Instruments for particle size and settling velocity observations in sediment transport

Agrawal, Y. C.; Pottsmith, H.C.

doi:10.1016/s0025-3227(00)00044-x

Cited by 521 publications

(402 citation statements)

References 29 publications

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“…The LISST uses laser diffraction techniques to measure floc sizes between 2.5-500 μm and their corresponding volume concentrations (Agrawal and Pottsmith, 2000). For this study, the LISST recorded one sample every 40 seconds during a 20-minute period every hour.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Effective energy controls on flocculation under various wave-current regimes

et al. 2016

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Transport of sediments is a critical process in the coastal zone because of its relation with coastal erosion, productivity and pollution. Of particular interest are the dynamics of suspended cohesive sediments, known as flocs, which can aggregate and break-up during the flocculation process. This changes their size, density, settling velocity and overall transport. Even though turbulence is widely accepted to be an important control on floc aggregation and break-up, specific and detailed floc behaviour is still not fully understood. The present study seeks to help in the understanding of the intra-tidal turbulence-induced flocculation under different current-wave regimes. Observations of floc size and currents at high sample rates are used to investigate the changes throughout a fortnightly cycle. The occurrence of waves at different stages during the sampling period enabled determination of three regimes of currents dominant, combined waves and currents,

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Section: Accepted Manuscriptmentioning

confidence: 99%

Effective energy controls on flocculation under various wave-current regimes

et al. 2016

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“…Diffraction-based techniques have been used for fifteen years to obtain size resolved information of PSD in situ (that is, which minimally affect aggregation state) by inversion of near-forward scattering measurements made using the Laser In Situ Scattering and Transmissometry (LISST) family of in situ sensors (Agrawal and Pottsmith, 2000). Sizes resolved with different LISST instruments span from about 2 to 500 lm.…”

Section: Multiple Angle Scatteringmentioning

confidence: 99%

Optical techniques for remote and in-situ characterization of particles pertinent to GEOTRACES

Boss

Guidi

Richardson

et al. 2015

Progress in Oceanography

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a b s t r a c tField and laboratory characterization of marine particles is laborious and expensive. Proxies of particle properties have been developed that allow researchers to obtain high frequency distributions of such properties in space or time. We focus on optical techniques used to characterize marine particles in-situ, with a focus on GEOTRACES-relevant properties, such as bulk properties including particle mass, crosssectional area, particle size distribution, particle shape information, and also single particle optical properties, such as individual particle type and size. We also address the use of optical properties of particles to infer particulate organic or inorganic carbon. In addition to optical sensors we review advances in imaging technology and its use to study marine particles in situ. This review addresses commercially available technology and techniques that can be used as a proxy for particle properties and the associated uncertainties with particular focus to open ocean environments, the focus of GEOTRACES.

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“…Principles of LISST-100 operation and data inversion-A detailed description of the principle of operation of the LISST-100 and its data inversion have been published (Agrawal and Pottsmith 2000). In short, a collimated beam of light (from a laser source with a wavelength λ = 670 nm) that is scattered by an assemblage of particles is collected on a receiving detector that is comprised of 32 concentric ring photodetectors.…”

Section: Introductionmentioning

confidence: 99%

“…The angular distribution of the intensity of the scattered light is therefore primarily determined by the size of the particles and their shape. As viewed by the ring detectors, small particles place maximum energy on the outer rings, whereas large particles place the maximum on inner rings (Agrawal andPottsmith 2000, Slade andBoss 2006). Scattering intensities detected by the different rings are recorded and then used to solve a matrix equation that provides a volume concentration as function of ESD.…”

Section: Introductionmentioning

confidence: 99%

“…Scattering intensities detected by the different rings are recorded and then used to solve a matrix equation that provides a volume concentration as function of ESD. The inversion algorithm is a modified Chahine method (Agrawal and Pottsmith, 2000). Inversion is performed using a kernel matrix that is based on Mie theory which provides the solution for the interactions of a plane parallel light with homogeneous spheres.…”

Section: Introductionmentioning

confidence: 99%

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LISST‐100 measurements of phytoplankton size distribution: evaluation of the effects of cell shape

Karp‐Boss

Azevedo

Boss

2007

Limnology & Ocean Methods

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Information on cell size is central to studies of phytoplankton ecology, yet in situ measurements of particle size distribution remain a challenge. The LISST‐100 (Laser In Situ Scattering and Transmissometry; Sequoia Scientific, Inc.) is one of few commercially available instruments that provide autonomous measurements of size distributions of suspended particles in situ. Its capability to size phytoplankton needs to be evaluated, however, for two reasons. First, size is not measured directly; rather, information on size is obtained from near‐forward scattering measurements that are inverted to obtain size distributions. The inversion assumes that particles are homogeneous spheres. Phytoplankton, however, display a wide range of cell shapes and their scattering behavior is likely to be different from that of spheres. Second, the LISST‐100 was originally designed for sediments and its inversion assumes an index of refraction typical of inorganic particles. We compared size and volume concentration distributions obtained by the LISST‐100 to those derived via microscopy for phytoplankton cultures of different cell sizes and shapes. Results demonstrate the success of the LISST‐100 in measuring size and volume concentrations of cells with a cell aspect ratio that is close to 1 and illustrate its limitations when nonspherical cells are present in the sample. Uses of the LISST‐100 in laboratory and field studies are discussed in light of the results from this study.

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Instruments for particle size and settling velocity observations in sediment transport

Cited by 521 publications

References 29 publications

Effective energy controls on flocculation under various wave-current regimes

Effective energy controls on flocculation under various wave-current regimes

Optical techniques for remote and in-situ characterization of particles pertinent to GEOTRACES

LISST‐100 measurements of phytoplankton size distribution: evaluation of the effects of cell shape

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