Mid Sweden University

Water hyacinth (WH) is an invasive aquatic species for which no universal biomass management strategy exists, although many developing countries use it in agriculture with limited understanding of its potential environmental impacts. As WH is an effective bioaccumulator it is essential to assess its composition and quantify potentially harmful elements before this surplus green biomass can be effectively valorised. Determining the thresholds for their effects is crucial to define safe and sustainable uses. In this context, this study characterized WH biomass from six Portuguese locations (four northern and two southern), focusing on nutrient and potentially toxic element (PTE) profiles, sugar, protein, and structural composition. Furthermore, the ecotoxicological profile of aqueous extracts from each WH biomass was evaluated using several freshwater species ( Raphidocelis subcapitata, Brachionus calyciflorus, Daphnia magna, and Danio rerio ) and multiple endpoints, to benchmark safe agricultural application rates. Structural analysis revealed tissue type (leaves, floaters, roots) had greater influence than sampling location, with roots showing highest absorbance linked to lignin, proteins, and cellulose. These wall components provide metal-binding sites, explaining root PTE levels being higher than other tissues. Elemental composition showed high primary nutrients (e.g., potassium, phosphorus), meeting EU requirements for organic soil improvers (EU Regulation 2019/1009). Whole-plant WH water extracts had high conductivity (≥ 6.98 mS/cm), nutrient and PTE concentrations, and caused adverse effects on all aquatic species. No clear toxicity ranking emerged, though Bico and Pateira extracts were least toxic, and Sorraia extract most severe (algal inhibition, zooplankton mortality, zebrafish effects at 0.78 % dilution). The findings indicate that WH biomass incorporation into soils should be considered on a site-specific basis, owing to variations in PTEs accumulation across locations, requiring contaminant screening and regulatory guidance before large-scale use. The results evidenced multispecies, multi-endpoint ecotoxicity that might justify the need for dilution strategies and controlled application rates of WH biomass on soils to minimize putative downstream impacts. 

Current agricultural techniques rely on plastic-based materials for irrigation, mulching, and greenhouse planting, thereby making agricultural soils a significant reservoir of plastic and microplastics particles. Given that saprophytic fungi are natural decomposers, that may serve as environmentally friendly soil remediators, this study aimed to evaluate the degradation potential of the plastic polymer polyethylene terephthalate (PET) by two white-rot fungi species – Trametes versicolor (Tv) and Pleurotus sajor caju (Psj), to propose them as potential remediation agents for plastic-laden soils. To achieve this objective, an experiment was conducted with the following treatments: (i) PET placed in minimum salt medium (MSM) in the presence of each of the fungal species; (ii) PET placed in MSM without the presence of any fungi species; and (iii) MSM with fungi alone. Each treatment included four replicates, each assembled in a 250-mL minireactor. The assays lasted for 56 days, with sampling every 14 days. Biodegradation was accompanied by: i) determination of ammonia production, lipase, alkaline and acid phosphatases, pectinase, and cellulolytic enzymatic activity in fungal exudates; and ii) PET pellets weight and functional groups characterization [Fourier-transform infrared spectroscopy (FTIR)]. Results indicated that Psj performed better in degrading PET pellets than Tv, with PET weight losses of 20.3% and 5.72% at days 14 and 56, respectively; accompanied by significant increases in lipase, pectinase, and cellulolytic enzyme activity in the PET + Psj treatment. The FTIR spectra revealed transient changes in peak areas associated with proteins and lipids, in PET exposed to fungi. These findings suggest that Psj may be a potential plastic degrader and that Tv presents lower tolerance to plastic biodegradation by-products or limitations related to the test medium. Thus, white-rot fungi species, such as Pleurotus sp. , may represent promising and sustainable strategies for plastic degradation in soil matrices. 

Chitosan films with potential application in triboelectric nanogenerators (TENGs) represent a promising approach to replace non-biobased materials in these innovative devices. In the present work, chitosan with varying molecular weights (MW) and degrees of deacetylation was dissolved in aqueous acetic acid (AA) at different acid concentrations. It was observed that the MW had a greater influence on the viscosity of the solution compared to either the acid concentration or deacetylation degree. Gel formation occurred in high-MW chitosan solutions prepared with low AA concentration. Films prepared from chitosan solutions, through solvent-casting, were used to prepare TENGs. The power output of the TENGs increased with higher concentrations of AA used in the chitosan dissolution process. Similarly, the residual AA content in the dried films also increased with higher initial AA concentrations. Additionally, hot-pressing of the films significantly improves the TENG power output due to the decrease in morphological defects of the films. It was demonstrated that a good selection of the acid concentration not only facilitates the dissolution of chitosan but also plays a key role in defining the properties of the resulting solutions and films, thereby directly impacting the performance of the TENGs. 

Microplastics (MPs) are widespread emerging contaminants for which routine, in situ detection remains a significant analytical challenge, especially in realistic, biologically active aquatic environments. Existing methods (e.g., FTIR, Raman) are labor-intensive, require extensive pre-processing, and often lack sensitivity to mixed or biofilm-coated MPs. This study addresses these limitations by implementing a direct, submersible electrical impedance spectroscopy (EIS) approach, systematically evaluating the impact of polymer type, particle size distribution, and E. coli biofilm formation on the electrical properties of MP suspensions. Results reveal that MP surface charge, size heterogeneity, and biological coatings all modulate impedance relaxation behavior in mechanistically distinct ways, enabling the discrimination of mixed polymers and realistic contamination scenarios. These mechanistic insights advance the development of rapid, minimally invasive EIS-based platforms for environmental microplastics monitoring and foster future integration with ecotoxicological risk assessment. Besides the under-development strategy, in opposition to the few found in the literature, does not require the collection of samples and can be directly used on-site. However, even if the results demonstrate strong mechanistic differentiation under controlled conditions, further validation is needed at environmentally relevant concentrations and in real-world water matrices. 

Microplastic pollution represents a significant environmental challenge, as microplastics accumulate in effluents and soils, causing serious risks to ecosystems and human health. Efficient removal of these contaminants is essential to mitigate their potential adverse effects. This review summarizes and critically analyses current methods for the removal of microplastics from effluents and soils, focusing on their effectiveness, advantages, and limitations. Conventional techniques—including filtration, flotation, chemical coagulation, flocculation, and adsorption—are discussed in the context of wastewater treatment and soil remediation. Emerging approaches, such as flocculation processes with special focus on the application of bio-based flocculants, are also highlighted as promising solutions. Key challenges in microplastic removal, including the diversity of microplastic types, their small size, and the complexity of environmental matrices, are addressed. This work intends to contribute to the urgent need for further research to develop more efficient and sustainable strategies for microplastic removal from environmental systems. 

In vitro culture is an important biotechnological tool in plant research and an appropriate culture media is a key for a successful plant development under in vitro conditions. The use of natural compounds to improve culture media has been growing and biopolymers are interesting alternatives to synthetic compounds due to their low toxicity, biodegradability, renewability, and availability. In the present study, different culture media containing one biopolymer (chitosan, gum arabic) or a biopolymer derivative [hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC)], at 100 or 1000 mg L−1, were tested regarding their influence on the growth and physiological responses of Thymus lotocephalus in vitro culture. Cellulose-based biopolymers (HEC and CMC) and gum arabic were used for the first time in plant culture media. The results showed that CMC at 100 mg L−1 significantly improved shoot elongation while chitosan, at the highest concentration, was detrimental to T. lotocephalus. Concerning only the evaluated physiological parameters, all tested biopolymers and biopolymer derivatives are safe to plants as there was no evidence of stress-induced changes on T. lotocephalus. The rheological and microstructural features of the culture media were assessed to understand how the biopolymers and biopolymer derivatives added to the culture medium could influence shoot growth. As expected, all media presented a gel-like behaviour with minor differences in the complex viscosity at the beginning of the culture period. Most media showed increased viscosity overtime. The surface area increased with the addition of biopolymers and biopolymer derivatives to the culture media and the average pore size was considerably lower for CMC at 100 mg L−1. The smaller pores of this medium might be related to a more efficient nutrients and water uptake by T. lotocephalus shoots, leading to a significant improvement in shoot elongation. In short, this study demonstrated that the different types of biopolymers and biopolymer derivatives added to culture medium can modify their microstructure and at the right concentrations, are harmless to T. lotocephalus shoots growing in vitro, and that CMC improves shoot length.