scholarly journals Will it float? Rising and settling velocities of common macroplastic foils

2021 ◽  
Author(s):  
Boaz Kuizenga ◽  
Tim van Emmerik ◽  
Kryss Waldschläger ◽  
Merel Kooi
Keyword(s):  
Additional Data ◽  
Velocity Model ◽  
Prevention Measures ◽  
Transport Models ◽  
Surface Areas ◽  
Settling Behaviour ◽  
Monitoring Strategies ◽  
High Durability ◽  
Waste Handling ◽  
The Vertical Distribution

Plastic accumulates in the environment because of insufficient waste handling and the materials' high durability. Better understanding of plastic behaviour in the aquatic environment is needed to estimate transport and accumulation, which can be used for monitoring strategies, prevention measures, and plastic clean-up activities. Plastic transport models benefit from accurate description of particle characteristics, such as rising and settling velocities. For macroplastics, these are however still scarce. In this research, the rising and settling behaviour of three different polymer types (PET, PP, and PE) was investigated, which are the most common in the environment. All of the plastic particles were foils of different surface areas. A new method for releasing rising plastics without interfering the flow and disturbing the column was used. Four models that estimate the velocity based on the characteristics of the plastics are discussed, of which three are from literature, and one is newly derived. These models are validated using the data generated in this research, and data from another study on rising and settling velocities of plastic. From the models that were discussed, the best results are from the newly introduced velocity model for foils (R^2 = 0.96 and 0.58, for both datasets). This model shows potential to estimate the rising and settling velocity of plastics, and should be examined further by using additional data. The results of our paper can be used to further explore the vertical distribution of plastics in rivers, lakes and oceans, which is crucial to optimize future monitoring and cleanup efforts.

scholarly journals Subtropical trace gas profiles determined by ground-based FTIR spectroscopy at Izaña (28° N, 16° W): Five-year record, error analysis, and comparison with 3-D CTMs

2005 ◽  
Vol 5 (1) ◽  
pp. 153-167 ◽  
Author(s):  
M. Schneider ◽  
T. Blumenstock ◽  
M. P. Chipperfield ◽  
F. Hase ◽  
W. Kouker ◽  
...  
Keyword(s):  
Error Analysis ◽  
Three Dimensional ◽  
Trace Gas ◽  
Transport Models ◽  
Solar Absorption ◽  
Annual Cycles ◽  
Mixing Ratios ◽  
Chemical Transport Models ◽  
Tenerife Island ◽  
The Vertical Distribution

Abstract. Within the framework of the NDSC (Network for the Detection of Stratospheric Change) ground-based FTIR solar absorption spectra have been routinely recorded at Izaña Observatory (28° N, 16° W) on Tenerife Island since March 1999. By analyzing the shape of the absorption lines, and their different temperature sensitivities, the vertical distribution of the absorbers can be retrieved. Unique time series of subtropical profiles of O3, HCl, HF, N2O, and CH4 are presented. The effects of both dynamical and chemical annually varying trace gas cycles can be seen in the retrieved profiles. These include enhanced upwelling and photochemistry in summer and a more disturbed atmosphere in winter, which are typical of the subtropical stratosphere. A detailed error analysis has been performed for each profile. The output from two different three-dimensional (3-D) chemical transport models (CTMs), which are forced by ECMWF analyses, are compared to the measured profiles. Both models agree well with the measurements in tracking abrupt variations in the atmospheric structure, e.g. due to tropical streamers, in particular for the lower stratosphere. Simulated and measured profiles also reflect similar dynamical and chemical annual cycles. However, the differences between their mixing ratios clearly exceed the error bars estimated for the measured profiles. Possible reasons for this are discussed.

scholarly journals The vertical distribution of buoyant plastics at sea

2014 ◽  
Vol 11 (11) ◽  
pp. 16207-16226 ◽  
Author(s):  
J. Reisser ◽  
B. Slat ◽  
K. Noble ◽  
K. du Plessis ◽  
M. Epp ◽  
...  
Keyword(s):  
Turbulent Transport ◽  
Marine Species ◽  
Decay Rates ◽  
Transport Models ◽  
The North ◽  
New Type ◽  
Multi Level ◽  
Load Size ◽  
The Vertical Distribution ◽  
Numerical Concentration

Abstract. Millimeter-sized plastics are numerically abundant and widespread across the world's ocean surface. These buoyant macroscopic particles can be mixed within the upper water column due to turbulent transport. Models indicate that the largest decrease in their concentration occurs within the first few meters of water, where subsurface observations are very scarce. By using a new type of multi-level trawl at 12 sites within the North Atlantic accumulation zone, we measured concentrations and physical properties of plastics from the air–seawater interface to a depth of 5 m, at 0.5 m intervals. Our results show that plastic concentrations drop exponentially with water depth, but decay rates decrease with increasing Beaufort scale. Furthermore, smaller pieces presented lower rise velocities and were more susceptible to vertical transport. This resulted in higher depth decays of plastic mass concentration (mg m−3) than numerical concentration (pieces m−3). Further multi-level sampling of plastics will improve our ability to predict at-sea plastic load, size distribution, drifting pattern, and impact on marine species and habitats.

scholarly journals Water Temperature and its Diversity in the Deepest Lakes of the Tuchola Forest and the Kashubian and Brodnickie Lakelands

2014 ◽  
Vol 7 (1) ◽  
pp. 105-119 ◽  
Author(s):  
Rajmund Skowron ◽  
Adam Piasecki
Keyword(s):  
Vertical Distribution ◽  
Water Temperature ◽  
Sea Level ◽  
Thermal Stratification ◽  
Thermal Structure ◽  
Surface Areas ◽  
The Vertical Distribution ◽  
Depth Water

Abstract This study presents the results of monthly examinations of the vertical distribution of water thermal structure (2008-2011) carried out over a four-year period in the deepest lakes located in the Kashubian and Brodnickie Lakelands and the Tuchola Forest1. Three lakes were selected for examination (Raduńskie Górne, Zbiczno and Ostrowite). Their maximum depths slightly exceed 40 m, and their surface areas range from 121 to 362.5 ha. The results of the measurements show that, despite only minor differences in depth, water temperature varied significantly between the studied lakes. These differences were mainly apparent in the extent of the epilimnion, water thermal stratification, and in the water temperature in the bottom-most layers in summer and winter. The diversity in thermal stratification of the lakes is mainly determined by their morphometric properties, their location above sea level, and the dynamic influences of winds.

scholarly journals Subtropical trace gas profiles determined by ground-based FTIR spectroscopy at Izaña (28° N, 16° W): Five-year record, error analysis, and comparison with 3-D CTMs

2004 ◽  
Vol 4 (5) ◽  
pp. 5261-5301 ◽  
Author(s):  
M. Schneider ◽  
T. Blumenstock ◽  
M. P. Chipperfield ◽  
F. Hase ◽  
W. Kouker ◽  
...  
Keyword(s):  
Error Analysis ◽  
Three Dimensional ◽  
Trace Gas ◽  
Transport Models ◽  
Solar Absorption ◽  
Annual Cycles ◽  
Mixing Ratios ◽  
Chemical Transport Models ◽  
Tenerife Island ◽  
The Vertical Distribution

Abstract. Within the framework of the NDSC (Network for the Detection of Stratospheric Change) ground-based FTIR solar absorption spectra have been routinely recorded at Izaña Observatory (28° N, 16° W) on Tenerife Island since March 1999. By analyzing the shape of the absorption lines, and their different temperature sensitivities, the vertical distribution of the absorbers can be retrieved. Unique time series of subtropical profiles of O3, HCl, HF, N2O, and CH4 are presented. The effects of both dynamical and chemical annually varying cycles can be seen in the retrieved profiles. These include enhanced upwelling and photochemistry in summer and a more disturbed atmosphere in winter, which are typical of the subtropical stratosphere. A detailed error analysis has been performed for each profile. The output from two different three-dimensional (3-D) chemical transport models (CTMs), which are forced by ECMWF analyses, are compared to the measured profiles. Both models agree well with the measurements in tracking abrupt variations in the atmospheric structure, e.g. due to tropical streamers, in particular for the lower stratosphere. Simulated and measured profiles also reflect similar dynamical and chemical annual cycles. However, the differences between their mixing ratios clearly exceed the error bars estimated for the measured profiles. Possible reasons for this are discussed.

The vertical distribution of hydropsychid larvae and pupae (Trichoptera: Hydropsychidae) in stream substrates

1985 ◽  
Vol 63 (6) ◽  
pp. 1306-1315 ◽  
Author(s):  
Jane E. Rutherford ◽  
Rosemary J. Mackay
Keyword(s):  
Vertical Distribution ◽  
Significant Variation ◽  
Physical Structure ◽  
Bottom Surface ◽  
Rock Surface ◽  
Layer Depth ◽  
Surface Areas ◽  
The Vertical Distribution ◽  
Mean Current ◽  
Rock Size

Vertical stratification of benthic samples at three stations on the Credit and Humber rivers revealed significant between-layer differences in the physical structure of riffles and abundances of larvae and pupal cases of Cheumatopsyche Wallengren and four species of Hydropsyche Pictet (Trichoptera: Hydropsychidae). Rock size and total rock surface area decreased from the top layer to the bottom (surface areas of pebbles excluded). Larvae of all five instars of H. sparna Ross were significantly more abundant (P < 0.05) in the top layer than in the bottom, but pupal cases were more numerous in the middle and bottom layers. Similar patterns were found for larvae and pupal cases of Hydropsyche bronta Ross, Hydropsyche slossonae Banks, and Cheumatopsyche. Pupal cases as well as larvae of Hydropsyche morosa Hagen were more numerous in the top layer. Depth and current conditions influenced sedimentation. Mean current velocities and total accumulation of fine material were greater at downstream stations. Significant variation in deposition of fine and coarse materials was found within the riffle at each station, suggesting that local streambed conditions govern sediment deposition at the microhabitat level.

Cerebral Tissue Response in Chronic Electrode Implantation

1977 ◽  
Vol 35 ◽  
pp. 624-625
Author(s):  
R.F. Dodson ◽  
L.W-F Chu ◽  
N. Ishihara
Keyword(s):  
Tissue Response ◽  
Whole Body ◽  
Platinum Electrodes ◽  
Fixed Tissue ◽  
Electrode Implantation ◽  
Surface Areas ◽  
Tissue Changes ◽  
Micron Diameter ◽  
Extent Of Damage ◽  
Electrode Sheath

The extent of damage surrounding an implanted electrode in the cerebral cortex is a question of significant importance with regard to attaining consistency and validity of physiological recordings. In order to determine the extent of such tissue changes, 150 micron diameter platinum electrodes were implanted in the cortex of four adult baboons, and after eight days the animals were sacrificed by whole body perfusion with a 3% glutaraldehyde in 0.1M phosphate fixative.The calvarium was carefully removed and the electrode tracts were readily discernible in the firm, glutaraldehyde fixed tissue.Careful dissection of the zone of the electrode tract resulted in a small block which was further sectioned into tip, mid-tract and surface areas. Ultrastructurally, damage extended from the electrode sheath to the greatest extent of from 0.2 to 3.5 mm.

Tissue section lifting for electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 86-87
Author(s):  
Adrian F. van Dellen
Keyword(s):  
Infectious Disease ◽  
Electron Microscopy ◽  
Tissue Culture ◽  
Organ System ◽  
Surrounding Tissue ◽  
Paraffin Sections ◽  
Surface Areas ◽  
Specific Determination ◽  
High Degree ◽  
Accuracy And Repeatability

The morphologic pathologist may require information on the ultrastructure of a non-specific lesion seen under the light microscope before he can make a specific determination. Such lesions, when caused by infectious disease agents, may be sparsely distributed in any organ system. Tissue culture systems, too, may only have widely dispersed foci suitable for ultrastructural study. In these situations, when only a few, small foci in large tissue areas are useful for electron microscopy, it is advantageous to employ a methodology which rapidly selects a single tissue focus that is expected to yield beneficial ultrastructural data from amongst the surrounding tissue. This is in essence what "LIFTING" accomplishes. We have developed LIFTING to a high degree of accuracy and repeatability utilizing the Microlift (Fig 1), and have successfully applied it to tissue culture monolayers, histologic paraffin sections, and tissue blocks with large surface areas that had been initially fixed for either light or electron microscopy.

In situ REM imaging of surface processes on ceramic bulk crystals from 300 to 1670 K in a conventional TEM

1991 ◽  
Vol 49 ◽  
pp. 660-661
Author(s):  
Z. L. Wang ◽  
J. Bentley
Keyword(s):  
High Temperatures ◽  
Image Resolution ◽  
Atomic Processes ◽  
Crystal Surfaces ◽  
Beam Radiation ◽  
Surface Areas ◽  
Transmission Electron ◽  
Reflection Electron Microscopy ◽  
Gas Reactions

Studying the behavior of surfaces at high temperatures is of great importance for understanding the properties of ceramics and associated surface-gas reactions. Atomic processes occurring on bulk crystal surfaces at high temperatures can be recorded by reflection electron microscopy (REM) in a conventional transmission electron microscope (TEM) with relatively high resolution, because REM is especially sensitive to atomic-height steps.Improved REM image resolution with a FEG: Cleaved surfaces of a-alumina (012) exhibit atomic flatness with steps of height about 5 Å, determined by reference to a screw (or near screw) dislocation with a presumed Burgers vector of b = (1/3)<012> (see Fig. 1). Steps of heights less than about 0.8 Å can be clearly resolved only with a field emission gun (FEG) (Fig. 2). The small steps are formed by the surface oscillating between the closely packed O and Al stacking layers. The bands of dark contrast (Fig. 2b) are the result of beam radiation damage to surface areas initially terminated with O ions.

Cell morphology, volume, and surface area determinations from multilevel contouring within HVEM micrographs of serial sections and whole-cell mounts

1987 ◽  
Vol 45 ◽  
pp. 588-589
Author(s):  
M. Marko ◽  
A. Leith ◽  
D. Parsons
Keyword(s):  
Surface Area ◽  
Electron Micrographs ◽  
Cell Morphology ◽  
Individual Variation ◽  
Serial Section ◽  
Stereo Pair ◽  
Complex Structures ◽  
Serial Sections ◽  
Surface Areas ◽  
Computer Based

The use of serial sections and computer-based 3-D reconstruction techniques affords an opportunity not only to visualize the shape and distribution of the structures being studied, but also to determine their volumes and surface areas. Up until now, this has been done using serial ultrathin sections.The serial-section approach differs from the stereo logical methods of Weibel in that it is based on the Information from a set of single, complete cells (or organelles) rather than on a random 2-dimensional sampling of a population of cells. Because of this, it can more easily provide absolute values of volume and surface area, especially for highly-complex structures. It also allows study of individual variation among the cells, and study of structures which occur only infrequently.We have developed a system for 3-D reconstruction of objects from stereo-pair electron micrographs of thick specimens.

Hair cell changes after cationic stimulation of corti's organ

1989 ◽  
Vol 47 ◽  
pp. 798-799
Author(s):  
Cesar D. Fermin ◽  
Hans-Peter Zenner
Keyword(s):  
Organ Of Corti ◽  
Cross Sectional ◽  
Surface Areas ◽  
High K ◽  
Anatomical Arrangement ◽  
Cell Cytosol ◽  
High Concentrations ◽  
K Concentration ◽  
Cell Changes

Contraction of outer and inner hair cells (OHC&IHC) in the Organ of Corti (OC) of the inner ear is necessary for sound transduction. Getting at HC in vivo preparations is difficult. Thus, isolated HCs have been used to study OHC properties. Even though viability has been shown in isolated (iOHC) preparations by good responses to current and cationic stimulation, the contribution of adjoining cells can not be explained with iOHC preparations. This study was undertaken to examine changes in the OHC after expossure of the OHC to high concentrations of potassium (K) and sodium (Na), by carefully immersing the OC in either artifical endolymph or perilymph. After K and Na exposure, OCs were fixed with 3% glutaraldehyde, post-fixed in osmium, separated into base, middle and apex and embedded in Araldite™. One μm thick sections were prepared for analysis with the light and E.M. Cross sectional areas were measured with Bioquant™ software.Potassium and sodium both cause isolated guinea pig OHC to contract. In vivo high K concentration may cause uncontrolled and sustained contractions that could contribute to Meniere's disease. The behavior of OHC in the vivo setting might be very different from that of iOHC. We show here changes of the cell cytosol and cisterns caused by K and Na to OHC in situs. The table below shows results from cross sectional area measurements of OHC from OC that were exposed to either K or Na. As one would expect, from the anatomical arrangement of the OC, OHC#l that are supported by rigid tissue would probably be displaced (move) less than those OHC located away from the pillar. Surprisingly, cells in the middle turn of the cochlea changed their surface areas more than those at either end of the cochlea. Moreover, changes in surface area do not seem to differ between K and Na treated OCs.

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