scholarly journals Effect of Physical Characteristics and Hydrodynamic Conditions on Transport and Deposition of Microplastics in Riverine Ecosystem

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2710
Author(s):  
Rakesh Kumar ◽  
Prabhakar Sharma ◽  
Anurag Verma ◽  
Prakash Kumar Jha ◽  
Prabhakar Singh ◽  
...  
Keyword(s):  
Particle Density ◽  
Biodiversity Loss ◽  
Horizontal Distribution ◽  
Physical Characteristics ◽  
Transport Processes ◽  
Limited Information ◽  
Riverine Ecosystems ◽  
Laminar And Turbulent Flow ◽  
Vertical And Horizontal Distribution ◽  
Gravity Driven

Microplastic disposal into riverine ecosystems is an emergent ecological hazard that mainly originated from land-based sources. This paper presents a comprehensive review on physical processes involved in microplastics transport in riverine ecosystems. Microplastic transport is governed by physical characteristics (e.g., plastic particle density, shape, and size) and hydrodynamics (e.g., laminar and turbulent flow conditions). High-density microplastics are likely to prevail near riverbeds, whereas low-density particles float over river surfaces. Microplastic transport occurs either due to gravity-driven (vertical transport) or settling (horizontal transport) in river ecosystems. Microplastics are subjected to various natural phenomena such as suspension, deposition, detachment, resuspension, and translocation during transport processes. Limited information is available on settling and rising velocities for various polymeric plastic particles. Therefore, this paper highlights how appropriately empirical transport models explain vertical and horizontal distribution of microplastic in riverine ecosystems. Microplastics interact, and thus feedback loops within the environment govern their fate, particularly as these ecosystems are under increasing biodiversity loss and climate change threat. This review provides outlines for fate and transport of microplastics in riverine ecosystems, which will help scientists, policymakers, and stakeholders in better monitoring and mitigating microplastics pollution.

A Study of the Chemical and Physical Characteristics of the Soils from the South of Piauí for Soil-Cement Brick Production

2016 ◽  
Vol 869 ◽  
pp. 112-115 ◽  
Author(s):  
Francisca Pereira de Araújo ◽  
Edson Cavalcanti Silva Filho ◽  
João Sammy Nery de Souza ◽  
Josy Anteveli Osajima ◽  
Marcelo Barbosa Furtini
Keyword(s):  
Organic Matter ◽  
Particle Density ◽  
Environmentally Friendly ◽  
Physical Characteristics ◽  
Chemical Characteristics ◽  
The South ◽  
Physical Chemical ◽  
Soil Cement ◽  
Made In

Soil-cement bricks are good examples of environmentally friendly products. This brick is the combination of soil with compacted cement with no combustion in its production. In this work the physical chemical characteristics of the soil from Piaui for producing this material were investigated. Samples of the soil were collected in three potteries from the county of Bom Jesus and pH analysis were carried out, as well as the rate of organic matter, texture, particle density, limits of liquidity and plasticity rates. The results have shown that the soils have acid tones (pH 5,49 a 6,11), which can be neutralized by adding cement, and organic matter percentages up to 1%. The samples have shown predominantly clay-rich textures with adequate plasticity limits, however, values of liquidity limits and particle density above recommended. Altogether, these soils tend to present viability concerning soil-cement brick production, provided that corrections with additives are made in order to minimize this effect.

Behavior and Distribution of Nonylphenol Ethoxylates and their Metabolites in Sediments of Nansi Lake, China

2011 ◽  
Vol 356-360 ◽  
pp. 1733-1738
Author(s):  
Fang He ◽  
Aya Obara ◽  
Shi Long Wang ◽  
Li Guo Wang
Keyword(s):  
Water Flow ◽  
Flow Direction ◽  
Sediment Cores ◽  
Sewage Treatment ◽  
Vertical Direction ◽  
Total Content ◽  
Horizontal Distribution ◽  
Nansi Lake ◽  
Increasing Trend ◽  
Vertical And Horizontal Distribution

The vertical and horizontal distribution of NPEOn and their metabolites of NP and NPEnC in the Upper Nansi Lake, North China were investigated using LC-MS and LC-MS/MS methods, sampling at three sites (St.1, St.2 and St.3) along the water flow direction. The total content of NPEOn (n=1–15) bound onto the sediment of this lake changed in the range of 60.7–631.5 μg/kg-dry with the horizontal flow direction and the vertical direction of the sediment cores with sediment thickness up to 35 cm. Compared to the presence levels of all detected NPEOn species, the content of NP was much higher, falling in 26.5–1,998.4 μg/kg-dry. A general increasing trend of the NP content along the water flow direction of this lake was revealed. NPEnC showed a roughly increasing trend from the upstream to the downstream, with the total concentrations being obviously lower than NPEOn and NP and falling in 2.13–23.1 μg/kg-dry. The short chain NPEOn dominant in NPEO mixtures in these sedimentary cores indicated that this lake received some effluents from STPs, and the sewage treatment ratio is relatively low in this area. Furthermore, the computed magnitudes of NPEO 1-2/NPEO1-15, NP/NPEO 1-15 and NPEC 1-10/NPEO 1-15 suggested that the non-oxidative hydrolytic transformation seemed to be a major process occurring within the sediment phase of Nansi Lake, while the oxidative hydrolytic transformation pathway was probably less involved.

scholarly journals Sub-Diffusive Dynamics Lead to Depleted Particle Densities Near Cellular Borders

2018 ◽  
Author(s):  
William R. Holmes
Keyword(s):  
Particle Density ◽  
Specific Model ◽  
Transport Processes ◽  
Generalized Langevin Equation ◽  
Diffusive Motion ◽  
Protein Activation ◽  
Cellular Environment ◽  
Anomalous Particle ◽  
Canonical Type ◽  
Different Characteristics

AbstractIt has long been known that the complex cellular environment leads to anomalous motion of intracellular particles. At a gross level, this is characterized by mean squared displacements that deviate from the standard linear profile. Statistical analysis of particle trajectories has helped further elucidate how different characteristics of the cellular environment can introduce different types of anomalousness. A significant majority of this literature has however focused on characterizing the properties of trajectories that do not interact with cell borders (e.g. cell membrane or nucleus). Numerous biological processes ranging from protein activation to exocytosis however require particles to be near a membrane. This study investigates the consequences of a canonical type of sub-diffusive motion, Fractional Brownian Motion (FBM), and its physical analogue Generalized Langevin Equation (GLE) Dynamics, on the spatial localization of particles near reflecting boundaries. Results show that this type of sub-diffusive motion leads to the formation of significant zones of depleted particle density near boundaries, and that this effect is independent of the specific model details encoding those dynamics. Rather these depletion layers are a natural and robust consequence of the anti-correlated nature of motion increments that is at the core of FBM / GLE dynamics. If such depletion zones are present, it would be of profound importance given the wide array of signaling and transport processes that occur near membranes. If not, that would suggest our understanding of this type of anomalous motion may be flawed. Either way, this result points to the need to further investigate the consequences of anomalous particle motions near cell borders from both theoretical and experimental perspectives.

scholarly journals Wątrobowce (Hepaticae) Beskidu Żywiecko-Orawskiego (Karpaty Zachodnie) [Liverworts (Hepaticae) of the Beskid Żywiecko-Orawski Range (Polish Western Carpathians)]

2014 ◽  
Vol 79 ◽  
pp. 1-144 ◽  
Author(s):  
Henryk Klama
Keyword(s):  
Endangered Species ◽  
Habitat Preferences ◽  
Horizontal Distribution ◽  
Western Carpathians ◽  
Vulnerable Species ◽  
Floristic Analysis ◽  
Vertical And Horizontal Distribution

The study area comprises two mountain groups – Wielka Racza and Pilsko – situated in western part of the Beskid Żywiecko-Orawski Range in Polish Western Carpathians. The flora of this area includes 111 species of liverworts and 2 species of hornworts. 81 species of liverworts and 2 species of hornworts were found in the area of the Wielka Racza group, 108 species of liverworts and 2 species of hornworts – in the area of the Pilsko group. The species new for the Polish part of the Beskid Żywiecki Range were found (27), as well as for the whole Range including the Slovakian part (22) and for the Western Beskids (2). Moreover, 20 species rare in the Western Beskids as well as 11 species rare in the whole area of the Western Carpathians were recorded. 6 species regarded as threatened in the Polish flora occur in the study area. Four of them belong to the category of endangered species (E):<em> Fossombronia wondraczekii, Frullania tamarisci, Porella baueri</em> and <em>P. platyphylla</em>, the remaining two belong to the category of vulnerable species (V): <em>Geocalyx graveolens</em> and <em>Metzgeria conjugata</em>. A particular attention should be payed to the species threatened on European scale: <em>Lophozia ascendens</em> (R category), <em>Porella baueri</em> (T) and <em>Scapania parvifolia</em> (T). The floristic analysis of habitats covered by liverworts as well as habitat groups of liverworts and habitat preferences of particular species arę presented in the paper. The phytogeographic characteristics of the flora is also given, including vertical and horizontal distribution of liverworts in the study area.

scholarly journals Occurrence and ecological notes on Rocinela signata (Isopoda, Flabellifera) off Brazil

1977 ◽  
Vol 26 (2) ◽  
pp. 293-301 ◽  
Author(s):  
Plínio Soares Moreira
Keyword(s):  
Host Specificity ◽  
Horizontal Distribution ◽  
Maximum Depth ◽  
Fish Parasite ◽  
Southern Brazil ◽  
Santa Catarina ◽  
Free Living ◽  
Southern Limit ◽  
Vertical And Horizontal Distribution

This paper discuss the vertical and horizontal distribution of the marine isopod Rocinela signata Schiödte & Meinert, 1879, along Brazil. Published records and new data gathered in recent years were used. The species, widely distributed along Brazil, has its most southern limit of occurrence considerably extended to off State of Santa Catarina (27º08'S, 48º11'W) . It is typically a shelf species. So far it was recorded off Brazil at a maximum depth of 73 m, while particularly in southern Brazil at 53 m. The species has been collected free living on the bottom or as a fish parasite, and a few times has been reported attacking and sucking swimmers. Available data suggest any host specificity. R. signata seems a facultative and not an obligate fish parasite.

Cadmium Migration and Distribution Process

2012 ◽  
Vol 518-523 ◽  
pp. 1873-1876
Author(s):  
Xue Ying Song ◽  
Xiao Jun Hu ◽  
Cai Xia Jin ◽  
Ji Song Yang ◽  
Hong Liang Chen ◽  
...  
Keyword(s):  
Vertical Migration ◽  
Horizontal Distribution ◽  
Two Phase ◽  
Public Property ◽  
Major Disaster ◽  
Distribution Process ◽  
Variation Rate ◽  
Vertical And Horizontal Distribution ◽  
Different Depths ◽  
And Migration

The significant pollution accidents which not only threaten public health and public property safety, but also bring major disaster, have become the world concerning environmental problems. The migration process and feature of CdCl2 in the vertical and horizontal profiles of soil were studied by the stimulating experiment to present the theory for the treatment of significant pollution accident. The column leaching device was taken to simulate the vertical and horizontal migration of CdCl2 in the soil profile under two-phase rainfall during 16 days. The portable manual control negative pressure pump was taken to extract soil solution sample and the CdCl2 concentration was determined by the atomic absorption spectrophotometer. Results showed that during the whole experiment, the obvious horizontal and vertical migration features of CdCl2 appeared. The CdCl2 covered the whole horizontal profile in 0.5 h and the whole vertical profile in 146 hours. The relative variation rate of CdCl2 in the different depth of bulk showed that the rapid passing time differed in the different depths. The simulating device used in this paper could well investigate the vertical and horizontal distribution and migration of contaminant. Under the condition of greater rainfall, the CdCl2 gave priority to the horizontal runoff in the surface soil, followed by the vertical migration.

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