in the coastal marsh. To evaluate the spatial variation of CH4 emission and soil organic carbon (SOC) storage along the invasion chronosequence, we selected four sites including bare mudflat (Control, as first year invasion), and marshes invaded by S. alterniflora in 2002 (SA-1), 1999 (SA-2) and 1995 (SA-3), respectively, in Sheyang county, Jiangsu, China and set up the marsh mesocosm system for flux measurement. The mean accumulation rate of SOC in the 0–30 cm layer exponentially increased with the invasion time, ranging from 1.08 (over the first 9 years) to 2.35 Mg Cha−1yr−1 (over the period of 12–16 years). The cumulative CH4 emission during the growth season was 20.5, 75.4, 81.0 and 92.2 kg CH4ha−1 in Control, SA-1, SA-2 and SA-3, respectively, and there was a binomial relationship between CH4 emission and invasion time. Cumulative CH4 emission was logarithmically increased with SOC concentration; however the ratio of CH4 emission to SOC concentration was inversely correlated with the invasion time in the S. alterniflora marsh, suggesting that the less increased SOC in the S. alterniflora marsh was converted into CH4. The net global warming potential (GWP) was estimated at 733 kg CO2-eq ha−1yr−1 in the tidal mudflat and reduced to −1273 (SA-1) to −2233 kg CO2-eq ha−1yr−1 (SA-3) in the S. alterniflora marsh. Our results indicated that S. alterniflora invasion effectively sequestrated atmospheric CO2 and mitigated GWP in the coastal marsh of China.

Can biotic indicators distinguish between natural and anthropogenic environmental stress in estuaries?

Because estuaries are naturally stressed, due to variations in salinity, organic loadings, sediment stability and oxygen concentrations over both spatial and temporal scales, it is difficult both to set baseline reference conditions and to distinguish between natural and anthropogenic environmental stresses. This contrasts with the situation in marine coastal and offshore locations. A very large benthic macroinvertebrate dataset and matching concentrations for seven toxic heavy metals (i.e. Cr, Ni, Cu, Zn, Cd, Hg and Pb), compiled over three years as part of the UK's National Marine Monitoring Programme (NMMP) for 27 subtidal sites in 16 estuaries and 34 coastal marine sites in the United Kingdom, have been analysed. The results demonstrate that species composition and most benthic biotic indicators (number of taxa, overall density, Shannon–Wiener diversity, Simpson's index and AZTI's Marine Biotic Index [AMBI]) for sites in estuarine and coastal areas were significantly different, reflecting natural differences between these two environments. Shannon–Wiener diversity and AMBI were not significantly correlated either with overall heavy metal contaminant loadings or with individual heavy metal concentrations (‘normalized’ as heavy metal/aluminium ratios) in estuaries. In contrast, average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+) did not differ significantly between estuarine and coastal environments, i.e. they were unaffected by natural differences between these two environments, but both were significantly correlated with overall heavy metal concentrations. Furthermore, Δ+ was correlated significantly with the Cu, Zn, Cd, Hg and Pb concentrations and Λ+ was correlated significantly with the Cr, Ni, Cu, Cd and Hg concentrations. Thus, one or both of these two taxonomic distinctness indices are significantly correlated with the concentrations for each of these seven heavy metals. These taxonomic distinctness indices are therefore considered appropriate indicators of anthropogenic disturbance in estuaries, as they allow a regional reference condition to be set from which significant departures can then be determined.

A Study About the Influence of Some New Additives Addition on the Properties of Magnetorheological Fluids

In order to study excellent properties of the magnetorheological fluids (MRFs), some relevant patents and researches are studied. Experiment materials, experimental method and test methods are elaborated, and two types of carriers are used to prepare MRFs samples with different additives addition. The microstructures of both uncoated magnetic particles and coated magnetic particles are observed by scanning electron microscope (SEM). The properties of these samples including sedimentation stability, zero field viscosity and shear yield stress are tested and analyzed. Experimental results show that MRFs with mineral oil 350N as their carrier liquid are better than dimethyl silicone oil; Organic Bentonite and TM-618 can improve the sedimentation stability and shear yield stress of MRFs. Moreover, they have influence on zero field viscosity and MRFs with Organic Bentonite 3% and TM-618 3.5% have good overall properties. Keywords: Magnetorheological fluids, new additives, preparation method, sedimentation stability, shear yield stress, zero field viscosity.

Study on Dispersion and Rheology of Particles in Water-Based Nano TiN Fluid

The water-based nanoTiN fluids were prepared by nanoTiN particles, dispersion medium and dispersant using a two-step method. The dispersion and rheology of nanoparticles in water-based fluid were studied under different preparation conditions. The dispersion and rheology of prepared nanoTiN fluids were evaluated and analyzed from the mass fraction of nanoparticles, mass fraction of dispersant and type of dispersion medium respectively by using the analysis of sedimentation stability and rheological properties. The results show that the above-mentioned factors all have different degree of influence on nanofluids’ dispersion and rheology. The viscosity of nanofluids increases with mass fraction of nanoparticles. A balance amount of mass fraction of dispersant will improve nanofluids’ dispersity and fluidity. The dispersion effect of deionized water is the best when the nanoparticles dispersed in different dispersion medium.

Transmission Performance of Water-Based Nano Fluid Based on Computational Fluid Dynamics

The nanoboron carbide particle size is 60nm, dispersed in RO reverse osmosis membrane treatment water form water-based nanofluid by adding the dispersant. In experiment, Water-based nanoboron carbide fluid has good resistance sedimentation stability when adding sodium carboxymethyl cellulose as a dispersing agent. Prepared three kinds of water-based nanoboron carbide fluid, the mass fraction of nanoparticles is 0.6%, 0.8%, 1.0%. By establishing a model of U-shaped tube, simulated the water-based nanofluids flow field in U-shaped tube using FLUENT, get velocity flow lines picture and pressure variation graph by CFD post-processing. From simulation results obtained: Water-based nanoboron carbide has good transmission fluid performance when nanoparticles mass fraction of 0.8%.

Biotic interactions influence sediment erodibility on wave-exposed sandflats

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 523:15-30 (2015) - DOI: https://doi.org/10.3354/meps11164 Biotic interactions influence sediment erodibility on wave-exposed sandflats Rachel J. Harris1,*, Conrad A. Pilditch1, Judi E. Hewitt2, Andrew M. Lohrer2, Carl Van Colen4, Michael Townsend2, Simon F. Thrush3 1School of Science, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand 2National Institute of Water and Atmospheric Research Ltd. (NIWA), PO Box 11115, Hamilton 3240, New Zealand 3Institute of Marine Science, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand 4Research Group of Marine Biology, Ghent University, Krijgslaan 281/S8, 9000 Ghent, Belgium *Corresponding author: harris.rachelj@gmail.com ABSTRACT: Biological activities in marine soft-sediments can modify the sedimentary environment through processes that change erosion rates. In low-energy environments, bioturbating macrofauna destabilizes sediments while microbes bind sediments and stabilize them. The degree to which these counter-acting processes influence sediment movement in a physically dynamic environment has not been well quantified. In a field experiment, we established 56 (1 m2) plots on an exposed intertidal sandflat. We used shade cloth and manipulated grazing pressure exerted by the deposit-feeding bivalve Macomona liliana (0-200 ind. m-2) to alter the microphytobenthic community. Three months post-manipulation, initiation of sediment transport (Ʈc) and change in sediment erosion rate with increasing bed shear stress (me) were measured. Mean grain size, density of the spionid polychaete Aonides trifida, density of adult M. liliana, and bulk carbohydrate concentration could account for 54% of the variation in Ʈc (0.3-1.1 N m-2 s-1). Mean grain size was the only significant predictor (p ≤ 0.01) of me explaining 22% of the variability (6-20 g N-1 s-1). Ʈc was negatively correlated with density of several abundant shallow-dwelling bioturbators (indicating sediment destabilization), but we did not observe the expected increase in Ʈc with microbial biomass. Furthermore, there was a positive correlation between adult M. liliana and Ʈc as well as evidence for several positive feedbacks between abundant shallow-dwelling macrofauna and microbial biomass. These study results demonstrate that despite frequent reworking by tidal currents and waves, bioturbating macrofauna are important to initiating sediment transport regardless of their effects on microbial biomass. KEY WORDS: Deposit-feeding · Microphytobenthos · Benthic macrofauna · Sediment stability · Infauna · Positive feedbacks · Macomona liliana · Habitat modifiers Full text in pdf format PreviousNextCite this article as: Harris RJ, Pilditch CA, Hewitt JE, Lohrer AM, Van Colen C, Townsend M, Thrush SF (2015) Biotic interactions influence sediment erodibility on wave-exposed sandflats. Mar Ecol Prog Ser 523:15-30. https://doi.org/10.3354/meps11164 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 523. Online publication date: March 16, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.

Study of the impact of solidifier inorganic components on the performance of a solidifiable gel plugging fluid

To solve the problems occurring during the treatment process in the case of any malignant lost circulation, such as the “door sealed” phenomenon, this paper studied a new type of solidifiable gel plugging fluid system. The door sealed phenomenon is caused during the addition of the blocking materials to the drilling fluid, when the weak gel fails to significantly improve the stratum bearing capacity, causing the gel plugging agent to be easily eroded. This erosion results in a lack of strength in the later period. Unlike the addition of various conventional chemical conditioning agents in the plugging fluid system, to optimally adjust the plugging fluid properties, this paper studied its impact on the system sedimentation stability, rheology, compressive strength, and so on by changing the percentage of the component substances, such as bentonite, CaO, MgO, and Al2O3, and analyzed the test samples and microstructure via X-Ray Diffractometer (XRD) and Scanning Electron Microscope (SEM) tests. In the analyses, bentonite was found to be able to adjust the sedimentation stability and shear thinning behavior. In addition, the solidifiers CaO, MgO, and other components were found to be able to increase the compressive strength of the samples. The studies indicated that this system could adjust the component percentage according to the actual leakage situation of oil/gas wells to meet the construction requirements while providing a certain basis for the selection of other chemical conditioning agents.