Particle flux and trace metal residence time in natural waters1,1

Santsch, Peter H.

doi:10.4319/lo.1984.29.5.1100

Cited by 88 publications

(35 citation statements)

References 26 publications

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“…Humic substances (HS) represent an active and important fraction of natural organic matter (NOM) in aquatic environments (Aiken 1985;Buffle et al 1998) and play important roles in water quality for many pollutants such as trace metals, radionuclides, and organic compounds owing to their strong sorbent properties, small size, and high charge density (Averett 1995;Maurice and Namjesnik-Dejanovic 1999;Murphy et al 1990;Santschi 1984). HS are also expected to adsorb on mineral and colloid surfaces, including manufactured nanoparticles (NPs), and the resulting adsorption layers and surface modification to have a significant impact on their fate and circulation (Ju-Nam and Lead 2008;Tipping and Higgins 1982).…”

Section: Introductionmentioning

confidence: 99%

Fulvic acids concentration and pH influence on the stability of hematite nanoparticles in aquatic systems

Palomino

Stoll

2013

J Nanopart Res

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In aquatic systems, fulvic acids (FAs) are expected to play key roles on the stability and aggregation behavior of manufactured nanoparticles (NPs). The exact conditions under which aggregation or dispersion occurs will depend on the nanoparticle surface charge properties, FAs concentration as well as solution conditions, such as pH and ionic strength. The systematic calculation of stability (aggregation versus disaggregation) diagrams is therefore a key aspect in the prediction of the environmental fate and behavior of manufactured nanoparticles in aquatic systems. In this study, the responses to changes in pH and FAs concentrations on the resulting surface charge of purified iron oxide nanoparticles (53 nm nominal diameter) is investigated. By adjusting the pH, different nanoparticle surface charge electrostatic regions are found, corresponding to positively, neutral, and negatively charged nanoparticle solutions. For each situation, the adsorption of negatively charged FAs at variable concentrations is considered by analyzing surface charge modifications and calculating experimental kinetics aggregation rates. Results show that, under the conditions used, and range of FAs environmental relevant conditions, the nanoparticle aggregation process is promoted only when the nanoparticle positive surface charge (solution pH less than the charge neutralization point) is compensated by the adsorption of FAs. In all the other cases, FAs adsorption and increase of FAs concentration are expected to promote not only the NPs stabilization but also the disaggregation of NPs aggregates. In addition, our study suggest that very low concentrations of FAs [0.1 mg/l are sufficient to rapidly stabilize iron hydroxide NPs solutions at concentration \5 mg/l.

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Section: Introductionmentioning

confidence: 99%

Fulvic acids concentration and pH influence on the stability of hematite nanoparticles in aquatic systems

Palomino

Stoll

2013

J Nanopart Res

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“…Lakes are often more dynamic and variable than oceans, which results in shorter time scales for transport processes. The residence time of particle-reactive radionuclides in lakes is controlled mainly by particle flux (Santschi 1984). Nevertheless, hydrodynamic factors, such as horizontal or vertical diffusion and advection, as well as the chemical sorption behavior of the element with respect to specific particle surfaces, need to be considered to understand the geochemical pathways of an element.…”

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confidence: 99%

Scavenging of 234Th and 7Be in Lake Constance

Vogler

Jung

Mangini

1996

Limnology & Oceanography

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Particulate and dissolved concentrations of 234Th and 'Be, along with fluxes of total mass and particulate 234Th and 'Be into sediment traps, were measured in Lake Constance (Elodensee) from March to December 1993. During the same period, atmospheric deposition rates of 7Be and 210Pb were determined. Variations in atmospheric fluxes of 'Be and 210Pb were found to reflect variability in rainfall. The mean atmospheric flux for 'Be was 13.5 dpm crned2 yr-' and for 2LoPb it was 0.65 dpm cm-2 yr-I. Total 234Th activities in surface water were generally high in winter and low in summer, primarily in response to the seasonality of biological activity. About 50-70% of 234Th was found in particulate form, depending on particle concentration and particle residence time. Scavenging rates for dissolved 234Th ranged from 0.14 to 0.88 d-l, having increased slightly with total particle concentration. 'Be activities in surface water exhibited large variations because of variable atmospheric input and particle flux. During pericds of high biological productivity, particulate 'Be in surface water increased from -20 to -60% of the total 'Be concentration. The scavenging rates for dissolved 'Be (0.0 1-O. 12 d-l) were generally lower than those for dissolved 234Th because of the lower particle reactivity of 'Be. Although the 'Be flux into sediment traps at 50 m did not differ significantly from the flux at 120 m, the 234Th flux increased with depth because of the further adsorption of water columnproduced 234Th onto sinking particles. The range of residence times for the total radionuclide inventories estimated from an irreversible scavenging model was 33-83 d for 234Th and 40-340 d for 'Be (box depth, 50 m). The residence times of both nuclides were controlled by the particle flux, which, in turn, was determined by biological productivity in the surface water.Natural and man-made radionuclides are useful in the study of the geochemical cycle of some particle-reactive metals and other contaminants in both surface waters and groundwaters (Santschi and Honeyman 1989;Murray 1987). The radiotracer methodology is well established in the marine sciences for processes with various time scales. Lakes are often more dynamic and variable than oceans, which results in shorter time scales for transport processes. The residence time of particle-reactive radionuclides in lakes is controlled mainly by particle flux (Santschi 1984). Nevertheless, hydrodynamic factors, such as horizontal or vertical diffusion and advection, as well as the chemical sorption behavior of the element with respect to specific particle surfaces, need to be considered to understand the geochemical pathways of an element.Although several investigators have studied seasonal cycling of 210Pb (half-life TP/, = 22.1 yr) and 210Po (TP/, = 138 d) in lakes (e.g. Talbot and Andren 1984;Stiller and Imboden 1986; Mangini et al. 1990), data for the shortlived radionuclides 7Be (75/Z = 53.3 d) and 234Th (7,/, = 24.1 d) in freshwater environments are rare (Robbins and Eadie 199...

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“…The spheres were provided in an aqueous suspension containing 81 g/L of latex particles. The particle number, per milliliter of solution, equalled to 1.5 Â 10 11 and the specific surface area to 5.7 Â 10 4 [cm 2 /g]. The latex particles exhibit negatively charged surfaces due to the presence of sulphate groups (7.6 Â 10 5 per particle) and the charge density has a constant value equal to 3.9 [mC/cm 2 ] for pH values above 4.…”

Section: Latex Particle Propertiesmentioning

confidence: 99%

“…In the aquatic systems, flocculation processes are playing essential roles in removing pollutants [1,2]. Trace metals and organic pollutants are mainly adsorbed at the surface of mineral particles like silicates, alumino-silicates or iron oxyhydroxides [3,4] owing to their high specific surface area, diffusivity and reactivity.…”

Section: Introductionmentioning

confidence: 99%

Comparison of two cationic polymeric flocculant architectures on the destabilization of negatively charged latex suspensions

Palomino

Hunkeler²,

Stoll

2011

Polymer

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. Flocculation studies between cationic polymers and oppositely charged colloidal particles are reported in which both flocculation kinetics and floc structures are systematically investigated. The flocculation rate constant, stability ratio and kinetics laws are experimentally determined using particle counting for two polymer architectures; a cationic linear polymer and a two-branched polymer. Comparisons are also made using NaCl at different ionic concentrations for the destabilization of the colloidal particles. Detailed measurements of electrophoretic mobility and kinetics rate constants on varying the polymer dosage are reported. Results suggest that the polymer architecture plays important roles on the polymer dosage for the rapid destabilization of the colloidal suspension. The branched polymer at optimal dosage exhibits the highest flocculation rate constant, whereas on the other hand, the linear polymer concentration range of flocculation is larger. In both cases, polymer flocculation is more efficient by a factor of 5e6 than charge screening effects due to the presence of salt. Analysis of the stability ratio indicates that tele-bridging flocculation and electrostatic forces dictate the stability of the charged latex particle suspension. It is shown that the fractal concepts which are valid for aggregation processes are also applicable here and branched polymers as well as linear polymers yield to the formation of compact flocs in comparison to those obtained with salt.

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Particle flux and trace metal residence time in natural waters1,1

Cited by 88 publications

References 26 publications

Fulvic acids concentration and pH influence on the stability of hematite nanoparticles in aquatic systems

Fulvic acids concentration and pH influence on the stability of hematite nanoparticles in aquatic systems

Scavenging of 234Th and 7Be in Lake Constance

Comparison of two cationic polymeric flocculant architectures on the destabilization of negatively charged latex suspensions

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