Impact of Middle Eastern dust sources on PM₁₀ in Iran: Highlighting the impact of Tigris‐Euphrates basin sources and Lake Urmia desiccation

Abstract

Contribution of different Middle Eastern dust origins to PM10 (PM with aerodynamic diameters less than 10 µm) levels in several receptor large cities in Iran was investigated. Initially, the major regional dust episodes were determined through statistical analysis of recorded PM levels at air quality stations and verified using satellite images. The particles dispersion was simulated by Hybrid Single‐Particle Lagrangian Integrated Trajectory (HYSPLIT) to regenerate PM10 during the dust episodes. The accuracy of the modeled results was rather convincing, with an average squared correlation coefficient (R2) of 0.7 (max = 0.95). Consequently, the contributions of different dust sources to the observed concentrations were determined. Basin of Tigris‐Euphrates Rivers encompasses active dust sources with significant rate of emission due to fluvial deposits. The sources in this basin with approximately 70–95% contribution, by far, had the most influence on PM10 levels at the receptor cities. In a finer resolution, northern and central parts of Iraq had the most influence on PM10 level during the dust episodes. Effect of probable improvement or deterioration of the current dust origin conditions on PM10 levels was analyzed by performing a sensitivity analysis through varying threshold friction velocities. The results demonstrated that 10% increase or decrease in threshold friction velocities of major dust sources could lead to average of 51% decrease or 77% increase in the receptor cities' PM10, respectively. Finally, effects of Lake Urmia desiccation, as a new hydrological prospect dust origin were analyzed. The predicted dust from the prospective dried lake bed could result in ~ 30–60% increase in PM10 of nearby cities during the studied dust episodes.

Interannual variations of dust activity in western Iran and their possible mechanisms

“…In particular, it is of primary importance to quantify the impact of climate factors, such as wind speed and precipitation, on the interannual variation of dust activities such that the contribution of anthropogenic activities during a specific period can be further identified. While the impact of upstream dust sources (Iraq, Syria, Saudi Arabia) on dust events over western Iran have been well investigated (e.g., Broomandi, Dabir, Bonakdarpour, & Rashidi, 2017b;Sotoudeheian, Salim, & Arhami, 2016), in this study, we focus on the impact of local meteorological factors (surface winds, precipitation, soil moisture) on dust phenomena over western and southwestern Iran.…”

The Lake Urmia environmental disaster in Iran: A look at aerosol pollution

“…A modeling study suggested that aerosol emitted from the lake bed can account for an estimated ~30–60% enhancement in PM 10 of nearby cities during dust episodes (Sotoudeheian et al, 2016), while other work suggests that crustal soil bordering LU, rather than lakebed salt, is the predominant source of aerosol emissions in the vicinity of LU (Gholampour et al, 2017). An examination of the spatiotemporal nature of aerosol around LU is highly relevant for the ~7.1 million people living in the lake’s watershed (http://irandataportal.syr.edu/census/census-2016., 2016) and ~80 million people living within a radius of 500 km (http://sedac.ciesin.columbia.edu/mapping/popest/gpw-v4/., 2016).…”

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

“…In general, larger AOD values begin in spring, reaching a maximum in summer, followed by a decrease in fall and winter. Furthermore, over Iraq, along the Mesopotamia plains, there is a distinct spatial northwestern pattern of aerosol loadings, in accordance with the prevailing shamal wind direction [12,13,[52][53][54]. Figure 6 shows that the seasonal variability in AOD indeed follows the general trend of increasing AOD toward spring-summer and a substantial decrease in fall-winter.…”

“…Opposing viewpoints have been expressed in recently published papers, as well as in the mainstream media. One side argues that increased dust-storm activity is caused by human factors, such as the abandonment of agricultural land and reduced irrigation [11][12][13][14][15], while the other side counters with favorable meteorological conditions as the cause [16][17][18][19].…”