https://www.um.edu.mt/library/oar/handle/123456789/375 2026-04-04T13:37:36Z 2026-04-04T13:37:36Z Scerri, Mark M. Haas, Kristin Gauci, Adam Schiedek, Thomas https://www.um.edu.mt/library/oar/handle/123456789/145170 2026-03-26T13:54:49Z 2026-01-01T00:00:00Z

Title: Atmospheric deposition of polycyclic aromatic hydrocarbons in southwestern German soils : sources, cancer risks and policy implications Authors: Scerri, Mark M.; Haas, Kristin; Gauci, Adam; Schiedek, Thomas Abstract: Background: Polycyclic aromatic hydrocarbons (PAHs) comprise a group of persistent carcinogenic pollutants whose transfer from air to soil via the atmospheric deposition represents a major chronic exposure pathway. Regulatory frameworks across Europe and beyond rely heavily on single compound indicators such as benzo[a]pyrene and focus predominantly on point source contamination, creating potential blind spots for contamination by deposition. This observational study quantified concentrations, identified emission sources and assessed the lifetime cancer risk of 20 PAHs in 97 topsoil samples from four locations in southwestern Germany. Results: The total concentrations of the 16 USEPA priority pollutants ranged from 52 to 3956 μg/kg, with median values between 214 μg/kg (Hunsrück) and 371 μg/kg (Saarland/Palatinate Forest). Most sites (76%) were classified as “not” or “weakly” contaminated, while 12% were “heavily contaminated”. PMF identified four major sources accounting for 97% of the total PAH mass: coal/coke combustion (34.5%), biomass combustion (9.8%), petrogenic sources (15.8%) and combustion of liquid fuels from vehicles and stationary sources (37.0%). A Monte Carlo based cancer risk assessment for ingestion, dermal contact, and inhalation indicated cumulative risks between 10-4 – 10-6, with ingestion and dermal contact as the dominant pathways. Localized hotspots with elevated risks were identified, indicating the need for site specific follow up. Conclusions: Liquid fuel combustion represents the dominant process influencing soil contamination by atmospherically deposited polycyclic aromatic hydrocarbons (PAHs) in the study area. While measured concentrations at most sites remain within current regulatory limits, the cumulative toxicity of PAH mixtures results in cancer risks that are not negligible. These findings point to a structural limitation in existing EU and national soil protection frameworks (e.g., the German BBodSchG/BBodSchV), which remain primarily oriented toward contamination from identifiable point sources and do not adequately account for diffuse deposition-driven inputs. Consequently, soils affected by atmospheric PAH deposition may fall outside current regulatory attention despite carrying a cumulative toxic burden of potential relevance for human health. Strengthening soil quality assessment approaches to incorporate cumulative toxicity metrics and deposition-driven contamination pathways would improve health protection and better align soil policy with contemporary emission patterns.

2026-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/144595 2026-03-04T14:00:00Z 2025-01-01T00:00:00Z

Title: Designing spaces for nature-based learning in small, urban primary schools Abstract: Nature connectedness, particularly when nurtured through regular childhood experiences, is a strong predictor of pro-environmental behaviour. Yet, in urban settings, limited access to nature restricts children’s opportunities to develop such connections. This thesis positions Nature-Based Learning (NBL), delivered through primary schooling, as a practical means of fostering children’s relationship with nature through curriculum-based nature experiences on school grounds. However, small urban schools, where these opportunities are most needed, face distinct spatial and infrastructural challenges in designing spaces that are able to provide such experiences. The research thus focused on how small, urban primary schools can be supported in designing curriculum-linked, nature-based learning environments that foster children’s connection with nature. The first stage involved a systematised review of peer-reviewed and grey literature to identify design guidance for NBL school grounds. This review highlighted both the educational value of school grounds and the relative absence of research addressing the realities of urban and small-footprint schools. These findings informed the development of a draft design framework, structured around three guiding questions that considered aims, users, and contextual factors influencing NBL in urban settings. The second stage involved testing the framework in the Maltese context. To provide a baseline for Malta as an implementation context, a survey of educators explored current practices and perspectives on outdoor learning, while a mapping study of primary school grounds identified opportunities and constraints for implementation. Findings confirmed the acute challenges of urban schools, the demand for suitable outdoor learning environments, and educators’ belief in the value of nature-based experiences for students, confirming the relevance of Malta as a case setting for implementation. The third stage tested the framework in three pilot Maltese schools, producing demonstrative site-specific designs based on the framework. These were evaluated through consultation with teachers, students, administrators, and experts, whose feedback led to refinement and validation of the framework and confirmed its practical and theoretical relevance. This thesis makes an original contribution by reframing NBL through a systems-design lens; it offers a context-sensitive framework for small, urban primary schools that integrates ecological function with developmental and curricular aims and positions spatial design as a key mediator of children’s connection with nature. Highlighting primary schools as pivotal sites for reconnection, the framework provides a transferable and adaptable approach for urban contexts and lays the groundwork for future empirical and comparative studies. Collectively, these contributions have practical and theoretical relevance for research, policy, and practice, helping address children’s diminishing access to nature in cities. Description: Ph.D.(Melit.)

2025-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/144363 2026-02-26T14:52:58Z 2025-01-01T00:00:00Z

Title: Investigating the spatial distribution of microplastics on Maltese sandy beaches Abstract: This study investigates the concentrations, composition, and spatial distribution of large microplastics (LMPs) across three sandy beaches in Malta: Golden Bay, Ġnejna Bay, and Riviera Beach. Fieldwork involved systematic sediment sampling, followed by laboratory analyses to characterise particle size, colour, roughness, and polymer type, with additional granulometric analysis to examine links between sediment properties and microplastic retention. Data were processed using Microsoft Excel, QGIS, and Python, and interpreted through statistical and spatial analysis. Results showed that microplastic abundance was dominated by particles in the upper size range (4 – 5 mm), with polyethylene (PE) and polypropylene (PP) identified as the most common polymers. Colour analysis revealed yellow and grey as dominant, with site-specific variations in secondary colours. Roughness analysis indicated that primary microplastics (PMPs) were more prevalent than secondary ones, though Riviera Beach exhibited a smaller gap between the two categories. Spatial mapping highlighted heterogeneous distributions, with accumulation zones varying by site: Golden Bay displayed the highest densities, Ġnejna showed shoreline-focused hotspots suggesting stronger marine-based inputs, and Riviera recorded the lowest levels, consistent with its reduced proximity to urban and road-based sources. The findings provide baseline evidence of widespread microplastic contamination on Maltese sandy beaches, shaped by both terrestrial and marine sources, as well as beach morphology and sediment characteristics. By combining polymer identification, granulometry, and spatial mapping, this research contributes to a deeper understanding of microplastic transport and accumulation dynamics in coastal systems. It also underscores the importance of standardised monitoring protocols in line with the Marine Strategy Framework Directive (MSFD) to better inform management strategies and policy responses aimed at mitigating microplastic pollution in Malta’s coastal environments. Description: M.Sc. (Melit.)

2025-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/144362 2026-02-26T14:48:56Z 2025-01-01T00:00:00Z

Title: Groundwater protection analysis for Malta using C-O-P method Abstract: Groundwater underpins Malta’s water security, contributing to about 54% of production in 2022. Long-term declines in the mean sea level aquifers combined with increased contamination levels underscore the need for further research in this area; defensible, map based guidance is a potential solution. This study develops an island-wide groundwater vulnerability map for Malta using the COP framework: integrating Concentration of flow (C), Overlying layers (O) and Precipitation (P) on a harmonised 10 metre grid. The O factor combines a soil layer and unsaturated-zone lithology in a five-class protection score. The C factor employs a two-domain strategy: within delineated swallow hole catchments, basin constrained Euclidean distances to sinks and sinking streams are modulated by a slope – vegetation factor; elsewhere, surface features and slope – vegetation are similarly applied. The P factor is parameterised using rainfall data from 2005–2024, yielding a uniform climatic scalar of 0.87. The resulting COP surface reproduces the expected vulnerability spectrum: very high vulnerability along sinking streams and within swallow hole basins; lowest vulnerability over Blue Clay and marly units; predominantly moderate values on fissured carbonate; and generally lower vulnerability across sealed urban tracts. Internal diagnostics—such as buffer-ring gradients and basin-wise rank correlations around sinks— confirm the intended index behaviour. An overlay with Malta’s Groundwater Protection Zones adds finer-scale detail, revealing both hotspot areas and zones that may warrant deprioritisation. Principal uncertainties stem from soil generalisation, DEM resampling, approximations in perched-aquifer floors, and gaps in near-shore soil data; these are retained and flagged as limited-confidence areas. The product offers a planning-ready baseline for prioritising protection and guiding field validation. Recommended further research includes testing alternative flow-routing algorithms and associated along-flow metrics; incorporating impedance-based (cost-distance) routing with explicit anthropogenic barriers and connectors; simulating event-based storm scenarios; and cross-comparing with other protection methods such as DRASTIC. A separate section outlines targeted field validation methods, including hydrochemistry, stable isotopes (δ¹⁸O, δ²H), dye-tracing tests, and nitrate measurements in monitoring wells. Description: M.Sc. (Melit.)

2025-01-01T00:00:00Z