Transfer of Cobalt Nanoparticles in a Simplified Food Web: From Algae to Zooplankton to Fish

Cobalt (Co) nanoparticles (NPs) may be diffusely dispersed into natural ecosystems from various anthropogenic sources such as traffic settings and eventually end up in aquatic systems. As environmentally dispersed Co NPs may be transferred through an aquatic food web, this study investigated this transfer from algae (Scendesmus sp.) to zooplankton (Daphnia magna) to fish (Crucian carp, Carassius carassius). Effects of interactions between naturally excreted biomolecules from D. magna and Co NPs were investigated from an environmental fate perspective. ATR-FTIR measurements showed the adsorption of both algae constituents and excreted biomolecules onto the Co NPs. Less than 5% of the Co NPs formed heteroagglomerates with algae, partly an effect of both agglomeration and settling of the Co NPs. The presence of excreted biomolecules in the solution did not affect the extent of heteroagglomeration. Despite the low extent of heteroagglomeration between Co NPs and algae, the Co NPs were transferred to the next trophic level (D. magna). The Co uptake in D. magna was 300 times larger than the control samples (without Co NP), which were not influenced by the addition of excreted biomolecules to the solution. Significant uptake of Co was observed in the intestine of the fish feeding on D. magna containing Co NPs. No bioaccumulation of Co was observed in the fish. Moreover, 10–20% of the transferred Co NP mass was dissolved after 24 h in the simulated gut solution of the zooplankton (pH 7), and 50–60% was dissolved in the simulated gut solution of the fish (pH 4). The results elucidate that Co NPs gain different properties upon trophic transfer in the food web. Risk assessments should hence be conducted on transformed and weathered NPs rather than on pristine particles

Characterization of Stainless Steel Welding Fume Particles : Influence of Stainless Steel Grade, Welding Parameters and Particle Size

Welding is a widely used method to join two pieces of stainless steel. Since it produces a large amount of fume during the process, it can cause adverse health effects. The welding fume particles contain many elements. Among them Cr, Mn and Ni are of concern. These three elements can cause diseases if inhaled by humans, especially Cr(VI). In this project, welding fume particles are collected during welding of different stainless steel grades (austenitic AISI 304L and duplex LDX2101). Furthermore, different welding types (manual metal arc welding and metal active gas welding), shielding gas (MISON 2, MISON 18 and CORGON 18) and welding electrodes were varied (solid and flux cored wire). The particles were tested by scanning electron microscopy, energy dispersive X-ray spectroscopy, cyclic voltammetry and atomic absorption spectroscopy. The composition of the particles was measured and the surface chemical speciation estimated. In addition, metal release (Fe, Cr, Mn, and Ni) in phosphate buffered saline solution (pH 7.4, 37℃, 24h) from the particles was tested. Fe, Cr and Mn were found on the surface of the particles and released to different extent in the phosphate buffered saline solution (dominated by Cr)

Transformation/dissolution characteristics of cobalt and welding fume nanoparticles in physiological and environmental media: surface interactions and trophic transfer

Nanoparticles (NPs) and nanomaterials (NMs) are present everywhere in the environment. They can form both as an act of nature and during human activities. Various kinds of NPs and NMs are engineered for different applications in the ongoing development of nanoscience and technology. Nowadays, concerns have emerged related to potential adverse effects of NPs on human health and the environment. Knowledge related to effects induced by more reactive metal NPs is scarce or even missing in some cases. Such information is crucial for risk assessments. The focus of this doctoral thesis has therefore mainly been placed on reactive metal NPs: stainless steel welding fume particles, cobalt (Co) NPs, and solution combustion synthesized (SCS) Co NPs, to investigate their transformation/dissolution characteristics in environmental and biological media.Environmental interaction studies were performed in terms of adsorption of biomolecules and natural organic matter (NOM) onto the surfaces of the NPs and their influence on dissolution, agglomeration, and size of the NPs in solution. Trophic transfer of Co NPs was investigated in an aquatic food web.The Co NPs rapidly agglomerated and sedimented in solution. Co ions were released from the NPs in both phosphate buffer solution and in freshwater, dissolution processes that were influenced by the adsorption of biomolecules and NOM. The trophic transfer of Co in the aquatic food web was shown to be affected by the extent of both agglomeration and sedimentation. No biomagnification was observed during the trophic transfer, and the addition of excreted biomolecules had no effect on the transfer.The dissolution of stainless steel welding fume particles was studied in PBS. The metal release data could help estimate the risk assessment of stainless steel welding fume particles.Nanopartiklar (NP) och nanomaterial finns överallt i vår omgivning. De produceras genom både naturliga och mänskliga aktiviteter. Olika typer av NP används inom tillämpningar såsom kosmetika och läkemedel. Det saknas dock fortfarande kunskaper om effekten av reaktiva metalliska NP på människors hälsa och miljö. Därför fokuserar denna doktorsavhandling på reaktiva metallnanopartiklars beteende i miljö- och biologiska media, till exempel svetspartiklar från rostfritt stål, koboltnanopartiklar och kobolt som producerats genom lösningsförbränning.Adsorptionen av biomolekyler och naturligt organisk material i både fosfatbuffert, saltlösning och ytvatten studerades och dess påverkan på agglomerering och storlek. Dessutom undersöktes trofisk överföringen av koboltnanopartiklar i en akvatisk näringskedja besående av alger, zooplankton och fisk. Vidare studerades hur adsorption av utsöndrade biomolekyler från zooplanktion påverkade överföringen i näringskedjan.De studerade reaktiva metallnanopartiklarna agglomererade och sedimenterade snabbt i lösning. Metalljoner frisattes från NP i både fosfatbuffertlösning och ytvatten. Adsorptionen av biomolekyler och naturligt organiskt material påverkade upplösningen av metallnanopartiklarna. Överföringen av koboltnanopartiklarna i den akvatiska näringskedjan påverkades av agglomerering och sedimentation av NP, och det var ingen bioackumulering under den trofiska överföringen. Tillsatsen av utsöndrade biomolekyler påverkade inte den trofiska överföringen av koboltnanopartiklar.Svetsrökpartiklar från rostfritt stål studerades med avseende på upplösning i PBS (simulerad lungvätska). Studien kan hjälpa till att uppskatta risken av svetsrökpartiklar från rostfritt stål genom att observera frisättningen av Cr(VI) från partiklarna.QC 2020-09-04</p

Food web transfer of cobalt nanoparticles in algae, zooplankton, and fish

Cobalt (Co) nanoparticles (NPs) may be diffusely dispersed to natural ecosystems from various sources such as traffic settings, and hence eventually end up in aquatic systems, such as lakes and oceans. This has motivated our studies on the transfer of Co NPs through an aquatic food web including algae (Scendesmus sp), zooplankton (Daphnia magna) and fish (Crucian carp, Carassius carassius). The influence of excreted biomolecules from D. magna, potentially adsorbing and forming an eco-corona at the surfaces of the Co NPs, was also investigated from an environmental fate perspective. ATR-FTIR measurements show adsorption of algae constituents and excreted biomolecules onto the Co NPs. The initially adsorbed smaller molecules of the excreted biomolecules were eventually replaced with larger molecules of higher surface affinity, originating from the algae. In tap water (TW) containing algae, less than 1.5% of the Co NPs mass was dissolved within 24 h, mainly as a result of the near neutral pH. Less than 5% of the Co NPs formed heteroagglomerates with algae, which was partly an effect of agglomeration and settling of the Co NPs. The presence of excreted biomolecules in solution did not affect the extent of heteroagglomeration between the Co NPs and the algae. Some Co NPs were transferred to the next trophic level (D. magna) despite the low extent of heteroagglomeration of Co NPs to algae. The Co uptake in D. magna was 300 times larger compared to the control samples (without Co NP), results that were not influenced by the addition of excreted biomolecules to the solution. A significant uptake of Co by the fish was observed in the intestine, without any evident effect of the presence of excreted biomolecules in the solution. No bioaccumulation of Co was observed in the fish feeding on D. magna containing Co NPs, and 10-20% of the Co NP mass was dissolved after 24 h in its simulated gut solution (pH 7.4). In all, extensive agglomeration and sedimentation of the Co NPs and small extent of heteroagglomeration between the Co NPs and the algae resulted in only a small fraction of Co transferred between the algae and D. magna. No significant bioaccumulation of Co NPs was observed in any of the fish organs, even though a small difference was observed in the fish stomachs and intestines. The dissolution findings in the simulated fish stomach solution (pH 7.4) imply that 60% of the Co NPs will dissolve within 24 h if reached this trophic level. QC 20200831</p

Food web transfer of cobalt nanoparticles in algae, zooplankton, and fish

Cobalt (Co) nanoparticles (NPs) may be diffusely dispersed to natural ecosystems from various sources such as traffic settings, and hence eventually end up in aquatic systems, such as lakes and oceans. This has motivated our studies on the transfer of Co NPs through an aquatic food web including algae (Scendesmus sp), zooplankton (Daphnia magna) and fish (Crucian carp, Carassius carassius). The influence of excreted biomolecules from D. magna, potentially adsorbing and forming an eco-corona at the surfaces of the Co NPs, was also investigated from an environmental fate perspective. ATR-FTIR measurements show adsorption of algae constituents and excreted biomolecules onto the Co NPs. The initially adsorbed smaller molecules of the excreted biomolecules were eventually replaced with larger molecules of higher surface affinity, originating from the algae. In tap water (TW) containing algae, less than 1.5% of the Co NPs mass was dissolved within 24 h, mainly as a result of the near neutral pH. Less than 5% of the Co NPs formed heteroagglomerates with algae, which was partly an effect of agglomeration and settling of the Co NPs. The presence of excreted biomolecules in solution did not affect the extent of heteroagglomeration between the Co NPs and the algae. Some Co NPs were transferred to the next trophic level (D. magna) despite the low extent of heteroagglomeration of Co NPs to algae. The Co uptake in D. magna was 300 times larger compared to the control samples (without Co NP), results that were not influenced by the addition of excreted biomolecules to the solution. A significant uptake of Co by the fish was observed in the intestine, without any evident effect of the presence of excreted biomolecules in the solution. No bioaccumulation of Co was observed in the fish feeding on D. magna containing Co NPs, and 10-20% of the Co NP mass was dissolved after 24 h in its simulated gut solution (pH 7.4). In all, extensive agglomeration and sedimentation of the Co NPs and small extent of heteroagglomeration between the Co NPs and the algae resulted in only a small fraction of Co transferred between the algae and D. magna. No significant bioaccumulation of Co NPs was observed in any of the fish organs, even though a small difference was observed in the fish stomachs and intestines. The dissolution findings in the simulated fish stomach solution (pH 7.4) imply that 60% of the Co NPs will dissolve within 24 h if reached this trophic level. QC 20200831</p

Interactions in Composite Film Formation of Mefp-1/graphene on Carbon Steel

Mefp-1 adhesive protein derived from marine blue mussels, together with the 2D material graphene, was used to build the green composite film with enhanced anti-corrosion property and mechanical strength. The corrosion inhibition of the composite film, formed by different methods, was evaluated by using electrochemical impedance spectroscopy. The non-degraded adhesion of the composite film to the carbon steel substrate was proved by nano-scratch tests. Infrared spectroscopy was utilized to investigate the film formation process and “three-body interactions” between Mefp-1, graphene and carbon steel surface. The results show that the Mefp-1 adsorbs on the carbon steel surface mainly through the covalent bond between catechols and Fe(III). Meanwhile, Mefp-1 can bond to non-adhesive graphene by forming hydrogen bonds and π−π interaction non-covalent bonds, which facilitate the formation of a robust Mefp-1/graphene composite film on the carbon steel surface

Transfer of Cobalt Nanoparticles in a Simplified Food Web: From Algae to Zooplankton to Fish

Cobalt (Co) nanoparticles (NPs) may be diffusely dispersed into natural ecosystems from various anthropogenic sources such as traffic settings and eventually end up in aquatic systems. As environmentally dispersed Co NPs may be transferred through an aquatic food web, this study investigated this transfer from algae (Scendesmus sp.) to zooplankton (Daphnia magna) to fish (Crucian carp, Carassius carassius). Effects of interactions between naturally excreted biomolecules from D. magna and Co NPs were investigated from an environmental fate perspective. ATR-FTIR measurements showed the adsorption of both algae constituents and excreted biomolecules onto the Co NPs. Less than 5% of the Co NPs formed heteroagglomerates with algae, partly an effect of both agglomeration and settling of the Co NPs. The presence of excreted biomolecules in the solution did not affect the extent of heteroagglomeration. Despite the low extent of heteroagglomeration between Co NPs and algae, the Co NPs were transferred to the next trophic level (D. magna). The Co uptake in D. magna was 300 times larger than the control samples (without Co NP), which were not influenced by the addition of excreted biomolecules to the solution. Significant uptake of Co was observed in the intestine of the fish feeding on D. magna containing Co NPs. No bioaccumulation of Co was observed in the fish. Moreover, 10–20% of the transferred Co NP mass was dissolved after 24 h in the simulated gut solution of the zooplankton (pH 7), and 50–60% was dissolved in the simulated gut solution of the fish (pH 4). The results elucidate that Co NPs gain different properties upon trophic transfer in the food web. Risk assessments should hence be conducted on transformed and weathered NPs rather than on pristine particles