Comparison of soluble ions in dust fall among various latitudes in western Iran

Dust particles moved by air streams influence the quality of the environment. Chemical compounds of these particles are influential on the life’s quality of the residents of every region. Dust fall particles originat-ed from the soil erosion has caused many problems for the residents of western Iran during recent years. Iran’s geographical location in the vicinity of Iraq, Syria, and Saudi Arabia, where are major sources of dust, alongside issues such as climate change are among the roots for making and worsening this critical phenomenon. Hence, investigation and recognition of characteristics of this phenomenon including chemical characteristics of it may help the adaptation of pre-emptive measures and reaching scientific clues to control harms of this phenomenon. The main objective of this study was to compare the concentration of soluble ions in dust fall particles among various latitudes in western Iran.

Simultaneous samplings were conducted monthly for one year in three cities i.e. Sanan-daj, Khorramabad and Andimeshk using the passive method. The obtained data were then analyzed by Excel and SPSS v.23. For comparison of chemical characteristics of the dust fall particles, Coefficient of Divergence (CD) and Duncan’s Multiple Range Test (MRT) were applied.

The results showed that calcium and sulfate with a concentration of 0.271 and 0.592 mg.g-1, respectively, had the highest concentration among the studied dust fall samples. High calcium concentra-tion confirmed that the dust fall on the three stations had natural origins, which were mainly calcareous soils and geological formations. Additionally, a high concentration of sulfate implied a share of evaporated sediments, par-ticularly gypsum (hydrated calcium sulfate), among the studied dust fall particles. Calculation of CD also showed that chemical characteristics of dust falls in the three stations were mostly similar (CD > 0.5). Correlation of CD between cations in Sanandaj and Khorramabad and the wind factor (r= 0.99, p> 0.05), anions of Sanandaj and Andimeshk and rainfall (r= 1, p> 0.01) and moisture factors (r= 0.89, p> 0.05), respectively, demonstrated that the meteorological factors influence chemical characteristics of dust fall particles. MRT also showed that sodium as a highly soluble element had different concentrations throughout the three stations in the spring season (> 0.05). Moreover, compounds such as CaSO4, Ca(NO3)2, Mg(NO3)2, NaCl, KF and CaF2 were found in the three stations, which confirmed the presence of gypsum, anhydrite, and halite in the dust fall particles.

Environmental conditions in various latitudes influence the chemical characteristics of dust fall par-ticles from various aspects. Nevertheless, values and changes in the concentration of soluble ions in the dust fall including Ca2+, Mg2+, Na+, and K+ cations and NO3-, SO42-, Cl-, and F- anions in the three stations of Sanandaj, Khorramabad, and Andimeshk were mainly similar. Hence, it can be concluded that the dust fall on the three stud-ied cities originated from the same sources.