Browsing by Issue Date, starting with "2025-04"
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- Clustered patterns of household water consumption in Portuguese municipalities: do regional location and population trajectory matter?Publication . Jacinto, Gonçalo; Barreira, Ana PaulaPortugal faces water scarcity challenges, yet studies on per-household water consumption are limited. This study aims to address this gap by employing cluster analyses to assess how population trajectories, a previously overlooked aspect, and the regional location influence per-household monthly water consumption across 122 municipalities. Findings highlight higher consumption in the South despite lower prices. Municipalities experiencing population growth and those with long-term population declines show higher per-household water consumption but lower prices. Interestingly, while higher prices correlate with lower consumption, southern municipalities show increased prices without reduced consumption. Clustering reveals slight changes in consumption patterns from 2011 to 2020.
- Enhancing efficiency in solar non-intrusive desalination: solar still prototype optimization in Southwest EuropePublication . Pacheco, André; Sequeira, Claudia; Silva, Manuela Fernanda Gomes Moreira da; Serrão Sousa, VâniaAccess to freshwater is a pressing global challenge. Despite being irreplaceable freshwater is an increasingly scarce resource, especially in regions as Southern Europe, due to high human pressure and climate change. Solar desalination presents a low impact solution to produce freshwater from seawater, particularly in sun-rich regions. The main goal of this study was to develop a modular solar desalination system based on a non-intrusive approach, with simple assemblage, installation, and maintenance, to produce freshwater for non-potable purposes. The modular design was chosen to allow scalability and adaptability, enabling effective response to variable water demands in small island communities. The case study is a small island from Algarve, Portugal (Southwest Europe). The study evaluates the performance enhancements accomplished by transitioning from an initial prototype solar desalination unit, smaller and with a simple design, to an enhanced pilot-scale system designed to improve efficiency and water output. The research showed that both systems exhibit a high conductivity removal (higher than 99 %), demonstrating the potential of this technology to produce freshwater from seawater, delivering high-quality desalinated water, across different seasons. Prototype 1 demonstrated limited productivity, around 0.45 L/day.m2, while pilot-scale unit presented a productivity of approximately 6 L/day.m2 in summertime. This substantial improvement reflects the design modifications implemented in the pilot-scale unit, positioning it as a valuable option for water desalination in regions with abundant solar resources. These findings confirm the strong potential of solar desalination as a non-intrusive and effective solution and lays the groundwork for future advancements, focusing on maximising efficiency by exploring innovative materials to enhance solar energy absorption and optimizing operational conditions.
- Heterotrophic cultivation of Chlorella vulgaris yellow mutant on sidestreams: Medium formulation and process scale-upPublication . Trovão, Mafalda; Barros, Ana; Machado, Adriana; Reis, Ana; Pedroso, Humberto; Espírito Santo, Gonçalo; Correia, Nádia; Costa, Monya; Ferreira, Sara; Varela, João; Cardoso, Helena; Silva, Joana; Pereira, Hugo; Freitas, FilomenaMicroalgal protein is a promising feedstock to complement and/or replace other protein sources. Besides requiring less land and water usage, microalgae production is a more sustainable process, especially if industrial sidestreams are used as nutrient sources. Additionally, the heterotrophic cultivation of microalgae, such as Chlorella vulgaris, enables the achievement of much higher biomass productivity and lower areal footprint than autotrophic cultivation. Chlorophyll-deficient strains of C. vulgaris, as the yellow strain 7Y, provide microalgal biomass with improved sensory properties. In line with this, a waste-based medium was formulated to cultivate this strain, aiming at maximum biomass productivity. In this context, several industrial sidestreams were screened, and two food wastes and corn molasses were selected for their high nitrogen and glucose concentrations, respectively. The waste-based medium formulated was compared to the inorganic optimised medium at laboratory scale in Erlenmeyer flasks and 7-L reactors. The results obtained in the 7-L fermenters revealed that both conditions achieved similar biomass productivities and growth rates of approximately 14 g L-1 d-1 and 0.8 d-1, respectively. The biomass and protein productivities were further enhanced by supplying a higher nitrogen concentration in the feeding solution when the process was scaled-up to 200-L reactors, reaching 22 and 6.3 g L-1 d-1, respectively, thus validating the developed industrial waste-based medium for the efficient cultivation of C. vulgaris under heterotrophic conditions.
- Are interconnectedness and spillover alike across green sectors during the COVID-19 and the Russia–Ukraine conflict?Publication . Hanif, Waqas; El Khoury, Rim; Arfaoui, Nadia; Hammoudeh, ShawkatThis study investigates interconnectedness and spillover dynamics among nineteen clean energy equity subsectors during the COVID-19 pandemic and the Russia-Ukraine conflict. Using the Time-Varying Parameter Vector Autoregression (TVP-VAR) Joint Connectedness approach, the findings reveal intensified interconnectedness during crises, with the Total Connectedness Index (TCI) surpassing 100 % during COVID-19, while stabilizing amid the Russia-Ukraine conflict, indicating a partial resilience in clean energy markets. Sub-sectors such as Energy Management, Recycling, and Water consistently serve as risk transmitters, while Wind and Geothermal absorb risks, emphasizing heterogeneous roles within the sector. This high level of interconnectedness limits the ability to reduce risks within the clean energy sector alone during turbulent times. Policy interventions, such as subsidies and regulatory support for critical risk-transmitting sub-sectors, could stabilize the market and reduce systemic vulnerabilities. Sectors like Solar and Smart Grid adapt to market conditions, taking on different roles depending on crisis-specific factors, particularly in response to energy security and sustainability policies. Investors may enhance their portfolio stability by focusing on the risk-absorbing subsectors, such as Wind and Geothermal, and also adopting dynamic asset allocation strategies during crises.
- Tailored cellulose-based flocculants for microplastics removal: mechanistic insights, pH influence, and efficiency optimizationPublication . Magalhães, Solange; Norgren, Magnus; Alves, Luís; Medronho, Bruno; Rasteiro, Maria da GraçaThis study explores the performance of novel cellulose-derived sustainable flocculants in the flocculation of different model microplastics (MPs), including polyethylene (PE), polyethylene terephthalate (PET) and polyvinyl chloride (PVC). The influence of key parameters, such as pH, flocculant structure and concentration was evaluated by Laser Diffraction Spectroscopy (LDS) and optical microscopy to access their effects on flocculation performance, kinetics and floc structure. The results reveal that a bioflocculant concentration of 0.001 g & sdot;mL- 1 is ideal for effective flocculation, as lower concentrations lead to insufficient floc growth. While electrostatic interactions are a dominant factor in the flocculation process, the study also highlights the role of hydrophobic interactions, its contribution depending on the characteristics of the MPs. Overall, this research highlights the importance of understanding the key interactions governing the flocculation process. It further paves the way for designing and fine-tuning cellulose-based flocculants with improved efficiency and optimized dosages for effective MPs removal strategies.
- A high-resolution chronology for the archaeological deposits at Pinnacle Point 5–6, Western Cape Province, South AfricaPublication . Jacobs, Zenobia; Karkanas, Panagiotis; Fahey, B. Patrick; Fisher, Erich Christopher; Marean, Curtis W.Pinnacle Point Site 5-6 (PP5-6) is a key archaeological and paleoenvironmental site located on the edge of the Palaeo-Agulhas Plain along the southern Cape coast of South Africa. Construction of high-resolution chronologies for archaeological sites beyond the range of radiocarbon dating is challenging. Geochronological methods such as optical dating are hampered by the availability of applicable materials that are directly associated with the events of interest. Optical dating relies on assumptions made about time-dependent changes and is made up of a series of measurements each with its own random and systematic uncertainties that together make up the age estimates. In this study, we explicitly took on the challenge to systematically produce a high-resolution chronology for PP5-6 made up of 197 individual age estimates of which 169 were input into a Bayesian age model. PP5-6 is ideal because of its fine-scale stratigraphy and use of modern excavation techniques and detailed recording of stratigraphy and plotted finds. Excavations and dating took place concurrently over almost two decades to inform the dating strategy, contextualise sample choice and data analysis, and to bring the scales of analysis of different proxies closer together. Here we present the optical dating process, including sensitivity tests of our instruments, data analysis procedures and modelling approach. We then construct a final timeline for comparisons with other proxy data and interpretation of the sedimentary sequence and occupation of PP5-6 over an interval of similar to 60,000 years from similar to 110,000 to similar to 50,000 years ago. We show how closely linked sediment deposition is to changes in global climate and sea-level, identify a few Pleistocene and Holocene erosional events that modified the site post-depositionally and place a variety of interconnected causes and effects coincident with different types of occupation on this timeline. This approach opens up opportunities to reduce the resolution of chronologies closer to the human timescales required to improve our understanding of changes through time and to make more direct comparisons between other sites and proxies that contain similarly highly resolved archives of human occupation and change.
- Insights into conservation success: analysing shore angling before implementing a marine protected areaPublication . Jacinto, Gonçalo; Veiga, Pedro; Monteiro, Pedro; Erzini, Karim; Gonçalves, Jorge Manuel Santos; Horta e Costa, Barbara; Pontes, João; Guerreiro, Pedro Miguel; Rangel, Mafalda; Nuñez Velazquez, Samira; Pilar Fonseca, TerezaIn January 2024, the "Natural Marine Park of the Algarve Reef - Pedra do Valado" (NMPAR-PV; southern Portugal), a community-based Marine Protected Area (MPA) was formally classified, setting the scene for a new paradigm for co-creating Portuguese MPAs. While complying with the best practices for MPA establishment, this area also contributes to national and international conservation targets. Measuring the success of MPAs relies on the availability of the best scientific information, including baseline data on biodiversity, habitat and human activities characterization. Marine recreational fishing is a significantly important human activity within this recently designated MPA. Hence, the systematic collection of quantitative data on this activity is critical for determining its impacts and ensuring the preservation and protection of fisheries resource. This study aims to collect and analyze socioeconomic and ecological data on shore angling fisheries at NMPAR-PV, implementing surveys and instantaneous counting. Data from 325 questionnaires and 27 counting surveys conducted between February 2022 and February 2023 highlighted the importance of shore angling. The activity is primarily conducted by local Portuguese men, over 50, employed and with low formal education. Most recreational fishers supported the MPA's implementation, suggesting community care for conservation efforts. The annual fishing effort was estimated at 52 198 +/- 6 631 angling hours, with peaks in Autumn. Annual catches, dominated by Scombridae and Sparidae species, were estimated at 10.41 +/- 1.96 tonnes of fish. This study provides valuable insights into the evolution of recreational fishing activity within the MPA, addressing important information to assess its effectiveness.
- The role of peer mentoring program elements in promoting academic success and preventing student dropout in higher education: a systematic literature reviewPublication . Pereira Guerreiro, Mariana; Neves de Jesus, SaúlPeer mentoring programs have been implemented to address higher education institutions' demands for promoting academic success and preventing student dropout. However, it is still unclear what elements best contribute to their effectiveness. A systematic literature review on the peer mentoring programs' elements focused on promoting academic success and preventing dropout was conducted to understand better how to improve peer mentoring effectiveness in academia. Twenty-three studies were included and evaluated for quality. A thematic analysis was developed to report patterns in the elements of the included peer mentoring programs. Results demonstrate the effectiveness of formal peer mentoring programs where participation is voluntary, no financial incentives are provided, and faculty members are involved. Future research must ensure a more detailed description of the peer mentoring programs' elements and robust methodology quality. It is necessary to evaluate the mentoring program's effectiveness by considering mentor screening based on academic performance, matching characteristics, mentoring models, and program coordination feedback, in addition to analysing mentor training efficacy.
- Behavioural responses to visual and chemical cues in Mozambique tilapia (Oreochromis mossambicus): a putative pheromonal activity for 17β-estradiol 3-glucuronatePublication . Ashoori, Samyar; Canario, Adelino; Hubbard, PeterIn reproduction of Mozambique tilapia (Oreochromis mossambicus), chemical communication mainly relies on urinary steroidal glucuronides (sex pheromones) that dominant males release to prime the final ovulation in pre-ovulatory females and increase reproductive readiness. However, the role of steroids in chemical communication in females has received less attention. Here, we aimed to determine whether 17 beta-estradiol 3-glucuronate released by pre-ovulatory females functions as a reproductive signal towards males. We investigated the preference of focal males to visual, chemical (female conditioned water), and a combination of both stimuli from pre-ovulatory or post-spawning females, as well as 10- 9 M 17 beta-estradiol 3-glucuronate. Compared to the control zone, where no stimuli were present, males were more responsive (time spent near the stimuli, digging behaviour, and urination frequency) in the visual and visual + chemical zones than in the chemical-only zone. Males preferred pre-ovulatory to post-spawning female-conditioned water. Interestingly, the time spent by focal males near the source of 17 beta-estradiol 3-glucuronate was similar to pre-ovulatory conditioned water. However, there was no significant difference in digging and urine pulses in response to 17 beta-estradiol 3-glucuronate compared to the control group. We suggest that male tilapia recognise the ovulation status of females using visual and chemical cues, and 17 beta-estradiol 3-glucuronate is part of the odorant content released by pre-ovulatory females to communicate their reproductive status.
- The impact of social, economic and political change in linear and appositional growth of children from the medieval islamic and christian periods of the Algarve, PortugalPublication . Kors, Carmen; González-Ruiz, Ana; Gonçalves, Maria José; Valente, Maria João; Garcia, Cristina; Cardoso, Hugo F. V.Archaeological data and historical research suggest that the Medieval Islamic Period (711-1249 A.D.) in Iberia was associated with conditions more favourable for child growth than the post-Islamic Christian Period (1249-1650 A.D.). This is due to agricultural prosperity, greater medical knowledge, and better hygienic practices of the former. As child growth is a sensitive indicator of environmental insults, it can be used as a proxy for the stress experienced by the whole population. The linear and appositional bone growth of 29 children (under the age of 12 years) recovered from archaeological sites in Silves and Cacela Velha- dating from the Medieval Islamic and Christian Period in the Algarve, Portugal- were compared to determine whether the environmental changes associated with the transition between these periods impacted the health and well-being of the populations. Age was estimated from tooth length. Linear growth of all long bones and the appositional growth of the femur and humerus at the midshaft were compared between periods using z-scores. Bone growth deficits were found among the medieval children in all samples. Overall, Islamic Period children had slightly greater growth deficits than Christian Period children, although these differences were not statistically significant. This finding suggests that neither Medieval Period was more favourable for growth. Statistically significant differences in appositional growth were found between the Medieval Santarem and Algarve populations, suggesting these differences to be related to the local environment, rather than religious or temporal differences within the Algarve or other regions of Portugal.