scholarly journals Rapid formation of large aggregates during the spring bloom of Kerguelen Island: observations and model comparisons

2014 ◽  
Vol 11 (3) ◽  
pp. 4949-4993 ◽  
Author(s):  
M.-P. Jouandet ◽  
G. A. Jackson ◽  
F. Carlotti ◽  
M. Picheral ◽  
L. Stemmann ◽  
...  
Keyword(s):  
Particle Size ◽  
Mixed Layer ◽  
Late Summer ◽  
Surface Mixed Layer ◽  
Particle Volume ◽  
Kerguelen Island ◽  
Underwater Vision ◽  
Rapid Formation ◽  
Total Particle ◽  
Spherical Diameter

Abstract. We recorded vertical profiles of particle size distributions (PSD, sizes ranging from 0.052 to several mm in equivalent spherical diameter) in the natural iron-fertilized bloom southeast of Kerguelen Island (Southern Ocean) from pre-bloom to early bloom stage. PSD were measured by the Underwater Vision Profiler during the Kerguelen Ocean and Plateau Compared Study cruise 2 (KEOPS 2, October–November 2011). The total particle numerical abundance was more than 4 fold higher during the early bloom phase compared to pre-bloom conditions as a result of the 2-weeks bloom development. We witnessed the rapid formation of large particles and their accumulation at the base of the mixed layer within a two days period, as indicated by changes in total particle volume (VT) and particle size distribution. The VT profiles suggest sinking of particles from the mixed layer to 200 m, but little export deeper than 200 m during the observation period. The results of a one dimensional particles dynamic model support coagulation as the mechanism responsible for the rapid aggregate formation and the development of the VT subsurface maxima. Comparison with KEOPS1, which investigated the same area during late summer, and previous iron fertilization experiments highlights physical aggregation as the primary mechanism for large particulate production during the earlier phase of iron fertilized bloom and its export from the surface mixed layer.

scholarly journals Rapid formation of large aggregates during the spring bloom of Kerguelen Island: observations and model comparisons

2014 ◽  
Vol 11 (16) ◽  
pp. 4393-4406 ◽  
Author(s):  
M.-P. Jouandet ◽  
G. A. Jackson ◽  
F. Carlotti ◽  
M. Picheral ◽  
L. Stemmann ◽  
...  
Keyword(s):  
Particle Size ◽  
Early Stage ◽  
Euphotic Zone ◽  
Carbon Export ◽  
Kerguelen Island ◽  
Underwater Vision ◽  
Large Particles ◽  
Rapid Formation ◽  
Marine Aggregates ◽  
Total Particle

Abstract. While production of aggregates and their subsequent sinking is known to be one pathway for the downward movement of organic matter from the euphotic zone, the rapid transition from non-aggregated to aggregated particles has not been reported previously. We made one vertical profile of particle size distributions (PSD; sizes ranging from 0.052 to several millimeters in equivalent spherical diameter) at pre-bloom stage and seven vertical profiles 3 weeks later over a 48 h period at early bloom stage using the Underwater Vision Profiler during the Kerguelen Ocean and Plateau Compared Study cruise 2 (KEOPS2, October–November 2011). In these naturally iron-fertilized waters southeast of Kerguelen Island (Southern Ocean), the total particle numerical abundance increased by more than fourfold within this time period. A massive total volume increase associated with particle size distribution changes was observed over the 48 h survey, showing the rapid formation of large particles and their accumulation at the base of the mixed layer. The results of a one-dimensional particle dynamics model support coagulation as the mechanism responsible for the rapid aggregate formation and the development of the VT subsurface maxima. The comparison of VT profiles between early bloom stage and pre-bloom stage indicates an increase of particulate export below 200 m when bloom has developed. These results highlight the role of coagulation in forming large particles and triggering carbon export at the early stage of a naturally iron-fertilized bloom, while zooplankton grazing may dominate later in the season. The rapid changes observed illustrate the critical need to measure carbon export flux with high sampling temporal resolution. Our results are the first published in situ observations of the rapid accumulation of marine aggregates and their export and the general agreement of this rapid event with a model of phytoplankton growth and coagulation.

scholarly journals A comparison of light backscattering and particle size distribution measurements in tropical cirrus clouds

2011 ◽  
Vol 4 (3) ◽  
pp. 557-570 ◽  
Author(s):  
F. Cairo ◽  
G. Di Donfrancesco ◽  
M. Snels ◽  
F. Fierli ◽  
M. Viterbini ◽  
...  
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Volume Density ◽  
Size Distributions ◽  
Backscatter Coefficient ◽  
Particle Size Distributions ◽  
Particle Volume ◽  
Total Particle ◽  
Research Aircraft

Abstract. An FSSP-100 Optical Particle Counter designed to count and size particles in the micron range and a backscattersonde that measures in-situ particle optical properties such as backscatter and depolarization ratio, are part of the payload of the high altitude research aircraft M55 Geophysica. This aircraft was deployed in tropical field campaigns in Bauru, Brasil (TROCCINOX, 2004) Darwin, Australia (SCOUT-Darwin, 2005) and Ouagadougou, Burkina Faso (SCOUT-AMMA, 2006). In those occasions, measurements of particle size distributions and optical properties within cirrus cloud were performed. Scope of the present work is to assess and discuss the consistency between the particle volume backscatter coefficient observed by the backscattersonde and the same parameter retrieved by optical scattering theory applied to particle size distributions as measured by the FSSP-100. In addition, empirical relationships linking the optical properties measured in-situ by the backscattersonde, which generally can be obtained by remote sensing techniques (LIDAR), and microphysical bulk properties like total particle number, surface and volume density will be presented and discussed.

scholarly journals A comparison of light backscattering and particle size distribution measurements in tropical cirrus clouds

2010 ◽  
Vol 3 (5) ◽  
pp. 4059-4089 ◽  
Author(s):  
F. Cairo ◽  
G. Di Donfrancesco ◽  
M. Snels ◽  
F. Fierli ◽  
M. Viterbini ◽  
...  
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Volume Density ◽  
Size Distributions ◽  
Backscatter Coefficient ◽  
Particle Size Distributions ◽  
Particle Volume ◽  
Total Particle ◽  
Research Aircraft

Abstract. An FSSP-100 Optical Particle Counter designed to count and size particles in the micron range and a backscattersonde that measures in-situ particle optical properties such as backscatter and depolarization ratio, are part of the payload of the high altitude research aircraft M55 Geophysica. This aircraft was deployed in tropical field campaigns in Bauru, Brasil (TROCCINOX, 2004) Darwin, Australia (SCOUT-Darwin, 2005) and Ouagadougou, Burkina Faso (SCOUT-AMMA, 2006). In those occasions, measurements of particle size distributions and optical properties within cirrus cloud were performed. Scope of the present work is to assess and discuss the consistency between the particle volume backscatter coefficient observed by the backscattersonde and the same parameter retrieved by optical scattering theory applied to particle size distributions as measured by the FSSP-100. In addition, empirical relationships linking the optical properties measured in-situ by the backscattersonde, which generally can be obtained by remote sensing techniques (LIDAR), and microphysical bulk properties like total particle number, surface and volume density will be presented and discussed.

scholarly journals Particle size grouping method as a control system of efficiency flotation process on the example of coal

2020 ◽  
pp. 33-33
Author(s):  
Dorota Kalisz ◽  
Kamil Kuglin ◽  
Anna Młynarczykowska
Keyword(s):  
Particle Size ◽  
Fine Particles ◽  
Flotation Kinetics ◽  
Particle Volume ◽  
Initial Size ◽  
Flotation Process ◽  
Carbon Particles ◽  
Coal Particles ◽  
Total Particle ◽  
Size Of Particles

Agglomeration of coal particles during flotation can be analysed with the Particle Size Grouping (PSG) method. Numerous experiments were carried out to theoretically explain the effect of carbon particles agglomeration, but the result still remains incomplete. In this paper the PSG method was used to analyse agglomeration groups of carbon particles of initial size 100-400 ?m, maintaining the total particle volume. The size of particles population with definite radius and density was determined for 1 Mg coal. The influence of density and size of particles with given mixing energies and parameter ? on agglomeration was analysed. It was stated that the size of the particles had an effect on their agglomeration. In the analysed cases the dimensionless parameter of collision turbulence t* needed for particles agglomeration in particular size groups was importantly shorter for particles of initial size 300 and 400 ?m. The change of the mixing energy did not have influence on the agglomeration of coal particles. The theoretical analyses based on computer calculations were supplemented by the analyses of the coal flotation process on an aqueous model. Experiments lied in introducing a foaming agent in the form of aqueous solution of hexanol which, without changing pH of the pulp, lowered surface tension value, and consequently increased the dispersion of air in the suspension. The experimental results were presented in the form of flotation kinetics curves. Fine particles 100-200?m. turned out to be best for flotation, unlike coarse 400-500 ?m.

Contribution of Calcite to the Particle-Size Spectrum of Lake Michigan Seston and Its Interactions with the Plankton

1987 ◽  
Vol 44 (11) ◽  
pp. 1898-1914 ◽  
Author(s):  
Henry A. Vanderploeg ◽  
Brian J. Eadie ◽  
James R. Liebig ◽  
Stephen J. Tarapchak ◽  
Rebecca M. Glover
Keyword(s):  
Particle Size ◽  
Feeding Rate ◽  
Lake Michigan ◽  
Light Extinction ◽  
Size Spectrum ◽  
Calcite Precipitation ◽  
Particle Volume ◽  
Total Particle ◽  
Different Seasons ◽  
A Minor

We determined the contribution of calcite to the total particle-size spectrum of Lake Michigan seston during different seasons in 1978–83 and 1985, employing a novel Coulter counter method, to examine the intensity and ecological effects of calcite whitings that result from autogenic precipitation of calcite. The whitings were most intense during September, when 12–56% of the total particle volume was calcite. Overall, food web dynamics were more controlling of than controlled by whitings. Year-to-year variation in calcite concentration was probably caused by predation-controlled variation in primary production, which drives calcite precipitation through CO2 uptake. Feeding rate of cladocerans in Lake Michigan is slightly reduced (16%) by calcite, but that of copepods is not. Light extinction is only slightly increased. Coprecipitation and sinking of P with calcite is probably a minor factor in regulating P concentration in the epilimnion of Lake Michigan. Removal of nutrients is enhanced by increased sinking rates caused by inclusion of calcite in fecal pellets and matter. Although all of the effects of calcite on plankton dynamics appear to be subtle in Lake Michigan, large effects can be expected for lakes of greater calcium hardness and eutrophy.

scholarly journals Minor Contribution by Biomineralizing Phytoplankton to Surface Ocean Biomineral Pools in the Late Stratified Period

Oceans ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 489-507
Author(s):  
Stuart C. Painter
Keyword(s):  
Mixed Layer ◽  
Inorganic Carbon ◽  
Late Summer ◽  
Euphotic Zone ◽  
Surface Mixed Layer ◽  
Surface Ocean ◽  
Minor Contribution ◽  
Vertical Distributions ◽  
Adequate Nutrient ◽  
Particulate Inorganic Carbon

Vertical distributions of biogenic silica (bSi), particulate inorganic carbon (PIC) and key biomineral-forming phytoplankton indicate vertical zoning, or partitioning, during the late summer stratified period in the northeast Atlantic. Coccolithophores were generally more numerous in the surface mixed layer, whilst PIC concentrations were more homogenous with depth throughout the euphotic zone. Diatoms were notably more abundant and more diverse in the lower euphotic zone beneath the mixed layer in association with subsurface maxima in chlorophyll-a, bSi and oxygen concentrations. The four dominant coccolithophore species (Emiliania huxleyi, Gephyrocapsa muellerae, Syracosphera spp., and Rhabdosphaera clavigera) represented 78 ± 20% (range 31–100%) of the observed community across all sampled depths yet simultaneously contributed an average of only 13% to measured PIC pools. The diatom community, which was dominated by Pseudo-nitzschia spp. and by a species tentatively identified as Nanoneis longta, represented only ~1% of the bSi pool on average, with contributions increasing within the chlorophyll maximum. Despite a slow gradual deepening of the surface mixed layer in the period prior to observation, and adequate nutrient availability beneath the mixed layer, biomineral pools at this time consisted largely of detrital rather than cellular material.

Mixed Layer Models and Their Application to Water Quality Problems

1994 ◽  
Vol 29 (2-3) ◽  
pp. 221-232
Author(s):  
M.J. McCormick
Keyword(s):  
Water Quality ◽  
Mixed Layer ◽  
Thermal Structure ◽  
Mass Conservation ◽  
Eddy Diffusion ◽  
Rate Of Change ◽  
Surface Mixed Layer ◽  
Storm Events ◽  
Quality Model ◽  
Mixing Processes

Abstract Four one-dimensional models which have been used to characterize surface mixed layer (ML) processes and the thermal structure are described. Although most any model can be calibrated to mimic surface water temperatures, it does not imply that the corresponding mixing processes are well described. Eddy diffusion or "K" models can exhibit this problem. If a ML model is to be useful for water quality applications, then it must be able to resolve storm events and, therefore, be able to simulate the ML depth, h, and its time rate of change, dh/dt. A general water quality model is derived from mass conservation principles to demonstrate how ML models can be used in a physically meaningful way to address water quality issues.

Improvement of monitoring of tertiary filtration with particle counting

2006 ◽  
Vol 6 (1) ◽  
pp. 1-9
Author(s):  
V. Miska ◽  
J.H.J.M. van der Graaf ◽  
J. de Koning
Keyword(s):  
Particle Surface ◽  
Minor Effect ◽  
Particle Size Distributions ◽  
Particle Volume ◽  
Mass Distributions ◽  
Particle Counting ◽  
Total Particle ◽  
Particle Counts ◽  
A Minor ◽  
Sample Dilution

Nowadays filtration processes are still monitored with conventional analyses like turbidity measurements and, in case of flocculation–filtration, with phosphorus analyses. Turbidity measurements have the disadvantage that breakthrough of small flocs cannot be displayed, because of the blindness regarding changes in the mass distributions. Additional particle volume distributions calculated from particle size distributions (PSDs) would provide a better assessment of filtration performance. Lab-scale experiments have been executed on a flocculation–filtration column fed with effluent from WWTP Beverwijk in The Netherlands. Besides particle counting at various sampling points, the effect of sample dilution on the accuracy of PSD measurements has been reflected. It was found that the dilution has a minor effect on PSD of low turbidity samples such as process filtrate. The correlation between total particle counts, total particle volume (TPV) and total particle surface is not high but is at least better for diluted measurements of particles in the range 2–10 μm. Furthermore, possible relations between floc-bound phosphorus and TPV removal had been investigated. A good correlation coefficient is found for TPV removal versus floc-bound phosphorus removal for the experiments with polyaluminiumchloride and the experiments with single denitrifying and blank filtration.

scholarly journals Simultaneous Monitoring of Particle-Bound PAHs Inside a Low-Energy School Building and Outdoors over Two Weeks in France

Atmosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 108
Author(s):  
Céline Liaud ◽  
Sarah Chouvenc ◽  
Stéphane Le Calvé
Keyword(s):  
Particle Size ◽  
Air Quality ◽  
High Performance ◽  
Sampling Period ◽  
Temporal Variations ◽  
Ventilation Rate ◽  
Low Energy ◽  
Total Particle ◽  
Polycyclic Aromatic ◽  
Individual Pahs

The emergence of new super-insulated buildings to reduce energy consumption can lead to a degradation of the indoor air quality. While some studies were carried out to assess the air quality in these super-insulated buildings, they were usually focused on the measurement of gas phase pollutants such as carbon dioxide and volatile organic compounds. This work reports the first measurements of Polycyclic Aromatic Hydrocarbons (PAHs) associated with particles as a function of time and particle size in a low-energy building. The airborne particles were collected indoors and outdoors over three to four days of sampling using two three-stage cascade impactors allowing to sample simultaneously particles with aerodynamic diameter Dae > 10 µm, 2.5 µm < Dae < 10 µm, 1 µm < Dae < 2.5 µm, and Dae < 1 µm. The 16 US-EPA priority PAHs were then extracted and quantified by high-performance liquid chromatography (HPLC) coupled to fluorescence detection. The resulting total particle concentrations were low, in the ranges 3.73 to 9.66 and 0.60 to 8.83 µg m-3 for indoors and outdoors, respectively. Thirteen PAHs were always detected in all the samples. The total PAH concentrations varied between 290 and 415 pg m−3 depending on the particle size, the environment (indoors or outdoors) and the sampling period considered. More interestingly, the temporal variations of individual PAHs highlighted that high molecular weight PAHs were mainly associated to the finest particles and some of them exhibited similar temporal behaviors, suggesting a common emission source. The indoor-to-outdoor concentration ratios of individual PAH were usually found close to or less than 1, except during the event combining rainy conditions and limited indoor ventilation rate.

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