Environments, Volume 10, Issue 1 (January 2023) – 13 articles

The systemic transformation towards climate neutral cities depends on a dramatic reduction in the use of natural resources, whose use are directly or indirectly associated with greenhouse gas emissions. This means improving Urban Metabolism (UM) and one of the most promising pathways is to promote Circular Economy (CE) practices in the existing building stock, as this approach could reduce global CO₂e emissions from building materials by 38% in 2050. However, although resource efficiency is at core of CE, there are still only a few established connections between CE and UM. This paper aims to fill this gap by adopting a three-tier approach based on the dimensions and the spatial implementation of CE (building, neighbourhood and UM scales), with the aim of discussing strategies for CE implementation. Although this not a one-size-fits-all process and cities must adapt these strategies to their local contexts, the strategic actions offered by this paper will facilitate the future development of a dedicated framework for buildings refurbishment using the principles of CE and the definition of multisectoral policy-based actions, in line with the decarbonization goals for cities, which will contribute to improving UM. Full article

The year-to-year variability of precipitation has significant consequences for water management and forest health. “Whiplash” describes an extreme mode of this variability in which hydroclimate switches abruptly between wet and dry conditions. In this study, a pool of total-ring-width indices from five conifer species (Abies magnifica, Juniperus grandis, Pinus ponderosa, Pinus jeffreyi, and Tsuga mertensiana) in the Sierra Nevada is used to develop reconstructions of water-year precipitation using stepwise linear regression on lagged chronologies, and the reconstructions are analyzed for their ability to track whiplash events. A nonparametric approach is introduced to statistically classify positive and negative events, and the success of matching observed events with the reconstructions is evaluated using a hypergeometric test. Results suggest that reconstructions can effectively track whiplash events, but that tracking ability differs among species and sites. Although negative (dry-to-wet) events (1921–1989) are generally tracked more consistently than positive events, Tsuga stands out for strong tracking of positive events. Tracking ability shows no clear relationship to variance explained by reconstructions, suggesting that efforts to extend whiplash records with tree-ring data should consider optimizing reconstruction models for the whiplash signal. Full article

Global climate change concerns have pushed international governmental actions to reduce greenhouse gas emissions by adopting cleaner technologies, hoping to transition to a more sustainable society. The hydrogen economy is one potential long-term option for enabling deep decarbonization for the future energy landscape. Progress towards an operating hydrogen economy is discouragingly slow despite global efforts to accelerate it. There are major mismatches between the present situation surrounding the hydrogen economy and previous proposed milestones that are far from being reached. The overall aim of this study is to understand whether there has been significant real progress in the achievement of a hydrogen economy, or whether the current interest is overly exaggerated (hype). This study uses bibliometric analysis and content analysis to historically map the hydrogen economy’s development from 1972 to 2020 by quantifying and analyzing three sets of interconnected data. Findings indicate that interest in the hydrogen economy has significantly progressed over the past five decades based on the growing numbers of academic publications, media coverage, and projects. However, various endogenous and exogenous factors have influenced the development of the hydrogen economy and created hype at different points in time. The consolidated results explore the changing trends and how specific events or actors have influenced the development of the hydrogen economy with their agendas, the emergence of hype cycles, and the expectations of a future hydrogen economy. Full article

One of the main preventive measures recognized by WHO and implemented to mitigate the COVID-19 epidemic impact, by controlling the transmission of coronavirus, was the use of a facemask. Since a facemask is an accessory that can be used several hours a day, through which the air we breathe passes, and which is in contact with the face skin, it must not cause discomfort to the wearer and must not contain toxic, irritating or sensitizing substances. Therefore, it is of utmost importance to identify the toxic chemical compounds present in the facemask material. Hence, the present study aims to discuss a proposal for a low-VOC emission label to be assigned to facemasks’ materials in terms of respiratory and skin health. Two types of tests were proposed, one for analysis of VOC emissions, to assess the user exposure by inhalation, and the other for analysis of the VOC content, for evaluating the user exposure by dermal contact. Nine facemasks of different types: surgical (M1–M3), FFP2 (M4–M6) and reusable (M7–M9), were tested according to these methods. Comparing all the analyzed facemask types, the calculated TVOC dose, resulting from the exposure by inhalation, is very diversified, with low and high values, varying between 0 (in M7) and 2374 µg/day (in M6). However, they are consistently higher for the three analyzed self-filtering FFP2 respirators (M4–M6). Concerning dermal exposure, it is not possible to generalize, but the reusable facemasks analyzed in this work (M7–M9) consistently present higher values of skin-sensitizing compounds than the disposable facemasks (M1–M6). An attempt was made to establish criteria for assigning the low-VOC emission label. The proposed values are suggestions, requiring further studies. The authors expect that the results of this study may lead to future implementation of standards and regulations regarding the chemical compounds present in facemasks materials. Full article

This paper reports the multifractal characteristics of lengthy PM₁₀ time series from five stations in the Greater Athens Area (GAA), Greece. A novel methodology based on the multifractal detrended fluctuation analysis (MFDFA) is applied to raw and shuffled series in 74 segments in 11 date-periods, previously located, with very strong self-organised critical (SOC) and fractal properties. The MFDFA identified multifractality in all segments. Generalised and classical Hurst exponents are in the range 0.8–1.5 and 9–4.5 for the raw and shuffled series, while the multifractal $f\left(a\right)-a$ is within 0.5–1.2 and 0.1–2, respectively. The $f\left(a\right)-a$ data are fitted to polynomials to calculate the multifractal parameters W, $FWHM$ and $f_{max}$. While these are bimodal, a new parameter, $FWHM/f_{max}$, is normally distributed, and due to this, it is employed to locate the important multifractal behaviour via the $FWHM/f_{max}$ outliers. Five date-periods are found. The date-period 8 January 2015 has extraordinary multifractality for raw and shuffled series for both the AGP and LYK stations. This date-period is one of the three reported in the most recent combination study. Finally, sliding window MFDFA evolution plots of all the series are given. The results provide very strong evidence of the multifractality of the PM₁₀ time series. Full article

With the advancement of technology and a global shift towards clean energy, the need for rare earth metals is increasing. Scandium, a rare earth metal, has been extensively used over the decades in solid oxide fuel cells and aluminum–scandium alloys that have a vast, evolving market in aerospace, automobiles and 3D printing. However, the market struggles to maintain the supply chain due to expensive production processes and the absence of uniform global distribution of primary sources. Therefore, identification of alternative sources and technological advancements for scandium recovery are needed. To this end, an effort has been made to provide a review of the advances in different technologies applied in scandium recovery from diverse sources. Emphasis has been given to the improvements and upgrades to technologies in terms of environmental impact and recovery efficacy. An attempt has been made to discuss and deliver a clear representation of the challenges associated with every source for scandium recovery and the major developments in solving them. The environmental impact of scandium recovery and recycling has also been discussed. Full article

The novel aspect of this research is the fabrication, characterisation, and application of an engineered adsorbent made from quartz sand coated with calcium ferric oxides (QS/CFO) derived from the wastepaper sludge ash (WPSA) for the removal of tetracycline (TC) from synthetic water. Initially, the new adsorbent was fabricated using a Ca/Fe molar ratio, sand/FeCl₃ ratio, pH (of synthesising environment), ethylene glycol dose, and temperature of 1:0.75, 1:1, 12, 6 mL/100 mL, and 95 °C, respectively. Then, the new adsorbent was applied to treat water having 50 mg/L of TC in batch experiments, taking into account the effects of the contact time (0–180 min), pH of water (2–12), the dose of adsorbent (0.05–0.5 g), and agitation speed (0–250 rpm). The results obtained proved the engineered adsorbent can remove as much as 90% of the TC (adsorption capacity of 21.96 mg/g) within 180 min at an initial pH, adsorbent dosage, and agitation speed of 7, 0.3 g per 50 mL, and 200 rpm, respectively. It was also found that the pseudo-second-order model describes the kinetic measurements better than the pseudo-first-order model, which indicates that the TC molecules have been bonded with the prepared sorbent through chemical forces. Furthermore, the intra-particle diffusion model results demonstrated that the diffusion mechanism plays a significant role in TC adsorption; however, it was not the predominant one. Finally, the outcomes of the characterisation analysis proved that the newly formed layer on the quartz sand substantially contributed to the removal of the TC from the contaminated water. Full article

An upsurge in global population and rapid urbanization has accelerated huge dependence on petroleum-derived fuels and consequent environmental concerns owing to greenhouse gas emissions in the atmosphere. An integrated biorefinery uses lignocellulosic feedstock as raw material for the production of renewable biofuels, and other fine chemicals. The sustainable bio-economy and the biorefinery industry would benefit greatly from the effective use of lignocellulosic biomass obtained from agricultural feedstocks to replace petrochemical products. Lignin, cellulose, hemicellulose, and other extractives, which are essential components of lignocellulosic biomass, must be separated or upgraded into useful forms in order to fully realize the potential of biorefinery. The development of low-cost and green pretreatment technologies with effective biomass deconstruction potential is imperative for an efficient bioprocess. The abundance of microorganisms along with their continuous production of various degradative enzymes makes them suited for the environmentally friendly bioconversion of agro-industrial wastes into viable bioproducts. The present review highlights the concept of biorefinery, lignocellulosic biomass, and its valorization by green pretreatment strategies into biofuels and other biochemicals. The major barriers and challenges in bioconversion technologies, environmental sustainability of the bioproducts, and promising solutions to alleviate those bottlenecks are also summarized. Full article

The grapevine (Vitis vinifera) is widely cultivated for the production of wine and other commodities. Wine is globally traded, with an annual market value of approximately USD 4 billion in Portugal alone. However, climate change is expected to profoundly alter regional temperature and precipitation regimes across the Iberian Peninsula and, thus, in continental Portugal, potentially threatening to impact viticulture. We used boosted regression trees and environmental variables describing the climate, soil, topography, and irrigation with a large number of presences (N = 7002) to estimate grapevine suitability for a baseline (1981–2010) and three future periods spanning from 2011 to 2100 using two climate trajectories (SSP3-7.0 and SSP5-8.5) and irrigation scenarios (continued and ceased). Under SSP3-7.0 with irrigation and SSP5-8.5 without irrigation, our results suggest a decline in suitable viticulture area across continental Portugal of ~20% and ~80% by 2041–2070 and 2011–2041, respectively. Following this decline, our data suggest a potential recovery by 2071–2100 of ~6% and ~186%, respectively. However, regional change is more complex: by 2071–2100, the Região Norte, the Douro wine region, and the Algarve, for example, each would experience future changes in suitable area in the range of approximately −92% to −48%, −86% to −24%, and −59% to 267%, respectively, depending mostly on the practicality of irrigation. Full article

Waste cork granules of Quercus cerris bark were subjected to isothermal and non-isothermal slow pyrolysis. The heat of the reaction, as well as the yields and properties of biochar, bio-oil, and pyrolysis gas were investigated by thermogravimetric analysis, FT-IR, CHN elemental analysis, higher heating value (HHV) determinations, scanning electron microscopy (SEM), and gas chromatography (GC). The slow pyrolysis was carried out in a semi-batch reactor using an isothermal or a non-isothermal dynamic approach. The results demonstrated that isothermal or non-isothermal slow pyrolysis of cork is a slightly exothermic reaction that produces biochars. The elemental analysis results indicated that non-isothermally produced chars have similar fuel properties compared to isothermally produced chars. The FT-IR results showed that cork suberin undergoes a higher degree of degradation in isothermal chars and aromatization begins in the char structure. Bio-oils are also produced and they consist of C₅–C₁₂ hydrocarbons with C₈ carbon compounds making up the main fraction. Lighter components, mainly C₁–C₂ hydrocarbons are collected in the gas phase. The overall results indicate a possible reduced-cost route for the production of cork-based biochars by using non-isothermal slow pyrolysis. Full article

Ecological modeling refers to the construction and analysis of mathematical models aimed at understanding the complexity of ecological processes and at predicting how real ecosystems might evolve. It is a quickly expanding approach boosted by impressive accelerations in the availability of computational resources and environmental databases. In the light of foreseeing the effect of climate change on forest ecosystems, the branch of ecological modeling focusing on species distribution models (SDMs) has become widely used to estimate indices of habitat suitability and to forecast future tree distributions. However, SDMs are usually informed based solely on environmental data without any reference to the genetic makeup underlying responses to the environment, the possibility of exchanging variants helping to persist in situ, or the capacity to chase suitable conditions elsewhere. Among the main evolutionary processes that may complement forecasts of range shifts are local adaptation and gene flow, i.e., the occurrence of genetic variants conferring a population the optimal fitness in its own habitat and the exchange of adaptive alleles between populations. Local adaptation and gene flow could be described by indices of genetic diversity and structure, genetic load, genomic offset, and an admixture of genetic lineages. Here, we advocate for the development of a new analytical approach integrating environmental and genomic information when projecting tree distributions across space and time. To this aim, we first provide a literature review on the use of genetics when modeling intraspecific responses to the environment, and we then discuss the potential improvements and drawbacks deriving from the inclusion of genomic data into the current SDM framework. Finally, we speculate about the potential impacts of genomic-informed predictions in the context of forest conservation and provide a synthetic framework for developing future forest management strategies. Full article

The aim of this study is to analyze the recent sedimentation rate in the center of the Limoncocha lagoon, a Ramsar site in the Ecuadorian Amazon, using the ²¹⁰Pb dating method and identifying the potentially toxic elements along a 50 cm sediment core. A strategy based on the application of three single and four integrated indices is used to evaluate trace element contamination with depth. Single indices show mainly As and Mo, and Cu, Ba, Cd, Ni, and Pb to a lesser extent, as responsible elements of a minor enrichment between −10 and −40 cm. The multielement slight pollution shows a mixture of potential contamination sources, probably due to agricultural, oil activities, and urban wastewater discharges. However, integrated indices applied, classify the complete core as without potential risk. The ²¹⁰Pb_excess profile shows three differentiated sections. A surface section where new materials with lower concentrations have been found, probably due to the underground currents that connect the lagoon and the nearby Napo River; a central section where CF-CS model and mass accumulation rate calculations provide a sediment accumulation rate of 0.56 ± 0.03 cm y⁻¹; finally, a deeper section with a constant ²¹⁰Pb_exces profile, showing sediment reworking probably due to local flooding’s. Full article

The treatment of waste and especially solid waste, the type with the highest increase in terms of annual generation over the last decade, is a key issue in the Balkan and Mediterranean region. Piecemeal efforts to deal with it within the prevailing linear economy model were not successful since the techniques used such as recycling and reusing could not be effective with the existing products. A definitive solution requires the switch to a new model, the circular economy model, which will facilitate the tackling of the excessive use of virgin raw materials and waste generation. The design and development of a digital solid waste reuse platform in the context of the EU-funded Interreg Project SWAN involving four countries: Albania, Bulgaria, Cyprus and Greece, was a step in this direction. The present paper based on the evidence drawn from this project examines the current situation and the future trends in the solid waste reuse and industrial symbiosis schemes in this region. Full article