Physical characteristics of suspended sediments, South Texas Continental Shelf

1979 ◽  
Author(s):  
Gerald L. Shideler
Keyword(s):  
Continental Shelf ◽  
Suspended Sediments ◽  
Physical Characteristics ◽  
South Texas

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.

Geobiologic study of the South Texas outer continental shelf

1982 ◽  
Author(s):  
Gary W. Hill ◽  
K.A. Roberts ◽  
J.L. Kindinger ◽  
G.D. Wiley
Keyword(s):  
Continental Shelf ◽  
South Texas ◽  
The South ◽  
Outer Continental Shelf

Turbidity sensor response to seasonal and spatial variability of suspended particle composition in open clear waters –(Portuguese continental shelf)

2021 ◽  
Author(s):  
Anabela Oliveira ◽  
Ana Isabel Santos ◽  
Rita Santos ◽  
Nuno Zacarias
Keyword(s):  
Continental Shelf ◽  
Suspended Particle ◽  
Gravimetric Method ◽  
Suspended Sediments ◽  
Sample Collection ◽  
X Ray Diffraction ◽  
Concentration Data ◽  
In Situ Calibration ◽  
Signal Sensitivity

<p>As part of AQUIMAR project (MAR2020 nº MAR-02.01.01-FEAMP-017 – AQUIMAR – Caraterização geral das áreas aquícolas para estabelecimento de culturas marinhas), intensive CTD surveys and turbidity/concentration data were collected in four cruises along the Portuguese continental shelf (30-200m depth), in 5 aquaculture areas from 2018 to 2020. In-situ calibration of the turbidity sensor (Seapoint Turbidity Meter) was done using the traditional gravimetric method of suspended sediments concentration (SSC) determination with water sampling and filtering. The obtained FTU/SSC relations resulted in correlations in the order of R<sup>2</sup>=70-80% for all considered surveys.</p><p>Measured turbidity and concentration values, were generally very low (<2 FTU and <2 mg/l) for all measuring periods, however variations of the FTU/SSC sensitivity between the different areas indicate that significant variations of suspended matter composition exist throughout the Portuguese continental shelf.</p><p>This study aims to understand the seasonal and spatial variations of the turbidity signal sensitivity to SSC. To this end, a closer look will be given to samples collected during two contrasting seasonal periods (spring and late autumn 2019), as well as to the general water column structure at the time of the sample collection. Additionally, results from X-Ray diffraction analysis performed in some of the filtered samples will be used to better understand the variations of the suspended sediment composition in open clear waters. The mineralogical signal shows a dominance of clay minerals in suspension (mean 83%) and calcite (mean 10%), reflecting the detritic and organic fraction of SSC, respectively.</p>

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