Environments

19 pages, 1468 KB

Open AccessArticle

Theoretical Validations and Analysis of Fine Aerosol Droplet Interactions with Submicron Contaminant Particles in Indoor Air Purification

by Olga Kudryashova, Andrey Shalunov, Vladimir Khmelev and Natalya Titova

Environments 2025, 12(10), 349; https://doi.org/10.3390/environments12100349 (registering DOI) - 26 Sep 2025

Abstract

Environmental problems associated with emergency emissions, indoor air pollution with harmful particles, and the spread of viruses and bacteria make the topic of cleaning indoor air from small particles of pollution relevant. In the event of a dangerous situation associated with the presence [...] Read more.

Environmental problems associated with emergency emissions, indoor air pollution with harmful particles, and the spread of viruses and bacteria make the topic of cleaning indoor air from small particles of pollution relevant. In the event of a dangerous situation associated with the presence of small particles in the air, especially those smaller than 10 μm, methods for quickly cleaning the air from such pollutants are required. One of these new methods is the efficient spraying of fine aerosol using the ultrasound technique. Fine aerosol with a droplet size of about 30–50 μm interacts more effectively with pollutant particles compared to larger aerosols. In this paper, the process of interaction of droplets with a characteristic size of 30–50 μm with airborne pollutant particles sized 0.1–10 μm is theoretically studied. Particular attention is paid to particles sized 0.1–2 μm, which are the most difficult to remove from the air. The work will serve as a theoretical basis for the development of methods for cleaning indoor air of pollutant particles using fine aerosol. Full article

17 pages, 643 KB

Open AccessArticle

Particulate Matter Pollution in an Agricultural Setting: A Community-Engaged Research Study

by Bonnie N. Young, Jessica Tryner, Luis Hernandez Ramirez, Sherry WeMott, Grant Erlandson, Xiaoying Li, Grace Kuiper, Daniel Alan Dean, Nayamin Martinez, Mollie Phillips, John Volckens and Sheryl Magzamen

Environments 2025, 12(10), 348; https://doi.org/10.3390/environments12100348 - 26 Sep 2025

Abstract

California’s San Joaquin Valley experiences some of the worst particulate matter (PM) air pollution in the U.S., but PM_2.5 and PM₁₀ exposures in agricultural communities are understudied. We collaborated with rural residents living adjacent to large-scale agricultural production and processing activities [...] Read more.

California’s San Joaquin Valley experiences some of the worst particulate matter (PM) air pollution in the U.S., but PM_2.5 and PM₁₀ exposures in agricultural communities are understudied. We collaborated with rural residents living adjacent to large-scale agricultural production and processing activities to assess 24-h-average personal and indoor PM_2.5 and PM₁₀ concentrations during different seasons. We visited 35 participants from 18 households during December 2023, May 2024, and the September 2024 harvest season to collect PM samples and survey data. Mixed effects linear regression models (with random effects for participant or household) assessed associations between natural log-transformed PM concentrations and regional ambient PM, harvest season, as well as participant/household characteristics. Participants were mostly female (69%) and Hispanic/Latino(a) (100%). Median household distance to processing facility silos was 633 m. Median personal exposures to PM_2.5 and PM₁₀ were 11.1 and 45.5 µg m⁻³. Median indoor PM_2.5 and PM₁₀ levels were 12.9 and 24.3 µg m⁻³. Overall, 29% of personal and indoor PM_2.5 samples and 33% of personal and indoor PM₁₀ samples exceeded WHO 24-h air quality guidelines (15 µg m⁻³ PM_2.5, 45 µg m⁻³ PM₁₀). The factors most strongly associated with personal and indoor PM were household members working in agriculture and regional ambient PM measures. Full article

(This article belongs to the Special Issue Ambient Air Pollution, Built Environment, and Public Health)

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33 pages, 1618 KB

Open AccessReview

Hydrothermal Treatment of Digestates: Challenges and Perspectives

by Ebtihal Abdelfatah-Aldayyat and Xiomar Gómez

Environments 2025, 12(10), 347; https://doi.org/10.3390/environments12100347 - 26 Sep 2025

Abstract

Anaerobic digestion (AD) effectively treats organic waste and biomass. This process recovers energy as biogas, while a by-product known as digestate requires proper treatment. The goal of enhancing biogas production as a way of increasing the share of renewable fuels in the transport [...] Read more.

Anaerobic digestion (AD) effectively treats organic waste and biomass. This process recovers energy as biogas, while a by-product known as digestate requires proper treatment. The goal of enhancing biogas production as a way of increasing the share of renewable fuels in the transport and industrial sectors comes with the drawback of managing digestates. When digestate cannot be used as an organic amendment, thermal processes provide alternatives for producing valuable energy products. Hydrothermal treatment is particularly promising due to its lower thermal requirements when paired with anaerobic digestion (AD), unlike gasification or pyrolysis. However, challenges such as managing by-products like process water and hydrochar contaminants, along with high operating and maintenance costs, need to be addressed before these technologies can be widely adopted in digestion plants. The present document reviews the current state of the art in hydrothermal carbonization and liquefaction as technologies for treating digestate, focusing on the key aspects that require further research and development. This review examines the existing gaps in the treatment and management of process water, as well as the techno-economic barriers faced when deploying hydrochar-related technologies and integrating them with digestion plants. Full article

(This article belongs to the Special Issue Thermochemical Treatments of Biomass, 2nd Edition)

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13 pages, 1961 KB

Open AccessArticle

Iron Oxide Nanoparticles for Photosynthetic Recovery in Iron-Deficient ‘Micro-Tom’ Tomato Plants

by João Pedro Sampaio Gama, Felipe Girotto Campos, Carla dos Santos Riccardi and Carmen Sílvia Fernandes Boaro

Environments 2025, 12(10), 346; https://doi.org/10.3390/environments12100346 - 26 Sep 2025

Abstract

In plant tissues, nanoparticles can stimulate the production of reactive oxygen species (ROS), which, in excess, cause cellular toxicity by damaging membranes, chloroplasts, and DNA. However, they can also activate antioxidant mechanisms, aiding metabolic recovery under oxidative stress. In agriculture, iron oxide (nFe) [...] Read more.

In plant tissues, nanoparticles can stimulate the production of reactive oxygen species (ROS), which, in excess, cause cellular toxicity by damaging membranes, chloroplasts, and DNA. However, they can also activate antioxidant mechanisms, aiding metabolic recovery under oxidative stress. In agriculture, iron oxide (nFe) nanoparticles stand out for their gradual release of the nutrient, preventing leaching and increasing productivity. This study aims to investigate whether iron oxide nanoparticles are effective alternatives for overcoming iron deficiencies, mitigating oxidative stress and restoring metabolic functions, while maintaining photosynthesis. The high H₂O₂ concentration observed in nFe 500 mg L⁻¹ (nFe 500) suggests that Fe, after being transported by the nanoparticles to the leaves, may have acted as a cofactor for antioxidant enzymes involved in H₂O₂ decomposition, reducing malondialdehyde concentration (MDA). Maintaining low oxidative stress suggests that H₂O₂ may function not only as a stress indicator but also as a signaling molecule in intracellular processes. nFe 500 suggests the ability of plants to utilize released Fe²⁺/Fe³⁺, restoring photosynthetic function in iron-deficient plants. Full article

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22 pages, 4859 KB

Open AccessArticle

Evaluating Native Grassland Species for Application in Extensive Green Roofs in Japan

by Tsukasa Iwata, Ryosuke Shimoda, Terumasa Takahashi and Kiyoshi Umeki

Environments 2025, 12(10), 345; https://doi.org/10.3390/environments12100345 - 26 Sep 2025

Abstract

Extensive green roofs (EGRs) are increasingly recognized as multifunctional components of urban green infrastructure. In recent years, interest is growing in the use of native grassland species as alternatives to conventional green roof plants, both to enhance ecological function and to support biodiversity [...] Read more.

Extensive green roofs (EGRs) are increasingly recognized as multifunctional components of urban green infrastructure. In recent years, interest is growing in the use of native grassland species as alternatives to conventional green roof plants, both to enhance ecological function and to support biodiversity conservation. This study evaluated the performance of six native grassland species on extensive green roofs by assessing their growth characteristics (cover, survival, and flowering) throughout a single growing season (May–November 2024). We used three different substrates that differed in nutrient level: a nutrient-rich reused substrate, a mixed substrate, and a nutrient-poor perlite-based substrate. The results indicated that most species successfully established across all substrate types, although patterns in growth and mortality varied. Substrate nutrient levels strongly influenced early growth, but their long-term effects may diminish as nutrient dynamics stabilize over time. These findings suggest that native grassland species represent promising alternatives to conventional green roof plants in Japan, with several species showing strong adaptability to EGR conditions. Substrate nutrient management is essential for balancing plant growth, biodiversity, and maintenance requirements. This study contributes to improving the ecological performance and long-term sustainability of green roofs in urban environments. Full article

(This article belongs to the Topic Climate, Health and Cities: Building Aspects for a Resilient Future)

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27 pages, 8433 KB

Open AccessArticle

DNA Metabarcoding of Soil Microbial Communities in a Postvolcanic Region: Case Study from Băile Lăzărești, Romania

by Alexandra-Constanța Dudu, Ana Bianca Pavel, Corina Avram, Gabriel Iordache, Andrei-Gabriel Dragoș, Oana Dobre, Constantin-Ștefan Sava and Lia Stelea

Environments 2025, 12(10), 344; https://doi.org/10.3390/environments12100344 - 25 Sep 2025

Abstract

This study investigates the impact of post-volcanic gas emissions on soil microbial communities in the Băile Lăzărești region (Romania). Nineteen soil samples across a CO₂ gradient ranging from background levels to ≈46,221 ppm. Methane and hydrogen sulfide showed localized peaks (CH₄ [...] Read more.

This study investigates the impact of post-volcanic gas emissions on soil microbial communities in the Băile Lăzărești region (Romania). Nineteen soil samples across a CO₂ gradient ranging from background levels to ≈46,221 ppm. Methane and hydrogen sulfide showed localized peaks (CH₄ up to 8271 ppm; H₂S up to ~10.12 ppm), with CH₄ contributing to outlier community patterns. eDNA metabarcoding identified 3064 OTUs, (2463 bacterial and 601 fungal). Bacteria were dominated by Proteobacteria, fungi by Ascomycota, with Thelebolales nearly ubiquitous. Alpha diversity (Chao1, Fisher) declined significantly in high-CO₂ soils (>3000 ppm), while intermediate concentrations (1000–3000 ppm) showed heterogeneous responses. Beta-diversity analyses (PCoA, clustering) revealed distinct grouping of high-CO₂ soils, with sample P16 (CH₄-rich) forming an outlier. A PCA including CO₂, CH₄, and H₂S confirmed CO₂ as the main driver of variance (>65%), with CH₄ accounting for local effects. At the genus level, Acidobacterium, Granulicella, Streptomyces, and Nocardia increased with CO₂, while Rhizobium and Pseudomonas declined. Fungal responses were mixed: Thelebolus and Cladosporium increased, whereas Mortierella and Cryptococcus decreased. Overall, elevated soil CO₂ reduced microbial richness and reorganized communities, while CH₄ shaped local niches. These findings provide key natural analog insights for assessing ecological risks of CO₂ leakage from geological storage. Full article

29 pages, 1623 KB

Open AccessReview

Electric Field Effects on Microbial Cell Properties: Implications for Detection and Control in Wastewater Systems

by Camelia Ungureanu, Silviu Răileanu, Daniela Simina Ștefan, Iosif Lingvay, Attila Tokos and Mircea Ștefan

Environments 2025, 12(10), 343; https://doi.org/10.3390/environments12100343 - 25 Sep 2025

Abstract

Electric fields (EFs) have emerged as effective, non-chemical tools for modulating microbial populations in complex matrices such as wastewater. This review consolidates current advances on EF-induced alterations in microbial structures and functions, focusing on both vegetative cells and spores. Key parameters affected include [...] Read more.

Electric fields (EFs) have emerged as effective, non-chemical tools for modulating microbial populations in complex matrices such as wastewater. This review consolidates current advances on EF-induced alterations in microbial structures and functions, focusing on both vegetative cells and spores. Key parameters affected include membrane thickness, transmembrane potential, electrical conductivity, and dielectric permittivity, with downstream impacts on ion homeostasis, metabolic activity, and viability. Such bioelectrical modifications underpin EF-based detection methods—particularly impedance spectroscopy and dielectrophoresis—which enable rapid, label-free, in situ microbial monitoring. Beyond detection, EFs can induce sublethal or lethal effects, enabling selective inactivation without chemical input. This review addresses the influence of field type (DC, AC, pulsed), intensity, and exposure duration, alongside limitations such as species-specific variability, heterogeneous environmental conditions, and challenges in achieving uniform field distribution. Emerging research highlights the integration of EF-based platforms with biosensors, machine learning, and real-time analytics for enhanced environmental surveillance. By linking microbiological mechanisms with engineering solutions, EF technologies present significant potential for sustainable water quality management. Their multidisciplinary applicability positions them as promising components of next-generation wastewater monitoring and treatment systems, supporting global efforts toward efficient, adaptive, and environmentally benign microbial control strategies. Full article

(This article belongs to the Special Issue Advanced Technologies for Contaminant Removal from Water)

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22 pages, 4854 KB

Open AccessArticle

Distribution, Characterization and Risk Assessment of Microplastics in Two Rivers in West Central Scotland: The Black Cart Water and White Cart Water

by Daniel E. Enenche, Christine M. Davidson, Walter B. Osungbemiro and John J. Liggat

Environments 2025, 12(10), 342; https://doi.org/10.3390/environments12100342 - 25 Sep 2025

Abstract

Improved understanding of the behaviour of microplastics in freshwater systems is important as rivers are major conduits for the transport of particles from land to sea. This study investigated microplastics in two tributaries of the River Clyde, Scotland, UK, that flow through rural, [...] Read more.

Improved understanding of the behaviour of microplastics in freshwater systems is important as rivers are major conduits for the transport of particles from land to sea. This study investigated microplastics in two tributaries of the River Clyde, Scotland, UK, that flow through rural, suburban and urban areas. Surface water and sediment were obtained from 25 locations in the Black Cart Water and White Cart Water. Microplastics were isolated and characterized by digital microscopy and ATR-FTIR spectroscopy. Particles were found in four water samples, all from the White Cart. Sediment analysis revealed microplastic abundance ranging from 300 to 600 items/kg in the Black Cart and 33.3 to 567 items/kg in the White Cart. Fragments were the most common particle type and white/transparent the most common particle colour. The most common polymers in the Black Cart were PP > PET > PS > PVC > PTFE and in the White Cart PE > PP > PTFE > PET > PA. Identification of some microplastics was challenging because their FTIR spectra did not correspond well to reference spectra of pure polymers. Although the polymer hazard index at some locations was high due to the presence of particles composed of PVC and PA, the ecological risk from microplastics in the Cart river system was generally low. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Plastic Contamination)

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28 pages, 60612 KB

Open AccessArticle

Reduction in Brake Wear Emissions with Cr₂O₃ and WC-CoCr Coatings for Cast Iron Discs

by Marie Hoff, Christophe Bressot, Yan-Ming Chen, Laurent Meunier and Martin Morgeneyer

Environments 2025, 12(10), 341; https://doi.org/10.3390/environments12100341 - 24 Sep 2025

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Abstract

The present contribution showcases the potential brake emission reduction with Cr₂O₃ (chromium oxide) and WC-CoCr (tungsten carbide–chromium–cobalt) rotor coatings, as realized in our joint public–private research consortium. Particulate matter (PM) emissions from automotive braking systems have been characterized using a [...] Read more.

The present contribution showcases the potential brake emission reduction with Cr₂O₃ (chromium oxide) and WC-CoCr (tungsten carbide–chromium–cobalt) rotor coatings, as realized in our joint public–private research consortium. Particulate matter (PM) emissions from automotive braking systems have been characterized using a pin-on-disc tribometer equipped with particle measurement devices: a CPC (Condensation Particle Counter), an APS (Aerodynamic Particle Sizer), an SMPS (Scanning Mobility Particle Sizer), and a PM_2.5 sampling unit. Brake pad samples made from the same low-steel friction material were tested against a grey flake cast iron disc and two types of custom coated discs: a Cr₂O₃-coated disc and a WC-CoCr-coated disc. The friction pairs were investigated at a constant contact pressure of 1.2 MPa while the sliding velocity varied during the test, starting with 25 sequences at 3.6 m/s, followed by 19 sequences at 6.1 m/s, and finishing with 6 sequences at 11.2 m/s. The test results show encouraging 64% to 84% reductions in particle number (PN) emissions between 4 nm and 3 µm and 84% to 95% reductions in mass emissions (PM_2.5) thanks to the respective coated discs. SEM-EDXS (Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy) analyses show that the hardness and roughness of the discs, the chemical reactivity (oxidation), and the abrasiveness of the three friction pairs are parameters that might explain this reduction in emission. Full article

(This article belongs to the Special Issue Advances in Urban Air Pollution: 2nd Edition)

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18 pages, 4863 KB

Open AccessArticle

Sediment Microplastic Pollution in Contrasting Estuarine Environments of the Biobío Region South-Central Chile

by Belén Cáceres-González, Alessandra Perfetti-Bolaño, Alberto Araneda, Marco A. Lardies, Nicolás Leppes and Ricardo O. Barra

Environments 2025, 12(10), 340; https://doi.org/10.3390/environments12100340 - 24 Sep 2025

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Abstract

Human activities have triggered microplastic pollution, and estuaries have emerged as critical yet understudied ecosystems in Chile. This study investigated sediment microplastic pollution in the Lenga (highly industrialized) and Tubul-Raqui (fisheries village) ecosystems, characterized by contrasting anthropogenic impacts, in the Biobío Region, Chile. [...] Read more.

Human activities have triggered microplastic pollution, and estuaries have emerged as critical yet understudied ecosystems in Chile. This study investigated sediment microplastic pollution in the Lenga (highly industrialized) and Tubul-Raqui (fisheries village) ecosystems, characterized by contrasting anthropogenic impacts, in the Biobío Region, Chile. Microplastic particles, including fibers, foam, fragments, and film, were detected in both estuaries. The Lenga estuary, heavily industrialized, exhibited a significantly higher total abundance of microplastics compared to the Tubul-Raqui estuary. However, the mean concentrations of microplastics in the studied estuaries are notably lower than those reported in other global studies, aligning more closely with levels found in less polluted estuaries around the world. FTIR analyses identified six types of polymers in Lenga, with polyamide (PA) being the most prevalent, constituting 35% of all polymers detected. Conversely, in Tubul-Raqui, polyvinyl chloride (PVC) emerged as the predominant polymer, comprising 25% of the total. Furthermore, significant correlations were observed with sediment physico-chemical parameters, such as organic matter and pH. These findings confirm the existence of microplastic pollution in both estuaries, highlighting the necessity of continued monitoring and assessment of potential environmental impacts in these ecologically valuable ecosystems. Full article

(This article belongs to the Special Issue Ecotoxicity of Microplastics)

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Environments, Volume 12, Issue 10 (October 2025) – 10 articles

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