The accumulation of engineered nanomaterials and nanoplastics in soils, especially sludge-treated soils, raises concerns regarding their potential environmental hazard and risks. This work applies probabilistic environmental risk assessment based on probabilistic species sensitivity distributions and published data from exposure models to derive risk characterization ratios for four nondissolvable nanomaterials: Titanium dioxide (TiO2), carbon nanotubes (CNTs), graphene-based materials (GBMs), and polystyrene nanoplastics. Median predicted no-effect concentration values were 36, 1.5, 56, and 0.5 mg.kg(-1 )for TiO2, CNTs, GBMs, and polystyrene nanoplastics, respectively. No statistically significant differences were found for the effects of nanomaterials on plants versus invertebrates or monocotyledonous versus dicotyledonous plants. Form-specific comparisons also showed no statistical difference among the nanomaterial forms: TiO2, P25 versus anatase versus rutile; CNTs, multi-versus single-walled CNTs; and GBMs, graphene versus graphene oxide versus reduced graphene oxide. At currently predicted environmental concentrations in European soils, none of the materials exhibited an environmental risk, except for TiO(2 )nanoparticles in sludge-treated soils, where 66% of the simulations resulted in an risk characterization ratio >1 (median = 1.38). However, a projected increase in environmental concentrations over time can result in larger potential risks in the future. This work also highlights the limitations of the current state of the art in terms of the availability of environmentally relevant ecotoxicity data in soils and realistic predicted environmental concentrations.
Abstract Assessing decadal-scale ecological recovery in mine-impacted rivers is crucial for effective ecosystem conservation. This study evaluated changes in the ecological status of the Watarase River system, Japan, approximately 50 years after the closure of the Ashio Copper Mine (1973). We conducted seasonal field surveys (2022–2023) of benthic macroinvertebrates and water quality in the Watarase River and its four tributaries. We also analyzed historical field survey data on macroinvertebrate community structure collected before mine closure, immediately prior to closure, and shortly after closure. We found that trace metal concentrations in the mainstream of the Watarase River have decreased remarkably since the 1960s. In contrast, no statistically significant associations were observed between typical structural measures of benthic macroinvertebrate communities (total abundance and taxon richness) and the extent of trace metal pollution in the 2020s. Non-metric multidimensional scaling analysis revealed that, from 50 years ago, the community structure of benthic macroinvertebrates in the mainstream remains distinct from that of the uncontaminated reference rivers. Metal-sensitive taxa (e.g., Ephemerellidae and Heptageniidae) remain scarce in the mainstream despite recovery from metal contamination, whereas the community continues to be dominated by metal-tolerant taxa (e.g., Baetidae and Chironomidae). These results suggest that potential factors hindering biological recovery include the indirect effects of wastewater treatment, such as biofilm formation on riverbed sediments resulting from the use of calcium hydroxide in flocculation–sedimentation processes; increased flood susceptibility associated with historical forest degradation; and a reduction in interstitial spaces within riverbed sediments. This study highlights the necessity of a comprehensive management approach that addresses stressors beyond the simple reduction of metal concentrations to achieve the ecological restoration of historically metal-polluted rivers.
Abstract Sediment porewater is a key medium for controlling contaminant mobility and bioavailability in aquatic systems. Yet, methodologies to extract porewater from sediment samples differ substantially in their efficiency, reliability, and suitability for field deployment. The present study compared four porewater extraction techniques: Laboratory centrifugation, portable centrifugation, Rhizon samplers, and a novel AeroPress-based extraction device, utilizing silty and sandy sediments from two boreal lakes. Extraction efficiency, sample contamination risks, and operational feasibility for field use were evaluated. Laboratory and portable centrifugation produced the highest porewater recoveries, generally exceeding 25–50% extraction efficiency, whereas AeroPress and Rhizon samplers yielded lower recoveries. The metal concentrations in the extracted pore water samples varied between the extraction methods and sediment types, with Rhizon samplers and AeroPress yielding higher concentrations of specific trace metals in some cases due to leaching of the metals from the components of the extraction devices, causing sample contamination. No consistent relationship was observed between extraction efficiency and metal concentrations in the extracted water samples. However, Pb showed a strong positive correlation with extraction efficiency, suggesting preferential recovery with higher-volume methods. Portable centrifugation provided the most practical balance between efficiency and field applicability based on both the volume of porewater that can be extracted and ease of use, while AeroPress offers a promising low-energy alternative in power-limited settings. These findings highlight that the porewater extraction method, the filter material, and sediment type affect the metal concentrations in the extracted porewater samples and should be carefully considered when applied for environmental monitoring.
Abstract Microplastics (MPs) are ubiquitous environmental contaminants of growing toxicological concern. Although the nematode Caenorhabditis elegans has emerged as a robust, genetically tractable model for evaluating MP toxicity, experimental methodologies remain highly fragmented, limiting cross-study comparability and hindering the development of reproducible risk assessment frameworks. This scoping review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines to systematically evaluate methodological trends in C. elegans MP toxicology research. Searches across Scopus, PubMed, and Web of Science identified 59 peer-reviewed studies that evaluated individual-level biological effects after exposure to MPs or their leachates. Data on polymer characteristics, exposure conditions, and concentration metrics were extracted and synthesized. The current methodological landscape remains heavily skewed toward simplified experimental designs, with pristine particles (44%) and spherical shapes (73%) most frequently reported and polystyrene the most common polymer. Most studies with reported sizes included at least one size or size range classified as ingestible within 1–3 µm (74%). Exposure conditions most frequently involved durations of ≤ 24 hr (42%), aqueous media (45%), and the L4 developmental stage (47%). Critically, although evidence indicates that chemical additives, leachates, and environmental weathering substantially influence MP toxicity, experimental designs still rely predominantly on virgin polymers. In addition, a substantial proportion of studies use single-concentration exposure designs (24%), while mass per volume is the dominant dosing metric (80%). Overall, a gap exists between conventional laboratory exposures and the complexity of real-world environmental contamination. To improve ecological validity and environmental relevance, future C. elegans research should build on existing protocols, prioritize standardized multi-dose frameworks with environmentally realistic concentrations, include environmentally weathered and irregularly shaped particles from diverse polymers, and expand longer-duration and stage-specific exposure assessments.
