scholarly journals Plastic microbeads from cosmetic products: an experimental study of their hydrodynamic behaviour, vertical transport and resuspension in phytoplankton and sediment aggregates

Elem Sci Anth ◽  
2018 ◽  
Vol 6 ◽  
Author(s):  
Paula Möhlenkamp ◽  
Autun Purser ◽  
Laurenz Thomsen
Keyword(s):  
Plastic Material ◽  
Suspended Sediments ◽  
Physical Characteristics ◽  
Benthic Boundary Layer ◽  
Cosmetic Products ◽  
Transport Pathway ◽  
Transport Pathways ◽  
Waste Products ◽  
Hydrodynamic Behaviour ◽  
Algal Material

Hydrodynamic behaviour and the transport pathways of microplastics within the ocean environment are not well known, rendering accurate predictive models for dispersal management of such pollutants difficult to establish. In the natural environment, aggregation between plastic microbeads and phytodetritus or suspended sediments in rivers and oceans further complicate the patterns of dispersal. In this laboratory study, the physical characteristics and hydrodynamic behaviour of a selection of common plastic microbeads, as used in exfoliation skincare cosmetic products, were investigated. Additionally, the potential for aggregation of these microbeads with phytodetritus and suspended sediments, as well as the subsequent sinking and resuspension behaviour of produced aggregates, were investigated with roller tanks, settling columns and erosion chamber. Physical characteristics of the plastic microbeads showed great heterogeneity, with various densities, sizes and shapes of plastic material being utilised in products designed for the same purpose. The majority of the plastics investigated were positively buoyant in both freshwater and seawater. Aggregation between plastic microbeads and phytoplankton was observed to be swift, with even extremely high concentrations of plastics being rapidly scavenged by suspended algal material. Following aggregation to sizes of 300 to 4400 μm diameter, some formerly buoyant plastics were observed to settle through the water column and enter the benthic boundary layer with settling velocities ranging between 32 and 831 m day–1. These aggregates could be resuspended in the laboratory under critical shear velocities of 0.67–1.33 cm s–1 (free stream velocities of > 10 cm s–1). This rapid aggregation and subsequent settling indicates a potentially important transport pathway for these waste products, a pathway that should be considered when modelling discharge and transport of plastic microbeads and determining the ecosystems that may be at risk from exposure.

scholarly journals Multiomics analyses of vesicular transport pathway-specific transcripts and proteins in ovine amnion: responses to altered intramembranous transport

2019 ◽  
Vol 51 (7) ◽  
pp. 267-278 ◽  
Author(s):  
Cecilia Y. Cheung ◽  
Debra F. Anderson ◽  
Robert A. Brace
Keyword(s):  
Energy Metabolism ◽  
Amniotic Fluid ◽  
Intracellular Trafficking ◽  
Cytoplasmic Dynein ◽  
Transport Rate ◽  
Fluid Replacement ◽  
Transport Pathway ◽  
Fetal Sheep ◽  
Transport Pathways ◽  
Fetal Urine

Amniotic fluid volume (AFV) is determined by the rate of intramembranous (IM) transport of amniotic fluid (AF) across the amnion. This transport is regulated by fetal urine-derived stimulators and AF inhibitors. Our objective was to utilize a multiomics approach to determine the IM transport pathways and identify the regulators. Four groups of fetal sheep with experimentally induced alterations in IM transport rate were studied: control, urine drainage (UD), urine drainage with fluid replacement (UDR), and intra-amniotic fluid infusion (IA). Amnion, AF, and fetal urine were subjected to transcriptomics (RNA-Seq) and proteomics studies followed by Ingenuity Pathway Analysis. The analysis uncovered nine transport-associated pathways and four groups of differentially expressed transcripts and proteins. These can be categorized into mediators of vesicular uptake and endocytosis, intracellular trafficking, pathway activation and signaling, and energy metabolism. UD decreased IM transport rate and AFV in conjunction with enhanced expression of vesicular endocytosis regulators but reduced expression of intracellular trafficking mediators. With UDR, IM transport rate decreased and AFV increased. Energy metabolism activators increased while trafficking mediators decreased in expression. IA increased IM transport rate and AFV together with enhanced expressions of vesicular endocytosis and trafficking mediators. We conclude that IM transport across the amnion is regulated by multiple vesicular transcytotic and signaling pathways and that the mediators of intracellular trafficking most likely play an important role in determining the rate of IM transport. Furthermore, the motor protein cytoplasmic dynein light chain-1, which coexpressed in AF and fetal urine, may function as a urine-derived IM transport stimulator.

Na+ and Cl- transport across rabbit nonciliated bronchiolar epithelial (Clara) cells

1989 ◽  
Vol 256 (4) ◽  
pp. C893-C901 ◽  
Author(s):  
M. R. Van Scott ◽  
C. W. Davis ◽  
R. C. Boucher
Keyword(s):  
Ion Transport ◽  
Short Circuit ◽  
Flux Ratio ◽  
Open Circuit ◽  
Clara Cell ◽  
Clara Cells ◽  
Transport Pathway ◽  
Transport Pathways ◽  
Serum Free ◽  
Significant Difference

Radioisotopic flux measurements were performed on rabbit Clara cell epithelium cultured in serum-free hormone-supplemented medium to identify the major ion transport pathways in the cell type. Clara cells cultured in serum-free hormone-supplemented medium exhibit a large short-circuit current compared with cells maintained in serum-containing medium (45 microA/cm2 vs. 15 microA/cm2). The responses to amiloride and isoproterenol, however, are similar for cells grown in the two media. A net amiloride-sensitive movement of Na+ in the mucosal (M)-to-serosal (S) direction undershort- and open-circuit conditions is detected (1.48 and 0.67 mueq.h-1.cm-2, respectively). No statistically significant difference in the unidirectional fluxes of Cl- is apparent in the basal state, but a net flux of Cl- in the S-to-M direction is observed after exposure of the apical membrane to amiloride (0.93 mueq.h-1.cm-2). The partial ionic conductances for Na+ and Cl- estimated from the fluxes measured in the passive directions (JNaS----M, JClM----S) exceed the total tissue conductance by 20%. Ussing flux ratio analyses of Cl- movements at clamped potentials between -60 and +20 mV show that Cl- movements are not strictly through passive conductive pathways at negative potentials. The movement of Cl- can be modeled by passive diffusion combined with Cl- -Cl- exchange equal to 20% of total passive fluxes of Na+ and Cl-. These observations indicate that 1) Na+ absorption is the major active ion transport pathway across cultured Clara cells, 2) active Cl- secretion is minimal in the basal state, and 3) approximately 20% of the unidirectional Cl- fluxes occur via nonconductive pathways.

MODELING THE ASSOCIATION OF PETROLEUM HYDROCARBONS AND SUB-ARCTIC SEDIMENTS

1979 ◽  
Vol 1979 (1) ◽  
pp. 621-623 ◽  
Author(s):  
Greggory Malinky ◽  
David G. Shaw
Keyword(s):  
Aromatic Hydrocarbon ◽  
Petroleum Hydrocarbons ◽  
Laboratory Experiments ◽  
Suspended Sediments ◽  
Saturated Solution ◽  
Transport Pathway ◽  
South Central ◽  
Major Chemical

ABSTRACT The extent of association between labeled hydrocarbons representing the major chemical classes of petroleum, and marine suspended sediments from south-central Alaska has been investigated in a series of laboratory experiments using hydrocarbon concentrations near or below saturated solution. For a saturated solution of either an aliphatic or aromatic hydrocarbon, the concentration of hydrocarbon in parts per million (ppm) associated with sediment is roughly 30 percent of the original aqueous concentration in ppm. Extrapolation of these results to permitted discharge concentrations and dilution rates encountered in south-central Alaska indicates that concentrations of hydrocarbons sorbed to sediments are in the parts per trillion (ppt) to parts per billion (ppb) range. It appears that this process cannot be a major transport pathway for the dispersal of oil under the conditions investigated.

scholarly journals Volume-responsive sodium and proton movements in dog red blood cells.

1984 ◽  
Vol 84 (3) ◽  
pp. 379-401 ◽  
Author(s):  
J C Parker ◽  
V Castranova
Keyword(s):  
Membrane Potential ◽  
Red Blood Cells ◽  
Fluorescent Probe ◽  
Blood Cells ◽  
Indirect Method ◽  
Cell Types ◽  
The Other ◽  
Na Transport ◽  
Transport Pathway ◽  
Transport Pathways

Shrinkage of dog red blood cells (RBC) activates a Na transport pathway that is Cl dependent, amiloride sensitive, and capable of conducting Na-proton counterflow. It is possible to establish transmembrane gradients for either Na or protons and to demonstrate that each cation species can drive reciprocal movements of the other. The nature of the coupling between Na and proton movements was investigated using the fluorescent probe diS-C3(5) and also by an indirect method in which K movements through valinomycin channels were used to draw inferences about the membrane potential. No evidence was found to suggest that the Na-proton pathway activated by shrinkage of dog RBC is a conductive one. By exclusion, it is presumed that the coupling between the counterflow of Na and protons is electroneutral. The volume-activated Na-proton fluxes in dog RBC have certain properties that distinguish them from similar transport pathways in other cell types.

scholarly journals Fisikokimia, Mikrobiologi dan Organoleptik Sosis Daging Sapi dengan Penambahan Tepung Biji Durian (Durio zibethinus Murr)

2021 ◽  
Vol 9 (2) ◽  
pp. 79-88
Author(s):  
A. Apriantini ◽  
D. Afriadi ◽  
N. Febriyani ◽  
I. I. Arief
Keyword(s):  
Physical Characteristics ◽  
Production Costs ◽  
National Standard ◽  
Plate Count ◽  
Waste Products ◽  
Seed Flour ◽  
Total Plate Count ◽  
Durian Seed ◽  
General Appearance ◽  
Color Texture

Durian seeds are waste products from durian fruit that have not been utilized properly. Durian seedflour contain high starch as well as tapioca flour, therefore, durian seed flour can be combined withtapioca flour as a filler for sausage dough, in order to reduce production costs of sausage products. Theaim of this study was to analyze the physicochemical, microbiological and organoleptic properties of beefsausage with the addition of 0%, 25% and 50% durian seed flour from a maximum 30% of the flour usedin making sausages. The results of physical characteristics showed that the addition of durian seed flourhad a significant effect (P <0.05) on the cohesiveness of sausages and had no significant effect (P>0.05) onother physical characteristics of sausages. The microbiological assay showed that durian seed flour didnot affect the total plate count (TPC) of beef sausages. However, the total plate count of the sausages withthe addition of 25% durian seed flour still met the SNI (Indonesian National Standard) for sausages,instead of sausages with 50% durian seed flour addition. The results of chemical analysis showed that theaddition of durian seed flour had no affect on moisture content, ash content, fat content, protein content,and carbohydrate content of the sausages. The hedonic test values on the parameters of aroma, color,texture and general appearance also showed no significant effect (P> 0.05), except for taste parameters.The hedonic quality test value also showed that the addition of durian seed flour had no different effect(P> 0.05) on the parameters of aroma, color, texture, and general appearance, but had different effect (P<0.05) on the sausage taste. The addition of durian seed flour produced a distinctive taste which coverthe flavor of sausage.

scholarly journals Long-range transport pathways of tropospheric source gases originating in Asia into the northern lower stratosphere during the Asian monsoon season 2012

2016 ◽  
Author(s):  
Bärbel Vogel ◽  
Gebhard Günther ◽  
Rolf Müller ◽  
Jens-Uwe Grooß ◽  
Armin Afchine ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Asian Monsoon ◽  
Lower Stratosphere ◽  
Monsoon Season ◽  
Transport Pathway ◽  
Transport Pathways ◽  
Air Masses ◽  
Horizontal Transport ◽  
Source Regions ◽  
Subtropical Jet

Abstract. Global simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) using artificial tracers of air mass origin are used to analyze transport pathways from the Asian monsoon region into the lower stratosphere. In a case study, the transport of air masses from the Asian monsoon anticyclone originating in India/China by an eastward migrating anticyclone breaking off from the main anticyclone on 20 September 2012 and filaments separated at the northeastern flank of the anticyclone are analyzed. Enhanced contributions of young air masses (younger than 5 months) are found within the separated anticyclone confined at the top by the thermal tropopause. Further, these air masses are confined by the anticyclonic circulation and at the polar side by the subtropical jet such as the vertical structure looks like a bubble within the upper troposphere. Subsequently, these air masses are transported eastwards along the subtropical jet and enter the lower stratosphere by quasi-horizontal transport in a region of double tropopauses most likely associated with Rossby wave breaking events. As a result, thin filaments with enhanced signatures of tropospheric trace gases are measured in the lower stratosphere over Europe during the TACTS/ESMVal campaign in September 2012 in very good agreement with CLaMS simulations. Our simulations demonstrate that source regions in Asia and in the Pacific Ocean have a significant impact on the chemical composition of the lower stratosphere of the Northern Hemisphere by flooding the extratropical lower stratosphere with young moist air masses in particular at end of the monsoon season in September/October 2012 (up to ~30 % at 380 K) in contrast to the southern hemisphere. End of October 2012, approximately 1.5 ppmv H2O is found in the lower northern hemisphere stratosphere (at 380 K) from source regions in Asia and the tropical Pacific compared to a mean water vapor content of ~5 ppmv. In addition to this main transport pathway from the Asian monsoon anticyclone to the east along the subtropical jet and subsequent transport into the northern lower stratosphere, a second horizontal transport pathway out of the anticyclone to the west into the tropics (TTL) is found in agreement with MIPAS HCFC-22 measurements.

scholarly journals In situ observations of CH<sub>2</sub>Cl<sub>2</sub> and CHCl<sub>3</sub> show efficient transport pathways for very short-lived species into the lower stratosphere via the Asian and North American summer monsoons

2021 ◽  
Author(s):  
Valentin Lauther ◽  
Bärbel Vogel ◽  
Johannes Wintel ◽  
Andrea Rau ◽  
Peter Hoor ◽  
...  
Keyword(s):  
North American ◽  
Lower Stratosphere ◽  
Stratospheric Ozone ◽  
Late Summer ◽  
Anthropogenic Sources ◽  
North American Monsoon ◽  
Transport Pathway ◽  
Transport Pathways ◽  
Mixing Ratios ◽  
The North

Abstract. Efficient transport pathways for ozone depleting very short-lived substances (VSLS) from their source regions into the stratosphere are a matter of current scientific debate, however they have yet to be fully identified on an observational basis. Understanding the increasing impact of chlorine containing VSLS (Cl-VSLS) on stratospheric ozone depletion is important in order to validate and improve model simulations and future predictions. We report on the first transport study using airborne in situ measurements of the Cl-VSLS dichloromethane (CH2Cl2) and trichloromethane (chloroform, CHCl3) to derive a detailed description of the two most efficient and fast transport pathways from (sub-)tropical source regions into the extratropical lower stratosphere (Ex-LS) in northern hemisphere (NH) late summer. The Cl-VSLS measurements were obtained in the upper troposphere and lower stratosphere (UTLS) above Western Europe and the mid latitude Atlantic Ocean in the frame of the WISE (Wave-driven ISentropic Exchange) aircraft campaign in autumn 2017 and are combined with the results from a three-dimensional simulation of a Lagrangian transport model as well as back-trajectory calculations. Compared to background measurements of similar age we find up to 150 % enhanced CH2Cl2 and up to 100 % enhanced CHCl3 mixing ratios in the Ex-LS. We link the measurements of enhanced mixing ratios to emissions in the region of southern and eastern Asia. Transport from this area to the Ex-LS at potential temperatures in the range of 370–400 K takes about 5–10 weeks via the Asian summer monsoon anticyclone (ASMA). Our measurements suggest anthropogenic sources to be the cause of these strongly elevated Cl-VSLS concentrations observed at the top of the lowermost stratosphere (LMS). A faster transport pathway into the Ex-LS is derived from particularly low CH2Cl2 and CHCl3 mixing ratios in the UTLS. These low mixing ratios reflect weak emission sources and a local seasonal minimum of both species in the boundary layer of Central America and the tropical Atlantic. We show that air masses uplifted by hurricanes, the North American monsoon, and general convection above Central America into the tropical tropopause layer to potential temperatures of about 360–370 K are transported isentropically within 1–5 weeks into the Ex-LS. This transport pathway linked to the North American monsoon mainly impacts the middle and lower part of the LMS with particularly low CH2Cl2 and CHCl3 mixing ratios. In a case study, we specifically analyze air samples directly linked to the uplift by the category 5 hurricane Maria that occurred during October 2017 above the Atlantic Ocean. Regionally differing CHCl3 : CH2Cl2 emission ratios derived from our UTLS measurements suggest a clear similarity between CHCl3 and CH2Cl2 when emitted by anthropogenic sources and differences between the two species mainly caused by additional, likely biogenic, CHCl3 sources. Overall, the transport of strongly enhanced CH2Cl2 and CHCl3 mixing ratios from southern and eastern Asia via the ASMA is the main factor for increasing the chlorine loading from the analyzed VSLS in the Ex-LS during NH late summer. Thus, further increases in Asian CH2Cl2 and CHCl3 emissions, as frequently reported in recent years, will further increase the impact of Cl-VSLS on stratospheric ozone depletion.

An apical K+-dependent HCO3− transport pathway opposes transepithelial HCO3− absorption in rat medullary thick ascending limb

2004 ◽  
Vol 287 (1) ◽  
pp. F57-F63 ◽  
Author(s):  
Bruns A. Watts ◽  
David W. Good
Keyword(s):  
Initial Rate ◽  
Apical Membrane ◽  
Channel Blockers ◽  
Thick Ascending Limb ◽  
Acid Base ◽  
Transport Pathway ◽  
Transport Pathways ◽  
Medullary Thick Ascending Limb ◽  
And Function

Absorption of HCO3− in the medullary thick ascending limb (MTAL) is mediated by apical membrane Na+/H+ exchange. The identity and function of other apical acid-base transporters in this segment have not been defined. The present study was designed to examine apical membrane HCO3−/OH−/H+ transport pathways in the rat MTAL and to determine their role in transepithelial HCO3− absorption. MTALs were perfused in vitro in Na+- and Cl−-free solutions containing 25 mM HCO3−, 5% CO2. Lumen addition of either 120 mM Cl− or 50 mM Na+ (50 μM EIPA present) had no effect on intracellular pH (pHi). Lumen Cl− addition also had no effect on pHi in the presence of 145 mM Na+ or in the nominal absence of HCO3−/CO2. Thus there was no evidence for apical Cl−/HCO3− (OH−) exchange, Na+-dependent Cl−/HCO3− exchange, or Na+-HCO3− cotransport. In contrast, in tubules studied in Na+- and Cl−-free solutions containing 25 mM HCO3−, 5% CO2 and 120 mM K+, removal of luminal K+ induced a rapid and pronounced decrease in pHi (ΔpHi = 0.56 ± 0.06 pH U). pHi recovered following lumen K+ readdition. The initial rate of net base efflux induced by lumen K+ removal was decreased 85% at the same pHi in the nominal absence of HCO3−/CO2, indicating a dependence on HCO3−/CO2 and arguing against apical K+/H+ exchange. A combination of the apical K+ channel blockers quinidine (0.1 mM) and glybenclamide (0.25 mM) had no effect on the lumen K+-induced pHi changes, arguing against electrically coupled K+ and HCO3− conductances. The effect of lumen K+ on pHi was inhibited by 1 mM H2DIDS. In addition, lumen addition of DIDS increased transepithelial HCO3− absorption from 10.7 ± 0.7 to 14.9 ± 0.7 pmol·min−1·mm−1 ( P < 0.001) and increased pHi slightly in MTAL studied in physiological solutions (25 mM HCO3− and 4 mM K+). Lumen DIDS stimulated HCO3− absorption in the absence and presence of furosemide. These results are consistent with an apical membrane K+-dependent HCO3− transport pathway that mediates coupled transfer of K+ and HCO3− from cell to lumen in the MTAL. This mechanism, possibly an apical K+-HCO3− cotransporter, functions in parallel with apical Na+/H+ exchange and opposes transepithelial HCO3− absorption.

Data Reduction for Radionuclide Transport Codes Used in Performance Assessments: An Example of Simplification Process

1997 ◽  
Vol 506 ◽  
Author(s):  
B. Dverstorp ◽  
B. Mendes ◽  
A. Pereira ◽  
B. Sundström
Keyword(s):  
Data Reduction ◽  
Transport Model ◽  
Computer Experiments ◽  
Simple Calculation ◽  
Radionuclide Transport ◽  
Transport Pathway ◽  
Transport Models ◽  
Transport Pathways ◽  
Flow Parameters ◽  
Spatially Varying

ABSTRACTThe input data required for transport models for use in long-term risk assessments of repositories for radioactive waste, in geological media, are intrinsic to the performance of the models. The flow parameters utilized in these models typically come from 2 or 3D hydro-geological calculations done in a prior phase of an assessment. This paper examines some of the standard simplifications introduced when hydrogeological data are reduced to ID as is often required for radionuclide transport models. Two key aspects of data reduction are the determination of average properties of fractured media between and along transport pathways. To quantify possible errors associated with these reduction procedures, two computer experiments have been done. We show that the use of effective flow parameters, representing the average properties of a set of independent transport pathways, in a 1 D radionuclide transport model can result in an underestimation of peak releases by one order of magnitude or more. This result is valid for short-lived nuclides whenever retardation is an important factor. On the other hand, averaging of spatially varying transport properties along a transport pathway may lead to unjustified conservatism. A simple calculation example using Monte Carlo technique, shows that a model that does not take into account spatially varying retardation properties along the transport pathways may overestimate peak release rates by several orders of magnitude. We conclude that more sophisticated transport models taking into account available hydrogeological information on spatial variability are needed to fully understand the potential errors associated with consequence calculations in the performance assessment

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