Colloidal stability of nanoparticles derived from simulated cloud-processed mineral dusts.

AbstractLaboratory simulation of cloud processing of three model dust types with distinct Fe-content (Moroccan dust, Libyan dust and Etna ash) and reference goethite and ferrihydrite were conducted in order to gain a better understanding of natural nanomaterial inputs and their environmental fate and bioavailability. The resulting nanoparticles (NPs) were characterised for Fe dissolution kinetics, aggregation/size distribution, micromorphology and colloidal stability of particle suspensions using a multi-method approach. We demonstrated that the: (i) acid-leachable Fe concentration was highest in volcanic ash (1mMg−1 dust) and was followed by Libyan and Moroccan dust with an order of magnitude lower levels; (ii) acid leached Fe concentration in theLibyan dust). The common occurrence of Fe-rich "natural nanoparticles" in atmospheric dust derived materials may indicate their more ubiquitous presence in the marine environment than previously thought

A Method for Cultivation, Fractionation, and Metal Determination to Evaluate Metal Removal by the Combination of NPS and Bacteria

Metals being released into the environment are posing an increasing risk to both environments and public health. Developing improved approaches to remove these metals from the environment is urgent. A current publication discovered that metal bioremediation was significantly improved by nanoparticles (NPs), and the remediation duration was shortened. However, there is no relevant method for the preparation and evaluation of this novel idea. Hence, we developed this method for bacteria -EPS (Extracellular Polymeric Substances) cultivation, bacteria sub-cellular fractionation, and metal determinations in cultivating solution, EPS and different fractions of bacteria to evaluate metal removal by the combination of NPs and bacteria, including (1) the enhancement of metal bioremediation by NPs, (2) the influence of NPs on bacteria growth and metal toxicity alleviation, (3) the ability of EPS to adsorb metals and the influence of NPs on the EPS metal adsorption, (4) the contribution of bacteria to metal removal in different part, the effects of NPs on metal distribution patterns in bacteria, and the role of NPs in this process.•The design and experimental procedure for the evaluation of metal removal by combing bacteria and NPs.• EPS cultivation and separation in the study of bioremediation for metals

Immobilization of Shewanella oneidensis MR-1 in diffusive gradients in thin films for determining metal bioavailability

Assessing metal bioavailability in soil is important in modelling the effects of metal toxicity on the surrounding ecosystem. Current methods based on diffusive gradient thin films (DGTs) and Gel-Integrated Microelectrode are limited in their availability and sensitivity. To address this, S. oneidensis, an anaerobic iron reducing bacterium, was incorporated into a thin layer of agarose to replace the polyacrylamide gel that is normally present in DGT to form biologically mobilizing DGT (BMDGT). Viability analysis revealed that 16-35% of the cells remained viable within the BMDGTs depending on the culturing conditions over a 20 h period with/without metals. Deployment of BMDGTs in standardized metal solutions showed significant differences to cell free BMDGTs when cells grown in Luria Broth (LB) were incorporated into BMDGTs and deployed under anaerobic conditions. Deployment of these BMDGTs in hematite revealed no significant differences between BMDGTs and BMDGTs containing heat killed cells. Whether heat killed cells retain the ability to affect bioavailability is uncertain. This is the first study to investigate how a microorganism that was incorporated into a DGT device such as the metal reducing bacteria, S. oneidensis, may affect the mobility of metals

Assessing exposure, uptake and toxicity of silver and cerium dioxide nanoparticles from contaminated environments

The aim of this project was to compare cerium oxide and silver particles of different sizes for their potential for uptake by aquatic species, human exposure via ingestion of contaminated food sources and to assess their resultant toxicity. The results demonstrate the potential for uptake of nano and larger particles by fish via the gastrointestinal tract, and by human intestinal epithelial cells, therefore suggesting that ingestion is a viable route of uptake into different organism types. A consistency was also shown in the sensitivity of aquatic, fish cell and human cell models to Ag and CeO2 particles of different sizes; with the observed sensitivity sequence from highest to lowest as: nano-Ag > micro Ag > nano CeO2 = micro CeO2. Such consistency suggests that further studies might allow extrapolation of results between different models and species

Effects of engineered silver nanoparticles on the growth and activity of ecologically important microbes

Summary: Currently, little is known about the impact of silver nanoparticles (AgNPs) on ecologically important microorganisms such as ammonia-oxidizing bacteria (AOB). We performed a multi-analytical approach to demonstrate the effects of uncapped nanosilver (uAgNP), capped nanosilver (cAgNP) and Ag2SO4 on the activities of the AOB: Nitrosomonas europaea, Nitrosospira multiformis and Nitrosococcus oceani, and the growth of Escherichia coli and Bacillus subtilis as model bacterial systems in relation to AgNP type and concentration. All Ag treatments caused significant inhibition to the nitrification potential rates (NPRs) of Nitrosomonas europaea (decreased from 34 to cAgNP>uAgNP. In conclusion, AgNPs (especially cAgNPs) and Ag2SO4 adversely affected AOB activities and thus have the potential to severely impact key microbially driven processes such as nitrification in the environment

Advancing the Understanding of Environmental Transformations, Bioavailability and Effects of Nanomaterials, an International US Environmental Protection Agency—UK Environmental Nanoscience Initiative Joint Program

Nanotechnology has significant economic, health, and environmental benefits, including renewable energy and innovative environmental solutions. Manufactured nanoparticles have been incorporated into new materials and products because of their novel or enhanced properties. These very same properties also have prompted concerns about the potential environmental and human health hazard and risk posed by the manufactured nanomaterials. Appropriate risk management responses require the development of models capable of predicting the environmental and human health effects of the nanomaterials. Development of predictive models has been hampered by a lack of information concerning the environmental fate, behavior and effects of manufactured nanoparticles. The United Kingdom (UK) Environmental Nanoscience Initiative and the United States (US) Environmental Protection Agency have developed an international research program to enhance the knowledgebase and develop risk-predicting models for manufactured nanoparticles. Here we report selected highlights of the program as it sought to maximize the complementary strengths of the transatlantic scientific communities by funding three integrated US-UK consortia to investigate the transformation of these nanoparticles in terrestrial, aquatic, and atmospheric environment. Research results demonstrate there is a functional relationship between the physicochemical properties of environmentally transformed nanomaterials and their effects and that this relationship is amenable to modeling. In addition, the joint transatlantic program has allowed the leveraging of additional funding, promoting transboundary scientific collaboration