Microplastics (MPs), miniscule plastic particles measuring less than 5 mm in size, have become a concern in terrestrial ecosystems, with primarily agricultural and wetland soils being the soils with highest plastic loadings. The adverse effect of MPs might lead to changes in physicochemical and biological characteristics of soil including soil properties, microbial communities, plants, as well as the potential or affirmed correlations among them. Therefore, understanding the risks and effects of MPs, particularly within the soil-plant-microbe context is challenging and have become a subject of substantial scientific inquiry. This comprehensive review is focused on the effects of MPs on the rhizosphere and plant-microbe symbiotic relationships, with implications for plant growth and ecosystem-level nutrient fluxes. MPs alter soil physicochemical properties, microbial community composition, and enzymatic activities in the rhizosphere, influencing nutrient availability and uptake by plants. These changes in the rhizosphere can disrupt plant-microbe symbiotic interactions, such as mycorrhizal associations and nitrogen-fixing symbioses, ultimately impacting plant growth and the cycling of nutrients within ecosystems. Furthermore, we elaborate on the effects of MPs on the rhizosphere and plant-microbe symbiotic relationships carrying implications for plant growth and ecosystem-level nutrient fluxes. Future research directions and solutions to the microplastics menace acknowledging combined effects of MPs and other contaminants, advanced technologies for MPs identification and quantification, and microbial engineering for MPs remediation. This knowledge of MPs-induced impacts on soil-plant-microbe interactions is essential to generate mitigating actions in soil environmental management and conservation.

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In 2050, over 80% of the worldwide electricity demand is expected to be supplied by renewables. The mismatch between supply and demand resulting from these intermittent energy sources and the physical limits of existing electrical grids are challenges in this transition, for which batteries are part of the solution. Therefore, there is a renewed interest to develop advanced and environmentally sound batteries, which requires assessing their environmental impacts by means of life cycle assessment (LCA). However, in current LCA studies the use phase is insufficiently addressed and even oftentimes excluded due to complexity. The aim of this research was to gain insight into current approaches of modelling the use phase in existing LCA and footprinting studies to provide LCA practitioners with recommendations and improved approaches. A literature review was performed which included 26 papers, Annex II of Regulation (EU) No 2019/1020 and the PEFCRs for High Specific Rechargeable Batteries for Mobile Applications. Next to storing renewable energy, batteries can serve different services, also called applications. The implications of incorporating the utilisation of a battery for multiple applications simultaneously, i.e., value stacking, in modelling the use phase are discussed in a qualitative way, since this is emerging as a practical and economically beneficial operational strategy. Finally, the relative effect on a battery’s life cycle impact assessment (LCIA) scores of four issues identified in the literature review is analysed in an illustrative case study about an organic redox flow battery (ORFB).

It appears that many studies do not provide clear information on how the functional unit (FU) is specified, which application(s) the battery is utilised for, application characteristics, modelling assumptions including the electricity and battery inputs or complete LCI data. Overall, the degree of transparency of many battery LCA studies is mediocre which complicates judging the usefulness of results and should be improved to improve comparability and reproducibility for which recommendations are provided. Moreover, the interaction of battery parameters and application characteristics is captured in proposed modelling guidelines for the electricity and battery system input flows. Value stacking results in environmental benefits, particularly when a battery is used to store renewable electricity which is used to serve another application simultaneously. It seems only interesting for battery technologies with high cycle lives such as RFBs and some lithium-ion batteries because these offer the ability to increase battery utilisation without considerably decreasing the battery’s lifetime.

To reach sustainability ambitions, battery applications leading to a reduction in environmental impacts should be promoted for which a general incentive policy is not appropriate. Such policy stimulates all battery applications, which could lead to small or even negative contributions to environmental impact reduction compared to the current situation. Even though this is a temporary transition problem, it could lead to an undesirable interim increase of environmental impacts during the transition. To this end, performing comparative assessments of applications that are expected to be served by batteries in the future, requiring the involvement of transmission network operators, and how these are served in the current situation are useful.

Novel nanomaterial-based pesticide formulations are increasingly perceived as promising aids in the transition to more efficient agricultural production systems. The current understanding of potential unintended (eco)toxicological impacts of nano-formulated pesticides is scarce, in particular with regard to (non-target) aquatic organisms and ecosystems. The present study reports the results of a long-term freshwater mesocosm experiment which assessed responses of individual zooplankton taxa and communities to a novel TiO₂-coated nano-formulation of the fungicide carbendazim. Population- and community trends were assessed and compared in response to the nano-formulation and its constituents applied individually (i.e. nano-sized TiO₂, carbendazim) and in combination (i.e. nano-sized TiO₂ & carbendazim). Minimal differences were observed between effects induced by the nano-formulation and its active ingredient (i.e. carbendazim) when applied at equivalent nominal test concentrations (4 μg L⁻¹). Nano-sized TiO₂ was found to affect zooplankton community trends when applied separately at environmentally realistic concentrations (20 μg L⁻¹ nominal test concentration). However, when nano-sized TiO₂ was applied in combination with carbendazim, nano-sized TiO₂ was found not to alter effects on community trends induced by carbendazim. The findings of the current study provide an extensive and timely addition to the current body of work available on non-target impacts of nano-formulated pesticides.

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Flame retardants are added to plastics in passenger vehicles to save lives. However, their releases can, in some cases, be accompanied by undesired impacts to human health and the environment. In the context of a transition to a Circular Economy, it is therefore important to keep track of the flow of flame retardants in passenger vehicle plastics. This study focuses on the flame retardant Decabromodiphenyl Ether (decaBDE), whose use in plastics has become banned in recent years.
Through a static layered material flow analysis, the flows of plastics and decaBDE are quantified for passenger vehicles in The Netherlands in 2019. Afterwards, six scenarios are created outlining different possible approaches to plastics and flame retardants: Reference, Recycling, Incineration, Less Cars, No DecaBDE Ban, and No Substitution. The first four of these scenarios acknowledge the progressive phasing out of decaBDE and include the use of an additional flame retardant, triphenyl phosphate (TPP). At the hands of a dynamic layered material flow analysis, the stocks and flows of plastics, decaBDE, and TPP, are calculated from 1980 until 2050. The emissions calculated in this step, as well as the flow of flame retardant directed to incineration, are then used to evaluate the environmental performance of each scenario by means of a life cycle impact assessment. The results from the life cycle impact assessment show that, from a midpoint perspective, no scenario is a clear winner. Moreover, the lack of characterization factors for some categories makes it difficult to assess the reliability of the results. From an endpoint perspective, the best performing scenarios are the TPP-free scenarios No DecaBDE Ban and No Substitution. This is because TPP is shown to have a significant influence in the global warming impacts. From the TPP-using scenarios, the best performing one is the Recycling scenario, which shows the advantages of promoting recycling strategies in the sector. Overall, TPP-using scenarios perform worse environmentally than decaBDE-using scenarios.
According to the findings in this study, some of the key elements that could smooth the transition to a sustainable and healthy circular economy are policy measures that incentivize plastic recycling in the automotive industry and the use of less cars per capita.
Further research is needed on the environmental performance of less harmful flame retardant alternatives to decaBDE. The methodology used in this study could serve as a framework in future research for other type of product applications as it is useful to evaluate different policies involving chemicals or additives embedded in materials over time. With this methodology, a link is made between the product, material, and chemical layers, able to bridge potential gaps in the often data scarce chemical layer.

Recently, the delivery of pesticides through novel controlled-release (nano-)formulations has been proposed intending to reduce (incidental) pesticide translocation to non-target sites. Concerns have however been raised with regards to the potentially enhanced toxicity of controlled-release (nano-)formulations to non-target organisms and ecosystems. We evaluated long-term (i.e. 1 and 3 month-) impacts of a novel controlled-release pesticide formulation (nano-TiO₂-coated carbendazim) and its individual and combined constituents (i.e. nano-sized TiO₂ and carbendazim) on naturally established freshwater macroinvertebrate communities. In doing so, we simultaneously assessed impacts of nano-sized TiO₂ (nTiO₂), currently one of the most used and emitted engineered nanomaterials world-wide. We determined ecological impacts on diversity (i.e. β-diversity), structure (i.e. rank abundance parameters), and functional composition (i.e. feeding guilds & trophic groups) of communities and underlying effects at lower organizational levels (i.e. population dynamics of individual taxa). Freshwater macroinvertebrate communities were negligibly impacted by nTiO₂ at environmentally realistic concentrations. The controlled-release (nano-)formulation significantly delayed release of carbendazim to the water column. Nevertheless, conventional- (i.e. un-coated-) and nTiO₂-coated carbendazim induced a similar set of adverse impacts at all investigated levels of ecological organization and time points. Our findings show fundamental restructuring of the taxonomic- and functional composition of macroinvertebrate communities as a result of low-level pesticide exposure, and thereby highlight the need for mitigating measures to reduce pesticide-induced stress on freshwater ecosystems.

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Assessment of chronic impact of metallic nanoparticles (NPs) in soil ecosystems is a necessity for ensuring safe and sustainable application. NPs affect plants and their associated microbial life, while the plants and their associated microbiota affect the NPs' fate. Here, we measured the available Ag pool (determined as diethylenetriaminepentaacetic acid-extractable Ag) in AgNP-amended sandy loam soil (1, 10, and 50 mg Ag per kg of soil) over a period of 63 d with and without lettuce. The associated impacts on soil pH, Ag accumulation in lettuce, and the responses of the rhizosphere bacterial community were determined. We found that the addition of AgNPs significantly increased the soil pH from 7.70 to 7.87 after a short-term (7 d) incubation. Noteworthily, the extractability of Ag in AgNP-amended soil was concentration-dependent and changed over time because of their continuous dissolution and uptake by plants. Ag uptake and upward translocation in lettuce positively correlated with the extractable Ag content in soil. Furthermore, a long-term (63 d) exposure to 50 mg/kg of AgNPs altered the structure and composition of the rhizosphere bacterial community potentially by regulation of bacterial groups associated with element (e.g., N and S) cycling and stress tolerance. In conclusion, our results demonstrated that the dynamic dissolution of AgNPs in sandy loam soil plays an important role in influencing the overall Ag bioavailability of the NPs in plants. The enhanced effects of AgNPs on the alterations in the rhizosphere bacterial community highlight that the long time-resolved dynamics of NP exposure should be taken into consideration for accurate ecological risk assessment of NPs in the soil ecosystem.

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Titanium dioxide nanoparticles (TiO₂ NPs) are widely used as nano-agrochemicals. In this study we investigated the influence of soil heterogeneity on bacterial communities exposed to TiO₂ NPs over time. Clay and sandy soils with low- and high-organic matter contents were exposed to environmentally relevant concentration of TiO₂ NPs (1 mg/kg) and soil bacterial communities were sampled after short-term (15 days) and long-term exposure (60 days). After short-term TiO₂ NPs exposure, significant effects regarding the enzyme activity, bacterial community structure and composition, and community functioning were observed in the clay soils with high organic matter (clay-HOM) but not in other soil groups. Response alterations were observed to taxa belonging to Acidobacteria and Verrucomicrobia, and functional pathways related to carbohydrates degradation. These results indicated that soil heterogeneity play more important roles in shaping the bacterial community in soil with low clay fraction and less organic matter, while TiO₂ NPs selection was the main driver in inducing the compositional and functional impacts on the soil bacterial community in the presence of clay soil with high organic matter content. As exposure time increased, the bacterial community recovered after a long-term exposure of 60 days, suggesting that the bacterial evolution and adaptation could overcome the TiO₂ NPs selection after long-term exposure. Our results highlighted the importance of soil heterogeneity including clay fraction and organic matter and exposure duration in assessing the impact of nanoparticle on soil bacterial activity, community and function. By comprehensively evaluating the risks of nanoparticles on soil ecosystem and explicitly and explicitly include spatial and temporal variations, the benefit of nano-agrochemical products has the potential to be promoted in future applications.

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Titanium dioxide nanoparticles (TiO₂NP) are increasingly released in soil ecosystems, while there is limited understanding of the impacts of TiO₂NP on soil bacterial communities. Here we investigated the effects of TiO₂NP on the taxonomic composition and functional profile of a soil bacterial community over a 60-day exposure period. In short-term exposure (1-day), contradictory effects on the taxonomic composition of soil bacterial communities were found after exposure to a low realistic environmental concentration of TiO₂NP at 1 mg/kg as compared to the effects induced by medium and high concentrations of TiO₂NP at 500 and 2000 mg/kg. After long-term exposure (60-day), the negative effects of TiO₂NP at the low concentration disappeared, and the inhibition by TiO₂NP of the abundance of core taxa was enhanced along with increasing exposure concentrations. However, although significant alterations were observed in the taxonomic composition over time and exposure concentrations, no significant change was observed in the community functional profile as well as enzyme activity after 60-day exposure, indicating that functional redundancy likely contributed to the bacterial community tolerance after the exposure to TiO₂NP. Our study highlighted the importance of assessing bacterial community compositional and functional responses in assessing the environmental risk of nanoparticles on soil ecosystems.

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Titanium dioxide nanoparticles (TiO₂NP) are often released into the soil through repeated discharge of wastewater and repetitive applications as fertilizers. Adverse effects of a single pulse on soil bacterial communities have been widely studied, while the impact of repeated exposure is poorly understood. This study compared the impacts of single and repeated exposure scenarios on the soil bacterial community. The repeated exposure promoted the total bacterial biomass but reduced the community diversity and induced larger alterations in community composition compared to the single exposure. Regarding the dosing frequencies of repeated exposure, community divergence increased in initial dosing cycles, and community stability was re-established and remained in subsequent dosing cycles. According to the different tolerance to dosing frequencies, the dynamic response patterns of the featured OTUs and functional genes could be classified into four types: 1) promotion, 2) suppression-recovery-promotion, 3) promotion-suppression-stable, and 4) suppression. These results suggest that chronic exposure with repetitive low-dosing of nanoparticles induced a tendency towards larger alteration of both community composition and functioning than in case of application of a single pulse of the same dosage. This study brings new insight into understanding the compositional and predicted functional dynamics of the soil bacterial community in response to nanoparticles and identifies a data gap in realistic time-variable exposure testing.

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