Meteorological controls on seasonal enrichment, contamination patterns, and environmental implications of atmospheric dust-fall elements in Zakho City, northern Iraq.

Abstract

Atmospheric dust fall can act as a sink and secondary source of potentially toxic elements in semi-arid urban environments, yet seasonal dust-bound metal data remain limited for northern Iraq. This study assessed the elemental composition, enrichment status, ecological risk, and screening-level inhalation health risk of deposited atmospheric dust fall in Zakho City, Kurdistan Region of Iraq. Dust-fall samples were collected at four urban sites in four seasons from June 2022 to June 2023 and analyzed by ICP-MS with selected isotope channels. Seasonal variation and source-oriented patterns were assessed using meteorological data, pollution indices, ecological risk indices, correlation analysis, PCA, and HCA. The dust matrix was dominated by crustal and mineral-associated elements, particularly Ca, Fe, Al, K, and Mg, indicating contributions from soil-derived particles, carbonate-rich material, construction dust, and resuspended urban surfaces. Among trace and potentially toxic elements, Zn, As, Cd, and Cr showed the main enrichment or contamination signals based on adopted screening-level background values. Seasonal and spatial analyses indicated that variations in dust-bound elemental composition were seasonally associated with meteorological conditions, dust accumulation, surface resuspension, and localized urban activities; however, these relationships should be interpreted as observational associations rather than direct evidence of causal controls. The annual PLI was 0.759, and the annual PERI was 94.754, indicating that the cumulative pollution was low and the ecological risk was low. Screening-level inhalation assessment indicated low non-carcinogenic risk for children and adults (HI < 1) and negligible carcinogenic risk. Overall, the Zakho dust fall was characterized by a mineral-dominated dust matrix with localized enrichment in selected trace elements, while seasonal environmental conditions were associated with variations in the environmental significance of deposited dust within the limitations of this baseline monitoring study.