Environments

12 pages, 1611 KiB

Open AccessArticle

Steam Stripping for Recovery of Ammonia from Wastewater Using a High-Gravity Rotating Packed Bed

by Min-Hao Yuan, Minh Viet Trinh, Yi-Hung Chen, Yong-Jhe Lu, Li-Pang Wang, Shikun Cheng, Zifu Li, Malee Santikunaporn and Channarong Asavatesanupap

Environments 2024, 11(9), 206; https://doi.org/10.3390/environments11090206 - 18 Sep 2024

Abstract

Steam stripping of ammonia from ammonia-rich wastewater (5000–20,000 mg/L) was conducted in a continuous-flow rotating packed bed (RPB) at a pH of 11. This study aimed to elucidate the influence of key operational parameters, including the steam-to-liquid ratio, rotational speed (ω), initial ammonia [...] Read more.

Steam stripping of ammonia from ammonia-rich wastewater (5000–20,000 mg/L) was conducted in a continuous-flow rotating packed bed (RPB) at a pH of 11. This study aimed to elucidate the influence of key operational parameters, including the steam-to-liquid ratio, rotational speed (ω), initial ammonia concentration, steam inlet temperature (T_Si), and liquid inlet temperature (T_Li), on critical performance metrics such as the ammonia removal efficiency (ARE), the volumetric liquid mass transfer coefficient (K_La), and the concentration of the recovered ammonia solution (C_R). The findings revealed that a C_R of 22.88 wt.% was achieved under the optimal conditions of a steam-to-liquid ratio of 0.175 kg/kg, an initial concentration of 20,000 mg/L, a T_Si of 120 °C, and a T_Li of 70 °C. Key experimental factors, including the initial ammonia concentration, T_Si, and T_Li, significantly impacted the achievement of higher ARE and C_R values. The K_La values exhibited a decrease with the increase in the steam-to-liquid ratio, while they increased with ω. However, the K_La remained relatively consistent with ω values within the range of 600 to 1200 rpm. In comparison with prior studies, steam stripping of ammonia exhibits a higher ARE than air stripping with RPB and a higher C_R than conventional stripping methods. Moreover, RPB requires a smaller size to achieve equivalent ARE compared to conventional stripping apparatuses. Thus, the steam stripping process with RPB equipment emerges as a suitable method for ammonia recovery from ammonia-rich wastewater. Full article

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11 pages, 3536 KiB

Open AccessArticle

Zinc Accumulation Pattern in Native Cortaderia nitida in High Andes (Ecuador) and Potential for Zinc Phytoremediation in Soil

by Karina I. Paredes-Páliz, Benito Mendoza and Jennifer Mesa-Marín

Environments 2024, 11(9), 205; https://doi.org/10.3390/environments11090205 - 18 Sep 2024

Abstract

The aim of this work was to determine the content of heavy metals in soil and, for the first time, in wild Cortaderia nitida, and to discuss its potential as a metal phytoremediator plant. We sampled sediments (bulk and rhizosphere) and C. [...] Read more.

The aim of this work was to determine the content of heavy metals in soil and, for the first time, in wild Cortaderia nitida, and to discuss its potential as a metal phytoremediator plant. We sampled sediments (bulk and rhizosphere) and C. nitida (roots and shoots) in three nearby spots with different land uses (urban, industrialized and agricultural) along the Chibunga river basin (Ecuador). We analyzed the physico-chemical parameters in soil and heavy metal contents in soil and plants. The agricultural sediments showed the highest conductivity and redox potential, but the lowest pH. Among all the metals analyzed in soil and plants, we only found significant values of Zn and Fe. We observed clear differences in patterns of Zn distribution throughout soil and plants among the three areas sampled, thus suggesting that soil properties played an important role in Zn compartmentalization. Also, C. nitida demonstrated effective Zn translocation from roots to shoots, especially in farmlands (translocation factors between 1.64 and 2.51). Together with the results obtained for other Cortaderia species in metal-polluted areas, this study proposes C. nitida as a candidate to further study its metal phytoremediation potential and encourages this research in heavy metal-enriched soils. Full article

(This article belongs to the Special Issue Environments: 10 Years of Science Together)

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17 pages, 1601 KiB

Open AccessArticle

Initial Insights into Teleworking’s Effect on Air Quality in Madrid City

by Jorge Bañuelos-Gimeno, Natalia Sobrino and Rosa Arce-Ruiz

Environments 2024, 11(9), 204; https://doi.org/10.3390/environments11090204 - 18 Sep 2024

Abstract

Commuting to work by private vehicle is one of the main sources of air pollution in cities, mainly from NO₂ and particulate matter (PM_2.5 and PM₁₀). With the spread of telework, traffic congestion during peak hours is reduced on [...] Read more.

Commuting to work by private vehicle is one of the main sources of air pollution in cities, mainly from NO₂ and particulate matter (PM_2.5 and PM₁₀). With the spread of telework, traffic congestion during peak hours is reduced on certain days of the week, improving air quality. This study analyzes the relationship between the improvement of air quality and urban traffic resulting from teleworking activities after the COVID-19 pandemic in Madrid, Spain. This article considers road traffic and teleworking before the COVID-19 pandemic (2018 and 2019), during the pandemic (2020 and 2021) and in the period after (2022 and 2023) in the city center and the influence on certain environmental factors. Daily NO₂, PM_2.5, PM₁₀, and O₃ concentration data were collected at air quality stations in Madrid municipality, and traffic data and some meteorological variables such as wind speed, precipitation and temperature were considered. When conducting correlation and regression analysis among the variables, there is a clear association between NO₂ and traffic before the pandemic, which is lower for both PM and O₃. This correlation was maintained during the pandemic, except for O₃, the association of which increased during this period and then decreased in the later period due to various motives. These results seem to indicate the existence of a relevant relationship between urban mobility and air quality and an especially relevant relationship with telework, suggesting the need for policies aimed at promoting sustainable mobility in the future. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Air Quality Assessment and Management)

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18 pages, 2820 KiB

Open AccessReview

Life Cycle Assessment of Per- and Polyfluoroalkyl Substances (PFAS) Remediation Technologies: A Literature Review

by Xingqiang Song, Malin Montelius and Christel Carlsson

Environments 2024, 11(9), 203; https://doi.org/10.3390/environments11090203 - 17 Sep 2024

Abstract

The remediation of environments contaminated with per- and polyfluoroalkyl substances (PFAS) has become a growing priority due to the persistent, bioaccumulative, and toxic characteristics of these compounds. To promote green and sustainable remediation practices, it is crucial to assess and minimize the environmental [...] Read more.

The remediation of environments contaminated with per- and polyfluoroalkyl substances (PFAS) has become a growing priority due to the persistent, bioaccumulative, and toxic characteristics of these compounds. To promote green and sustainable remediation practices, it is crucial to assess and minimize the environmental impacts of PFAS remediation projects through life cycle assessment (LCA) at the early stages of planning. So far, no systematic literature review has been published to assess the current state of the art or identify the challenges associated with applying LCA to PFAS remediation. This article provides a review of the recent literature on LCAs of PFAS remediation, following the ISO 14040 and 14044 standards. The results indicate that the application of LCA to PFAS remediation remains in its infancy and is highly fragmented. Significant methodological variations, including differences in system boundaries and data quality, hinder the comparability and benchmarking of LCA results across studies. To enhance the use of LCA as a decision support tool for environmental assessment, there is a pressing need for methodological harmonization and improved practices. Key areas for improvement include enhancing data quality, reducing uncertainties, and increasing the robustness of PFAS LCAs, thereby enabling more informed and sustainable decision-making in PFAS remediation efforts. Full article

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12 pages, 2555 KiB

Open AccessArticle

Plastics at an Offshore Fish Farm on the South Coast of Madeira Island (Portugal): A Preliminary Evaluation of Their Origin, Type, and Impact on Farmed Fish

by Mariana Martins, Ana Pombo, Susana Mendes and Carlos A. P. Andrade

Environments 2024, 11(9), 202; https://doi.org/10.3390/environments11090202 - 14 Sep 2024

Abstract

Plastic pollution is a global problem affecting all ecosystems, and it represents most of the marine litter. Offshore aquaculture is a sector particularly vulnerable to this issue. To investigate this concern, the present study employed videography to monitor macroplastics at an offshore fish [...] Read more.

Plastic pollution is a global problem affecting all ecosystems, and it represents most of the marine litter. Offshore aquaculture is a sector particularly vulnerable to this issue. To investigate this concern, the present study employed videography to monitor macroplastics at an offshore fish farm on Madeira Island (Portugal) and analysis of fish gut content to evaluate macroplastic ingestion by farmed sea bream Sparus aurata. Our analysis revealed that the majority of identified plastic debris originated from domestic use (66.66%) and fisheries/aquaculture activities (24.99%). While the number of dead fish suitable for sampling was limited (1.05% of the total mortality), macroplastic debris ingestion was identified in 5.15% of the total mortalities and reported for the first time in species in offshore farming conditions. Fish ingested fragmented plastic sheets, with the amount positively correlated with fish weight (r = 0.621, p = 0.031, n = 12). Notably, the stretched length of these fragments exceeded 50% of the standard length of most fish. Inconsistencies were observed in the number of samples collected per cage and per week. To ensure robust results, these discrepancies should be rectified in future studies. Additionally, extending the sampling period to encompass all seasons would be beneficial for a more comprehensive understanding of seasonal variations in plastic occurrence. Full article

(This article belongs to the Special Issue Plastics Pollution in Aquatic Environments)

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31 pages, 3780 KiB

Open AccessArticle

Coal Ash Triggers an Elevated Temperature Landfill Development: Lessons from the Bristol Virginia Solid Waste Landfill Neighboring Community

by Reagan Patton Witt and Marcelo I. Guzman

Environments 2024, 11(9), 201; https://doi.org/10.3390/environments11090201 - 14 Sep 2024

Abstract

Landfills for disposing of solid waste are designed, located, managed, and monitored facilities expected to comply with government regulations to prevent contamination of the surrounding environment. After the average life expectancy of a typical landfill (30 to 50 years), a large investment in [...] Read more.

Landfills for disposing of solid waste are designed, located, managed, and monitored facilities expected to comply with government regulations to prevent contamination of the surrounding environment. After the average life expectancy of a typical landfill (30 to 50 years), a large investment in the construction, operation, final closure, and 30-year monitoring of a new site is needed. In this case study, we provide a holistic explanation of the unexpected development of elevated temperature landfills (ETLFs), such as that in the city of Bristol (United States) on the border of the states of Virginia and Tennessee, including the initial role played by coal ash. Despite the increasing frequency of ETLF occurrence, there is limited knowledge available about their associated environmental problems. The study uses mixed (qualitative, quantitative, and mapping) methods to analyze (1) the levels of odoriferous reduced sulfur compounds, ammonia, and volatile organic compounds (VOCs) emitted, (2) the ratio of methane to carbon dioxide concentrations in five locations, which dropped from unity (normal landfill) to 0.565, (3) the location of gas well heads with gradients of elevated temperatures, and (4) the correlation of the filling rate (upward of ~12 m y⁻¹) with depth for registered events depositing coal ash waste. The work identifies spatial patterns that support the conclusion that coal ash served as the initiator for an ETLF creation. The case of the city of Bristol constitutes an example of ETLFs with elevated temperatures above the regulatory United States Environmental Protection Agency (EPA) upper threshold (65 °C), having alongside low methane emissions, large production of leachate, land subsidence, and a large production of organic compounds. Such landfills suffer abnormal chemical reactions within the waste mass that reduce the life expectancy of the site. Residents in such communities suffer intolerable odors from fugitive emissions and poor air quality becomes prominent, affecting the well-being and economy of surrounding populations. Conclusive information available indicates that the Bristol landfill has been producing large amounts of leachate and hazardous gases under the high pressures and temperatures developed within the landfill. A lesson learned, which should be used to prevent this problem in the future, is that the early addition of coal ash into the landfill would have catalyzed the process of ETLF creation. The work considers the public health risks and socioeconomic problems of residents exposed to emissions from an ETLF and discusses the efforts needed to prevent further incidents in other locations. Full article

(This article belongs to the Special Issue Environments: 10 Years of Science Together)

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34 pages, 6632 KiB

Open AccessArticle

Ecosystem Services of the Baltic Sea—State and Changes during the Last 150 Years

by Gerald Schernewski, Thomas Neumann, Martynas Bučas and Miriam von Thenen

Environments 2024, 11(9), 200; https://doi.org/10.3390/environments11090200 - 14 Sep 2024

Abstract

We assess the ecosystem services across the entire Baltic Sea using ecosystem model simulations and historical socio-economic data. Our approach covers 150 years, aggregated for the years around 1880, 1960, and 2010. The ecosystem services assessed include commercially usable wild fish biomass and [...] Read more.

We assess the ecosystem services across the entire Baltic Sea using ecosystem model simulations and historical socio-economic data. Our approach covers 150 years, aggregated for the years around 1880, 1960, and 2010. The ecosystem services assessed include commercially usable wild fish biomass and wild plant biomass, water quality regulation (nitrogen and phosphorus retention), carbon storage, biodiversity and habitats, as well as active recreation and landscape aesthetics. In 2010, the commercially usable fish biomass in the entire Baltic Sea was 9.24 million tons. The total retention of nitrogen in the Baltic Sea was 884,135 t/a, phosphorus retention was 32,058 t/a, and carbon storage was 3,668,100 t/a. Between 1880 and 2010, the Baltic Sea-wide average biodiversity index decreased from 73 to 60, the active recreational quality index decreased from 76 to 69, and the observational recreation index declined from 91 to 78. In 2010, the most monetarily significant single ecosystem service in the Baltic Sea was nitrogen retention with EUR 26,822 million/a, followed by cultural ecosystem services. Other relevant services were fish catches (EUR 277 million/a), phosphorus retention (EUR 3854 million/a), and carbon storage (202 million/a). The latter recently showed a steep increase due to rising prices for CO₂ certificates. Full article

(This article belongs to the Special Issue Monitoring and Assessment of Environmental Quality in Coastal Ecosystems Volume III)

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24 pages, 723 KiB

Open AccessArticle

Climate Change Adaptation through Renewable Energy: The Cases of Australia, Canada, and the United Kingdom

by Avri Eitan

Environments 2024, 11(9), 199; https://doi.org/10.3390/environments11090199 - 12 Sep 2024

Abstract

In recent years, climate change has escalated significantly, with forecasts indicating that this trend will further accelerate in the future. Renewable energy systems play a crucial role in global efforts to mitigate climate change due to their minimal greenhouse gas emissions. These systems [...] Read more.

In recent years, climate change has escalated significantly, with forecasts indicating that this trend will further accelerate in the future. Renewable energy systems play a crucial role in global efforts to mitigate climate change due to their minimal greenhouse gas emissions. These systems also have the potential to facilitate the energy sector’s adaptation to climate change, given their decentralized nature, which enhances the resilience of energy infrastructure to extreme climate events. Nevertheless, existing literature predominantly focuses on their role in global mitigation efforts, often overlooking their significant adaptation capacity, particularly as reflected in national policies. This study seeks to bridge this gap through a qualitative examination of how renewable energy is incorporated into climate change adaptation policies in three countries: Australia, Canada, and the United Kingdom. It highlights a growing awareness of the role of renewable energy within these countries’ adaptation policies. However, while there is consensus on the importance of policy factors such as local focus, research initiatives, and risk assessment in utilizing renewable energy for adaptation, this study reveals that the actual deployment of renewable energy remains largely centered on mitigation efforts, partly neglecting crucial adaptation needs in the energy sector, such as geographical and technological diversification. Full article

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19 pages, 4428 KiB

Open AccessFeature PaperArticle

Adsorption of a Mixture of Daily Use Pharmaceuticals on Pristine and Aged Polypropylene Microplastics

by Dimitrios Kalaronis, Eleni Evgenidou, George Z. Kyzas, Dimitrios N. Bikiaris and Dimitra A. Lambropoulou

Environments 2024, 11(9), 198; https://doi.org/10.3390/environments11090198 - 11 Sep 2024

Abstract

The main goal of this study is the examination of polypropylene (PP) microplastics (MPs) as possible carriers of daily use pharmaceutical compounds. The selected compounds can be separated into three groups: (i) antibiotics (Trimethoprim, Metronidazole, Indomethacin, Isoniazid), (ii) anti-inflammatories (Ketoprofen, Diclofenac), and (iii) [...] Read more.

The main goal of this study is the examination of polypropylene (PP) microplastics (MPs) as possible carriers of daily use pharmaceutical compounds. The selected compounds can be separated into three groups: (i) antibiotics (Trimethoprim, Metronidazole, Indomethacin, Isoniazid), (ii) anti-inflammatories (Ketoprofen, Diclofenac), and (iii) anti-hypertensive (Valsartan). Two types of PP MPs (virgin and UV-aged) were used in the experimental procedure, and the effect of time and the effect of the initial concentrations of the drugs were examined. The impact of various environmental factors such as pH, salinity, and natural organic matter were also explored. The last two factors were studied using real aqueous matrices such as wastewater and seawater. According to the obtained results, the highest uptake was observed in indomethacin (9.3 mg/g) and diclofenac (7.3 mg/g), owing to their physiochemical properties. Aged particles showed enhanced adsorption ability in accordance with the existing literature, as their adsorption capacity was between 0.5–1.5 times greater than that of the virgin ones. Regarding the desorption of compounds from the virgin and aged PP MPs at three different pH values, diclofenac and indomethacin exhibited the highest desorption capacity, while alkaline conditions favored the desorption ability of PP MPs for most of the target compounds. Full article

(This article belongs to the Special Issue Advanced Technologies of Water and Wastewater Treatment (2nd Edition))

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Graphical abstract

22 pages, 6667 KiB

Open AccessArticle

Assessing the Resilience of Enteric Bacteria in Manure in Response to Changes in Relative Humidity and UV-B Light

by Ingrid M. Leon, Brent W. Auvermann, Kevin Jack Bush, Kenneth Casey, William E. Pinchak, Javier Vinasco, Sara D. Lawhon, Jason K. Smith, Harvey Morgan Scott and Keri N. Norman

Environments 2024, 11(9), 197; https://doi.org/10.3390/environments11090197 - 10 Sep 2024

Abstract

Dehydrated manure from agricultural animal feedlots can become aerosolized and may potentially harbor viable antimicrobial-resistant bacteria. Little is known about the dynamics and risk of bacteria in bioaerosols originating from the feedyard environment. Nutrient deficiency, desiccation, UV exposure, temperature, and pH changes can [...] Read more.

Dehydrated manure from agricultural animal feedlots can become aerosolized and may potentially harbor viable antimicrobial-resistant bacteria. Little is known about the dynamics and risk of bacteria in bioaerosols originating from the feedyard environment. Nutrient deficiency, desiccation, UV exposure, temperature, and pH changes can affect bacterial viability. In this study, we investigated the impact of changes in relative humidity (RH) and UV-B exposure on enteric bacterial survival in vitro to simulate environmental conditions in cattle feedyards. Cattle manure samples were placed in two separate chambers with 73% RH and 31% RH, respectively. For the UV-B experiment, samples were placed in a chamber exposed to UV-B (treated) or in a chamber exposed to LED light (control). Samples from both experiments were spiral plated in triplicate onto selective agar media to quantify total aerobic bacteria, E. coli (total and antimicrobial-resistant (AMR)), and Enterococcus spp. (total and AMR). Results showed that enteric bacteria from cattle manure can withstand at least two stress conditions, including low RH levels and UV-B exposure. Moreover, the data revealed that antimicrobial-resistant bacteria can persist in manure under the harsh conditions that may be encountered in a feedyard environment. These findings underscore the need for mitigation strategies in feedlots to minimize the overall risk of bioaerosol formation. Full article

(This article belongs to the Special Issue Antimicrobial Resistance and Its Environmental Risk)

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28 pages, 719 KiB

Open AccessReview

A Review of the Adverse Effects of Neonicotinoids on the Environment

by Zyanya L. Mota, Itzel A. Díaz, Adriana E. Martínez-Ávila, M. Otero-Olvera, Dania Leyva-Ruíz, L. S. Aponte-Pineda, S. G. Rangel-Duarte, J. R. Pacheco-Aguilar, Aldo Amaro-Reyes, J. Campos-Guillén, L. A. Montes-Flores and M. A. Ramos-López

Environments 2024, 11(9), 196; https://doi.org/10.3390/environments11090196 - 10 Sep 2024

Abstract

Neonicotinoids are a group of insecticides developed in the 1980s, reaching extensive use in agriculture in the 1990s due to their effectiveness against pests in various types of crops. In 2014, their use reached 25% of the global market. In the last decade, [...] Read more.

Neonicotinoids are a group of insecticides developed in the 1980s, reaching extensive use in agriculture in the 1990s due to their effectiveness against pests in various types of crops. In 2014, their use reached 25% of the global market. In the last decade, studies on their possible effects have been conducted, leading to bans and regulations in several European Union countries. Their persistence in soil and water can result in chronic exposure in aquatic and terrestrial organisms, including pollinator species. The accumulation of these compounds in the environment can disrupt ecosystems and affect the health of humans, plants, and animals. This review presents current knowledge on neonicotinoids, their mechanisms of action, and their transport in ecological spheres. Their presence in water and soil is evidenced, with specific concentrations reported in various regions. Their effects on non-target organisms, including aquatic animals and humans, can be negative, causing direct and indirect neurological and renal problems after exposure. More research is needed on the long-term effects on health and non-target organisms to fully understand the implications of these insecticides. Full article

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24 pages, 12223 KiB

Open AccessArticle

Quantification and Categorization of Macroplastics (Plastic Debris) within a Headwaters Basin in Western North Carolina, USA: Implications to the Potential Impacts of Plastic Pollution on Biota

by Nathaniel Barrett, Jerry Miller and Suzanne Orbock-Miller

Environments 2024, 11(9), 195; https://doi.org/10.3390/environments11090195 - 10 Sep 2024

Abstract

Plastic production on a commercial scale began in the 1950s, reaching an annual production of 460 million metric tons in 2019. The global release of 22% of produced plastics into the environment has raised concerns about their potential environmental impacts, particularly on aquatic [...] Read more.

Plastic production on a commercial scale began in the 1950s, reaching an annual production of 460 million metric tons in 2019. The global release of 22% of produced plastics into the environment has raised concerns about their potential environmental impacts, particularly on aquatic ecosystems. Here, we quantify and categorize plastic debris found along Richland Creek, a small, heavily forested watershed in western North Carolina, USA. Plastics within the riparian zone of seven 50 m reaches of Richland Creek and its tributaries were sampled two or three times. The 1737 pieces of collected plastic debris were returned to the lab where they were measured and categorized. A small-scale laboratory study using seven of the items collected was performed to determine their ability to break down into microplastics (particles < 5 mm in size). The majority (76%) of collected items were made of either plastic film (particularly bags and food wrappers, 43%) or hard plastics (e.g., bottles, 2%). However, when viewed on a surface area basis, films and synthetic fabrics (e.g., clothing, sleeping bags) equally dominated. Roughly three-quarters of the items collected had a width less than 10 cm, due primarily to the fragmentation of the original items; over two-thirds of the collected items were fragmented. Items composed of foams and films exhibited the highest fragmentation rates, 93% and 86%, respectively. Most collected plastics were domestic in nature, and the number of items increased downstream through more developed areas. Laboratory studies showed that plastic debris has a propensity to break down into microplastics. We believe the data collected here should be replicated in other streams, as these freshwater environments are the source of plastics that eventually enter the oceans. Full article

(This article belongs to the Special Issue Plastics Pollution in Aquatic Environments)

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20 pages, 4994 KiB

Open AccessArticle

Development of a Hydrometallurgical Process for the Extraction of Cobalt, Manganese, and Nickel from Acid Mine Drainage Treatment By-Product

by Alejandro Agudelo Mira and Qingqing Huang

Environments 2024, 11(9), 194; https://doi.org/10.3390/environments11090194 - 8 Sep 2024

Abstract

Critical minerals (CMs) are pivotal in modern industries, such as telecommunications, defense, medicine, and aerospace, contributing significantly to regional and global economic growth. However, the reliance on external sources for 26 out of 50 identified CMs raises concerns about supply chain vulnerabilities. To [...] Read more.

Critical minerals (CMs) are pivotal in modern industries, such as telecommunications, defense, medicine, and aerospace, contributing significantly to regional and global economic growth. However, the reliance on external sources for 26 out of 50 identified CMs raises concerns about supply chain vulnerabilities. To address this, the research focused on developing a hydrometallurgical process for extracting cobalt, manganese, and nickel from acid mine drainage (AMD) treatment by-products, emphasizing the need to diversify CM supply chains within the United States (US). A solution composed of an REE solvent extraction raffinate loaded with cobalt, manganese, nickel, and various impurity metals was utilized as a feedstock in this study. The developed hydrometallurgical process involved initial sodium hydroxide precipitation to remove impurities like aluminum and iron from an SX raffinate solution generated during the extraction of rare earth elements (REEs). Precipitation stages were performed in a pH region ranging from 2 to 12 to identify the optimum pH values, achieving a tradeoff between recovery and impurity removal. A subsequent precipitation process at pH 5–10 yielded a product rich in CMs, such as manganese, cobalt, and nickel. Further separation steps involved nitric acid washing, resulting in a Mn product with a purity of 47.9% by weight and a solution with extractable concentrations of cobalt and nickel. Stagewise precipitation with sodium sulfide subsequently produced three solid products: cobalt and nickel product at pH 1–5, manganese product at pH 5–10, and magnesium at pH 10–12. The study also explored other separation approaches, including solvent extraction, to enhance the separation of nickel from cobalt. Overall, the developed hydrometallurgical process generated the following products with varying degrees of purities: cobalt (9.92 wt.%), nickel (14 wt.%), manganese (47.9 wt.%), and magnesium (27.49 wt.%). This research aimed to contribute to the sustainable extraction of CMs from secondary sources, reducing the US’ reliance on imports and promoting a more resilient supply chain for these crucial elements. Full article

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19 pages, 2059 KiB

Open AccessArticle

Ecological Shifts: Plant Establishment in an Animal-Based Ecosystem

by Linda J. Walters, Paul E. Sacks, Katherine Harris and Giovanna McClenachan

Environments 2024, 11(9), 193; https://doi.org/10.3390/environments11090193 - 8 Sep 2024

Abstract

Shifts from saltmarsh to mangroves are well-documented at mangrove poleward boundaries. A regime shift from intertidal oyster (Crassostrea virginica) reefs to mangrove islands has recently been documented in transitional phases in Florida, USA. To understand the local drivers of an oyster/mangrove [...] Read more.

Shifts from saltmarsh to mangroves are well-documented at mangrove poleward boundaries. A regime shift from intertidal oyster (Crassostrea virginica) reefs to mangrove islands has recently been documented in transitional phases in Florida, USA. To understand the local drivers of an oyster/mangrove regime shift and potential tipping points leading to a permanent mangrove state, we tracked all mangrove propagules (n = 1681) across 15 intertidal oyster reefs with or without adult mangroves for 15 months in Mosquito Lagoon, FL. While no propagule bottleneck was observed, few (3.2%) mangrove propagules/seedlings survived on reefs with no prior encroachment, compared to 11.3% and 16.1% on reefs with established older (pre-1943) or newer (1943 to present) adult mangrove stands, respectively. In total, 90.6% of the arriving propagules were from the red mangrove Rhizophora mangle; 13.2% of these were alive at the end of this study. Survival was <1% for black (Avicenna germinans) and 0% for white (Laguncularia racemosa) mangroves. Factors that promoted red mangrove success included close proximity (≤0.3 m) to adult mangroves, especially black mangroves; partial, upright burial of propagules in sediment; and arrival on reefs after annual high-water season. Additionally, once reefs had 50% mangrove cover, the density of red mangrove seedlings increased from 0.04 to 0.46 individuals m⁻². Although climate change has alleviated the impact of extreme freezes on mangroves, local factors determine whether the regime shift will be complete and permanent; positive feedback loops associated with established mangroves suggest mangrove recruitment on intertidal oyster reefs will continue to increase. Full article

(This article belongs to the Special Issue Monitoring and Assessment of Environmental Quality in Coastal Ecosystems Volume III)

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9 pages, 1727 KiB

Open AccessArticle

Innovative Pavement Materials: Utilizing Corn Stover and Fly Ash in Geopolymers

by Anu Paneru, Viral Sagar, Mohammad Tarikuzzaman, Joan G. Lynam, Stephen T. Gordon II and Shaurav Alam

Environments 2024, 11(9), 192; https://doi.org/10.3390/environments11090192 - 7 Sep 2024

Abstract

The development of each nation is evaluated by its infrastructure, and each nation is competing with the others in infrastructure advancement, especially in the construction of roadways, since they play a vital role in the economic and social development of the nation. The [...] Read more.

The development of each nation is evaluated by its infrastructure, and each nation is competing with the others in infrastructure advancement, especially in the construction of roadways, since they play a vital role in the economic and social development of the nation. The conventional materials used for road construction are concrete and asphalt, which pose significant environmental challenges. This research gives insight into the potential of fly ash (FA) and corn stover (CS) in synthesizing geopolymer, as an alternative material for the construction of roads. This study examines the impact of three FA and CS mixture percentages and the particle size of CS on the compressive strength and porosity of geopolymer. The results indicate that incorporating larger amounts of CS in fly ash-based geopolymer may decrease the compressive strength of the geopolymer. Smaller CS particle sizes also tend to lead to lower compressive strength. Porosity of the geopolymer tended to increase with the incorporation of higher percentages of CS, particularly for smaller corn stover sizes. As a fine aggregate replacement for geopolymer, CS incorporation has the potential to reduce mined aggregate obtained from a process that harms the environment. Full article

(This article belongs to the Special Issue Deployment of Green Technologies for Sustainable Environment II)

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37 pages, 10164 KiB

Open AccessReview

Management of Wadden Sea Salt Marshes in the Context of Nature Conservation, Coastal Flooding and Erosion Risks: A Review

by Angela Eden and Frank Thorenz

Environments 2024, 11(9), 191; https://doi.org/10.3390/environments11090191 - 6 Sep 2024

Abstract

Salt marshes in the southern North Sea are part of the UNESCO World Heritage Site, Wadden Sea, the largest unbroken system of intertidal sand and mud flats in the world. They provide a very high nature value while significantly contributing to coastal flood [...] Read more.

Salt marshes in the southern North Sea are part of the UNESCO World Heritage Site, Wadden Sea, the largest unbroken system of intertidal sand and mud flats in the world. They provide a very high nature value while significantly contributing to coastal flood and erosion risk management as a nature-based element of flood and erosion risk management systems for densely populated coastal areas. Climate change-induced sea-level rise is a significant concern: an integrated approach to salt marsh management adapted to the effects of climate change necessitates an understanding of the impact of different management strategies. This review commences with a description of the biogeomorphological conditions and processes in salt marshes for a better understanding of the natural dynamics and how they are influenced by management and climate change. Next, the impact of salt marshes on hydrodynamic processes and their role as nature-based elements of flood and erosion risk management is presented; management options and implementation methods are discussed and analysed concerning coastal flood management and nature conservation requirements. In conclusion, targeted salt marsh management needs to consider the initial conditions and the development aims of the specific site are integrated into a conceptual framework. Salt marshes have the potential to adapt to sea-level rise, thereby contributing to the long-term protection of coastal areas. Full article

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15 pages, 1930 KiB

Open AccessArticle

Air Pollution and Climate Change: A Pilot Study to Investigate Citizens’ Perception

by Ilaria Stanisci, Giuseppe Sarno, Olivia Curzio, Sara Maio, Anna Antonietta Angino, Patrizia Silvi, Liliana Cori, Giovanni Viegi and Sandra Baldacci

Environments 2024, 11(9), 190; https://doi.org/10.3390/environments11090190 - 5 Sep 2024

Abstract

Air pollution and climate change are risk factors for noncommunicable diseases of paramount importance and of major concern in a population. Their complex interaction suggests the need for an integrated and participatory approach by health professionals and citizens. During the Italian BRIGHT-NIGHT (European [...] Read more.

Air pollution and climate change are risk factors for noncommunicable diseases of paramount importance and of major concern in a population. Their complex interaction suggests the need for an integrated and participatory approach by health professionals and citizens. During the Italian BRIGHT-NIGHT (European Researchers’ Night) at the Pisa Research Campus of National Research Council (CNR), a laboratory focusing on environmental epidemiology issues and open to the public was set up. A self-administered questionnaire was distributed, with the aim of investigating the individual perception, knowledge, opinions and attitudes in relation to 12 different environmental, natural and anthropogenic hazards. The questionnaire was completed by 44 subjects aged over 18 years (47.6% female, 56.8% university graduates, 61.4% employed). Air pollution and climate change were considered two priorities for environmental protection and public health by 72.1%, prompting about one third of the subjects to commit to increasing active commuting. The results of this pilot survey indicate a diffuse awareness of air pollution and climate change as main environmental determinants to be tackled in order to protect public health. Full article

(This article belongs to the Special Issue Air Pollution in Urban and Industrial Areas II)

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12 pages, 1835 KiB

Open AccessArticle

Low Concentrations of Biochar Improve Germination and Seedling Development in the Threatened Arable Weed Centaurea cyanus

by Riccardo Fedeli, Tiberio Fiaschi, Leopoldo de Simone, Claudia Angiolini, Simona Maccherini, Stefano Loppi and Emanuele Fanfarillo

Environments 2024, 11(9), 189; https://doi.org/10.3390/environments11090189 - 4 Sep 2024

Abstract

In the context of sustainable agriculture, the search for soil improvers that boost crop growth without harming biodiversity is gaining much attention. Biochar, the solid residue resulting from the pyrolysis of organic material, has recently emerged as a promising bioproduct in enhancing crop [...] Read more.

In the context of sustainable agriculture, the search for soil improvers that boost crop growth without harming biodiversity is gaining much attention. Biochar, the solid residue resulting from the pyrolysis of organic material, has recently emerged as a promising bioproduct in enhancing crop yield, but there is a lack of information regarding its effects on arable biodiversity. Thus, in this study, we tested the effect of biochar application on the germination and seedling growth of cornflower (Centaurea cyanus L., Asteraceae), a threatened arable weed, under laboratory conditions. We investigated various parameters, including germination percentage (GP%), mean germination time (MGT), germination rate index (GRI), germination energy (GE%), fresh and dry weight (mg) of seedlings, and radicle length (mm) under biochar treatments at different concentrations: 0% (control), 0.1%, 0.2%, 0.5%, 1%, and 2%. Our findings revealed a significant increase in GP, GE, and GRI at biochar concentrations of 0.5% and 1%. MGT slightly increased at 0.1% biochar. Seedling fresh weight was unaffected by biochar application, whereas seedling dry weight exhibited a significant increase at 0.5% biochar. Radicle length showed a substantial increase under 0.1% biochar on day one, and was significantly higher at 0.2% and 1% biochar on day two. However, by day three, no more statistically significant differences in radicle length were observed between biochar-treated diaspores and controls (i.e., biochar had positive effects only in the first stages). These results suggest that the application of biochar at intermediate concentrations (0.5% and 1%) overall provides the most benefit to the germination and seedling growth of C. cyanus. Full article

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20 pages, 786 KiB

Open AccessReview

Impacts of PFAS Exposure on Neurodevelopment: A Comprehensive Literature Review

by Seth D. Currie, Jia-Sheng Wang and Lili Tang

Environments 2024, 11(9), 188; https://doi.org/10.3390/environments11090188 - 1 Sep 2024

Abstract

Neurodevelopmental disorders (NDDs) encompass a range of conditions that begin during the developmental stage and cause deficits that lead to disruptions in normal functioning. One class of chemicals that is of increasing concern for neurodevelopmental disorders is made up of per- and polyfluoroalkyl [...] Read more.

Neurodevelopmental disorders (NDDs) encompass a range of conditions that begin during the developmental stage and cause deficits that lead to disruptions in normal functioning. One class of chemicals that is of increasing concern for neurodevelopmental disorders is made up of per- and polyfluoroalkyl substances (PFAS). In this comprehensive literature review, we investigated data from epidemiological studies to understand the connection between PFAS exposure and neurodevelopmental endpoints such as cognitive function, intelligence (IQ), and memory, along with behavioral changes like Attention-Deficit Hyperactivity Disorder (ADHD) and Autism Spectrum Disorders (ASD). When we reviewed the findings from individual studies that analyzed PFAS levels in biological samples and their association with NDD, we concluded that there was a correlation between PFAS and neurodevelopmental disorders. The findings suggest that children exposed to higher PFAS levels could potentially have an increased risk of ASD and ADHD along with an inhibitory effect on IQ. While the results vary from one study to another, there is increasing association between PFAS exposure and neurodevelopmental disorders. Importantly, the findings provide valuable insights into the adverse effects associated with PFAS exposure and neurodevelopment. Full article

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