Secular Changes in Atmospheric Turbidity over Iraq and a Possible Link to Military Activity

The challenge of identifying dust events in a highly polluted Eastern Mediterranean region

Dust pollution largely impacts our environment, health and well-being. However, there is no agreement on how dust-contaminated days are identified to study exposures, as methods differ across disciplines. Different quantitative thresholds, which rely on ground measurements, are generally used to define these events. In this study, we used ground-based lidar measurements to detect dust layers. The dataset was then compared to methods that are widely used to define the presence of dust on the ground. Our results show that dust layers extend to a height of up to 10 km and a depth of up to 6.3 km. We show that at least 50 % of days that include dust components according to the lidar were not included by any of the methods that we investigated. As a result, these days are not considered in many health-related studies and climate models. Many dust events exhibit a high anthropogenic component and can be misinterpreted: (Ångström exponent>1.2), high-altitude (on average above 1.7 km) and relatively shallow (average depth 1.4 km) dust layers, and low PM10 on the ground. Mixed pollution (0.8 < Ångström exponent < 1.2) accounts for 45 % of these events. The most accurate dust-detection method considered the aerosol optical depth and Ångström exponent parameters, and provided 60 % of the dust days as determined by lidar. It does not seem to be possible to differentiate between anthropogenic and dust events because most measurements contained dust, resulting in further biased estimations. Our results indicate that there is a need to change our perception of what constitutes a dust day, when studying the impact of dust exposure. We suggest that in arid and semiarid, and in particular Eastern Mediterranean climates, where dust is a frequent and strong meteorological component, a greater number of days need to be included in the analyses or critically evaluated.

Changing particle content of the modern desert dust storm: a climate × health problem

Climate and land use changes together are altering the particle content of desert dust storms on regional and local scales. These storms now carry a wide variety of pollutants and pathogens arising from urbanization, industrialization, mass transportation, warfare, or aerosolized waste in locations worldwide where deserts are intertwined with built infrastructure, transportation centers, and high-density human habitation. Accordingly, the modern desert dust storm has an anthropogenic particle load which presumably sets it apart from pre-industrial dust storms. Evidence for how particle content for modern dust storms is changing over the Arabian Peninsula holds relevance because dust storms are now more frequent and more severe. Furthermore, the Arabian Peninsula has asthma rates which are the highest worldwide. How the modern desert dust storm contributes to asthma and human health is a nascent issue. Meanwhile, public health decisions can benefit from a climate × health framework for dust storms, as proposed here. An imperative is testing each dust storm's particle content type, and for this, we propose the A-B-C-X model. Sampling a dust storm for its particle content data and then archiving samples for future analyses is advised. A storm's particle content data, once combined with its atmospheric data, allows a particle's source, transport, and deposition to be determined. In closing, the modern desert dust storm's changing particle content has far-reaching consequences for public health, transboundary issues, and international climate dialog. SIGNIFICANCE : Locally and regionally sourced particle pollution is a growing problem in deserts worldwide. Proposed here is a climate × health framework for studying how dust storm particles, entrained from both natural and engineered systems, may be contributing to declining human respiratory health.

Mineralogical, geochemical, and textural characteristics of soil and airborne samples during dust storms in Khuzestan, southwest Iran

Dust storms are frequent phenomena in Khuzestan Province, southwest Iran, leading to environmental hazards and deleterious impacts on human health. This work analyzes mineralogic and geochemical characteristics of dust sediments at the source regions and in deposition areas in southwest Iran during three dust-storm events in winter and spring 2018. Twenty soil and airborne dust samples were collected and analyzed for compositions of dust at different distances from the source regions in Iraq and southwest Iran, aiming to assess the source characterization and possible mixing processes in the atmosphere. The grain size distributions were also analyzed at specific sites. The results show that about 50 % of the volume size distribution corresponds to particle sizes of above 20 μm, indicating local/regional dust storms of coarse to giant particles. XRD analysis indicates that calcite is the dominant mineral in all the samples, with a high quartz and dolomite fraction. The most abundant major compounds are SiO₂ and CaO, while Cl, Ba, Sr, Pb, Ni, Zn, Cr, V are the main trace elements. The enrichment factor (EF) analysis showed that apart from Th, Nb, Ce, and V, all the other elements (Pb, Zn, Cr, etc.) have an anthropogenic origin or represent high amounts of pollutant contamination. High levels of elemental enrichment are attributable to intensive pollution in Khuzestan Province and at sampling sites due to fossil-fuel combustion, gas and petroleum drilling activities. Moreover, based on the geo-accumulation index (Igeo), all samples are found to be contaminated by heavy metals due to prior war-related materiel, oil and gas extraction, and emissions from polluting industries.