Auflistung nach Autor:in "Metreveli, George"

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Distribution of engineered Ag nanoparticles in the aquatic-terrestrial transition zone: a long-term indoor floodplain mesocosm study
(2021) Metreveli, George; Klitzke, Sondra; Kurtz, Sandra; Rosenfeldt, Ricki R.
The fate of engineered nanoparticles in the aquatic-terrestrial transition zone is decisive for their effect in the environment. However, our knowledge on processes within this interface is rather low. Therefore, we used a floodplain stream mesocosm to enhance our understanding of the long-term distribution and biological effects of citrate-coated silver nanoparticles (Ag-NPs) in this ecosystem. Parallel to pulsed dosing of Ag-NPs, we observed fluctuating but successively increasing concentrations of aqueous Ag, 88-97% of which was categorized as particles. The remaining dissolved fraction was mainly complexed with natural organic matter (NOM). The major Ag fraction (50%) was associated with the uppermost sediment layer. The feeding activity of benthic amphipods was largely unaffected, which could be explained by the low Ag concentration and complexation of released Ag+ with NOM. According to our hypothesis, only a small nanoparticle fraction (6%) moved to the terrestrial area due to aquatic aging and enrichment of Ag-NPs in sediments and biota. Nanoparticle infiltration in deeper sediment and soil layers was also limited. We expect that a small fraction of nanoparticles remaining in the water for several weeks can be transported over large distances in rivers. The Ag-NPs accumulated in the top layer of sediment and soil may serve as a source of toxic Ag+ ions or may be remobilized due to changing physico-chemical conditions. Furthermore, the high enrichment of Ag-NPs on algae (up to 250 000-fold) and leaves (up to 11 000-fold) bears risk for organisms feeding on those resources and for the transfer of Ag within the food web. © Royal Society of Chemistry 2021
Influence of aging and changes in physico-chemical conditions on the remobilization of Ag NP from sediments of an artificial riverbank filtration system
(2017) Degenkolb, Laura; Metreveli, George; Zehlike, Lisa; Philippe, A.; Kaupenjohann, Martin; Klitzke, Sondra
Remobilization of Ag NP retained in sediments of an artificial riverbank filtration system
(2017) Degenkolb, Laura; Metreveli, George; Zehlike, Lisa; Philippe, A.; Leopold, K.; Brandt, A.; Kaupenjohann, Martin; Klitzke, Sondra
Remobilization of Ag NP retained in sediments of an artificial riverbank filtration system
(2017) Degenkolb, Laura; Metreveli, George; Zehlike, Lisa; Philippe, A.; Kaupenjohann, Martin; Klitzke, Sondra
Remobilization of Ag NP retained in sediments of an artificial riverbank filtration system
(2016) Degenkolb, Laura; Metreveli, George; Zehlike, Lisa; Kumahor, Samuel; Schaumann, Gabriele E.; Baumann, Thomas; Vogel, Hans-Jörg; Kaupenjohann, Martin; Lang, Friederike; Klitzke, Sondra
Nanoparticles (NP) can enter aquatic environments via various pathways such as industrial or municipalwaste water or surface run-off from farmland. Once they enter aquatic systems they may impair the quality of the environment and drinking water reservoirs. Riverbank filtration systems can prevent contaminants from reaching such resources. The retention capacity of riverbank filtration systems and the reversibility of NP immobilization are therefore important aspects for risk assessment.
To simulate a riverbank filtration scenario, Ag NP aged in different media (soil solution, river water, Millipore water) were applied to a water-saturated column (length 1.5 m) filled with medium quartz sand.All types of particles were mainly retained in the first 10 cm of the sediment column, ranging from 50 % for soil-aged particles to approximately 100 % for particles aged in Millipore and river water. However, it is unclear under which conditions the retained Ag NP can be remobilized. Therefore, the aim of our study is to determine the remobilization of the NP and the physico-chemical factors (i.e. shear forces and hydrochemical properties) controlling this process.
In batch experiments, the sediment containing NP will be exposed to varying shear forces (i.e. ultrasonic treatment of 1.5 W/cṃand horizontal shaking of 1 h up to 7 days) in the presence of dissolved organic matter and reduced ionic strength. The total amount of remobilized silver in the supernatantwill be measured by ICP-MS following acid microwave digestion. The size and composition of mobilized homo-and heteroaggregates will be analysed by HDC-ICP-MS.
First results show that strong shear forces induced by ultrasonic treatment lead to highest remobilization of the retained Ag NP of up to 60 % for particles aged in river water. One hour of shaking remobilizes 15-20 % of the Ag NP in the sediment. Further results of the remobilization experiments will be presented.
In: Degenkolb, L; Klitzke, S Metreveli, G; Kumahor, S; Schaumann, G; Baumann, T; Vogel, HJ; Kaupenjohann, M; Lang, F (2016):Remobilization of Ag NP retained in sediments of an artificial riverbank filtration system. In: Abstract Booklet of the InternationalWorkshop "Nanoparticles in Soils and Waters: Fate, Transport and Effects", p. 32, 20 th - 21 st October, Landau in der Pfalz
Retention and remobilization mechanisms of environmentally aged silver nanoparticles in an artificial riverbank filtration system
(2018) Metreveli, George; Degenkolb, Laura; Philippe, Allan; Klitzke, Sondra; Brandt, Anja; Zehlike, Lisa