Monitoring the spatial-temporal concentrations of Black Carbon Aerosols over Iraq during 1980-2022

Abstract

Black Carbon (BC) concentration has a significant impact on the climate, environment, and human health. In the Middle East, rapid urbanization, outdated vehicles, outdated air quality standards, and decaying infrastructure contribute to poor air quality. Remote sensing data on BC were used in this research to monitor the annual, seasonal, and monthly spatial distributions of BC concentrations in Iraq. This study examines the temporal and spatial distribution pattern of black carbon (BC) concentrations in Iraq during 1980–2022. The Mann–Kendall test was used to detect trends in BC monthly, seasonal, and annual data. The analysis shows a statistically significant positive trend (p < 0.05) for all months and seasons. The highest mean monthly slope magnitudes were in November, December, and January (Q = 0.012 μg·m⁻³/year), while the lowest occurred in May, June, and July (Q = 0.0054–0.0058 μg·m⁻³/year). The annual change in BC concentration was 0.34 μg·m⁻³/year, and the highest increase (0.51 μg·m⁻³) occurred in November and December. On a seasonal basis, the increase was strongest in winter (Q = 0.0117 μg·m-³/year), followed by autumn and spring, with summer displaying the weakest trend of all seasons. Spatially, the central and southern regions of Iraq had consistently high BC concentrations (greater than 1.8 μg/m³ in winter), compared with lower concentrations on the order of 0.2–1.0 μg/m³ in the northern and western areas. The central region came first, followed by the southern, northern, and western regions. Seasonal fluctuations were significant: the most polluted seasons were winter and autumn, due to heavy fuel combustion for building heating, which creates calm atmospheric conditions with high humidity. In summer, concentrations were lower due to deep convective mixing driven by a deeper turbulent planetary boundary layer, leading to greater dispersion. The spatial gradient persisted across all seasons, pinpointing the focal southern urban-modern belt as a persistent contamination hotspot. The results thus underpin mitigation strategies to reduce combustion emissions from domestic heating, diesel generators, and other anthropogenic sources.