Quantifying the contribution of Middle Eastern dust sources to PM10 levels in Ahvaz, Southwest Iran

Abstract

The contribution of the Middle East dust storms to PM10 concentrations in Ahvaz, SW Iran, has been evaluated in this study. Daily PM10 concentrations between winter 2015 and autumn 2017 have been acquired from an urban station in Ahvaz, while the dust episodes have been determined using meteorological observation data. A statistical analysis was performed to calculate the change in PM10 concentrations during each dust episode and subtract the non-dusty PM10 amount. In the next step, all the dust-source regions in the Middle East have been divided into 1° × 1° spatial grid resulting in 460 subzones. Using the HYSPLIT model, the proportion of dust particles from each of the 460 subzones has been quantified. The calibration of the HYSPLIT model is mostly influenced by P10F, which determines the threshold friction velocity in dust-source areas.Three statistical indices were considered for evaluation of the HYSPLIT predictions, the fractional bias (FB), root normalized mean square error (RNMSE), and Pearson correlation coefficient (R), which exhibited a range of values from −1.8 to 1.1 (mean of −0.33), 1.1 to 6.6 (mean: 2.64), and 0.3 to 0.9 (mean: 0.62), respectively, signifying a satisfactory alignment between model predictions and PM10 measurements. According to the results, the deserts in Iraq, Iran, Saudi Arabia, and Kuwait are the main contributing dust sources in Ahvaz, with mean contributions of 32%, 26%, 16%, and 10%, respectively. The contribution from the dust-source regions to PM10 in Ahvaz during dust-storm episodes can be detailed as follows: 29% from the Mesopotamian Marshes, 19% from Alluvial Plains, 11% from the Empty Quarter, 11% from the Ad-Dahna Desert, 7% from the Khuzestan Plain, while other desert regions in the Middle East contribute lesser fractions.These findings shed light on the complex relation between dust sources and PM10 concentrations, offering a basis for strategic mitigation planning in Ahvaz and informing public health management and policy formulation.