Dispersion Modeling and Model-Based Source Contribution Analysis of Air Pollutants from Gas-Fired Power Plants in the Niger Delta

Gas-fired power plants are increasingly central to Nigeria’s electricity supply, yet their localized air quality impacts remain insufficiently quantified, particularly within the environmentally sensitive Niger Delta region. This study applies dispersion modeling and model-based source contribution analysis to assess the spatial distribution, seasonal variability, and source contributions of key atmospheric pollutants emitted from major gas-fired power plants in selected Niger Delta states. Ambient concentrations of PM₂.₅, PM₁₀, NO₂, SO₂, CO, O₃, and VOCs were assessed across 100 georeferenced locations surrounding four power plant clusters—Afam IV (Rivers State), Transcorp Ughelli (Delta State), NIPP Gbarain–Ubie (Bayelsa State), and NIPP Ihovbor (Edo State). Meteorological parameters and operational data were integrated within a GIS-based dispersion modeling framework to simulate downwind pollutant dispersion under wet- and dry-season conditions. Results reveal pronounced spatial gradients, with peak ground-level concentrations occurring within 2–5 km downwind of emission sources. Modeled annual average concentrations reached up to 45.6 µg/m³ for PM₂.₅, 78.2 µg/m³ for PM₁₀, and 45.7 µg/m³ for NO₂ in communities closest to major facilities. Source contribution analysis indicates that individual gas-fired power plants accounted for approximately 48–71% of local NO₂ concentrations and 52–68% of PM₂.₅ burdens at nearby receptors, with higher contributions observed during the dry season when atmospheric stability limited dispersion. In industrialized and urbanized zones, background and co-located industrial sources contributed an additional 13–52% of observed pollutant loads. These findings provide quantitative, policy-relevant evidence to support area-wide emission management, improved land-use planning, and the integration of dispersion modeling into regulatory decision-making for sustainable energy development in the Niger Delta.