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Nanoplastics are an increasing environmental concern. In aquatic environments, nanoplastics will acquire an eco-corona by interacting with macromolecules (e.g., humic substances and extracellular polymeric substances (EPS)). Here, we show that the properties of the eco-corona and, consequently, its ability to enhance the transport of nanoplastics vary significantly with the surface functionality of nanoplastics and sources of macromolecules. The eco-corona derived from the EPS of Gram-negative

The release of fragments from plastic products, that is, secondary microplastics, is a major concern in the context of the global plastic pollution. Currently available (thermoplastic) polyurethanes [(T)PU] are not biodegradable and therefore should be recycled. However, the ester bond in (T)PUs might be sufficiently hydrolysable to enable at least partial biodegradation of polyurethane particles. Here, we investigated biodegradation in compost of different types of (T)PU to gain insights into their fragmentation and biodegradation mechanisms. The studied (T)PUs varied regarding the chemistry of their polymer backbone (aromatic/aliphatic), hard phase content, cross-linking degree, and presence of a hydrolysis-stabilizing additive. We developed and validated an efficient and non-destructive polymer particle extraction process for partially biodegraded (T)PUs based on ultrasonication and density separation. Our results showed that biodegradation rates and extents decreased with increasing cross-linking density and hard-segment content. We found that the presence of a hydrolysis stabilizer reduced (T)PU fragmentation while not affecting the conversion of (T)PU carbon into CO

Understanding the environmental fate of microplastics is essential for their risk assessment. It is essential to differentiate size classes and degradation states. Still, insights into fragmentation and degradation mechanisms of primary and secondary microplastics into micro- and nanoplastic fragments and other degradation products are limited. Here, we present an adapted NanoRelease protocol for a UV-dose-dependent assessment and size-selective quantification of the release of micro- and nanoplastic fragments down to 10 nm and demonstrate its applicability for polyamide and thermoplastic polyurethanes. The tested cryo-milled polymers do not originate from actual consumer products but are handled in industry and are therefore representative of polydisperse microplastics occurring in the environment. The protocol is suitable for various types of microplastic polymers, and the measured rates can serve to parameterize mechanistic fragmentation models. We also found that primary microplastics matched the same ranking of weathering stability as their corresponding macroplastics and that dissolved organics constitute a major rate of microplastic mass loss. The results imply that previously formed micro- and nanoplastic fragments can further degrade into water-soluble organics with measurable rates that enable modeling approaches for all environmental compartments accessible to UV light.

An increase in fire-prone conditions in non-fire adapted regions is rooted in climatic and anthropogenic changes. Such pyrogeographical shifts are observable, for example, in alpine regions. In 2021, Austria, experienced a fire larger than 100 ha for the first time in a century in the Schneeberg-Rax mountain region. In depth understanding of post-fire effects on carbon cycling at such non-fire adapted sites is still scarce. To help close this knowledge gap, post-fire changes were investigated at the abovementioned site, including soil organic matter composition and soil chemical conditions. Samples were taken immediately after the fire, 3 months, 6 months and 12 months thereafter from four sampling sites. Selected sites consisted of 1. a pine forest affected by a crown fire, 2. a pine and beech mixed forest affected by a surface fire, and two non-fire affected controls with similar site conditions (vegetation, slope, altitude, and exposition). Samples were analyzed for pH, carbon content, elemental composition, leachable dissolved organic carbon and trace elements, organic matter composition, and environmentally persistent free radical concentrations. pH increased after the fire at both sites investigated. This increase was the strongest (up to 1.5 units) immediately after the fire but was still substantial 1 year after the fire. Carbon contents decreased approximately 2fold in the crown fire affected soil compared to the control soil, but remained similar between surface fire affected soil and the respective control. However, aromaticity of bulk carbon and the leachable fraction increased in both fire-affected soils, which can be related to the formation of pyrogenic carbon during the fire. Pyrogenic carbon is a highly aromatic and recalcitrant carbon pool produced during incomplete combustion of biomass. Pyrogenic carbon can also contain substantial amounts of environmentally persistent free radicals (EPFR), which can form reactive oxygen species, which can induce oxidative stress on microbiota. Our EPFR measurements showed an increase by at least 1.5 orders of magnitude of EPFR in fire affected soils. This study suggests that changes in soil carbon cycling can be expected following fires in non-adapted alpine forests.

It is often assumed that the physical disintegration of biochar determines its persistence and mobility in soil. Freeze-thawing can cause physical stress on biochar, breaking it down into smaller and presumably more reactive particles. We here investigated the physical decay and subsequent mobilisation of five different biochars under "realistic worst-case scenarios" in a laboratory sand column setup, in shaking as well as in sonication experiments. Mobilisation of carbon from biochar particles (0.25 - 1 mm) was studied in a sand column (pH 6.3, with and without 80 freeze-thaw cycles). Small biochar particles did not disintegrate much after the freeze-thawing, possibly due to freezing point depression in biochar micropores. Freeze-thaw-induced physical decay of biochar is a process that is more pronounced in large biochar particles with substantial meso- and macropores, based on our results compared to literature data. Biochar with larger ash fractions disintegrated more, presumably due to the formation of unstable voids within the biochar associated with ash pockets. The physical stability of biochars produced from the same feedstock at different pyrolysis temperatures decreased with increasing aromaticity, which could be related to higher stiffness of the more aromatic structures. Soil moisture content increased carbon mobilisation from biochar more than physical stresses such as freeze-thawing. The physical disintegration of biochar and subsequent mobilisation of micro- and nanoscale carbon should therefore be considered less important and in many cases is not expected to be a decisive factor for the stability of biochar in soil.

Nitriding has been used for decades to improve the corrosion resistance of iron and steel materials. Moreover, iron nitrides (Fe

Tire wear particle (TWP)-derived compounds may be of high concern to consumers when released in the root zone of edible plants. We exposed lettuce plants to the TWP-derived compounds diphenylguanidine (DPG), hexamethoxymethylmelamine (HMMM), benzothiazole (BTZ)

The persistence of the artificial sweetener acesulfame potassium (ACE) in wastewater treatment and subsequently in the aquatic environment has made it a widely used marker of wastewater in both surface water and groundwater. However, the recently observed biodegradation of ACE during wastewater treatment has questioned the validity of this application. In this study, we assessed the use of ACE not only as a marker of wastewater, but also as a transient wastewater tracer that allows both the calculation of mixing ratios and travel times through the aquifer as well as the calibration of transient groundwater flow and mass transport models. Our analysis was based on the data obtained in a nearly 8-year river water and groundwater sampling campaign along a confirmed wastewater-receiving riverbank filtration site located close to a drinking water supply system. We confirm that temperature controls ACE concentrations and thus their seasonal oscillation. River water data showed that ACE loads decreased from 1,500-4,000 μg·s−1 from December to June (cold season; T10°C). This seasonal oscillation was transferred to the aquifer and preserved >3 km through the aquifer, with ACE concentrations oscillating between values below the detection limit in the warm season to 0.15 μg·L−1 in the cold season. The seasonal variation in ACE degradation during wastewater treatment enables the sweetener’s use as a transient tracer of wastewater inflows and riverbank filtration. In addition, the arrival time of the ACE concentration peak can be used to estimate groundwater flow velocity and mixing ratios, thereby demonstrating its potential in the calibration of groundwater numerical models.

The increasing use of gadolinium (Gd)-based contrast agents in magnetic resonance imaging and the recalcitrant behavior of Gd during municipal wastewater treatment have led to increased concentrations of the tracer in aquatic environments. These anthropogenic Gd emissions to wastewater and, subsequently, to surface and groundwater systems can be exploited to calculate groundwater travel times and mixing ratios, identify wastewater inputs, and calibrate groundwater models. However, analytical complexity, costs, and the time needed to directly measure anthropogenic inputs hinder the practical use of Gd. While direct measurements with inductively coupled plasma-mass spectrometry (ICP-MS) are highly efficient and feasible, only total Gd can be detected with this approach. In unknown hydrogeological systems, the differentiation between total, anthropogenic, and geogenic Gd by interpolating rare earth element patterns requires complex sample pre-treatment and pre-concentration. Direct measurements of Gd can be obtained using anion-exchange chromatography coupled to ICP-MS but the limit of quantification will be higher. Here we provide guidelines for selecting the optimal method for the analysis of Gd as a wastewater tracer in surface-groundwater systems.•The cost-effectiveness of existing analytical strategies to measure Gd when used as a wastewater tracer in surface-groundwater systems is addressed•A novel analytical strategy for direct determination of total Gd is presented.

Environmental context The effects of the presence of polymer additives and polymeric structure on sorption of xenobiotics to microplastics remain unclear. Our results combined data from experimental sorption batch experiments using three environmentally relevant model sorbates with confocal microscopy. This provides clear evidence that both factors play a major role in sorption strength and the underlying sorption process, affecting sorption onto the particle surface and partitioning into the bulk polymer. Abstract Microplastics are particulate contaminants of global concern. Interactions of microplastics with organic contaminants are frequently studied with commercially available polymer materials as surrogates. The influence of the polymer structure (i.e. internal 3D polymer geometry and monomer chain length) and the presence of additives on their interactions with xenobiotics remains unclear. This work investigates sorption of three sorbates of environmental concern to two polyamide (PA) and two polyvinyl chloride (PVC) sorbents of different molecular composition and additive content, respectively. Sorption was studied using complementary data from sorption isotherms and confocal laser-scanning microscopy. The additives in PVC increased sorption affinity owing to an increased sorbent hydrophobicity and a higher void volume within the polymer. Surface area normalisation indicated surface adsorption for unplasticised PVC and absorption for 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH)-plasticised PVC, which were confirmed using confocal laser-scanning microscopy. The strong sorption to PA was mainly driven by hydrogen-bond interactions. The contribution depended on the molecular features of the sorbent and the sorbate. Confocal laser-scanning microscopy showed that PA6 was taking up more sorbate into its bulk polymer matrix than PA12, the two being different in their chemical composition. This difference could be attributed to the higher swelling capability of PA6. The results emphasise that the molecular structure of the polymer and the presence of additives have to be taken into consideration when sorption of organic substances to plastics is investigated.

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. 13C-DNA added to sediment microcosms was largely degraded within 10 d and mineralized to 13CO2. SIP probing of DNA revealed diverse ‘Candidatus Izemoplasma’, Lutibacter, Shewanella and Fusibacteraceae incorporated DNA-derived 13C-carbon. NanoSIMS confirmed incorporation of 13C into individual bacterial cells of Fusibacteraceae sorted from microcosms. Genomes of the 13C-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., Using microcosms, stable isotope probing, genome-resolved metagenomics and NanoSIMS, the authors identify diverse bacterial taxa that can degrade extracellular DNA in marine sediments, including ‘Candidatus Izemoplasma’, which encode numerous extracellular nucleases.

Sulfidation and, more recently, nitriding have been recognized as promising modifications to enhance the selectivity of nanoscale zero-valent iron (nZVI) particles for trichloroethene (TCE). Herein, we investigated the performance of iron nitride (Fe

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.

Bank filtration is widely used for drinking water production around the world. Due to the general composition of river water and the possibility of direct anthropogenic inputs, it is of great importance to understand the interaction between river and groundwater as well as the subsurface flow conditions. These can alter with increased runoff during flood events. Higher gradients between the surface water and groundwater, enlarged infiltration zones or the removal of colmation layers can lead to elevated infiltration rates and thus to changes in the river aquifer system. Due to often high hydraulic permeabilities and the potential spatial proximity between the river and the extraction system, short dwell times may therefore occur. Additionally, associated with stormwater runoff of wastewater treatment plants, higher contamination risks can therefore be expected in the extraction system during flood events.In our investigations, we use a regional three-dimensional numerical groundwater model to help prevent changes in the quality of the extracted water through optimized operational management. However, the need to predict the flow paths between the river and the water work with maximum precision makes it necessary to complement the regional model with high resolution local models. To better capture vertical heterogeneities constraining local flow paths, a two-dimensional vertical model following the direction of maximum contribution of bank filtration to the water work was additionally created using FEFLOW 7.5 (DHI). Along this transect, the X-ray contrast agent gadolinium was sampled for use as a conservative anthropogenic tracer at different depths.The sampling of gadolinium every 12 hours during a minor flood event showed a weekly, wastewater-influenced signal in the surface water, which could also be followed in the transect. This signal, together with 222Rn tracer ages, complements the time-resolved observations of groundwater levels to calibrate the vertical distribution of hydraulic parameters of the two-dimensional mass transport model. These are supposed to improve the conceptual regional model to ultimately optimize the operation of the waterworks and allow the extraction of the groundwater with the best possible quality.

A sub-alpine catchment hosts a drinking water plant that collects groundwater through a series of drains. The catchment is crossed by a river that recharges the aquifer with potentially polluted water. The waterworks managers need a management strategy to maximize groundwater collection and minimize the probability to extract river water. This request was addressed by means of a groundwater model that simulates the mixing of river water and groundwater under a stochastic framework.Samples of river water show the presence of Gadolinium, a rare earth element used as a contrast agent (GBCA) for magnetic resonance imaging. This element is also recurrently found in samples taken from some monitoring wells, and previous studies have determined its suitability as a tracer of solute dispersion. We used it as an indicator of partitioning between river water and original groundwater.We built a simple, fast-running numerical groundwater model with the FEM code Feflow (DHI). We coupled it with PESTPP-IES, an optimization tool that implements the ensemble-smoother form of the Gauss-Levenberg-Marquardt algorithm. Through it, an ensemble of "realistic" parameter fields was generated, all of which support a good fit between model outputs and the calibration dataset. The latter included mixing ratios (calculated by measured Gadolinium concentrations) and groundwater levels. To simulate Gadolinium spread in groundwater, we used particle tracking instead of building an advective-dispersive transport model, because the latter is costlier to build and slower to run, therefore it does not allow the high number of runs required by PESTPP-IES. Although dispersion is not explicitly represented, its role is surrogated by uncertainty in hydraulic conductivity.With this study, we built the engine of a decision support system that will optimize waterworks management. We also demonstrated that a lean, purpose-driven model is adequate in simulating solute transport in complex hydrogeological systems. Gadolinium concentrations were instrumental in identifying the partitioning between river water and groundwater.

In this work we aim to understand how current questions in hydrogeology can be answered using new methods of data analysis developed in recent years. Water works supplying drinking water to large cities represent a hydrogeological challenge of great global interest. Ensuring optimal water quality not only under normal conditions but also during flood events is a public health issue. The pollution processes associated with flood events are the result of a combination of numerous factors at the basin scale, which complicates their prediction. Numerical models are powerful tools to simulate and manage groundwater flow around water works, but due to their high computational costs, simplifications and assumptions must be made, which reduces modelling precision. We selected a water work located in a subalpine fluvio-glacial aquifer, providing water to a large city. The water work is compound of several drains that extract the water from the aquifer by gravity. Hydrochemistry is stable under normal conditions but changes drastically during flood events, with a decrease in water quality. Due to the vast amount of data, on hydraulic heads, river levels and hydrochemistry, that is available from over 40 locations across the relevant area, modern data analysis tools perfectly complement the numerical model. The goal of our work is to review how to predict critical flood events and optimize water work operations accordingly by complementing numerical models with new methods of data analysis. To reach the ultimate goal of building a decision support system for water work operations state-of-the art data visualization tools must be combined with machine learning methods such as deep neural networks. These methods have a lower computational cost than numerical models, which makes them suitable for real-time predictions. They can also answer questions that are too complex for the numerical model. We provide an overview on the current literature on data visualization tools and neural networks for ground water modelling and suggest approaches relevant for the selected site. Customized data visualization tools are used to allow both researchers and water work operators gain information directly from the data, without further computations. A neural network trained with parameters describing rainfall in the area as well as groundwater and river levels is able to predict the correlation between rain events and water levels. A second neural network links river and groundwater levels to water quality at the water work. In a next step, water quality at the water work under different conditions is correlated with different modes of operation.

Fire derived pyrogenic organic matter / charcoal is a source of environmentally persistent free radicals, which are precursors of potentially harmful reactive oxygen species. We analyzed charcoal samples from ten wildfires, including crown as well as surface fires in boreal, temperate, subtropical and tropical climate regions. Concentrations of environmentally persistent free radicals in these samples were orders of magnitude higher than those found in soils or other “background” matrices, as measured via electron spin resonance spectroscopy. The highest concentrations were measured in woody charcoals that were highly carbonized. We also found that environmentally persistent free radicals remained unexpectedly stable in the field for at least 5 years. More details can be found in our recently published article: https://www.nature.com/articles/s43247-021-00138-2

Stromatolitic carbonates were formed in ancient microbial mats, and, thus, provide unique geochemical archives to reconstruct palaeo-environments in which microbial life thrived and evolved. In this study, we report the first geochemical data of Miocene stromatolites from the Oberpullendorf Basin (Austria) that were formed during the Badenian salinity crisis at the north-western coast of the Paratethys Sea. The combined approach of trace element data obtained by quadrupol ICP-MS with C-O isotopes of individual stromatolite laminae is used to reconstruct short-term variations of palaeo-environmental conditions in microbial habitats of the Oberpullendorf Basin.Stromatolitic carbonates in the lower stromatolite units show negative δ13Ccarb values and typical shale-normalized seawater-like rare earths and yttrium (REYSN) patterns with positive LaSN, GdSN anomalies, super-chondritic Y/Ho ratios, and heavy REYSN enrichments to light REYSN, indicating an open marine-dominated depositional setting. Stratigraphic upwards, stromatolitic carbonates show suppressed seawater-like REYSN signatures and increasing δ13Ccarb values that argue for the development of a restricted environment. Seawater-like REYSN patterns and homogenously distributed negative δ13Ccarb values in the stratigraphic uppermost part resemble the transition to fully marine environmental conditions again. Enrichment factors of bio-essential elements (Fe, Mn, Co, Zn, Mo, W) reflect sufficient element availability during marine conditions but limitation during the development of the (semi)closed lagoon.We show that combined REY, C isotopes, and enrichment factors of bio-essential elements bear the unique potential to reconstruct temporal changes in paleo-environments and determine the availability of bio-essential elements in microbial habitats. This approach provides the groundwork for a better understanding of the evolution and development of microbial metabolisms under severely different atmospheric-hydrospheric on planet Earth and beyond.

The application of carbonaceous materials for the restoration of degraded soil has been a field of active research for the last decades. Several studies show their ability to immobilize heavy metals and polycyclic aromatic compounds (PACs) in contaminated soils. However, there is still a lack of guidance to translate what has been demonstrated in the lab into practice. The possibility of immobilising a contaminant depends on the type of material used and its specific chemical and physical properties, as well as the quantity applied. The suitable sorbent selection from the variety of carbon-based materials available, including biochar and activated carbon, is one of the major difficulties for practitioners. Nevertheless, a generic assement of sorbent quantities needed for a specific immobilization at a given site is not possible, due to specific material properties, as well as differences in contamination scenario and soil properties. To overcome this bottleneck, we propose a workflow to evaluate the applicability of carbon-based materials for heavy metal- and PACs contaminated soil remediation, for scientists and practitioners alike.We initially carried out a literature review collecting knowledge on the influence of feedstock, production temperature and possible modification steps on a material’s physical and chemical characteristics. We further conducted expert interviews with practitioners and regulators in Austria. Thereafter, we performed laboratory scale experiments to complement the knowledge collected. For our experimental work, eleven carbon-based materials were used. A total of ten anonymized contaminated soil samples from existing remediation sites containing varying amounts of arsenic, antimony, cadmium, zinc, lead and PACs were used for batch and column experimentation to determine suitability and amendment rate of biochar for soil remediation. These experiments included the investigation of amendment scenarios at different scales (laboratory batch- to percolation column scale) to assess the suitability of small-scale batch experiments in our workflow. Batch tests with 5g of Our work will be summarized by a contaminant and site specific decision tree for suitability of biochar application. The decision tree will guide the practitioner through a series of questions that will assess whether the site is suitable for biochar-based soil remediation, which contaminants can be treated, what characteristics a suitable sorbent should have, what range in sorption affinity could be expected for a suitable sorbent, and what are potential application rates in the field.This study was partially funded by the Austrian Federal Ministry of Sustainability and Tourism (BMNT), management by Kommunalkredit Public Consulting GmbH (grant number B820017).

Drinking water systems providing water to large cities are frequently located in alluvial or fluvio-glacial aquifers because their high permeability allows high extraction rates. Under normal conditions, these systems are recharged by river bank filtration and groundwater is collected at a sufficient distance to ensure that filtration through the aquifer provides water of good quality. However, during flood events, infiltration from the river bank may increase reducing the transit time, which may result in a higher risk of contamination. Identifying the water origin and its path from the river to the water work is key to establish operational strategies that minimize or prevent contamination during flood events. In this study, we investigate the potential of using anthropogenic gadolinium, which is increasingly used as a contrast agent in magnetic resonance imaging (MRI) and finally verted into rivers, as a conservative tracer to identify pathways of river bank filtration and then contribute to minimize the uncertainty of numerical models.The test site is located in a rural sub-alpine basin. Several horizontal drains extract water from a fluvio-glacial aquifer by gravity. Under normal conditions, good quality water is collected; during flood events, due to the sudden increase in infiltration and decrease in transit times, water quality might deteriorate, as shown by the appearance of E. coli and coliforms. The concentration of anthropogenic gadolinium was measured in the river, in observation wells, and in the extracted drinking water over several years. The results demonstrated the great potential of gadolinium to identify and delineate the infiltration plumes produced by river bank filtration, which is contributing to reduce model uncertainty and evaluate the best pumping strategy for each of the drains in order to prevent water quality degradation.

Foraminifera are protists thriving in marine and estuarine environments. They occupy all sorts of habitats, from nearly fresh water to the abyssal ocean. In this study we investigated the uptake of inorganic carbon (C) and nitrogen (N) with respect to the presence of heavy metals (Cu, Fe, Pb, Zn) on the photosymbiont-bearing benthic coral reef foraminifera H. depressa d'Orbigny 1826. This species does not ingest food, it feeds exclusively on the products of its symbionts. Recent studies demonstrated the vulnerability of this species in the context of shifting environmental parameters (e.g. pCO2, temperature). Here, we analyzed the impact of heavy metal contamination on the metabolism of these diatom-hosting foraminifera. Incubation experiments were accomplished with artificial seawater enriched with heavy metals at 50 μg/L and 500 μg/L. Additionally, the stable isotopes 13C (sodium bicarbonate) and 15N (ammonium chloride) were added into the water to trace their assimilation. Seven individuals of H. depressa were used per replicate, placed in crystallization dishes and incubated for several time points (1d, 3d, 5d, 7d). Furthermore, Microscopy-PAM measurements were performed. The fluorometer consisting of a modified epi-fluorescence microscope equipped with a modulated LED light source and a photomultiplier for detection of modulated chlorophyll fluorescence was applied to monitor the heavy metal effects on the photosymbiont activity. We saw that copper exhibited the greatest toxicity, while iron increased symbiotic activity. Lead caused biased results, forming dark, brown spots in the cultures. While low concentrations of zinc promoted the growth and metabolism of the foraminifera, high concentrations were toxic.

Coal fly ash is used in the construction industry and holds potential as a resource for the extraction of rare earth elements and high-value metals such as scandium. It is commonly stored in uncovered landfills or ash ponds close to the coal-fired power stations. Major releases from these surface impoundments into adjacent rivers pose an environmental concern due to the harmful effects of associated heavy metals. Future releases may occur more frequently as the globally impounded ash volume continues to grow and climate change threatens to further increase extreme rainfall events, which can cause overflows of surface impoundments and failure of their retention dams. Minor releases of fly ash from the storage sites could be early warning signs of their declining retention. When reaching a river, fly ash particles deposit in its sediments. Thereby, fly ash particles may leave a sedimentary record of minor releases over many years, but these particles are difficult to detect due to their small size and low concentration.We used single particle inductively-coupled plasma time-of-flight mass spectrometry (spICP-TOF-MS) to identify element fractionation patterns in micrometer- and nanometer-sized fly ash particles. Some intermediately-volatile elements such as nickel, cobalt, and vanadium fractionate towards smaller particle sizes during coal combustion. These elements were enriched in fly ash up to three orders of magnitude above the natural sedimentary background levels. We found particles with this characteristic fly ash elemental fingerprint in four depths of a sediment core downstream of a fly ash landfill, indicating fly ash release into the river. Upstream river sediment reference samples, on the contrary, did not contain these particles. The detected releases of fly ash deposited only trace amounts of fly ash in the sediment, which were neither detected applying major and trace element analysis (ICP-OES, ICP-MS, and XRF), nor found through mineralogical (XRD) or morphological (SEM) investigations.We demonstrated that spICP-TOF-MS can be used to identify fly ash particles in river sediment at previously undetectable concentrations. This technique can thus help assess surface impoundment integrity to prevent catastrophic future spills.

The increase in the frequency of extreme precipitation events due to climate change, together with the continuous development of cities and surface sealing that hinder water infiltration into the subsoil, is accelerating the search for new facilities to manage stormwater. The Canary Islands (Spain) are taking advantage of the knowledge acquired in the construction of water mines to exploit a novel stormwater management facility, which we have defined as a dry gallery. Dry galleries are constituted by a vertical well connected to a horizontal gallery dug into highly permeable volcanic layers of the vadose zone, from where infiltration takes place. However, the lack of scientific knowledge about these facilities prevents them from being properly dimensioned and managed. In this work, we simulate for the first time the infiltration process and the wetting front propagation from dry galleries based on a 3D unsaturated flow model and provide some recommendations for the installation and sizing of these facilities. The fastest advance of the wetting front takes place during the earliest times of infiltration ( rates higher than 1000m∙d−1 and 2m3∙s−1. As time progresses, the propagation velocity and infiltration rate decrease as a consequence of the hydraulic gradient attenuation between the gallery and the aquifer. Therefore, stormwater infiltration is a highly transient process in which a sizing underestimation of 100%may be committed if unsaturated conditions or geological configuration are neglected.

This study improves the understanding of ZnO NP transformation and Zn behavior in redox-dynamic slightly alkaline freshwater sediments.

Gunshot residues (GSRs) from different types of ammunition have been characterized using a new method based on single-particle inductively coupled plasma time-of-flight mass spectrometry (sp-ICP-TOF-MS). This method can analyze thousands of particles per minute enabling rapid sample screening for GSR detection with minimal sample preparation. GSR particles are multi-elemental nanoparticles that are mainly defined by the elements lead, barium, and antimony. Sp-ICP-TOF-MS was also used to identify other elements contained in GSR particles while standard particle classification protocols do not consider the complexities of GSR compositions and can therefore miss out on valuable information. The proposed method can be used to support existing GSR detection methods, especially when lead-free, antimony-free, or tagged ammunition has been used; it also provides a possibility for multi-elemental fingerprinting of GSR particles.