Abdullah S. Alnasser

Backward-trajectory statistics locate arid-region dust sources on the assumption that trajectories separate emission from transport, an assumption seldom tested where the local contribution is known. We build one from ten years (2016–2025) of routine METAR observations at Riyadh, Saudi Arabia, where present-weather codes distinguish locally lifted dust (BLDU/BLSA) from dust in suspension (DU/SA). Suspension-dominated days outnumbered locally lifted days 345 to 179 (1.9:1), and ERA5-driven models reproduced the locally lifted class substantially better (held-out AUC 0.914 versus 0.765), indicating distinct meteorological signatures. Dust activity then fell 85.9% below the 2016–2022 baseline in 2023–2024, recovering only to 56.0% below it in 2025. The model did not anticipate this: observed dust days in 2023–2024 were 13–27% of the calibrated expectation in every class while local surfaces in 2024 stayed favorable for emission; upwind dust availability and transport remain hypotheses. We then computed PSCF and CWT fields from 14,612 HYSPLIT trajectories, running the locally lifted class, for which a distant source is not required, as an imperfect negative control, tested against permutation nulls. Under unmatched and season-matched backgrounds, the control was more enriched than the suspension-dominated class over the eight a priori candidate regions (p ≤ 0.007), and wind matching removed most regional structure from both. Both fields are shaped largely by the shared Shamal transport climatology and the wind selection of dust days, limiting their ability to identify emitting terrain. At wind-selected, single-regime receptors, PSCF and CWT source fields should be interpreted alongside such a control.

Valorization of lignocellulosic waste into functional carbonaceous materials offers a sustainable approach for removing emerging organic contaminants from water. In this study, sawdust was directly carbonized at 300, 500, and 700 °C and functionalized with ferrocene (0.05–250 wt%) to produce composites for the removal of amoxicillin and Brilliant Blue R-250 under visible/simulated solar irradiation. The materials were characterized by FTIR, XRD, SEM, UV–visible spectroscopy, optical band-gap analysis, and N ₂ adsorption–desorption. Among the prepared composites, S ₆ (25 wt% ferrocene) exhibited the highest apparent photocatalytic activity toward Brilliant Blue, whereas S ₄ achieved approximately 75–80% removal within 120 min. The degradation kinetics followed the pseudo-first-order Langmuir–Hinshelwood model (R ² > 0.98), indicating surface-mediated photochemical processes. Overall, Ferrocene@AC500 (1:1) and AC300 exhibited the best removal/degradation performance toward the investigated pollutants.

Sustainable coastal environmental management relies on continuous assessment of sediment quality. In the Saudi Arabian Red Sea, such sediments function as both sinks and potential secondary sources of heavy metals (HMs) originating from natural processes and anthropogenic activities. The present study investigated the concentrations of HMs in surface sediments from Jeddah and Rabigh. Contamination levels, as well as possible natural and anthropogenic inputs and potential risks to human health through ingestion, dermal contact, and inhalation pathways, were evaluated. The results indicated that Fe is the most abundant metal at both sites (1570.40 mg/kg at Jeddah and 1804.11 mg/kg at Rabigh). Cu, Ni, and Zn are present in the sediments at concentrations ranging between 3.12 and 4.49 mg/kg, while Cd and Pb remain below the detection limits in all samples. Generally, the contamination index values indicated low levels in both regions. The evaluation of human health risks identified ingestion as the primary exposure pathway. Non-carcinogenic risk levels were within safe limits for both adults and children. However, the carcinogenic risk assessment of nickel (Ni) indicated that all values fall within the acceptable range (10⁻⁶–10⁻⁴), although children consistently showed higher risks than adults. Despite the overall low levels of pollution, the moderate enrichment of Cu, Ni, and Zn in Jeddah and Cu in Rabigh, along with the higher non-carcinogenic risks to children at the Rabigh site, highlights the need for continuous environmental monitoring and further investigation to support the sustainable management of coastal ecosystems.

In the Kingdom of Saudi Arabia (KSA) and other arid regions, higher education institutions account for a significant share of energy consumption and greenhouse gas (GHG) emissions. Improving the environmental performance of higher education institutions is important to achieving nationwide impact reduction. This study evaluates the water, energy, and carbon (WEC) footprint of higher education campuses in arid environments. Qassim University (QU), KSA, is a leading public institution of higher education and research in Buraydah City and was selected for this study. A comprehensive assessment based on the GHG Protocol was conducted for the period 2022–2025, covering Scope I, II, and III emissions. This study analyzed institutional data on water use, wastewater, electricity consumption, transportation, waste generation, and air travel. The results show that total water consumption increased from 354,747 m³ in 2022 to 547,268 m³ in 2025, with per capita use rising from 46.2 to 61.7 L/c/day. Net water demand, including irrigation, reached 877,456 m³ in 2025. The declining trend in energy consumption between 2022 and 2025 reflects significant (33%) energy savings with the use of sensors and the overall tendency towards sustainability. Correspondingly, Scope II emissions decreased significantly from 147.2 million kg CO₂/year to 99.1 million kg CO₂/year and were the dominant CO₂ contributor (60–75% of total emissions). In contrast, Scope III emissions from commuting staff and students increased, with transport-related emissions rising from 36.4 million kg CO₂/year in 2022 to 52.2 million kg CO₂/year in 2025. This study also evaluated current and potential CO₂ emission reduction scenarios targeting energy and transportation systems on the QU campus. The findings indicate that the deployment of a 5.1 MW solar energy system can generate approximately 8.6 million kWh annually, resulting in a reduction of around 4000 tCO₂ and contributing to nearly 43% of the 2030 emission reduction target. In addition, transportation-focused strategies—including modal shift, vehicle electrification, and hybrid learning approaches—demonstrate significant mitigation potential, with total reductions reaching up to 18,700 tCO₂ by 2030. Overall, this study contributes to the limited body of knowledge on WEC footprint assessments on university campuses in arid regions and provides a baseline for future sustainability planning.