Publications by authors named "Thilo Hofmann"

96 Publications

Genomic insights into diverse bacterial taxa that degrade extracellular DNA in marine sediments.

Nat Microbiol 2021 Jul 14;6(7):885-898. Epub 2021 Jun 14.

Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria.

Extracellular DNA is a major macromolecule in global element cycles, and is a particularly crucial phosphorus, nitrogen and carbon source for microorganisms in the seafloor. Nevertheless, the identities, ecophysiology and genetic features of DNA-foraging microorganisms in marine sediments are largely unknown. Here, we combined microcosm experiments, DNA stable isotope probing (SIP), single-cell SIP using nano-scale secondary isotope mass spectrometry (NanoSIMS) and genome-centric metagenomics to study microbial catabolism of DNA and its subcomponents in marine sediments. C-DNA added to sediment microcosms was largely degraded within 10 d and mineralized to CO. SIP probing of DNA revealed diverse 'Candidatus Izemoplasma', Lutibacter, Shewanella and Fusibacteraceae incorporated DNA-derived C-carbon. NanoSIMS confirmed incorporation of C into individual bacterial cells of Fusibacteraceae sorted from microcosms. Genomes of the C-labelled taxa all encoded enzymatic repertoires for catabolism of DNA or subcomponents of DNA. Comparative genomics indicated that diverse 'Candidatus Izemoplasmatales' (former Tenericutes) are exceptional because they encode multiple (up to five) predicted extracellular nucleases and are probably specialized DNA-degraders. Analyses of additional sediment metagenomes revealed extracellular nuclease genes are prevalent among Bacteroidota at diverse sites. Together, our results reveal the identities and functional properties of microorganisms that may contribute to the key ecosystem function of degrading and recycling DNA in the seabed.
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http://dx.doi.org/10.1038/s41564-021-00917-9DOI Listing
July 2021

Sulfidated nano-scale zerovalent iron is able to effectively reduce in situ hexavalent chromium in a contaminated aquifer.

J Hazard Mater 2021 03 24;405:124665. Epub 2020 Nov 24.

Regional Centre of Advanced Technologies and Materials, Palacký University Olomouc, Šlechtitelů 27, 783 71 Olomouc, Czech Republic. Electronic address:

In a number of laboratory studies, sulfidated nanoscale zero-valent iron (S-nZVI) particles showed increased reactivity, reducing capacity, and electron selectivity for Cr(VI) removal from contaminated waters. In our study, core-shell S-nZVI particles were successfully injected into an aquifer contaminated with Cr(VI) at a former chrome plating facility. S-nZVI migrated towards monitoring wells, resulting in a rapid decrease in Cr(VI) and Cr concentrations and a long-term decrease in groundwater redox potential observed even 35 m downstream the nearest injection well. Characterization of materials recovered from the injection and monitoring wells confirmed the presence of nZVI particles, together with iron corrosion products. Chromium was identified on the surface of the recovered iron particles as Cr(III), and its occurrence was linked to the formation of insoluble chromium-iron (oxyhydr)oxides such as CrFe(OH). Injected S-nZVI particles formed aggregates, which were slowly transformed into iron (oxyhydr)oxides and carbonate green rust. Elevated contents of Fe were detected even several months after injection, indicating good S-nZVI longevity. The sulfide shell was gradually disintegrated and/or dissolved. Geochemical modelling confirmed the overall stability of the resulting Cr(III) phase at field conditions. This study demonstrates the applicability of S-nZVI for the remediation of a Cr(VI)-contaminated aquifer.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124665DOI Listing
March 2021

Methanol-based extraction protocol for insoluble and moderately water-soluble nanoparticles in plants to enable characterization by single particle ICP-MS.

Anal Bioanal Chem 2021 Jan 29;413(2):299-314. Epub 2020 Oct 29.

Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA, 15213, USA.

The detection and characterization of soluble metal nanoparticles in plant tissues are an analytical challenge, though a scientific necessity for regulating nano-enabled agrichemicals. The efficacy of two extraction methods to prepare plant samples for analysis by single particle ICP-MS, an analytical method enabling both size determination and quantification of nanoparticles (NP), was assessed. A standard enzyme-based extraction was compared to a newly developed methanol-based approach. Au, CuO, and ZnO NPs were extracted from three different plant leaf materials (lettuce, corn, and kale) selected for their agricultural relevance and differing characteristics. The enzyme-based approach was found to be unsuitable because of changes in the recovered NP size distribution of CuO NP. The MeOH-based extraction allowed reproducible extraction of the particle size distribution (PSD) without major alteration caused by the extraction. The type of leaf tissue did not significantly affect the recovered PSD. Total metal losses during the extraction process were largely due to the filtration step prior to analysis by spICP-MS, though this did not significantly affect PSD recovery. The methanol extraction worked with the three different NPs and plants tested and is suitable for studying the fate of labile metal-based nano-enabled agrichemicals.
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http://dx.doi.org/10.1007/s00216-020-03014-8DOI Listing
January 2021

Key Physicochemical Properties Dictating Gastrointestinal Bioaccessibility of Microplastics-Associated Organic Xenobiotics: Insights from a Deep Learning Approach.

Environ Sci Technol 2020 10 25;54(19):12051-12062. Epub 2020 Sep 25.

College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300350, P. R. China.

A potential risk from human uptake of microplastics is the release of plastics-associated xenobiotics, but the key physicochemical properties of microplastics controlling this process are elusive. Here, we show that the gastrointestinal bioaccessibility, assessed using an in vitro digestive model, of two model xenobiotics (pyrene, at 391-624 mg/kg, and 4-nonylphenol, at 3054-8117 mg/kg) bound to 18 microplastics (including pristine polystyrene, polyvinyl chloride, polyethylene terephthalate, polypropylene, thermoplastic polyurethane, and polyethylene, and two artificially aged samples of each polymer) covered wide ranges: 16.1-77.4% and 26.4-83.8%, respectively. Sorption/desorption experiments conducted in simulated gastric fluid indicated that structural rigidity of polymers was an important factor controlling bioaccessibility of the nonpolar, nonionic pyrene, likely by inducing physical entrapment of pyrene in porous domains, whereas polarity of microplastics controlled bioaccessibility of 4-nonylphenol, by regulating polar interactions. The changes of bioaccessibility induced by microplastics aging corroborated the important roles of polymeric structures and surface polarity in dictating sorption affinity and degree of desorption hysteresis, and consequently, gastrointestinal bioaccessibility. Variance-based global sensitivity analysis using a deep learning neural network approach further revealed that micropore volume was the most important microplastics property controlling bioaccessibility of pyrene, whereas the O/C ratio played a key role in dictating the bioaccessibility of 4-nonylphenol in the gastric tract.
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http://dx.doi.org/10.1021/acs.est.0c02838DOI Listing
October 2020

Comment on Predicting Aqueous Adsorption of Organic Compounds onto Biochars, Carbon Nanotubes, Granular Activated Carbons, And Resins with Machine Learning.

Environ Sci Technol 2020 09 25;54(18):11636-11637. Epub 2020 Aug 25.

Department of Environmental Geosciences, Centre for Microbiology and Environmental Systems Science, University of Vienna, Althanstrasse 14, 1090 Wien, Austria.

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http://dx.doi.org/10.1021/acs.est.0c03931DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7498140PMC
September 2020

The importance of aromaticity to describe the interactions of organic matter with carbonaceous materials depends on molecular weight and sorbent geometry.

Environ Sci Process Impacts 2020 Sep;22(9):1888-1897

Environmental Geosciences, Centre for Microbiology and Environmental Systems Science, University of Vienna, Althanstraße, 1090 Wien, Austria.

Dissolved organic matter (DOM) is ubiquitous in aquatic environments where it interacts with a variety of particles including carbonaceous materials (CMs). The complexity of both DOM and the CMs makes DOM-CM interactions difficult to predict. In this study we have identified the preferential sorption of specific DOM fractions as being dependent on their aromaticity and molecular weight, as well as on the surface properties of the CMs. This was achieved by conducting sorption batch experiments with three types of DOM (humic acid, Suwannee River natural organic matter, and a compost extract) and three types of CMs (graphite, carbon nanotubes, and biochar) with different geometries and surface complexities. The non-adsorbed DOM fraction was analyzed by size exclusion chromatography and preferentially sorbed molecular weight fractions were analyzed by UV/vis and fluorescence spectroscopy. All three sorbent types were found to preferentially sorb aromatic DOM fractions, but DOM fractionation depended on the particular combination of sorbent and sorbate characteristics. Single-walled carbon nanotubes only sorbed the smaller molecular weight fractions (<1 kDa). The sorption of smaller DOM fractions was not accompanied by a preference for less aromatic compounds, contrary to what was suggested in previous studies. While graphite preferentially sorbed the most aromatic DOM fraction (1-3 kDa), the structural heterogeneity of biochar resulted in reduced selectivity, sorbing all DOM > 1 kDa. The results explain the lack of correlation found in previous studies between the amount of aromatic carbon in a bulk DOM and its sorption coefficient. DOM sorption by CMs was generally controlled by DOM aromaticity but complex sorbent surfaces with high porosity, curvatures and functional groups strongly reduced the importance of aromaticity.
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http://dx.doi.org/10.1039/d0em00267dDOI Listing
September 2020

Anthropogenic gadolinium in freshwater and drinking water systems.

Water Res 2020 Sep 29;182:115966. Epub 2020 May 29.

University of Vienna, Centre for Microbiology and Environmental Systems Science, Environmental Geosciences, Althanstraße 14, UZA2, 1090, Vienna, Austria. Electronic address:

The increasing use of gadolinium-based contrast agents (GBCAs) for magnetic resonance imaging is leading to widespread contamination of freshwater and drinking water systems. Contrary to previous assumptions that GBCAs are stable throughout the water cycle, they can degrade. The stability of GBCAs depends largely on their organic ligands, but also on the physicochemical conditions. There is specific concern regarding UV end-of-pipe water treatments, which may degrade GBCAs. Degradation products in drinking water supplies can increase the risk of adverse health effects. This is of particular relevance where the raw water for drinking water production has a higher proportion of recycled wastewater. GBCAs concentrations in aquatic systems, often referred to as anthropogenic gadolinium, are determined using a variety of calculation methods. Where anthropogenic gadolinium concentrations are low, the inconsistent use of these methods results in high discrepancies and high levels of uncertainty. The current COVID-19 crisis will, in the short-term, drastically decrease the input of GBCAs to freshwater systems. Temporal variations in anthropogenic gadolinium concentrations in river water can be used to better understand river-aquifer interactions and groundwater flow velocities. Collecting urine from all patients following MRI examinations could be a way forward to halt the generally increasing concentrations of Gd in drinking water systems and recover this technologically critical element.
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http://dx.doi.org/10.1016/j.watres.2020.115966DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7256513PMC
September 2020

Combined Chemisorption and Complexation Generate siRNA Nanocarriers with Biophysics Optimized for Efficient Gene Knockdown and Air-Blood Barrier Crossing.

ACS Appl Mater Interfaces 2020 Jul 23;12(27):30095-30111. Epub 2020 Jun 23.

Faculty of Life Sciences, Center of Pharmaceutical Sciences, Department of Pharmaceutical Chemistry, Laboratory of MacroMolecular Cancer Therapeutics (MMCT), University of Vienna, Althanstrasse 14, 1090 Vienna, Austria.

Current nucleic acid (NA) nanotherapeutic approaches face challenges because of shortcomings such as limited control on loading efficiency, complex formulation procedure involving purification steps, low load of NA cargo per nanoparticle, endosomal trapping, and hampered release inside the cell. When combined, these factors significantly limit the amount of biologically active NA delivered per cell , delivered dosages for a prolonged biological effect, and the upscalability potential, thereby warranting early consideration in the design and developmental phase. Here, we report a versatile nanotherapeutic platform, termed auropolyplexes, for improved and efficient delivery of small interfering RNA (siRNA). Semitelechelic, thiolated linear polyethylenimine (PEI) was chemisorbed onto gold nanoparticles to endow them with positive charge. A simple two-step complexation method offers tunable loading of siRNA at concentrations relevant for studies and the flexibility for inclusion of multiple functionalities without any purification steps. SiRNA was electrostatically complexed with these cationic gold nanoparticles and further condensed with polycation or polyethyleneglycol-polycation conjugates. The resulting auropolyplexes ensured complete complexation of siRNA into nanoparticles with a high load of ∼15,500 siRNA molecules/nanoparticle. After efficient internalization into the tumor cell, an 80% knockdown of the luciferase reporter gene was achieved. Auropolyplexes were applied intratracheally in Balb/c mice for pulmonary delivery, and their biodistribution were studied spatio-temporally and quantitatively by optical tomography. Auropolyplexes were well tolerated with ∼25% of the siRNA dose remaining in the lungs after 24 h. Importantly, siRNA was released from auropolyplexes and a fraction also crossed the air-blood barrier, which was then excreted via kidneys, whereas >97% of gold nanoparticles were retained in the lung. Linear PEI-based auropolyplexes offer a combination of successful endosomal escape and better biocompatibility profile . Taken together, combined chemisorption and complexation endow auropolyplexes with crucial biophysical attributes, enabling a versatile and upscalable nanogold-based platform for siRNA delivery and .
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http://dx.doi.org/10.1021/acsami.0c06608DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7467563PMC
July 2020

Accurate quantification of TiO nanoparticles in commercial sunscreens using standard materials and orthogonal particle sizing methods for verification.

Talanta 2020 Aug 15;215:120921. Epub 2020 Mar 15.

Department of Environmental Geosciences, Centre for Microbiology and Environmental Systems Science, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria. Electronic address:

The implementation and enforcement of product labeling obligation as required, for example, by the cosmetic product regulation, needs simple and precise validated analytical methods. This also applies to the analysis of nanoparticles in products such as cosmetics. However, the provision of such methods is often hampered by inaccurate sizing due to unwanted nanoparticle changes, interference of matrix components with sizing and interactions between nanoparticles and analytical instrumentation. It is, therefore, necessary to develop appropriate sample preparation methods that preserve NP properties and reduce or remove matrix compounds that interfere with sizing. Further, accurate particle size analysis of samples containing unknown and possibly multiple nanoparticulate constituents is needed. In this study, we evaluated three sample preparation methods to identify and quantify TiO nanoparticles in sunscreens. Specifically, we used a combination of ultracentrifugation and hexane washing, thermal destruction of the matrix, and surfactant assisted particle extraction. The method accuracy was assessed by two internal reference samples: pristine TiO nanoparticles (NM104) and similar TiO nanoparticles dispersed in a sunscreen matrix. The PSDs were determined using an asymmetrical flow field-flow fractionation hyphenated with multi-angle light scattering and inductively coupled plasma-mass spectroscopy. Particle sizing was based on size calibration of the particle retention time in the AF. Computation of radius of gyration from MALS data was used as an orthogonal particle sizing approach to verify ideal elution and particle size data from the AF calibration. Among the three tested sample preparation methods surfactant assisted particle extraction revealed TiO nanoparticle recoveries of above 90% and no increase in particle size due to sample preparation was observed. Finally, the sample preparation methods were applied to two commercial sunscreen samples revealing the existence of TiO-NP < 100 nm. Conclusively, the surfactant assisted particle extraction method can provide valid data for TiO-NPs in sunscreen and possibly for cosmetic samples of similar matrix.
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http://dx.doi.org/10.1016/j.talanta.2020.120921DOI Listing
August 2020

Deep Learning Neural Network Approach for Predicting the Sorption of Ionizable and Polar Organic Pollutants to a Wide Range of Carbonaceous Materials.

Environ Sci Technol 2020 04 27;54(7):4583-4591. Epub 2020 Mar 27.

Department of Environmental Geosciences, Centre for Microbiology and Environmental Systems Science, University of Vienna, Althanstrasse 14, 1090 Wien, Austria.

Most contaminants of emerging concern are polar and/or ionizable organic compounds, whose removal from engineered and environmental systems is difficult. Carbonaceous sorbents include activated carbon, biochar, fullerenes, and carbon nanotubes, with applications such as drinking water filtration, wastewater treatment, and contaminant remediation. Tools for predicting sorption of many emerging contaminants to these sorbents are lacking because existing models were developed for neutral compounds. A method to select the appropriate sorbent for a given contaminant based on the ability to predict sorption is required by researchers and practitioners alike. Here, we present a widely applicable deep learning neural network approach that excellently predicted the conventionally used Freundlich isotherm fitting parameters log and ( > 0.98 for log , and > 0.91 for ). The neural network models are based on parameters generally available for carbonaceous sorbents and/or parameters freely available from online databases. A freely accessible graphical user interface is provided.
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http://dx.doi.org/10.1021/acs.est.9b06287DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7205386PMC
April 2020

Groundwater Chemistry Has a Greater Influence on the Mobility of Nanoparticles Used for Remediation than the Chemical Heterogeneity of Aquifer Media.

Environ Sci Technol 2020 01 3;54(2):1250-1257. Epub 2020 Jan 3.

Department of Environmental Geosciences, Centre for Microbiology and Environmental Systems Science , University of Vienna , Althanstrasse 14 , 1090 Vienna , Austria.

The application of nanoscale zerovalent iron (nano-ZVI) particles for groundwater remediation has spurred research into the influence of the collector heterogeneity on the nano-ZVI mobility. The chemical heterogeneity of surfaces within aquifer media affects their surface charge distribution and their affinity for nano-ZVI. The groundwater chemistry affects the properties of both aquifer surfaces and the nano-ZVI particles. Commercial poly(acrylic acid)-coated nano-ZVI (PAA-nano-ZVI) particles were tested in column experiments using two solution chemistries and silica collectors with different degrees of chemical heterogeneity, achieved by ferrihydrite coating. A porous media filtration model was used to determine the attachment efficiency of PAA-nano-ZVI particles, and the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory was used to describe the interactions between PAA-nano-ZVI particles and the aquifer "collectors". The mobility of PAA-nano-ZVI particles suspended in ultrapure water depended on the extent of ferrihydrite coating on the collector surfaces. The mobility of PAA-nano-ZVI particles under environmentally relevant conditions was independent of the collector chemical heterogeneity. The size of PAA-nano-ZVI aggregates doubled, inducing gravitational sedimentation and possibly straining as mechanisms of particle deposition. There was no repulsive energy barrier between particles and collectors, and the DLVO theory was unable to explain the observed particle attachment. Our results suggest that the groundwater chemistry has a greater influence on the mobility of PAA-nano-ZVI particles than the collector chemical heterogeneity. A better understanding of polymer adsorption to nanoparticles and its conformation under natural groundwater conditions is needed to further elucidate nanoparticle-collector interactions.
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http://dx.doi.org/10.1021/acs.est.9b06135DOI Listing
January 2020

The leaching of phthalates from PVC can be determined with an infinite sink approach.

MethodsX 2019 6;6:2729-2734. Epub 2019 Nov 6.

Research Platform Plastics in the Environment and Society -PLENTY, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria.

Polyvinyl chloride (PVC) is the third most used polymer for plastic products in the European Union (+NO/ CH) and contains the highest amounts of additives, especially phthalic acid esters (phthalates). Leaching kinetics of additives from (micro-) plastics into aqueous environments are highly relevant for environmental risk assessment and modelling of the fluxes of plastics and its associated additives. Investigating the leaching of phthalates into aqueous environments in batch experiments is challenging due to their low solubility and high hydrophobicity and there are no standard methods to study release processes. Here we describe an infinite sink method to investigate the leaching of phthalates from PVC into the aqueous phase. Spiking and leaching experiments using bis(2-ethylhexyl) phthalate as a model phthalate enabled the validation and evaluation of the designed infinite sink method. The developed method offers: •a low-cost and simple approach to investigate leaching of phthalates from PVC into aqueous environments•the use of a high-surface activated carbon powder as an infinite sink•a tool to elucidate the transport fluxes of plastics and additives.
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http://dx.doi.org/10.1016/j.mex.2019.10.026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6880001PMC
November 2019

The molecular interactions of organic compounds with tire crumb materials differ substantially from those with other microplastics.

Environ Sci Process Impacts 2020 Jan 6;22(1):121-130. Epub 2019 Nov 6.

Department of Environmental Geosciences, Center for Microbiology, Environmental Systems Science, Austria and Research Platform Plastics in the Environment and Society (PLENTY), University of Vienna, Althanstrasse 14, 1090 Vienna, Austria.

Tire materials are the most commonly found elastomers in the environment and they account for a significant fraction of microplastic pollution. In the discussions on the environmental impact of microplastics tire materials and their sorption properties have been largely overlooked. In this study we used experimental sorption data from six organic probe sorbates sorbing to two tire materials and their major components, styrene butadiene rubber and carbon black, to gain a better understanding of the underlying sorption processes of tire materials. Commonly applied models used to describe non-linear sorption processes were unable to fully explain sorption to tire materials but showed that absorption into the rubber fraction dominated the sorption process. Hydrophobicity was approximated using the hexadecane-water partitioning constant, which correlated very well with the distribution data obtained for styrene rubber, whereas the correlations between hydrophobicity of sorbates and the sorption data to the tire materials were poor. Although hydrophobicity plays an important role in sorption to tire materials, additional interactions must be taken into account. Overall, the processes involved in sorption to tire materials differed significantly from those governing sorption to other microplastics.
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http://dx.doi.org/10.1039/c9em00423hDOI Listing
January 2020

NO and natural organic matter affect both soot aggregation behavior and sorption of S-metolachlor.

Environ Sci Process Impacts 2019 Oct;21(10):1729-1735

Chair of Analytical Chemistry and Water Chemistry, Technical University of Munich, Marchioninistrasse 17, 81377 Munich, Germany.

Soot is an important carbonaceous nanoparticle (CNP) frequently found in natural environments. Its entry into surface waters can occur directly via surface runoff or infiltration, as well as via atmospheric deposition. Pristine soot is likely to rapidly undergo aggregation and subsequent sedimentation in aquatic environments. Further, soot can sorb a variety of organic contaminants, such as S-metolachlor (log KD = 3.25 ± 0.12). During atmospheric transport, soot can be chemically transformed by reactive oxygen species including NO2. The presence of natural organic matter (NOM) in surface waters can further affect the aquatic fate of soot. To better understand the processes driving the fate of soot and its interactions with contaminants, pristine and NO2-transformed model soot suspensions were investigated in the presence and absence of NOM. NO2-oxidized soot showed a smaller particle size, a higher number of particles remaining in suspension, and a decreased sorption of S-metolachlor (log KD = 2.47 ± 0.40). In agreement with findings for other CNPs, soot stability against aggregation was increased for both pristine and NO2 transformed soot in the presence of NOM.
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http://dx.doi.org/10.1039/c9em00354aDOI Listing
October 2019

Biochar particle aggregation in soil pore water: the influence of ionic strength and interactions with pyrene.

Environ Sci Process Impacts 2019 Oct;21(10):1722-1728

Department of Environmental Geosciences, Centre for Microbiology and Environmental Systems Science, University of Vienna, Althanstraße 14, 1090 Wien, Austria.

The beneficial properties of biochar have led to its increasing application to soils for environmental management. Despite its stability in soil, biochar can physically disintegrate into smaller particles, which can then be relocated from the application area. Biochar transport is strongly dependent on the biochar particle size and aggregation, with the extent of aggregation depending on the chemistry of the soil pore water. Biochar has a strong sorption affinity for polyaromatic hydrocarbons (PAHs) such as pyrene, which can also affect its transport. We therefore investigated biochar particle aggregation in solutions of different ionic strengths (ultrapure water, 0.01 M CaCl2, and 0.1 M CaCl2) with suspensions of biochar particles, and with suspensions of biochar particles loaded with pyrene (0.2 and 3.6 g kg-1). Increasing the pyrene concentration in ultrapure water resulted in an increase in the biochar particle size, an effect that was more pronounced following equilibration for 28 days than following equilibration for only 24 hours. Biochar particle aggregation in solutions containing both pyrene and 0.01 M CaCl2 was greatly enhanced compared to aggregation in similar solutions with no pyrene. However, the influence of pyrene became negligible at high CaCl2 concentrations (0.1 M CaCl2). To determine the fate of biochar in soil, both the presence of PAHs and the influence of the pore water's ionic strength therefore need to be taken into account.
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http://dx.doi.org/10.1039/c9em00277dDOI Listing
October 2019

Chemosymbiotic bivalves contribute to the nitrogen budget of seagrass ecosystems.

ISME J 2019 12 8;13(12):3131-3134. Epub 2019 Aug 8.

University of Vienna, Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria.

In many seagrass sediments, lucinid bivalves and their sulfur-oxidizing symbionts are thought to underpin key ecosystem functions, but little is known about their role in nutrient cycles, particularly nitrogen. We used natural stable isotopes, elemental analyses, and stable isotope probing to study the ecological stoichiometry of a lucinid symbiosis in spring and fall. Chemoautotrophy appeared to dominate in fall, when chemoautotrophic carbon fixation rates were up to one order of magnitude higher as compared with the spring, suggesting a flexible nutritional mutualism. In fall, an isotope pool dilution experiment revealed carbon limitation of the symbiosis and ammonium excretion rates up to tenfold higher compared with fluxes reported for nonsymbiotic marine bivalves. These results provide evidence that lucinid bivalves can contribute substantial amounts of ammonium to the ecosystem. Given the preference of seagrasses for this nitrogen source, lucinid bivalves' contribution may boost productivity of these important blue carbon ecosystems.
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http://dx.doi.org/10.1038/s41396-019-0486-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6863832PMC
December 2019

The composition of bacterial communities associated with plastic biofilms differs between different polymers and stages of biofilm succession.

PLoS One 2019 5;14(6):e0217165. Epub 2019 Jun 5.

Department of Limnology and Bio-Oceanography, Center of Functional Ecology, University of Vienna, Vienna, Austria.

Once in the ocean, plastics are rapidly colonized by complex microbial communities. Factors affecting the development and composition of these communities are still poorly understood. Additionally, whether there are plastic-type specific communities developing on different plastics remains enigmatic. We determined the development and succession of bacterial communities on different plastics under ambient and dim light conditions in the coastal Northern Adriatic over the course of two months using scanning electron microscopy and 16S rRNA gene analyses. Plastics used were low- and high-density polyethylene (LDPE and HDPE, respectively), polypropylene (PP) and polyvinyl chloride with two typical additives (PVC DEHP and PVC DINP). The bacterial communities developing on the plastics clustered in two groups; one group was found on PVC and the other group on all the other plastics and on glass, which was used as an inert control. Specific bacterial taxa were found on specific surfaces in essentially all stages of biofilm development and in both ambient and dim light conditions. Differences in bacterial community composition between the different plastics and light exposures were stronger after an incubation period of one week than at the later stages of the incubation. Under both ambient and dim light conditions, one part of the bacterial community was common on all plastic types, especially in later stages of the biofilm development, with families such as Flavobacteriaceae, Rhodobacteraceae, Planctomycetaceae and Phyllobacteriaceae presenting relatively high relative abundances on all surfaces. Another part of the bacterial community was plastic-type specific. The plastic-type specific fraction was variable among the different plastic types and was more abundant after one week of incubation than at later stages of the succession.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0217165PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6550384PMC
January 2020

Legal and practical challenges in classifying nanomaterials according to regulatory definitions.

Nat Nanotechnol 2019 03 5;14(3):208-216. Epub 2019 Mar 5.

University of Vienna, Research Platform Nano-Norms-Nature, Vienna, Austria.

The European Union (EU) has adopted nano-specific provisions for cosmetics, food and biocides, among others, which include binding definitions of the term "nanomaterial". Here we take an interdisciplinary approach to analyse the respective definitions from a legal and practical perspective. Our assessment reveals that the definitions contain several ill-defined terms such as "insoluble" or "characteristic properties" and/or are missing thresholds. Furthermore, the definitions pose major and so far unsolved analytical challenges that, in practice, make it nearly impossible to classify nanomaterials according to EU regulatory requirements. An important purpose of the regulations, the protection of human health and the environment, may remain unfulfilled and the development of innovative applications of nanomaterials may be facing a path full of (legal) uncertainties. Based on our findings, we provide five recommendations for a more coherent and practical approach towards the regulation of nanomaterials.
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http://dx.doi.org/10.1038/s41565-019-0396-zDOI Listing
March 2019

Emerging contaminants in sediment core from the Iron Gate I Reservoir on the Danube River.

Sci Total Environ 2019 Apr 17;662:77-87. Epub 2019 Jan 17.

University of Vienna, Department of Environmental Geosciences and Environmental Science Research Network, Althanstrasse 14, 1090 Vienna, Austria.

The Iron Gate I Reservoir is the largest impoundment on the Danube River. It retains >50% of the incoming total suspended solids load and the associated organic contaminants. In the sediment core of the Iron Gate I Reservoir we report the presence and fate of four classes of emerging contaminants (pharmaceuticals, pesticides, steroids and perfluorinated compounds), predominantly not covered by the EU monitoring programs, but considered as future candidates. Based on contaminant's partitioning behavior in the water/sediment system and the suspected ecotoxicological potential asserted from the literature data, the risk of recorded concentrations for sediment-dwelling organisms was discussed. The high anticipated risk was associated with antibiotics sulfamethoxazole and erythromycin, and pesticides linuron and carbendazim (banned in the EU, but still approved for use in the investigated area) and malathion. This indicated the need for better control of release of these compounds into the river, and implied their inclusion in future regular monitoring. Higher concentrations of pharmaceuticals and most pesticides and sterols were recorded in the fragment of allochthonous coarser sediment, assumed to have entered the reservoir during a high discharge event. Only one perfluorinated compound was recorded in the upper part of the sediment core. The vertical concentration profiles of pesticides propazine and malathion indicated their uniform source, most likely atmospheric transport and deposition of particles deriving from agricultural land.
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http://dx.doi.org/10.1016/j.scitotenv.2019.01.205DOI Listing
April 2019

Polyethylene microplastics influence the transport of organic contaminants in soil.

Sci Total Environ 2019 Mar 5;657:242-247. Epub 2018 Dec 5.

University of Vienna, Department of Environmental Geosciences and Environmental Science Research Network, Althanstrasse 14, 1090 Vienna, Austria; University of Vienna, Research Platform Plastics in the Environment and Society (PLENTY), Althanstrasse 14, 1090 Vienna, Austria. Electronic address:

Plastics are now found in all natural environments including soil. The effects of microplastics in terrestrial systems, however, remain largely unexplored. Polyethylene is one of the mass-manufactured polymers found in terrestrial environments. It is used in many different sectors, for example in agricultural mulches, composite materials, and packaging. The presence of microplastics in soil, including polyethylene, can affect the transport of hydrophobic organic pollutants including pesticides. The objective of this study was to investigate the influence of polyethylene microplastics (<250 μm) on the transport of two selected organic plant-protection agents (atrazine and 4-(2,4-dichlorophenoxy) butyric acid) in soil under different aqueous conditions, using inverse liquid chromatography. The distribution coefficients for the sorbates that were sorbed to pure polyethylene microplastic were found to be significantly smaller than those for the sorbates sorbed to pure soil. The addition of 10% (w/w) polyethylene to the soil therefore led to an overall reduction in sorption, but the sorption trends due to variations in pH and ionic strength were not affected. The results imply that the presence of polyethylene microplastics in soil may therefore increase the mobility of organic contaminants by reducing the sorption capacity of natural soils, which must be validated by further research.
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http://dx.doi.org/10.1016/j.scitotenv.2018.12.047DOI Listing
March 2019

Synthesis and biological evaluation of biotin-conjugated anticancer thiosemicarbazones and their iron(III) and copper(II) complexes.

J Inorg Biochem 2019 01 19;190:85-97. Epub 2018 Oct 19.

Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Waehringer Str. 42, A-1090 Vienna, Austria; Research Cluster "Translational Cancer Therapy Research", Vienna, Austria.

Triapine, the most prominent anticancer drug candidate from the substance class of thiosemicarbazones, was investigated in >30 clinical phase I and II studies. However, the results were rather disappointing against solid tumors, which can be explained (at least partially) due to inefficient delivery to the tumor site. Hence, we synthesized the first biotin-functionalized thiosemicarbazone derivatives in order to increase tumor specificity and accumulation. Additionally, for Triapine and one biotin conjugate the iron(III) and copper(II) complexes were prepared. Subsequently, the novel compounds were biologically evaluated on a cell line panel with different biotin uptake. The metal-free biotin-conjugated ligands showed comparable activity to the reference compound Triapine. However, astonishingly, the metal complexes of the biotinylated derivative showed strikingly decreased anticancer activity. To further analyze possible differences between the metal complexes, detailed physico- and electrochemical experiments were performed. However, neither lipophilicity or complex solution stability, nor the reduction potential or behavior in the presence of biologically relevant reducing agents showed strong variations between the biotinylated and non-biotinylated derivatives (only some differences in the reduction kinetics were observed). Nonetheless, the metal-free biotin-conjugate of Triapine revealed distinct activity in a colon cancer mouse model upon oral application comparable to Triapine. Therefore, this type of biotin-conjugated thiosemicarbazone is of interest for further synthetic strategies and biological studies.
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http://dx.doi.org/10.1016/j.jinorgbio.2018.10.006DOI Listing
January 2019

Sorption to soil, biochar and compost: is prediction to multicomponent mixtures possible based on single sorbent measurements?

PeerJ 2018 11;6:e4996. Epub 2018 Jun 11.

Department of Environmental Geosciences, University of Vienna, Vienna, Austria.

Amendment with biochar and/or compost has been proposed as a strategy to remediate soil contaminated with low levels of polycyclic aromatic hydrocarbons. The strong sorption potential of biochar can help sequestering contaminants while the compost may promote their degradation. An improved understanding of how sorption evolves upon soil amendment is an essential step towards the implementation of the approach. The present study reports on the sorption of pyrene to two soils, four biochars and one compost. Detailed isotherm analyzes across a wide range of concentration confirmed that soil amendments can significantly increase the sorption of pyrene. Comparisons of data obtained by a classical batch and a passive sampling method suggest that dissolved organic matter did not play a significant role on the sorption of pyrene. The addition of 10% compost to soil led to a moderate increase in sorption (<2-fold), which could be well predicted based on measurements of sorption to the individual components. Hence, our result suggest that the sorption of pyrene to soil and compost can be relatively well approximated by an additive process. The addition of 5% biochar to soil (with or without compost) led to a major increase in the sorption of pyrene (2.5-4.7-fold), which was, however, much smaller than that suggested based on the sorption measured on the three individual components. Results suggest that the strong sorption to the biochar was attenuated by up to 80% in the presence of soil and compost, much likely due to surface and pore blockage. Results were very similar in the two soils considered, and collectively suggest that combined amendments with compost and biochar may be a useful approach to remediate soils with low levels of contamination. Further studies carried out in more realistic settings and over longer periods of time are the next step to evaluate the long term viability of remediation approaches based on biochar amendments.
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http://dx.doi.org/10.7717/peerj.4996DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6001708PMC
June 2018

Data on sorption of organic compounds by aged polystyrene microplastic particles.

Data Brief 2018 Jun 16;18:474-479. Epub 2018 Mar 16.

University of Vienna, Department of Environmental Geosciences and Environmental Science Research Network, Althanstrasse 14, 1090 Vienna, Austria.

This article contains data on experimental sorption isotherms of 21 probe sorbates by aged polystyrene microplastics. The polymeric particles were subjected to an UV-induced photo-oxidation procedure using hydrogen peroxide in a custom-made aging chamber. Sorption data were obtained for aged particles. The experimental sorption data was modelled using both single- and poly-parameter linear free-energy relationships. For discussion and interpretation of the presented data, refer to the research article entitled "Sorption of organic compounds by aged polystyrene microplastic particles" (Hüffer et al., 2018) [1].
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http://dx.doi.org/10.1016/j.dib.2018.03.053DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5996293PMC
June 2018

Environmental fate of nanopesticides: durability, sorption and photodegradation of nanoformulated clothianidin.

Environ Sci Nano 2018 Apr 22;5(4):882-889. Epub 2018 Feb 22.

Department of Environmental Geosciences and Environmental Science Research Network , University of Vienna , Althanstrasse 14, 5 UZA2 , 1090 Vienna , Austria . Email: ; Email:

A lot of research efforts are currently dedicated to the development of nano-enabled agrochemicals. Knowledge about their environmental behaviour is however scarce, which impedes the assessment of the new risk and benefits relative to currently used agrochemicals. With the aim to advance our understanding of the fate of nanopesticides in the environment and support the development of robust exposure assessment procedures, the main objectives of the study were to (i) investigate the extent to which three nanoformulations can affect the photodegradation and sorption of the insecticide clothianidin, and (ii) evaluate various approaches to estimate durability, a key parameter for the exposure assessment of nanopesticides. The nanoformulations increased the photodegradation half-life in water by a maximum of 21% relative to the conventional formulation. Sorption to soil was investigated by two methods and over time, and results show that sorption was increased by up to 51% and 10%, relative to unformulated clothianidin and the commercial formulation, respectively. Our results generally indicate that nanoformulations may have a greater impact on the fate of pesticide active ingredients than commercial formulations. It is important to note however that differences in fate parameters were generally very moderate, including in realistic worst-case conditions (high pesticide concentration and ionic strength). Our results collectively suggest that clothianidin was rapidly released from the nanocarrier systems and that the durability of the three nanoformulations would be short in water as well as in soil environments (including under realistic soil to solution ratio). The durability of nanoformulations after their application in the environment is an essential parameter that needs to be characterised for the development as well as for the evaluation of nano-enabled agrochemicals. This study illustrates how performances of nano-enabled products can be critically benchmarked against existing products to support an objective assessment of new environmental risks and benefits. In this context, the fate of the nanocarrier system is of great interest and should be the topic of further research.
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http://dx.doi.org/10.1039/c8en00038gDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5918303PMC
April 2018

Tire wear particles in the aquatic environment - A review on generation, analysis, occurrence, fate and effects.

Water Res 2018 08 24;139:83-100. Epub 2018 Mar 24.

Helmholtz Centre for Environmental Research - UFZ, Department of Analytical Chemistry, Permoserstrasse 15, 04318 Leipzig, Germany. Electronic address:

Tire wear particles (TWP), generated from tire material during use on roads have gained increasing attention as part of organic particulate contaminants, such as microplastic, in aquatic environments. The available information on properties and generation of TWP, analytical techniques to determine TWP, emissions, occurrence and behavior and ecotoxicological effects of TWP are reviewed with a focus on surface water as a potential receptor. TWP emissions are traffic related and contribute 5-30% to non-exhaust emissions from traffic. The mass of TWP generated is estimated at 1,327,000 t/a for the European Union, 1,120,000 t/a for the United States and 133,000 t/a for Germany. For Germany, this is equivalent to four times the amount of pesticides used. The mass of TWP ultimately entering the aquatic environment strongly depends on the extent of collection and treatment of road runoff, which is highly variable. For the German highways it is estimated that up to 11,000 t/a of TWP reach surface waters. Data on TWP concentrations in the environment, including surface waters are fragmentary, which is also due to the lack of suitable analytical methods for their determination. Information on TWP properties such as density and size distribution are missing; this hampers assessing the fate of TWP in the aquatic environment. Effects in the aquatic environment may stem from TWP itself or from compounds released from TWP. It is concluded that reliable knowledge on transport mechanism to surface waters, concentrations in surface waters and sediments, effects of aging, environmental half-lives of TWP as well as effects on aquatic organisms are missing. These aspects need to be addressed to allow for the assessment of risk of TWP in an aquatic environment.
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http://dx.doi.org/10.1016/j.watres.2018.03.051DOI Listing
August 2018

Optimising the transport properties and reactivity of microbially-synthesised magnetite for in situ remediation.

Sci Rep 2018 03 9;8(1):4246. Epub 2018 Mar 9.

Williamson Research Centre for Molecular Environmental Science, School of Earth and Environmental Science, University of Manchester, Manchester, M13 9PL, UK.

Engineered nanoparticles offer the potential for remediation of land and water that has been contaminated by organics and metals. Microbially synthesized nano-scale magnetite, prepared from Fe(III) oxides by subsurface Fe(III)-reducing bacteria, offers a scalable biosynthesis route to such a nano-scale remediation reagent. To underpin delivery of "bionanomagnetite" (BNM) nanomaterial during in situ treatment options, we conducted a range of batch and column experiments to assess and optimise the transport and reactivity of the particles in porous media. Collectively these experiments, which include state of the art gamma imaging of the transport of Tc-labelled BNM in columns, showed that non-toxic, low cost coatings such as guar gum and salts of humic acid can be used to enhance the mobility of the nanomaterial, while maintaining reactivity against target contaminants. Furthermore, BNM reactivity can be enhanced by the addition of surface coatings of nano-Pd, extending the operational lifetime of the BNM, in the presence of a simple electron donor such as hydrogen or formate.
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http://dx.doi.org/10.1038/s41598-018-21733-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5844888PMC
March 2018

Sorption of organic compounds by aged polystyrene microplastic particles.

Environ Pollut 2018 May;236:218-225

University of Vienna, Department of Environmental Geosciences and Environmental Science Research Network, Althanstrasse 14, 1090 Vienna, Austria. Electronic address:

Microplastics that are released into the environment undergo aging and interact with other substances such as organic contaminants. Understanding the sorption interactions between aged microplastics and organic contaminants is therefore essential for evaluating the impact of microplastics on the environment. There is little information available on how the aging of microplastics affects their sorption behavior and other properties. We have therefore investigated the effects of an accelerated UV-aging procedure on polystyrene microplastics, which are used in products such as skin cleaners and foams. Physical and chemical particle characterizations showed that aging led to significant surface oxidation and minor localized microcrack formation. Sorption coefficients of organic compounds by polystyrene microplastics following aging were up to one order of magnitude lower than for pristine particles. Sorption isotherms were experimentally determined using a diverse set of probe sorbates covering a variety of substance classes allowing an in-depth evaluation of the poly-parameter linear free-energy relationship (ppLFER) modelling used to investigate the contribution of individual molecular interactions to overall sorption. The ppLFER modelling was validated using internal cross-validation, which confirmed its robustness. This approach therefore yields improved estimates of the interactions between aged polystyrene microplastics and organic contaminants.
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http://dx.doi.org/10.1016/j.envpol.2018.01.022DOI Listing
May 2018

Influence of compost and biochar on microbial communities and the sorption/degradation of PAHs and NSO-substituted PAHs in contaminated soils.

J Hazard Mater 2018 Mar 10;345:107-113. Epub 2017 Nov 10.

University of Vienna, Department of Environmental Geosciences and Environmental Science Research Network, Althanstrasse 14, UZA2, 1090 Vienna, Austria. Electronic address:

Diffusely contaminated soils often remain untreated as classical remediation approaches would be disproportionately expensive. Adding compost can accelerate the biodegradation of organic contaminants and adding biochar can immobilize contaminants through sorption. The combined use of compost and biochar to reduce polycyclic aromatic hydrocarbon (PAH) and NSO-substituted PAH contamination has, however, not previously been systematically investigated. We have therefore investigated the processes involved (i) through sorption batch experiments, (ii) by monitoring changes in bacterial, fungal and archaeal communities using denaturing gradient gel electrophoresis, and (iii) through degradation experiments with fluorene, phenanthrene, pyrene, carbazole, dibenzothiophene, and dibenzofuran. Sorption coefficients for organic contaminants in soils increased tenfold following 10% compost addition and up to a hundredfold with further addition of 5% biochar. The rate of PAH and NSO-PAH degradation increased up to twofold following compost addition despite increased sorption, probably due to the introduction of additional microbial species into the autochthonous soil communities. In contrast, degradation of PAHs and NSO-PAHs in soil-compost-biochar mixtures slowed down up to tenfold due to the additional sorption, although some degradation still occurred. The combined use of biochar and compost may therefore provide a strategy for immobilizing PAHs and NSO-PAHs and facilitating degradation of remaining accessible contaminant fractions.
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http://dx.doi.org/10.1016/j.jhazmat.2017.11.010DOI Listing
March 2018

Effect of field site hydrogeochemical conditions on the corrosion of milled zerovalent iron particles and their dechlorination efficiency.

Sci Total Environ 2018 Mar 28;618:1619-1627. Epub 2017 Oct 28.

University of Vienna, Department of Environmental Geosciences and Environmental Science Research Network, Althanstraße 14, 1090 Vienna, Austria. Electronic address:

Milled zerovalent iron (milled ZVI) particles have been recognized as a promising agent for groundwater remediation because of (1) their high reactivity with chlorinated aliphatic hydrocarbons, organochlorine pesticides, organic dyes, and a number of inorganic contaminants, and (2) a possible greater persistance than the more extensively investigated nanoscale zerovalent iron. We have used laboratory-scale batch degradation experiments to investigate the effect that hydrogeochemical conditions have on the corrosion of milled ZVI and on its ability to degrade trichloroethene (TCE). The observed pseudo first-order degradation rate constants indicated that the degradation of TCE by milled ZVI is affected by groundwater chemistry. The apparent corrosion rates of milled ZVI particles were of the same order of magnitude for hydrogeochemical conditions representative for two contaminated field sites (133-140mmolkgday, indicating a milled ZVI life-time of 128-135days). Sulfate enhances milled ZVI reactivity by removing passivating iron oxides and hydroxides from the Fe surface, thus increasing the number of reactive sites available. The organic matter content of 1.69% in the aquifer material tends to suppress the formation of iron corrosion precipitates. Results from scanning electron microscopy, X-ray diffraction, and iron K-edge X-ray adsorption spectroscopy suggest that the corrosion mechanisms involve the partial dissolution of particles followed by the formation and surface precipitation of magnetite and/or maghemite. Numerical corrosion modeling revealed that fitting iron corrosion rates and hydrogen inhibitory terms to hydrogen and pH measurements in batch reactors can reduce the life-time of milled ZVI particles by a factor of 1.2 to 1.7.
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http://dx.doi.org/10.1016/j.scitotenv.2017.10.002DOI Listing
March 2018