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  • Schaumann, Gabriele E.
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  • 1
    Language: English
    In: The Science of the Total Environment, Dec 1, 2015, Vol.535, p.54(7)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.scitotenv.2014.10.108 Byline: Sondra Klitzke, George Metreveli, Andre Peters, Gabriele E. Schaumann, Friederike Lang Abstract: Nanoparticles enter soils through various pathways. In the soil, they undergo various interactions with the solution and the solid phase. We tested the following hypotheses using batch experiments: i) the colloidal stability of Ag NP increases through sorption of soil-borne dissolved organic matter (DOM) and thus inhibits aggregation; ii) the presence of DOM suppresses Ag oxidation; iii) the surface charge of Ag NP governs sorption onto soil particles. Citrate-stabilized and bare Ag NPs were equilibrated with (colloid-free) soil solution extracted from a floodplain soil for 24h. Nanoparticles were removed through centrifugation. Concentrations of free Ag ions and DOC, the specific UV absorbance at a wavelength of 254nm, and the absorption ratio [alpha].sub.254/[alpha].sub.410 were determined in the supernatant. Nanoparticle aggregation was studied using time-resolved dynamic light scattering (DLS) measurement following the addition of soil solution and 1.5mM Ca.sup.2+ solution. To study the effect of surface charge on the adsorption of Ag NP onto soil particles, bare and citrate-stabilized Ag NP, differing in the zeta potential, were equilibrated with silt at a solid-to-solution ratio of 1:10 and an initial Ag concentration range of 30 to 320[mu]g/L. Results showed that bare Ag NPs sorb organic matter, with short-chained organic matter being preferentially adsorbed over long-chained, aromatic organic matter. Stabilizing effects of organic matter only come into play at higher Ag NP concentrations. Soil solution inhibits the release of Ag.sup.+ ions, presumably due to organic matter coatings. Sorption to silt particles was very similar for the two particle types, suggesting that the surface charge does not control Ag NP sorption. Besides, sorption was much lower than in comparable studies with sand and glass surfaces. Article History: Received 29 September 2014; Revised 30 October 2014; Accepted 30 October 2014 Article Note: (miscellaneous) Editor: D. Barcelo
    Keywords: Nanoparticles ; Adsorption
    ISSN: 0048-9697
    Source: Cengage Learning, Inc.
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  • 2
    Language: English
    In: The Science of the Total Environment, Dec 1, 2015, Vol.535, p.1(2)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.scitotenv.2015.06.006 Byline: Gabriele E. Schaumann, Thomas Baumann, Friederike Lang, George Metreveli, Hans-Jorg Vogel
    Keywords: Soils
    ISSN: 0048-9697
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Science of the Total Environment, 01 December 2015, Vol.535, pp.54-60
    Description: Nanoparticles enter soils through various pathways. In the soil, they undergo various interactions with the solution and the solid phase. We tested the following hypotheses using batch experiments: i) the colloidal stability of Ag NP increases through sorption of soil-borne dissolved organic matter (DOM) and thus inhibits aggregation; ii) the presence of DOM suppresses Ag oxidation; iii) the surface charge of Ag NP governs sorption onto soil particles. Citrate-stabilized and bare Ag NPs were equilibrated with (colloid-free) soil solution extracted from a floodplain soil for 24 h. Nanoparticles were removed through centrifugation. Concentrations of free Ag ions and DOC, the specific UV absorbance at a wavelength of 254 nm, and the absorption ratio α /α were determined in the supernatant. Nanoparticle aggregation was studied using time-resolved dynamic light scattering (DLS) measurement following the addition of soil solution and 1.5 mM Ca solution. To study the effect of surface charge on the adsorption of Ag NP onto soil particles, bare and citrate-stabilized Ag NP, differing in the zeta potential, were equilibrated with silt at a solid-to-solution ratio of 1:10 and an initial Ag concentration range of 30 to 320 μg/L. Results showed that bare Ag NPs sorb organic matter, with short-chained organic matter being preferentially adsorbed over long-chained, aromatic organic matter. Stabilizing effects of organic matter only come into play at higher Ag NP concentrations. Soil solution inhibits the release of Ag ions, presumably due to organic matter coatings. Sorption to silt particles was very similar for the two particle types, suggesting that the surface charge does not control Ag NP sorption. Besides, sorption was much lower than in comparable studies with sand and glass surfaces.
    Keywords: Isoelectric Point ; Cation Valency ; Initial Nanoparticle Concentration ; Exchangeability of Sorbed Ag Ions ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 4
    Language: English
    In: Science of the Total Environment, 01 December 2015, Vol.535, pp.1-2
    Keywords: Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 5
    Language: English
    In: Science of the Total Environment, 01 December 2015, Vol.535, pp.3-19
    Description: Engineered inorganic nanoparticles (EINP) from consumers' products and industrial applications, especially silver and titanium dioxide nanoparticles (NP), are emitted into the aquatic and terrestrial environments in increasing amounts. However, the current knowledge on their environmental fate and biological effects is diverse and renders reliable predictions complicated. This review critically evaluates existing knowledge on colloidal aging mechanisms, biological functioning and transport of Ag NP and TiO NP in water and soil and it discusses challenges for concepts, experimental approaches and analytical methods in order to obtain a comprehensive understanding of the processes linking NP fate and effects. Ag NP undergo dissolution and oxidation with Ag S as a thermodynamically determined endpoint. Nonetheless, Ag NP also undergo colloidal transformations in the nanoparticulate state and may act as carriers for other substances. Ag NP and TiO NP can have adverse biological effects on organisms. Whereas Ag NP reveal higher colloidal stability and mobility, the efficiency of NOM as a stabilizing agent is greater towards TiO NP than towards Ag NP, and multivalent cations can dominate the colloidal behavior over NOM. Many of the past analytical obstacles have been overcome just recently. Single particle ICP-MS based methods in combination with field flow fractionation techniques and hydrodynamic chromatography have the potential to fill the gaps currently hampering a comprehensive understanding of fate and effects also at a low field relevant concentrations. These analytical developments will allow for mechanistically orientated research and transfer to a larger set of EINP. This includes separating processes driven by NP specific properties and bulk chemical properties, categorization of effect-triggering pathways directing the EINP effects towards specific recipients, and identification of dominant environmental parameters triggering fate and effect of EINP in specific ecosystems (e.g. soil, lake, or riverine systems).
    Keywords: Transport ; Aggregation ; Analytics ; Environment ; Aging ; Ecotoxicology ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 6
    Language: English
    In: Science of the Total Environment, 15 December 2018, Vol.645, pp.192-204
    Description: Riverbank filtration systems are important structures that ensure the cleaning of infiltrating surface water for drinking water production. In our study, we investigated the potential risk for a breakthrough of environmentally aged silver nanoparticles (Ag NP) through these systems. Additionally, we identified factors leading to the remobilization of Ag NP accumulated in surficial sediment layers in order to gain insights into remobilization mechanisms. We conducted column experiments with Ag NP in an outdoor pilot plant consisting of water-saturated sediment columns mimicking a riverbank filtration system. The NP had previously been aged in river water, soil extract, and ultrapure water, respectively. We investigated the depth-dependent breakthrough and retention of NP. In subsequent batch experiments, we studied the processes responsible for a remobilization of Ag NP retained in the upper 10 cm of the sediments, induced by ionic strength reduction, natural organic matter (NOM), and mechanical forces. We determined the amount of remobilized Ag by ICP-MS and differentiated between particulate and ionic Ag after remobilization using GFAAS. The presence of Ag-containing heteroaggregates was investigated by combining filtration with single-particle ICP-MS. Single and erratic Ag breakthrough events were mainly found in 30 cm depth and Ag NP were accumulated in the upper 20 cm of the columns. Soil-aged Ag NP showed the lowest retention of only 54%. Remobilization was induced by the reduction of ionic strength and the presence of NOM in combination with mechanical forces. The presence of calcium in the aging- as well as the remobilizing media reduced the remobilization potential. Silver NP were mainly remobilized as heteroaggregates with natural colloids, while dissolution played a minor role. Our study indicates that the breakthrough potential of Ag NP in riverbank filtration systems is generally low, but the aging in soil increases their mobility. Remobilization processes are associated to co-mobilization with natural colloids.
    Keywords: Heteroaggregation ; Nanoparticle Transformation ; Breakthrough ; Mobility ; Reversibility ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 7
    Language: English
    In: Journal of Soils and Sediments, 2015, Vol.15(1), pp.1-12
    Description: Byline: Daniela Gildemeister (1,2), George Metreveli (1), Sandra Spielvogel (3), Sabina Hens (1,4), Friederike Lang (5), Gabriele E. Schaumann (1) Keywords: Cation bridges; Cross-link; Differential scanning calorimetry; Dissolved organic matter; Glass transition; Water molecule bridges Abstract: Purpose Precipitation of dissolved organic matter (DOM) by multivalent cations is important for biogeochemical cycling of organic carbon. We investigated to which extent cation bridges are involved in DOM precipitation and how cross-links by cations and water molecule bridges (WaMB) stabilise the matrix of precipitated DOM. Materials and methods DOM was precipitated from the aqueous extract of a forest floor layer adding solutions of Ca(NO.sub.3).sub.2, Al(NO.sub.3).sub.3 and Pb(NO.sub.3).sub.2 with different initial metal cation/C (Me/C) ratios. Precipitates were investigated by differential scanning calorimetry before and after ageing to detect cation bridges, WaMB and restructuring of supramolecular structure. Results and discussion Twenty-five to sixty-seven per cent of the dissolved organic carbon was precipitated. The precipitation efficiency of cations increased in the order Ca〈Al〈Pb, while the cation content of precipitates increased in the order Pb〈Ca〈Al. The different order and the decrease in the WaMB transition temperature (T*) for Al/C〉3 is explained by additional formation of small AlOOH particles. Thermal analysis indicated WaMB and their disruption at T* of 53--65 [degrees]C. Like cation content, T* increased with increasing Me/C ratio and in the order Ca〈Pb〈Al for low Me/C. This supports the general assumption that cross-linking ability increases in the order Ca〈Pb〈Al. The low T* for high initial Me/C suggests less stable and less cross-linked precipitates than for low Me/C ratios. Conclusions Our results suggest a very similar thermal behaviour of OM bound in precipitates compared with soil organic matter and confirms the relevance of WaMB in stabilisation of the supramolecular structure of cation-DOM precipitates. Thus, stabilisation of the supramolecular structure of the DOM precipitates is subjected to dynamics in soils. Author Affiliation: (1) Institute for Environmental Sciences, Group of Environmental and Soil Chemistry, Universitat Koblenz-Landau, Fortstr. 7, 76829, Landau, Germany (2) Umweltbundesamt, FG IV 2.2 Pharmaceuticals, Worlitzer Platz 1, 06844, Dessau-Ro[sz]lau, Germany (3) Department of Geography, Institute of Integrated Natural Sciences, Universitat Koblenz-Landau, Universitatsstr. 1, 56070, Koblenz, Germany (4) GN Dr. Netta Beratende Ingenieure und Geowissenschaftler, Bienengarten 3, 56072, Koblenz, Germany (5) Albert-Ludwigs-Universitat Freiburg, Institute of Forest Sciences, 79085, Freiburg i.Br., Germany Article History: Registration Date: 09/07/2014 Received Date: 02/04/2014 Accepted Date: 09/07/2014 Online Date: 30/07/2014 Article note: Responsible editor: Dong-Mei Zhou Electronic supplementary material The online version of this article (doi: 10.1007/s11368-014-0946-9) contains supplementary material, which is available to authorized users.
    Keywords: Cation bridges ; Cross-link ; Differential scanning calorimetry ; Dissolved organic matter ; Glass transition ; Water molecule bridges
    ISSN: 1439-0108
    E-ISSN: 1614-7480
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  • 8
    Language: English
    In: Geochimica et Cosmochimica Acta, 2006, Vol.70(12), pp.2957-2969
    Description: Hydration of organic coatings in soils is expected to affect the sorption of oxyanions onto hydrous Fe and Al oxides. We hypothesized that the hydration of polygalacturonate (PGA) coatings on alumina (Al O ) increases their permeability for phosphate. Pure and PGA-coated alumina were equilibrated in deionized water for 2 and 170 h at pH 5 and 20 °C before studying (i) their porosity with N gas adsorption and H NMR relaxometry, (ii) structural changes of PGA-coatings with differential scanning calorimetry (DSC), and (iii) the kinetics of phosphate sorption and PGA desorption in batch experiments. Scanning electron micrographs revealed that PGA molecules formed three-dimensional networks with pores ranging in size from 〈10 to several hundred nanometers. Our NMR results showed that the water content of intraparticle alumina pores decreased upon PGA sorption, indicating a displacement of pore water by PGA. The amount of water in interparticle alumina pores increased strongly after PGA addition, however, and was attributed to water in pores of PGA and/or in pores at the PGA-alumina interface. The flexibility of PGA molecules and the fraction of a PGA gel phase increased within one week of hydration, implying restructuring of PGA. Hydration of PGA coatings increased the amount of phosphate defined as instantaneously sorbed by 84%, showing that restructuring of PGA enhanced the accessibility of phosphate to external alumina surfaces. Despite the fact that the efficacy of phosphate to displace PGA was higher after 170 h than after 2 h, a higher phosphate surface loading was required after 170 h to set off PGA desorption. Our findings imply that the number of PGA chain segments directly attached to the alumina surface decreased with time. We conclude that hydration/dehydration of polymeric surface coatings affects the sorption kinetics of oxyanions, and may thus control the sorption and transport of solutes in soils.
    Keywords: Geology
    ISSN: 0016-7037
    E-ISSN: 1872-9533
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  • 9
    Language: English
    In: Journal of Contaminant Hydrology, December 2016, Vol.195, pp.31-39
    Description: Engineered nanoparticles released into soils may be coated with humic substances, potentially modifying their surface properties. Due to their amphiphilic nature, humic coating is expected to affect interaction of nanoparticle at the air-water interface. In this study, we explored the roles of the air-water interface and solid-water interface as potential sites for nanoparticle attachment and the importance of hydrophobic interactions for nanoparticle attachment at the air-water interface. By exposing Ag nanoparticles to soil solution extracted from the upper soil horizon of a floodplain soil, the mobility of the resulting “soil-aged” Ag nanoparticles was investigated and compared with the mobility of citrate-coated Ag nanoparticles as investigated in an earlier study. The mobility was determined as a function of hydrologic conditions and solution chemistry using column breakthrough curves and numerical modeling. Specifically, we compared the mobility of both types of nanoparticles for different unsaturated flow conditions and for pH = 5 and pH = 9. The soil-aged Ag NP were less mobile at pH = 5 than at pH = 9 due to lower electrostatic repulsion at pH = 5 for both types of interfaces. Moreover, the physical flow field at different water contents modified the impact of chemical forces at the solid-water interface. An extended Derjaguin-Landau-Verwey-Overbeek (eDLVO) model did not provide satisfactory explanation of the observed transport phenomena unlike for the citrate-coated case. For instance, the eDLVO model assuming sphere-plate geometry predicts a high energy barrier (〉 90 ) for the solid-water interface, indicating that nanoparticle attachment is less likely. Furthermore, retardation through reversible sorption at the air-water interface was probably less relevant for soil-aged nanoparticles than for citrate-coated nanoparticles. An additional cation bridging mechanism and straining within the flow field may have enhanced nanoparticle retention at the solid-water interface. The results indicate that the mobility of engineered Ag nanoparticles is sensitive to solution chemistry, especially pH and the concentration of multivalent cations, and to the unsaturated flow conditions influencing particle interaction at biogeochemical interfaces.
    Keywords: Unsaturated Transport ; Water Dynamics ; Cation Bridging ; Amphiphilic ; Edlvo ; Engineering ; Environmental Sciences ; Geography
    ISSN: 0169-7722
    E-ISSN: 1873-6009
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  • 10
    Language: English
    In: Journal of Soils and Sediments, 2012, Vol.12(8), pp.1209-1210
    Description: Issue Title: Special issue: Coevolution of organic substances and soils
    Keywords: Environment ; Environmental Physics ; Soil Science & Conservation ; Environment, General ; Agriculture;
    ISSN: 1439-0108
    E-ISSN: 1614-7480
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