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چکیده
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Atmospheric particulate matter (PM), particularly nuisance dust in arid regions, poses significant environmental and health risks due to its complex composition and ability to transport toxic elements. This thesis investigates the soluble, insoluble, and total concentrations of key elements including sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), and manganese (Mn) in dust particles larger than 10 µm collected from Tikrit city, Iraq, a semi-arid urban area prone to dust storms. The study aims to assess temporal variations in elemental profiles, evaluate contamination levels using the geo-accumulation index (Igeo), and identify influencing factors to inform air quality management. Sampling was conducted weekly from early June to late November at three monitoring stations using a sedimentometer method standardized by ASTM (1982). Soluble cations (Na, K, Ca, Mg) were analyzed via flame photometry, while insoluble trace elements (Fe, Mn) were determined using atomic absorption spectrometry (AAS). Results revealed pronounced seasonal trends, with peaks in soluble and insoluble fractions during mid-summer (July-August), driven by high temperatures, low precipitation, and shamal winds mobilizing crustal materials. Calcium dominated total concentrations (mean 242-250 mg/g), reflecting carbonate-rich soils, followed by Mg (45 mg/g), Fe (40-48 mg/g), Na (23-24 mg/g), K (12-14 mg/g), and Mn (2.4-2.9 mg/g). Sedimentation rates varied from 0.5 to 4.2 g/m²/week, with site-specific differences highlighting urban influences. Igeo values indicated uncontaminated to moderately contaminated levels for most elements, with Ca showing mild enrichment (Igeo 2.5-3.3), while Fe and K were below background, underscoring primarily natural origins with minor anthropogenic contributions from traffic and industry. The findings emphasize the role of regional dust cycles and local geology in PM dynamics, with implications for respiratory health and ecosystem impacts. Recommendations include enhanced monitoring, vegetative barriers, and urban planning to mitigate dust resuspension. This study provides baseline data for policymakers in arid regions facing escalating dust challenges, highlighting the need for integrated strategies to reduce exposure risks.
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