Chemical Leachate Research Articles

Releasing characteristics of toxic chemicals from polystyrene microplastics in the aqueous environment during photoaging process

Microplastics (MPs) are pervasive in the environment and inevitably undergo photoaging due to UV irradiation. This study delved into the dynamic releasing and transformation process of toxic chemicals from polystyrene microplastics (PS MPs) during photoaging, a subject that remains underexplored. It was revealed that photoaging led to substantial alterations in the physicochemical properties of PS MPs, initiating polymer chain scission and facilitating the release of a large number of toxic chemicals, including numerous organic compounds and several inorganic compounds. The kinetic analysis revealed a dynamic release pattern for PS MPs, where under varying UV intensities (2, 5, and 10 mW/cm2), the release rate (kDOC) initially increased and then decreased, peaking at a total irradiation energy of approximately 7 kW·h/m2. Furthermore, chemicals in leachate were transformed into compounds with smaller molecular weight, higher oxidized and greater unsaturated state over the prolonged photoaging. This transformation was primarily attributed to two reasons. Firstly, the aged PS MPs released chemicals with higher oxidized state compared to the pristine MPs. Secondly, the chemicals previously released underwent further reactions. Besides, among the complex leachate generated by aged PS MPs, the organic chemicals characterized by small molecular weight and high oxidized state exhibited notable acute toxicity, whereas heavy metal ions showed lesser toxicity, and anions were non-toxic. This study shed more light on the photoaging process of PS MPs, releasing characteristics of organic chemicals, and the potential environmental risks associated with plastic wastes.

Microbially Mediated Rubber Recycling to Facilitate the Valorization of Scrap Tires.

The recycling of scrap tire rubber requires high levels of energy, which poses challenges to its proper valorization. The application of rubber in construction requires significant mechanical and/or chemical treatment of scrap rubber to compatiblize it with the surrounding matrix. These methods are energy-consuming and costly and may lead to environmental concerns associated with chemical leachates. Furthermore, recent methods usually call for single-size rubber particles or a narrow rubber particle size distribution; this, in turn, adds to the pre-processing cost. Here, we used microbial etching (e.g., microbial metabolism) to modify the surface of rubber particles of varying sizes. Specifically, we subjected rubber particles with diameters of 1.18 mm and 0.6 mm to incubation in flask bioreactors containing a mineral medium with thiosulfate and acetate and inoculated them with a microbial culture from waste-activated sludge. The near-stoichiometric oxidation of thiosulfate to sulfate was observed in the bioreactors. Most notably, two of the most potent rubber-degrading bacteria (Gordonia and Nocardia) were found to be significantly enriched in the medium. In the absence of added thiosulfate in the medium, sulfate production, likely from the desulfurization of the rubber, was also observed. Microbial etching increased the surface polarity of rubber particles, enhancing their interactions with bitumen. This was evidenced by an 82% reduction in rubber-bitumen separation when 1.18 mm microbially etched rubber was used. The study outcomes provide supporting evidence for a rubber recycling method that is environmentally friendly and has a low cost, promoting pavement sustainability and resource conservation.

Deep dive into the chronic toxicity of tyre particle mixtures and their leachates

Particles from the tread of vehicle tyres are a global pollutant, which are emitted into the environment at an approximate rate of 1.4 kg.year−1 for an average passenger-car. In this study, popular tyre brands were used to generate a tyre tread microparticle mixture. The chronic toxicity of both particles and chemical leachates were compared on a planktonic test species (Daphnia magna). Over 21 days of exposure, pristine tyre tread microparticles were more toxic (LC50 60 mg.L−1) than chemical lechates alone (LC50 542 mg.L−1). Microparticles and leachates showed distinct effects on reproduction and morphological development at environmentally relevant concentrations, with dose-dependent uptake of particles visible in the digestive tract. Chemical characterization of leachates revealed a metal predominance of zinc, titanium, and strontium. Of the numerous organic chemicals present, at least 54 were shared across all 5 tyre brands, with many classified to be very toxic. Our results provide a critically needed information on the toxicity of tyre tread particles and the associated chemicals that leach from them to inform future mitigation measures. We conclude that tyre particles are hazardous pollutants of particular concern that are close to or possibly above chronic environmental safety limits in some locations.

Plastic pellets make Excirolana armata more aggressive: Intraspecific interactions and isopod mortality differences between populations

Plastic pellets represent a significant component of microplastic (< 5 mm) pollution. Impacts caused by plastic pellets involve physical harm and toxicity related to ingestion and non-ingestion (such as the release of chemicals in leachates). The latter is the main route of exposure for invertebrate macrobenthic populations. This study aimed to compare the toxicity of plastic pellets in distinct marine macrobenthic populations, considering the influence of sediment characteristics (organic matter and grain size) and quality (contamination by hydrophobic chemicals) on ecotoxicological effects, as well as the influence of color on the toxicity of beach-stranded plastic pellets. We performed three experiments on plastic pellet exposure using Excirolana armata from beaches with high and low pellet density. When exposed to pellets, populations that inhabit beaches without pellets demonstrate higher mortality than those inhabiting beaches with high pellet densities. The mortality of E. armata to pellets was higher when the exposure occurred in sediment with high organic matter (OM), suggesting that chemicals were transferred from pellets to OM. Yellowish beach-stranded pellets induced higher mortality of E. armata than the white tones did. We also observed lethargic (near-dead) and dead individuals being preyed upon by healthy individuals, a cannibalistic behavior that raises an ecological concern regarding the negative effects of this exposure on intraspecific interactions in marine macrobenthic populations.

Microplastics and chemical leachates from plastic pipes are associated with increased virulence and antimicrobial resistance potential of drinking water microbial communities

There is increasing recognition of the potential impacts of microplastics (MPs) on human health. As drinking water is the most direct route of human exposure to MPs, there is an urgent need to elucidate MPs source and fate in drinking water distribution system (DWDS). Here, we showed polypropylene random plastic pipes exposed to different water quality (chlorination and heating) and environmental (freeze-thaw) conditions accelerated MPs generation and chemical leaching. MPs showed various morphology and aggregation states, and chemical leaches exhibited distinct profiles due to different physicochemical treatments. Based on the physiological toxicity of leachates, oxidative stress level was negatively correlated with disinfection by-products in the leachates. Microbial network analysis demonstrated exposure to leachates (under three treatments) undermined microbial community stability and increased the relative abundance and dominance of pathogenic bacteria. Leachate physical and chemical properties (i.e., MPs abundance, hydrodynamic diameter, zeta potential, total organic carbon, dissolved ECs) exerted significant (p < 0.05) effects on the functional genes related to virulence, antibiotic resistance and metabolic pathways. Notably, chlorination significantly increased correlations among pathogenic bacteria, virulence genes, and antibiotic resistance genes. Overall, this study advances the understanding of direct and indirect risks of these MPs released from plastic pipes in the DWDS.

Unlocking the potential of 3D printed microfluidics for mass spectrometry analysis using liquid infused surfaces

Combining microfluidics with mass spectrometry (MS) analysis has great potential for enabling new analytical applications and simplifying existing MS workflows. The rapid development of 3D printing technology has enabled direct fabrication of microfluidic channels using consumer grade 3D printers, which holds great promise to facilitate the adoption of microfluidic devices by the MS community. However, photo polymerization-based 3D printed devices have an issue with chemical leeching, which can introduce contaminant molecules that may present as isobaric ions and/or severely suppress the ionization of target analytes when combined with MS analysis. Although extra cure and washing steps have alleviated the leeching issue, many such contaminant peaks can still show up in mass spectra. In this work, we report a simple surface modification strategy to isolate the chemical leachates from the channel solution thereby eliminating the contaminant peaks for MS analysis. The channel was prepared by fabricating a layer of polydimethylsiloxane graft followed by wetting the graft using silicone oil. The resulting liquid infused surface (LIS) showed significant reduction in contaminant peaks and improvement in the signal intensity of target analytes. The coating showed good stability after long-term usage (7 days) and long-term storage (∼6 months). Finally, the utility of the coating strategy was demonstrated by printing herringbone microfluidic mixers for studying fast reaction kinetics, which obtained comparable reaction rates to literature values. The effectiveness, simplicity, and stability of the present method will promote the adoption of 3D printed microdevices by the MS community.

Investigation on microfiber release from elastane blended fabrics and its environmental significance

Elastane blended apparel is one of the most preferred items by consumers with fashion interest due to its enhanced comfort and fit. The environmental impact and microfiber release due to elastane usage is often ignored due to its lower percentage in apparel. To address such a gap, this study aimed to quantify and characterize the microfiber release behavior of cotton/elastane knitted fabric. Cotton/Elastane blended knitted fabrics with three different proportions of Cotton/Elastane (98/2, 95/5, and 92/8) were considered for this analysis. Upon laundry and quantification, the results of the study showed that 98/2 Cotton/Elastane fabric released 21.04 ± 12.46 microfibers/sq.cm, whereas, 92/8 Cotton/Elastane fabric released 46.56 ± 6.21 microfibers/sq.cm. An increase in elastane proportion increased the overall emission of microfibers per unit area of fabric. The results also showed a higher contribution of elastane fibers in the total microfibers released. 13.40% of the total fibers released were elastane microfibers in the case of 98/2 Cotton/Elastane fabric, whereas, 92/8 Cotton/Elastane fabric released 19.60% of elastane microfibers. The elastane percentage of the fabric showed a significant positive correlation with total microfiber emission (r = 63%) and elastane microfiber emission (r = 62%). Repeated laundering results showed an overall reduction in microfiber emissions in subsequent washes. However, interestingly, an increase in the wash cycle increased the proportion of elastane microfibers in the total microfibers released. 92/8 Cotton/Elastane fabric released 20% of elastane microfibers in the first wash and the proportion increased to 36% in the 4th wash. In contrast to that, the release of cotton microfibers is noted to decrease with the number of laundry cycles. As far as the length of microfiber is considered, elastane microfibers are shorter than cotton microfibers. The length of elastane microfibers was higher in the initial wash (98/2 Cotton/Elastane fabric - 352.5 μm; 95/5 Cotton/Elastane fabric - 920 μm; 92/8 Cotton/Elastane fabric - 695 μm) and it is reduced with increment in the number of washes with a strong negative correlation of −0.88. A higher proportion of emissions and lower fiber length are the alarming negative impacts of elastane fibers in apparel. Based on this analysis, it is estimated that one square meter of fabric with a lower elastane percentage (2%) can release up to 2.81 × 104 microfibers into the environment at the first wash. The threatening issues of microfibers on aquatic life, particularly in terms of bioaccumulation and biomagnification, are alarming. Elastane blended fabrics should be given special attention because they can make the problem more serious by posing a risk of chemical leachates, such as bisphenols.

Physical and chemical effects of conventional microplastic glitter versus alternative glitter particles on a freshwater plant (Lemnaceae: Lemna minor)

Glitters are primary microplastics which are directly littered into the environment, yet the ecological effects have seldom been tested. When microplastics enter the environment, their physical presence and chemical leachate may alter the physiology of primary producers. Glitter can be composed of plastic or natural and/or biodegradable materials, often with additives. Three experiments were run for 14 days to separate chemical and physical effects of different types of glitter: polyethylene terephthalate (PET), biodegradable modified regenerated cellulose (MRC), synthetic mica, and a natural particle control (kaolinite) on several physical characteristics of Lemna minor (common duckweed). L. minor was exposed to either fresh (chemical and physical effects), leachate from glitter (chemical) or aged glitter (physical). Overall, there was little effect of PET, synthetic mica, kaolinite or of any aged glitter. High concentrations of fresh MRC glitters, however, decreased root length, biomass and chlorophyll content of L. minor. Some of these effects were also present when exposed to leachate from MRC glitters, but were less pronounced. Elemental analysis revealed the presence of metals in MRC glitters which may explain these responses. Short-term ecotoxicity of biodegradable glitters can arise due to their physical and chemical properties, but may lessen over time as their surface coating degrades.

Ecological risk assessment of tire and road wear particles: A preliminary screening for freshwater sources in Canada

Abrasion of tires on road surfaces leads to the formation of tire and road wear particles (TRWPs). Approximately 5.9 million tonnes/year of TRWPs are emitted globally, and 12–20% of emissions generated on roads are transmitted into surface waters, where they can release (i.e., leach) chemical compounds that adversely affect aquatic species. To better understand the ecological risk of TRWPs, an acute, probabilistic ecological risk assessment model was developed and applied. This was a screening-level, conceptual ecological risk assessment (ERA) based on secondary data from published scientific studies. The model was demonstrated using British Columbia (BC) Highway 97 (TRWP source) and Kalamalka Lake (receiving water) in Canada, considering two spatial scenarios with varied highway (HWY) lengths and lake volumes. TRWP-derived chemical leachates considered for ERA were aniline, anthracene (ANT), benzo(a)pyrene (B(a)P), fluoranthene (Fl), mercaptobenzothiazole (MBT), and zinc (Zn). An assumed ‘total TRWP-derived leachate set’ was also assessed, representing all compounds present in tire-derived leachate test solutions. The results indicated the risk to aquatic species in two spatial scenarios. In scenario 1, ecotoxicity risk was high from exposure to TRWP-derived zinc and the total TRWP-derived leachate set. Scenario 2 results indicated acute risk was high from all TRWP-derived chemicals examined, except MBT. This preliminary ecological risk screening provides an early signal that freshwater lakes adjacent to busy highways may be at risk from TRWP contamination, indicating a need for further research. This research is the first ERA of TRWPs in Canada, and the results and methodology provide a foundation for future research and solutions development.

Effect of salt permeants on the consolidation and hydraulic behaviour of fibre treated black cotton soil for landfill application

Clay liner functions as an impermeable barrier between leachate and groundwater in landfills. In this work, naturally available black cotton (BC) soil is adopted as a liner material due to its high swelling and low hydraulic conductivity, which helps to eliminate the risk of groundwater pollution by preventing pollutant mobility. The liner's potential is threatened by two issues: shrinkage cracks and chemical attacks. BC soil induces desiccation cracks and high compressibility due to its high shrinkage potential upon drying, which severely impacts its hydraulic conductivity behaviour. In recent years, fibres have been used as reinforcing materials to control compressibility and shrinkage cracks of the liner. In this investigation, waste tire fibres, which were used as a reinforcing material, mixed with BC soil in the proportion of 5, 10 and 15% by their dry weight. Since the essential parameters of liner would change due to the interaction of chemicals in leachate, hence, this study examined the consolidation and hydraulic properties of fibre mixed BC soil in the presence of two inorganic salt permeants (NaCl and CaCl2) of two concentrations (0.1 and 1N) to mimic the leachate effect. The results revealed that when salt solutions were utilised as saturating pore liquids, the time to achieve the 90% of consolidation (t90) of fibre-treated BC soil was decreased, thereby increasing the coefficient of consolidation (cv). These changes were more significant at higher concentrations of pore liquids. The t90 value for 15% fibre-treated soil with DI water is 27.0 min, and it decreased drastically to 0.8 min (97.0% reduction) for 1N NaCl solution and 0.6 min (97.8% reduction) for 1N CaCl2 solution at the higher consolidation pressure of 784.5 kPa. Compression index (Cc) and void ratio (e) were reduced with the salt permeants irrespective of the fibre content. Finally, it was shown that salts substantially impact the hydraulic conductivity values of fibre-treated soil and that up to 10% fibre content is appropriate for landfill liner application.

Sustainable leachate pre-treatment using microbial desalination cell for simultaneous desalination and energy recovery

Leachate treatment technologies struggle with low treatment efficiencies due to complex and toxic chemicals in leachate. Therefore, mixing leachate with low-density wastewater could be beneficial. This research studied the feasibility of pretreating a mixture of leachate and municipal wastewater (1:4) in a microbial desalination cell (MDC) for the first time. The study examined the MDC potential in removing organics and NH3-N from leachate-wastewater mixture along with measuring the desalination efficiency and energy recovery at different applied external resistance (Rext). The results showed that MDC-1 (at Rext = 1 Ω) showed a higher desalination rate (DR) (35.71 mg/h) and higher NH3-N removal (36%) with lower COD removal (28%) compared to MDC-100 (at Rext = 100 Ω) with DR = 17.98 mg/h, NH3-N removal of 10% and COD removal of 78.26%. The results revealed that Rext could regulate the pollutants (organics, NH3-N) removal and desalination efficiency. The lack of soluble organics could also result in significant discrepancies in bioelectrochemical performance. MDC-100 showed four times higher energy output (5.63 W·m−3) compared to MDC-1 (1.39 W·m−3), while MDC-1 showed five times higher columbic efficiency (29.3%) compared to MDC-100 (5.52%). Future studies should investigate the best MDC configurations for the optimum leachate-wastewater ratio for sustainable leachate treatment.

Leachate analysis of two waste dumpsites in Pretoria, South Africa

Improper waste management practices may increase concentrations of noxious chemicals in leachate. This study analysed concentrations of trace metals in leachate collected from two waste dumpsites in Pretoria, South Africa. An open ended questionnaire was implemented to managers to gather information on management options. Leachate samples were collected in triplicates from leachate ponds and stored below 10°C. Trace metal contents from samples were analysed using inductively coupled plasma mass spectrometry-7700 (ICP-MS-7700). Significant differences in the concentrations of trace metals were analysed using the student t-test. Both sites lacked leachate collection and treatment systems and official recycling programmes. The levels of lead (Pb), manganese (Mn), chromium (Cr), mercury (Hg), arsenic (As) and nickel (Ni) were above the recommended limits. Significant differences in trace metal concentrations were established at both dumpsites. Proper waste management can reduce concentrations of trace metals levels and environmental contamination.

Impacts to Larval Fathead Minnows Vary between Preconsumer and Environmental Microplastics.

Microplastics are a complex suite of contaminants varying in size, shape, polymer, and associated chemicals and are sometimes referred to as a "multiple stressor." Still, the majority of studies testing hypotheses about their effects use commercially bought microplastics of a uniform size, shape, and type. We investigated the effects of polyethylene and polypropylene microplastics purchased as preproduction pellets (referred to as "preconsumer") and a mixture of polyethylene and polypropylene collected from the environment (environmental microplastic). Embryo-stage fathead minnows were exposed to either the physical plastic particles and their leachates or the chemical leachates alone at an environmentally relevant (280 particles/L) or high (2800 particles/L) concentration for 14 d. The effects of microplastics differed by polymer type and presence of environmental contaminants, and effects can be driven by the physical particles and/or the chemical leachates alone. Larvae exposed to preconsumer polyethylene experienced a decrease in survival, length, and weight, whereas preconsumer polypropylene caused an increase in weight. Environmental microplastics caused a more drastic increase in length and weight and almost 6 times more deformities as the preconsumer microplastics. Although preconsumer microplastics caused effects only when organisms were exposed to both the particles and the chemical leachates, the environmental microplastics caused effects when organisms were exposed to the chemical leachates alone, suggesting that the mechanism of effects are context-dependent. The present study provides further support for treating microplastics as a multiple stressor and suggests that testing for effects with pristine microplastics may underestimate the true effects of microplastics in the environment. Environ Toxicol Chem 2022;41:858-868. © 2021 SETAC.

Tire wear particle and leachate exposures from a pristine and road-worn tire to Hyalella azteca: Comparison of chemical content and biological effects

Tire emissions have emerged as an environmental contaminant of concern. To fully understand their effects to biota, research is needed from different stages of a tire’s lifecycle. In this study we exposed freshwater Hyalella azteca to tire wear particles (TWPs) as particle suspensions or their respective chemical leachates (the chemicals released from tire particles into water) from a pristine (P-TWP) and worn (W-TWP) tire of same make and model. Acute and long-term toxicity experiments on H. azteca showed that P-TWP suspensions were more toxic than W-TWP suspensions with estimated LC50 values of 364 ± 64 particles (0.19 ± 0.03 g L−1) and 3073 ± 211 particles (0.91 ± 0.06 g L−1), respectively. However, leachates from W- and P-TWPs appeared equally toxic, but did not conform to a sigmoidal dose-response pattern and LC50 values could not be derived. In long-term tests (21 d) P-TWP suspensions showed no significant effects on H. azteca mortality (p = 0.970) or reproduction (p = 0.123), but growth was significantly reduced (p = 0.003) at the highest concentration tested (250 particles mL−1 or 0.127 g L-1). Chemical analysis of both particle types and their leachates showed that four compounds, benzothiazole, 1-indanone, aluminum and zinc, consistently leached from TWPs into water. Analysis of the two TWPs showed a difference in the concentration of the various compounds. Specifically, P-TWPs contained significantly more 1-octanethiol, phenanthrene, anthracene and aluminum than W-TWPs, suggesting that they are possible candidates for the increased toxicity observed following P-TWP exposure.

Brominated flame retardants and perfluoroalkyl substances in landfill leachate from Ireland

Between June and November 2017, leachate samples were collected from 40 landfills across the Republic of Ireland. Concentrations of perfluoroalkyl substances (PFASs), polybrominated diphenyl ethers (PBDEs), and hexabromocyclododecane (HBCDD) determined in these samples were within the range previously reported in other countries. Average concentrations of PFASs exceeded those of PBDEs and HBCDD; likely due to the higher water solubility of PFASs. Log-transformed concentrations of BDEs-47, 100, 153, and 183, as well as perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorobutane sulfonate (PFBS) were significantly (p < 0.05) higher in leachate from newer, lined landfills than in samples from unlined landfills. These higher concentrations in lined landfills are likely related to the fact that lined landfills are found to retain organic matter leading to a higher organic content of leachate from such landfills. This is evidenced by the significant (p < 0.05) correlation between log-transformed concentrations in leachate of most of the same contaminants and those of chemical oxygen demand (COD). Concentrations of the less water-soluble, higher molecular weight BDE-209 were not correlated with leachate COD, nor landfill age or the presence of a landfill liner. This suggests that the presence of BDE-209 in landfill leachate is driven more by physical abrasion of particles and fibres from waste articles, than dissolution into the aqueous phase. The higher concentrations of some PFASs and PBDEs in leachate from lined landfills present a challenge with respect to leachate disposal, when leachate is sent to wastewater treatment plants that do not necessarily have mechanisms in place to remove or destroy these chemicals prior to discharge into the environment. Moreover, the presence of these persistent organic chemicals in leachate from unlined landfills raises concerns about releases to the environment including groundwater over the lifetime of such landfills and beyond.

Biological soil crust and vascular plant interactions in Western Myall (Acacia papyrocarpa) open woodland in South Australia

AbstractAimBiological soil crust (BSC) is a key component of arid environments and plays a major role in determining ecological structure and function. Our research aim was to examine several mechanisms that contribute to BSC–plant interactions at species and community levels, to increase our understanding of plant community dynamics.LocationYellabinna Regional Reserve, South Australia (30°50′17.99″ S, 132°12′10.37″ E).MethodsWe used seed extraction techniques to examine soil seed banks beneath patches with and without BSC, and field and glasshouse experiments to study the effects of crust presence and disturbance on seedling emergence and survival. We also explored the influence of chemical leachates from BSC on seed germination.ResultsBiological soil crust plays a pivotal role in influencing spatial patterns in soil seed bank composition. Our results showed less propagules accumulate in soils beneath crust when compared with patches without crust, and that propagule size is a contributing factor to determining their distribution between patch types. We found that late‐stage BSC physically inhibited seedling emergence, which increased when the BSC was disturbed in field experiments. Low seedling survivorship in both patch types suggests that although BSC may suppress recruitment in favourable years, it is low precipitation levels that have the over‐riding impact on recruitment success. Finally, leachates from late‐stage BSC were found to inhibit germination in three annual plant species, whilst early‐stage BSC accelerated germination in one annual plant. This clearly shows that leachate effects on seed germination vary according to plant species and crust successional stage.ConclusionOverall, we identified several mechanisms through which BSC has complex effects on the annual and short‐lived perennial plant guilds of arid lands. These mechanisms contribute to species diversity through the creation of spatial heterogeneity in soil seed bank structure and emergence opportunities.

Germanium speciation using liquid chromatography-inductively coupled plasma-triple quadrupole mass spectrometry: Germanium in biological and chemical leaching solutions of fine-grained residues from copper smelting

A new method for the speciation analysis of inorganic germanium (Ge(OH)4), monomethylgermanium (MMGe) and dimethylgermanium (DMGe) in complex acidic aqueous leachates by liquid chromatography coupled to inductively coupled plasma mass spectrometry (LC-ICP-MS) was developed. The species are separated using anion exchange chromatography with tartrate added as complexing agent. When tartrate was added to the sample and the eluent chromatography was not affected by sulfate concentrations up to 100 mM. The He collision mode (MS/MS mode) removes polyatomic plasma- and matrix-based interferences, thus providing the selectivity in Ge speciation required for the complex samples. With LOQs of 62 ng L−1 (DMGe), 67 ng L−1 (MMGe) and 164 ng L−1 (Ge(OH)4) the method was sufficiently sensitive for the intended application. The developed method was applied to biological and chemical leachates of sulfidic flue dust from copper shale smelting (Theisen sludge). Only small amounts of methylated Ge species were determined next to inorganic Ge in these leachates.

Feasibility and Biocompatibility of 3D‐Printed Photopolymerized and Laser Sintered Polymers for Neuronal, Myogenic, and Hepatic Cell Types

The integration of additive manufacturing (AM) technology within biological systems holds significant potential, specifically when refining the methods utilized for the creation of in vitro models. Therefore, examination of cellular interaction with the physical/physicochemical properties of 3D-printed polymers is critically important. In this work, skeletal muscle (C2 C12 ), neuronal (SH-SY5Y) and hepatic (HepG2) cell lines are utilized to ascertain critical evidence of cellular behavior in response to 3D-printed candidate polymers: Clear-FL (stereolithography, SL), PA-12 (laser sintering, LS), and VeroClear (PolyJet). This research outlines initial critical evidence for a framework of polymer/AM process selection when 3D printing biologically receptive scaffolds, derived from industry standard, commercially available AM instrumentation. C2 C12 , SH-SY5Y, and HepG2 cells favor LS polymer PA-12 for applications in which cellular adherence is necessitated. However, cell type specific responses are evident when cultured in the chemical leachate of photopolymers (Clear-FL and VeroClear). With the increasing prevalence of 3D-printed biointerfaces, the development of rigorous cell type specific biocompatibility data is imperative. Supplementing the currently limited database of functional 3D-printed biomaterials affords the opportunity for experiment-specific AM process and polymer selection, dependent on biological application and intricacy of design features required.

Leachate From Expanded Polystyrene Cups Is Toxic to Aquatic Invertebrates (Ceriodaphnia dubia)

Expanded polystyrene (EPS) products and their associated chemicals (e.g., styrenes) are widespread in the marine environment. As a consequence, bans on their use for single-use packaging materials are being proposed in several municipalities. To better understand how science can inform decision-making, we looked at the available scientific literature about contamination and effects and conducted experiments to measure chemical leachate from polystyrene products and toxicity from the leachate. We conducted leaching experiments with common food matrices (water, soup broth, gravy, black coffee and coffee with cream and sugar) at relevant temperatures (70oC and 95oC) that are consumed in or with several polystyrene products (coffee cup lids, polystyrene stir sticks, polystyrene spoons, EPS cups, EPS bowls and EPS takeout containers). We analyzed each sample for styrene, ethylbenzene, toluene, benzene, meta- and para- xylene, isopropylbenzene, and isopropyltoluene – chemicals associated with polystyrene products. To determine whether the leachates are toxic, we conducted chronic toxicity tests, measuring survival and reproductive output in Ceriodaphnia dubia. Toxicity tests included nine treatments: seven concentrations of ethylbenzene, EPS cup leachate and a negative control. Overall, we found that temperature has a significant effect on leaching. We only detected leachates in trials conducted at higher temperature – 95oC. Ethylbenzene was the only target analyte with final concentrations above the method limit of detection, and was present in the greatest concentrations in EPS and with soup broth. Measurable concentrations of ethylbenzene in the leachate ranged from 1.3 to 3.4 µg/L. In toxicity tests, the calculated LC50 for ethylbenzene was 14 mg/L and the calculated LC20 was 210 µg/L. For the treatment exposed to the EPS cup leachate, mortality was 40% - four times greater than the negative control. Finally, there was no significant difference (p = 0.17) between reproductive output for any treatment with ethylbenzene, but there was a significant reduction (p = 0.01) in reproductive output for the treatment exposed to the EPS leachate compared to the negative control. Thus, although the target analyte ethylbenzene was not toxic at concentrations detected in the leachate, significant adverse effects were detected in the whole EPS cup leachate sample.

Hazards associated with municipal waste storage. Vol. I

Depositing municipal waste in a responsible and controlled manner in landfills allows their decomposition to stabilized material. However, there are many environmental risks during operation and stabilization after landfill closure. These include: dusts, odors, potential fires associated with the presence of landfill gas and it is microbiological hazards and leachates. The latter are also generated many years after closure and reclamation of the landfill. In the event of a leak trough the anti-filtration shutter, toxic compounds found in the leachates can migrate and contaminate to groundwater. The article presents the quantitative and qualitative analysis of leachates in the final operational period of the landfill and after its closure. In both cases, the chromatographic analysis was carried out using the same conditions, i.e. solvent, extraction time, chromatograph and conditions for chromatographic analysis of samples. Physical and chemical leachate examinations were performed on the basis of valid standards. Their results show that the waste deposit is subject to increasingly advanced biodegradation processes of organic compounds. The values of such indicators as COD and BZT5 are decreasing. However, they remain quite significant, which indicates the presence of hard-to decompose and newly compounds in the leachates.