scholarly journals In situ Particle Size and Volume Concentration of Suspended Sediment in Seomjin River Estuary, Determined by an Optical Instrument,'LISST-100'

2004 ◽  
Vol 37 (4) ◽  
pp. 323-329 ◽  
Author(s):  
Seok Yun KIM ◽  
Byoung Kwan LEE
Keyword(s):  
Particle Size ◽  
Suspended Sediment ◽  
Volume Concentration ◽  
River Estuary ◽  
Optical Instrument ◽  
Seomjin River

Inferring suspended sediment carbon content and particle size at high frequency from the optical response of a submerged spectrometer 

2021 ◽  
Author(s):  
Dhruv Sehgal ◽  
Núria Martínez-Carreras ◽  
Christophe Hissler ◽  
Victor Bense ◽  
AJF (Ton) Hoitink
Keyword(s):  
Particle Size ◽  
Absorption Spectrum ◽  
Carbon Content ◽  
Suspended Sediment ◽  
High Frequency ◽  
Suspended Sediments ◽  
Ex Situ ◽  
Frequency Measurements ◽  
Component Form

<p>Manual and unattended sampling in the field and laboratory analysis are common practices to measure suspended sediment (SS) carbon content and particle size. However, one of the major drawbacks of these ex-situ methods is that they make high frequency measurements challenging. This includes restricted data collection due to limited access to the sampling locations during turbulent conditions or high flows, when the largest amount of sediments is transported downstream, introducing uncertainty in quantification of SS properties (particle size and carbon content) and sediment loads. Knowledge on SS carbon content and particle size is also important to better understand the multi-component form of suspended sediments (i.e. flocs) that directly affect sediment transport and other sediment properties (e.g. settling velocity and density). Moreover, SS carbon content and particle size exert an impact on the optical sensor readings that are traditionally used to measure turbidity. In that respect, high frequency measurements of SS carbon content and particle size could eventually help us to move from ‘local’ calibrations towards ‘global’ dependencies based on in-situ SS characterization.</p><p>In this study, we propose to use a submerged UV-VIS spectrometer to infer SS carbon content and particle size. The sensor measures the entire light absorption spectrum of water between 200 nm and 750 nm at sampling intervals as short as 2-minutes. To this end, we first test our approach under controlled conditions with an experimental laboratory setup consisting of a cylindrical tank (40-L) with an open top. An UV-VIS spectrometer and a LISST-200X sensor (to measure particle size distribution) are installed horizontally. A stirrer facilitates the homogeneous mixing of SS and prevents the settling of heavy particles at the bottom. We use the sediments sampled from 6 sites in Luxembourg with contrasting composition and representing different land use types and geological settings. The sampled sediments were wet sieved into 3 size classes to clearly recognize the effect of particle size on absorption. In our investigation, we use specific wavelengths, chemometric techniques and carbon content specific absorbance indices to infer SS composition and particle size from the absorption spectrum. Results are then validated using in-situ field data from two instrumented field sites in Luxembourg. Amid the challenge of associating laboratory and field results, the preliminary results indicate that the absorption spectrum measured with a submerged UV-VIS spectrometer can be used to estimate SS particle size and carbon content.</p>

Measurement in situ of the effective particle-size characteristics of fluvial suspended sediment by means of a field-portable laser backscatter probe: Some preliminary results

1995 ◽  
Vol 46 (1) ◽  
pp. 349 ◽  
Author(s):  
JM Phillips ◽  
DE Walling
Keyword(s):  
Particle Size ◽  
Suspended Sediment ◽  
Fluvial Systems ◽  
Hydrodynamic Behaviour ◽  
Geochemical Properties ◽  
Effective Particle Size ◽  
Particle Size Data ◽  
Effective Particle ◽  
Significant Spatial Variation

Sediment-associated transport frequently represents an important component of the flux of nutrients and contaminants through fluvial systems, and particle size exerts a fundamental influence upon the hydrodynamic behaviour and geochemical properties of the suspended sediment particles involved. Recent work has highlighted the need to distinguish between the ultimate and effective particle-size characteristics of fluvial suspended sediment. The latter may differ appreciably from the former owing to the existence of composite particles (aggregates or flocs). Obtaining representative data of the effective particle-size distribution ideally requires measurements to be made in situ. This paper describes the use of an immersible, portable laser backscatter probe (Par-Tec 200/300) to make measurements in situ of the effective particle-size characteristics of suspended sediment transported by the River Exe and its tributaries in Devon, UK. Within the study basin the effective and absolute particle-size characteristics of suspended sediment were documented at four sites. Significant spatial variation and inter- and intra-event temporal variation in the mean effective size are identified. The degree of aggregation is assessed by comparing the effective and absolute particle-size data. Such comparisons show aggregation to be an important process in the study basin, although its precise magnitude varies in both space and time.

scholarly journals High frequency un-mixing of soil samples using a submerged spectrophotometer in a laboratory setting—implications for sediment fingerprinting

2021 ◽  
Author(s):  
Niels F. Lake ◽  
Núria Martínez-Carreras ◽  
Peter J. Shaw ◽  
Adrian L. Collins
Keyword(s):  
Particle Size ◽  
Soil Sample ◽  
Suspended Sediment ◽  
Temporal Frequency ◽  
Soil Samples ◽  
Sediment Sources ◽  
High Temporal Frequency ◽  
Novel Method ◽  
The Relationship

Abstract Purpose This study tests the feasibility of using a submersible spectrophotometer as a novel method to trace and apportion suspended sediment sources in situ and at high temporal frequency. Methods Laboratory experiments were designed to identify how absorbance at different wavelengths can be used to un-mix artificial mixtures of soil samples (i.e. sediment sources). The experiment consists of a tank containing 40 L of water, to which the soil samples and soil mixtures of known proportions were added in suspension. Absorbance measurements made using the submersible spectrophotometer were used to elucidate: (i) the effects of concentrations on absorbance, (ii) the relationship between absorbance and particle size and (iii) the linear additivity of absorbance as a prerequisite for un-mixing. Results The observed relationships between soil sample concentrations and absorbance in the ultraviolet visible (UV–VIS) wavelength range (200–730 nm) indicated that differences in absorbance patterns are caused by soil-specific properties and particle size. Absorbance was found to be linearly additive and could be used to predict the known soil sample proportions in mixtures using the MixSIAR Bayesian tracer mixing model. Model results indicate that dominant contributions to mixtures containing two and three soil samples could be predicted well, whilst accuracy for four-soil sample mixtures was lower (with respective mean absolute errors of 15.4%, 12.9% and 17.0%). Conclusion The results demonstrate the potential for using in situ submersible spectrophotometer sensors to trace suspended sediment sources at high temporal frequency.

scholarly journals A Four-Step Method for Estimating Suspended Particle Size Based on In Situ Comprehensive Observations in the Pearl River Estuary in China

2021 ◽  
Vol 13 (24) ◽  
pp. 5172
Author(s):  
Zuomin Wang ◽  
Shuibo Hu ◽  
Qingquan Li ◽  
Huizeng Liu ◽  
Xiaomei Liao ◽  
...  
Keyword(s):  
Particle Size ◽  
Coastal Waters ◽  
Suspended Particle ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Pearl River ◽  
Step Method ◽  
The Pearl River ◽  
Suspended Particle Size

The suspended particle size has great impacts on marine biology environments and biogeochemical processes, such as the settling rates of particles and sunlight transmission in marine water. However, the spatial–temporal variations in particle sizes in coastal waters are rarely reported due to the paucity of appropriate observations and the limitations of particle size retrieval methods, especially in areas with complex optical properties. This study proposed a remote sensing-based method for estimating the median particle size Dv50 (calculated with a size range of 2.05–297 μm) that correlates Dv50 with the inherent optical properties (IOPs) retrieved from in situ remote sensing reflectance above the water’s surface (Rrs(λ)) in the Pearl River estuary (PRE) in China. Rrs(λ) was resampled to simulate the Multispectral Instrument (MSI) onboard Sentinel-2A/B, and the wavebands in 490, 560, and 705 nm were utilized for the retrieval of the IOPs. The results of this method had a statistical performance of 0.86, 18.52, 21.28%, and −1.85 for the R2, RMSE, MAPE, and bias values, respectively, in validation, which indicated that Dv50 could be estimated by Rrs(λ) with the proposed four-step method. Then, the proposed method was applied to Sentinel-2 MSI imagery, and a clear difference in Dv50 distribution which was retrieved from a different time could be seen. The proposed method holds great potential for monitoring the suspended particle size of coastal waters.

Novel Formulation Development and Evaluation of Nanoparticles Based in Situ Gelling System for The Ophthalmic Delivery of Ciprofloxacin Hydrochloride

2015 ◽  
Vol 5 (4) ◽  
Author(s):  
Kranti Singh ◽  
Surajpal Verma ◽  
Shyam Prasad ◽  
Indu Bala
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Drug Loading ◽  
In Vitro Release ◽  
Formulation Development ◽  
Ciprofloxacin Hydrochloride ◽  
Potential Value ◽  
The Mean ◽  
In Situ Gelling

Ciprofloxacin hydrochloride loaded Eudragit RS100 nanoparticles were prepared by using w/o/w emulsification (multiple emulsification) solvent evaporation followed by drying of nanoparticles at 50°C. The nanoparticles were further incorporated into the pH-triggered in situ gel forming system which was prepared using Carbopol 940 in combination with HPMC as viscosifying agent. The developed nanoparticles was evaluated for particle size, zeta potential value and loading efficiency; nanoparticle incorporated in situ gelling system was evaluated for pH, clarity, gelling strength, rheological studies, in-vitro release studies and ex-vivo precorneal permeation studies. The nanopaticle showed the mean particle size varying between 263.5nm - 325.9 nm with the mean zeta potential value of -5.91 mV to -8.13 mV and drug loading capacity varied individually between 72.50% to 98.70% w/w. The formulation was clear with no suspended particles, showed good gelling properties. The gelling was quick and remained for longer time period. The developed formulation was therapeutically efficacious, stable and non-irritant. It provided the sustained release of drug over a period of 8-10 hours.

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