Spatio-temporal analysis of air pollution from geothermal power plants: insights from ground and satellite observations.

Türkiye is ranked fourth worldwide in terms of electricity generation from geothermal power plants (GPPs). With recent legal restrictions about GPPs, additional H2S measurements were started along with routine criteria air pollutants at selected air quality monitoring stations (AQMSs) in regions with GPPs in western Türkiye. This study aims to analyze the relationship between GPP-associated variables and air pollutants for 2022, and focuses on four regions (Region-1-4) determined according to GPP clusters with available H2S and SO2 measurements in close proximity. Ground-based (gr) H2S, SO2 measurements, TROPOMI SO2, NO2, HCHO, CH4, and IASI NH3 retrievals were used along with GPP electricity production (EP) and meteorological measurements. The higher EP, gr-H2S, and gr-SO2 values were observed during winter, spring and fall in all regions with similar temporal patterns. The wind speed and direction analysis showed that higher gr-H2S and gr-SO2 concentrations were associated with GPP locations, especially in Region-1: All (E, ENE) and Region-2: Germencik (NW, WNW, and W) indicating transport. Daily gr-H2S and gr-SO2 correlations were significant in all regions with highest in Region-2: Germencik (R = 0.63) followed by Region-1: All (R = 0.58). Seasonal and monthly correlations showed highest in fall season, in particular November. Spatial distributions of SO2 and NH3 satellite retrievals indicated particularly higher levels around GPP regions in spring and autumn, specifically in March, April, October, and November in which total EP were also higher. Finally, correlations of monthly total EP with pollutants of focus showed positive relationship with gr-H2S, gr-SO2, and SO2 retrievals, and negative relationship with NH3, and HCHO.