scholarly journals Study on Analysis and Sedimentation of Alumina Nanoparticles

2019 ◽  
Vol 16 (3) ◽  
pp. 510 ◽  
Author(s):  
Xuehong Zheng ◽  
Yuehan Li ◽  
Ding Chen ◽  
Airong Zheng ◽  
Qikang Que
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Ecological Risk ◽  
Sedimentation Rate ◽  
Aquatic Environment ◽  
Artificial Seawater ◽  
Alumina Nanoparticles ◽  
Natural Seawater ◽  
Ultrasonic Dispersion ◽  
Risk Effects

Dispersion and aggregation behavior of nanoparticles in aquatic environment may be affected by pH, salinity, and dissolved organic matter, which would change its ecological risk. Effects of time, power and temperature on the alumina nanoparticles (nano-Al2O3) ultrasonic dispersion in water were discussed. Al2O3 had a best ultrasonic dispersion for 30 min at 105 W and 30 °C. The concentration of Al2O3 could be measured by ultraviolet (UV) spectrophotometer, and the method was efficient and accurate. Furthermore, the sedimentation rate of Al2O3 was related to pH, salinity, and its concentration in the artificial seawater. When pH was 7.31, approaching the isoelectric point of Al2O3, they aggregated and settled fastest. Settlement coefficient (k) of Al2O3 increased by 3 and 2.7 times while the salinity and its concentration increased. The sedimentation rate was higher in natural seawater than that in artificial seawater. All results indicated that nano-Al2O3 would be removed in aquatic environment.

Characterization of dissolved organic matter for understanding the adsorption on nanomaterials in aquatic environment: A review

Chemosphere ◽  
2020 ◽  
pp. 128690
Author(s):  
Quang Viet Ly ◽  
Tahir Maqbool ◽  
Zhenghua Zhang ◽  
Quyet Van Le ◽  
Xiaochan An ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Aquatic Environment

scholarly journals Mixing State of Submicrometer Sea Spray Particles Enriched by Insoluble Species in Bubble-Bursting Experiments

2014 ◽  
Vol 31 (1) ◽  
pp. 93-104 ◽  
Author(s):  
Ji Yeon Park ◽  
Sungil Lim ◽  
Kihong Park
Keyword(s):  
Organic Matter ◽  
Membrane Filtration ◽  
Volume Fraction ◽  
Silica Particles ◽  
Artificial Seawater ◽  
Sea Spray ◽  
Natural Seawater ◽  
Mixing State ◽  
High Concentration ◽  
Dissolved Salts

Abstract Measurements of size distribution, hygroscopicity, and volatility of submicrometer sea spray particles produced by the bubble busting of artificial and natural seawater were conducted to determine their mixing state and volume fractions of hygroscopic and nonhygroscopic species or volatile and nonvolatile species. The particles sprayed from artificial seawater having insoluble silica particles were found to be an external mixture of two groups of particles having hygroscopic growth factors (HGFs) of 1.33 (an internal mixture of nonhygroscopic silica particles and hygroscopic salt species) and 1.68 (a similar mixture having more salt species) when the mass ratio of insoluble particles to dissolved salts was higher than 2. For sea spray particles from natural seawater, the external mixing was not significantly observed because of a high concentration of dissolved salts. The HGFs of sea spray particles (80–140 nm) from natural seawater were in the range of 1.70–1.76, which were lower than from pure artificial seawater (1.87), and the HGFs had no change before and after membrane filtration of seawater, suggesting that the sea spray particles from natural seawater contained a significant amount of nonhygroscopic dissolved organic matter in addition to hygroscopic salt species. The volume fraction of the nonhygroscopic species ranged from 20% to 29%, and the highest value was observed for seawater samples from the site where strong biological activity occurred, suggesting that biological materials played an important role in the formation of nonhygroscopic organic matter. Volatility measurements also identified the existence of volatile organic species in single particles from natural seawater, with the volume fraction of volatile species evaporated at 100°C being 4%–5%.

scholarly journals Biological factors of water quality in a mesotrophic ecosystem

Fisheries ◽  
2021 ◽  
Vol 2021 (1) ◽  
pp. 16-19
Author(s):  
Anatoliy Sadchikov ◽  
Sergei Ostroumov
Keyword(s):  
Water Quality ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Aquatic Environment ◽  
Aquatic Ecosystems ◽  
Biological Factors ◽  
Physiological Processes ◽  
Negative Effect

Dissolved organic matter (DOM) is one of the important parameters of water quality in aquatic ecosystems. In the experiments, phyto- and bacterioplankton actively consumed 14C-labeled chlorella hydrolyzate. Removal (by filtration) of cyanobacteria from the aquatic environment leads to an increase in the rate of DOM consumption by bacteria. This indicates the possibility of a negative effect of cyanobacterial metabolites on the physiological processes of bacterioplankton.

scholarly journals Deformation Control and Mass Transfer in the Tunic of Halocynthia roretzi

2018 ◽  
Vol 5 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Yoko Kato
Keyword(s):  
Mass Transfer ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Water Content ◽  
Artificial Seawater ◽  
Mechanical Stimuli ◽  
Halocynthia Roretzi ◽  
Mechanical Environment ◽  
Deformation Control ◽  
Histological Characteristics

Background:It has been previously reported that the tunic ofHalocynthia roretzi, mainly composed of cellulose, is actively deformed with mass transfer by the mechanical stimuli.Objective:In this study, how the tunic deforms in response to the mechanical environment was investigated.Method:The tunic specimen in the artificial seawater was still at 5˚C or underwent the mechanical stimuli at the temperature less than 10˚C. The mass and moisture content of the tunic, the concentrations of nitrate and dissolved organic matter in the artificial seawater used for the tunic, and the histological characteristics were evaluated.Results:The increase in mass of the tunic became lower as the region was closer to the bottom ofHalocynthia roretzi. However, the decrease in mass caused by the mechanical stimuli was not different between the adjacent regions. Also, the tunic of the siphon, the tubular tissue for influx and efflux of the seawater, increased the mass more slowly after the stimuli. The size of the layer covering the outside of the tunic was inversely related to the increment in mass. The change in mass was corresponding to that in water content. The concentrations of nitrate and dissolved organic matter in the artificial seawater were enhanced 5 days after the stimuli while the concentration ratio of dissolved organic matter to nitrate was kept constant.Conclusion:The water content in the tunic was used for controlling the mass response to the mechanical environment.

scholarly journals On the impacts of phytoplankton-derived organic matter on the properties of the primary marine aerosol – Part 2: Composition, hygroscopicity and cloud condensation activity

2011 ◽  
Vol 11 (6) ◽  
pp. 2585-2602 ◽  
Author(s):  
E. Fuentes ◽  
H. Coe ◽  
D. Green ◽  
G. McFiggans
Keyword(s):  
Organic Matter ◽  
Particle Production ◽  
Cloud Condensation Nuclei ◽  
Companion Paper ◽  
Artificial Seawater ◽  
Natural Seawater ◽  
Marine Biota ◽  
Marine Aerosol ◽  
Hygroscopic Growth ◽  
Ccn Activity

Abstract. The effect of nanogel colloidal and dissolved organic matter <0.2 μm, secreted by marine biota, on the hygroscopic growth and droplet activation behaviour of the primary marine aerosol was studied. Seawater proxies were prepared by the combination of artificial seawater devoid of marine organics and natural seawater enriched in organic exudate released by laboratory-grown phytoplankton cultures, as described in a companion paper. The primary aerosol was produced by bubble bursting, using a plunging multijet system as an aerosol generator. The aerosol generated from seawater proxies enriched with marine exudate presented organic volume fractions on the order of 8–37%, as derived by applying a simple mixing rule. The hygroscopic growth and cloud condensation nuclei (CCN) activity of the marine organics-enriched particles where 9–17% and 5–24% lower, respectively, than those of the aerosol produced from artificial seawater devoid of exudate. Experiments in a companion paper indicated that the cloud nuclei formation could be enhanced in diatom bloom areas because of the increase in the primary particle production induced by marine organics. The experiments in the present study, however, indicate that the impacts of such an enhancement would be counteracted by the reduction in the CCN activity of the primary particles enriched in marine organics. The extent of the effect of the biogenic matter on the particle behaviour was dependent on the seawater organic concentration and type of algal exudate. Aerosol produced from seawater proxies containing diatomaceous exudate presented higher hydrophobicity and lower CCN activity than those enriched with nanoplankton exudate. The organic fraction of the particles was found to correlate with the seawater organic concentration, without observing saturation of the particle organic mass fraction even for unrealistically high organic matter concentration in seawater. These findings are indicative that discrepancies on the composition of the primary aerosol between different studies could partly be explained by the difference in the nature and concentration of the organic matter in the source seawater employed. Consistently across the experiments, theoretical analysis based on the Köhler model predicted a reduction in the primary marine aerosol CCN activity upon the incorporation of marine organics into the particle composition. This effect is consequence of the replacement of small inorganic sea salt molecules by large molar mass organic molecules, together with a moderate suppression of the surface tension at the point of activation of 5–0.5%, which leads to a dominance of the reduction in the dissolved solute in the Raoult term.

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