Microplastic loads in Eurasian otter (Lutra lutra) feces-targeting a standardized protocol and first results from an alpine stream, the River Inn.

Microplastics (MP) are omnipresent in a wide range of environments, constituting a potential threat for aquatic and terrestrial wildlife. Effects in consumers range from physical injuries to pathological reactions. Due to potential bioaccumulation of MP, predators are of particular concern for MP induced health effects. The Eurasian otter is an apex predator in (semi-)aquatic habitats feeding primarily on fish. Furthermore, the species is classified as "near threatened" on the IUCN Red List. Thus, the Eurasian otter is of conservation concern and may serve as a bioindicator for MP pollution. Feces can be used to detect pollutants, including MP. Initial studies confirmed the presence of MP in otter feces (= spraints). However, as specific, validated protocols targeting at an efficient and standardized extraction of MP from otter spraints are missing, experimental results reported from different groups are challenging to compare. Therefore, we (i) present steps towards a standardized protocol for the extraction of MP from otter feces, (ii) give recommendations for field sample collection of otter spraints, and (iii) provide a user-friendly step-by-step workflow for MP extraction and analysis. Applying this framework to field samples from five study sites along the River Inn (n = 50), we detected MP of different sizes and shapes (ranging from microfibers to road abrasion and tire wear) in all otter spraint samples.

Electrophoretic Deposition of Nanoporous Oxide Coatings from Concentrated CuO Nanoparticle Dispersions.

Electrophoretic deposition (EPD) of nanoporous oxide coatings is an interesting research avenue owing to the experimental simplicity and broad scope of applications and materials. In this study, the properties of concentrated (up to 5000 mg/L), nonaqueous CuO nanoparticle (NP) dispersions were tailored to produce micrometer-thick, nanoporous CuO films by EPD. In particular, we performed a systematic investigation of the electrophoretic mobilities and size distributions of dispersed CuO aggregates and developing agglomerates in different organic solvents for concentrations ranging from 50 to 5000 mg/L with and without surfactant addition. Time-resolved dynamic light scattering analyses showed that aggregate mobilities and agglomeration rates decrease with increasing hydrocarbon chain length of the organic solvent (from ethanol to hexanol) and thus with increasing viscosity. The highest electrophoretic mobility was obtained for CuO NP aggregates and agglomerates dispersed in ethanol as a solvent. However, the addition of ≥0.5 wt % acetylacetone as a surfactant is required to stabilize these dispersions for subsequent EPD and at the same time introduce a net attractive (electrostatic) interaction between neighboring agglomerates on the substrate to promote layer formation during the EPD step. The produced micrometer-thick nanoporous CuO coatings can serve as high surface area nanostructured materials or nanoporous scaffolds in catalysis, combustion, propellants, and nanojoining.

Wood-based activated biochar to eliminate organic micropollutants from biologically treated wastewater.

Implementing advanced wastewater treatment (WWT) to eliminate organic micropollutants (OMPs) is a necessary step to protect vulnerable freshwater ecosystems and water resources. To this end, sorption of OMP by activated carbon (AC) is one viable technology among others. However, conventional AC production based on fossil precursor materials causes environmental pollution, including considerable emissions of greenhouse gases. In this study, we produced activated biochar (AB) from wood and woody residues by physical activation and evaluated their capability to eliminate OMPs in treated wastewater. Activated biochar produced under optimized conditions sorbed 15 model OMPs, of which most were dissociated at circumneutral pH, to the same or higher extent than commercial AC used as a reference. While wood quality played a minor role, the dosage of the activation agent was the main parameter controlling the capacity of ABs to eliminate OMP. Our results highlight the possibility for local production of AB from local wood or woody residues as a strategy to improve WWT avoiding negative side effects of conventional AC production.

Cost-effective sol-gel synthesis of porous CuO nanoparticle aggregates with tunable specific surface area.

CuO nanoparticles (NPs) are applied in various key technologies, such as catalysis, energy conversion, printable electronics and nanojoining. In this study, an economic, green and easy-scalable sol-gel synthesis method was adopted to produce submicron-sized nanoporous CuO NP aggregates with a specific surface area > 18 m²/g. To this end, a copper-carbonate containing precursor was precipitated from a mixed solution of copper acetate and ammonia carbonate and subsequently calcinated at T ≥ 250 °C. The thus obtained CuO nanopowder is composed of weakly-bounded agglomerates, which are constituted of aggregated CuO NPs with a tunable size in the range of 100-140 nm. The CuO aggregates, in turn, are composed of equi-axed primary crystallites with a tunable crystallite size in the range of 20-40 nm. The size and shape of the primary CuO crystallites, as well as the nanoporosity of their fused CuO aggregates, can be tuned by controlled variation of the degree of supersaturation of the solution via the pH and the carbonate concentration. The synthesized submicron-sized CuO aggregates can be more easily and safely processed in the form of a solution, dispersion or paste than individual NPs, while still offering the same enhanced reactivity due to their nanoporous architecture.

Evaluation of a TEM based Approach for Size Measurement of Particulate (Nano)materials.

An approach for the size measurement of particulate (nano)materials by transmission electron microscopy was evaluated. The approach combines standard operating procedures for specimen preparation, imaging, and image analysis, and it was evaluated on a series of certified reference materials and representative test materials with varying physical properties, including particle size, shape, and agglomeration state. The measurement of the median value of the minimal external particle diameter distribution was intra-laboratory validated. The validation study included an assessment of the limit of detection, working range, selectivity, precision, trueness, robustness, and ruggedness. An uncertainty that was associated to intermediate precision in the range of 1-7% and an expanded measurement uncertainty in the range of 7-20% were obtained, depending on the material and image analysis mode. No bias was observed when assessing the trueness of the approach on the certified reference materials ERM-FD100 and ERM-FD304. The image analysis method was validated in an inter-laboratory study by 19 laboratories, which resulted in a within-laboratory precision in the range of 2-8% and a between-laboratory precision of between 2% and 14%. The automation and standardization of the proposed approach significantly improves labour and cost efficiency for the accurate and precise size measurement of the particulate materials. The approach is shown to be implementable in many other electron microscopy laboratories.

The role of size and protein shells in the toxicity to algal photosynthesis induced by ionic silver delivered from silver nanoparticles.

Because of their biocide properties, silver nanoparticles (AgNPs) are present in numerous consumer products. The biocidal properties of AgNPs are due to both the interactions between AgNP and cell membranes and the release of dissolved silver (Ag+). Recent studies emphasized the role of different nanoparticle coatings in complexing and storing Ag+. In this study, the availability of dissolved silver in the presence of algae was assessed for three AgNPs with different silver contents (59%, 34% and 7% of total Ag), silver core sizes and casein shell thicknesses. The impact of ionic silver on the photosynthetic yield of Chlamydomonas reinhardtii was used as a proxy to estimate the amount of ionic silver toxically active during in vivo assays. The results showed that cysteine, a strong silver ligand, mitigated the toxicity of AgNPs in all cases, demonstrating the key role of Ag+ in this toxicity. The results showed that the AgNPs presenting an intermediate level of silver (34%) were 10 times more effective in terms of total mass (EC50 ten times smaller) than those presenting more (59%) or less (7%) silver. The higher toxicity was due to the higher release of Ag+ under biotic conditions due to the high surface/mass ratio of the nanoparticle silver core. Protein shells played a minor role in altering the availability of Ag+, probably acting as intermediate reservoirs. This study highlighted the utility of a very sensitive biological endpoint (i.e., algal photosynthesis) for the optimization of ionic silver delivery by nanomaterials.

Long-term effects of sulfidized silver nanoparticles in sewage sludge on soil microflora.

The use of silver nanoparticles (AgNPs) in consumer products such as textiles leads to their discharge into wastewater and consequently to a transfer of the AgNPs to soil ecosystems via biosolids used as fertilizer. In urban wastewater systems (e.g., sewer, wastewater treatment plant [WWTP], anaerobic digesters) AgNPs are efficiently converted into sparingly soluble silver sulfides (Ag2 S), mitigating the toxicity of the AgNPs. However, long-term studies on the bioavailability and effects of sulfidized AgNPs on soil microorganisms are lacking. Thus we investigated the bioavailability and long-term effects of AgNPs (spiked in a laboratory WWTP) on soil microorganisms. Before mixing the biosolids into soil, the sludges were either anaerobically digested or directly dewatered. The effects on the ammonium oxidation process were investigated over 140 d. Transmission electron microscopy (TEM) suggested an almost complete sulfidation of the AgNPs analyzed in all biosolid samples and in soil, with Ag2 S predominantly detected in long-term incubation experiments. However, despite the sulfidation of the AgNPs, soil ammonium oxidation was significantly inhibited, and the degree of inhibition was independent of the sludge treatment. The results revealed that AgNPs sulfidized under environmentally relevant conditions were still bioavailable to soil microorganisms. Consequently, Ag2 S may exhibit toxic effects over the long term rather than the short term. Environ Toxicol Chem 2017;36:3305-3313. © 2017 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Quantification of Carbon Nanotubes in Environmental Matrices: Current Capabilities, Case Studies, and Future Prospects.

Carbon nanotubes (CNTs) have numerous exciting potential applications and some that have reached commercialization. As such, quantitative measurements of CNTs in key environmental matrices (water, soil, sediment, and biological tissues) are needed to address concerns about their potential environmental and human health risks and to inform application development. However, standard methods for CNT quantification are not yet available. We systematically and critically review each component of the current methods for CNT quantification including CNT extraction approaches, potential biases, limits of detection, and potential for standardization. This review reveals that many of the techniques with the lowest detection limits require uncommon equipment or expertise, and thus, they are not frequently accessible. Additionally, changes to the CNTs (e.g., agglomeration) after environmental release and matrix effects can cause biases for many of the techniques, and biasing factors vary among the techniques. Five case studies are provided to illustrate how to use this information to inform responses to real-world scenarios such as monitoring potential CNT discharge into a river or ecotoxicity testing by a testing laboratory. Overall, substantial progress has been made in improving CNT quantification during the past ten years, but additional work is needed for standardization, development of extraction techniques from complex matrices, and multimethod comparisons of standard samples to reveal the comparability of techniques.

Scientific Basis for Regulatory Decision-Making of Nanomaterials Report on the Workshop, 20-21 January 2014, Center of Applied Ecotoxicology, Dübendorf.

The key findings of a workshop jointly organized by the Swiss Centre of Applied Ecotoxicity, the Swiss Centre for Applied Human Toxicology (SCAHT), and the Federal Office of Public Health (FOPH) are summarized and provide a critical analysis of the current regulatory framework for nanomaterials and a snapshot of some hot topics in nanoscience.

Scientific Basis for Regulatory Decision-Making of Nanomaterials Report on the Workshop, 20-21 January 2014, Center of Applied Ecotoxicology, Dübendorf.

The key findings of a workshop jointly organized by the Swiss Centre of Applied Ecotoxicity, the Swiss Centre for Applied Human Toxicology (SCAHT), and the Federal Office of Public Health (FOPH) are summarized and provide a critical analysis of the current regulatory framework for nanomaterials and a snapshot of some hot topics in nanoscience.

Adsorption of arsenic on polyaluminum granulate.

The kinetics and efficiencies of arsenite and arsenate removal from water were evaluated using polyaluminum granulates (PAG) with high content of aluminum nanoclusters. PAG was characterized to be meso- and macroporous, with a specific surface area of 35 ± 1 m(2) g(-1). Adsorption experiments were conducted at pH 7.5 in deionized water and synthetic water with composition of As-contaminated groundwater in the Pannonian Basin. As(III) and As(V) sorption was best described by the Freundlich and Langmuir isotherm, respectively, with a maximum As(V) uptake capacity of ~200 µmol g(-1) in synthetic water. While As(III) removal reached equilibrium within 40 h, As(V) was removed almost entirely within 20 h. Micro X-ray fluorescence and electron microscopy revealed that As(III) was distributed uniformly within the grain, whereas As(V) diffused up to 81 µm into PAG. The results imply that As(V) is adsorbed 3 times faster while being transported 10(5) times slower than As(III) in Al hydroxide materials.

Solid solutions between CrO4- and SO4-ettringite Ca6(Al(OH)6)2[(CrO4)x(SO4)(1-x)]3*26 H2O.

Chromate is a toxic contaminant of potential concern, as it is quite soluble in the alkaline pH range and could be released to the environment. In cementitous systems, CrO4(2−) is thought to be incorporated as a solid solution with SO4(2−) in ettringite. The formation of a solid solution (SS) could lower the soluble CrO4(2−) concentrations. Ettringite containing SO4(2−) or CrO4(2−) and mixtures thereof have been synthesized. The resulting solids and their solubility after an equilibration time of 3 months have been characterized. For CrO4-ettringite at 25 °C, a solubility product log K(S0) of −40.2 ± 0.4 was calculated: log K(CrO4−ettringite) = 6log{Ca2+} + 2log{Al(OH)4(−)} + 3log{CrO4(2−)} + 4log{OH−} + 26log{H2O}. X-ray diffraction and the analysis of the solution indicated the formation of a regular solid solution between SO4- and CrO4-ettringite with a miscibility gap between 0.4 ≤ XCrO4 ≤ 0.6. The miscibility gap of the SO4- and CrO4-ettringite solid solution could be reproduced with a dimensionless Guggenheim fitting parameter (a0) of 2.03. The presence of a solid solution between SO4- and CrO4-ettringite results in a stabilization of the solids compared to the pure ettringites and thus in an increased uptake of CrO4(2−) in cementitious systems.

Development of a mobile fast-screening laser-induced breakdown detection (LIBD) system for field-based measurements of nanometre sized particles in aqueous solutions.

Laser-induced breakdown detection (LIBD) is a promising method to detect trace amounts of nanoparticles (NP, <100 nm) in aqueous suspensions. Based on available systems, we developed a mobile LIBD, designed for on-site and on-line measurements. We used the energy ratio of every laser pulse before and after passing the laser beam through the aqueous sample as a new method to detect laser-induced plasma events. The particle size and the particle number density are derived from recorded energy curves. Our LIBD is operated with a Nd:YAG laser at 100 Hz significantly reducing the measurement times compared to other LIBD systems operated at 20 Hz and increasing the capabilities for monitoring purposes. Long-term experiments on water samples revealed losses of NP up to 75% in 15 mL and 35% in 5 L sample containers after 3 months. The size of the particles remained constant (5 L) or slightly decreased (15 mL) indicating significant adsorption of NP to the walls of the sampling containers. Furthermore, we monitored the NP content of water after different purification steps at a drinking water plant (Maennedorf, Lake Zurich, Switzerland). Activated carbon filtration resulted in an increase of the particle size from approximately 20 nm to approximately 75 nm possibly caused by the release of organic fragments derived from the biology within the activated carbon tank. After the final ultrafiltration step the particle size was around 10 nm in agreement with the nominal cutoff of 100 kDa of the membrane. The results underline the strength of a fast-screening LIBD to detect relative changes in NP size and concentration.

In situ nanomanipulators as a tool to separate individual tobermorite crystals for AFM studies.

Atomic force microscopy (AFM) studies of cementitious materials are limited, mainly due to the lack of appropriate sample preparation techniques. In porous autoclaved aerated concrete (AAC), calcium silicate hydrate (C-S-H) is produced in its crystalline form, tobermorite. The crystals are lath-like with a length of several micrometers. In this work, we demonstrate the application of nanomanipulators to separate an individual tobermorite crystal from the bulk AAC for subsequent AFM investigations. The nanomanipulators are operated directly in an environmental scanning electron microscope (ESEM). We studied the interaction between moisture and the tobermorite surface under controlled relative humidity (RH). The results of topography and adhesion force measurements with AFM suggest that the surface of tobermorite is hydrophobic, which contrasts the macroscopic material properties (e.g. moisture transport in capillary pores).

Volatile composition, emission pattern, and localization of floral scent emission in Mirabilis jalapa (Nyctaginaceae).

We elucidated scent components, daily emission patterns, and the localization of floral scent release of Mirabilis jalapa. Volatiles emitted by the whole plant as well as by detached flowers were investigated using dynamic headspace analysis and gas chromatography/ mass spectrometry. Among several constituents including (Z)-3-hexenyl acetate, ß-myrcene, (Z)-ocimene, and benzyl benzoate, the monoterpene (E)-ß-ocimene was the major fragrance component. Fragrance release occurred in a time-dependent manner. The emission of volatiles, including (E)-ß-ocimene, showed an evening-specific maximum (1700-2000 pm). The emission of (Z)-3-hexenyl acetate reached its maximum 3 h later. Histological (neutral red staining) and morphological studies (electron and light microscopy) of the flower surface and tissues of M. jalapa revealed differences in surface structures and tissue characteristics. The flower could be divided into four main sections, including the tube, the transition zone between tube and limb, a star-shaped center of the limb, and petaloid lobes of the limb. These petaloid lobes are the site of (E)-ß-ocimene release. Stomata and trichomes found on the abaxial flower surface were not directly involved in fragrance release. Clear indications of osmophores involved in scent release could not be found. Thus, the results indicate that floral volatiles probably are released by diffuse emission in M. jalapa.