An overview of airborne dust characterization in Sistan region, Eastern Iran

Dust storm is a main source of atmospheric mineral particles and it occurs in arid and semi-arid areas frequently and considered as a serious environmental hazard. The Sistan region in eastern part of Iran is one of the most active sources of dust storms in Asia because of frequent droughts and strong wind blows known as Wind of 120 days . The aim of this study is overview of physical, chemical, biological and mineralogical properties of airborne dust in Sistan region. Airborne dust samples were collected from 5 cities located in Sistan plain, including Zabol, Zahak, Hirmand, Nimruz and Hamoun cities. The results showed Silt particle size was the dominant particle size in the airborne dust and therefore Silt Loam was the most soil texture class [2, 3]. EC and pH showed saline and alkaline source conditions of airborne dust [2]. The Calcium (Ca) was the maximum nutrient elements associated with dust, and the minimum was Phosphorus (P) [2]. The highest amount of enrichment ratio related to P and the lowest enrichment ratio related to Sodium (Na) [2]. Investigating the concentrations of the heavy metal elements and the relevant indices showed that the concentration of Zinc (Zn) and then Copper (Cu) from the studied elements (Zinc, Manganese, Iron, Copper and Chromium) in the airborne dust of the studied areas can be mainly due to traffic, and it is problematic for the residents of the area [4]. The biological results showed maximum aerobic bacteria population was observed in Nimruz city and maximum anaerobic bacteria population was observed in Hirmand city [2]. Maximum aerobic fungi population was observed in Hamoun city and maximum anaerobic fungi population observed in Zahak city [2]. The most frequent type of bacteria was Bacillus sp followed by Streptomyces pactum [2]. The most frequent type of fungi in this research was Penicillium sp and the second type was Aspergillus [2]. The most common type of phosphate solubilizing fungi associate with airborne dust was Aspergillus niger [1]. Mineralogical results of airborne dust samples showed dominance of Quartz, Calcite and Feldspars, respectively [3]. Characteristics of the airborne dust carried over the cities of Sistan plain reflected the conditions of dust origin and indicated the expansion of land degradation in these areas. It seems, the main challenge in Sistan region is land degradation caused by drought, salinization and alkalization and nutrient elements loss by wind erosion and consequently reduces soil fertility and vegetation cover. Ecological danger of land degradation will increase quickly by occurrence of saline dust storm and this issue is the principle threaten for Sistan region ecosystem. In other words, it seems, Hamoun wetlands are main source of dust in the Sistan region and the knowledge base management of these wetlands can be considered as the key to ecosystem health and stability in the region.

کلیدواژه ها:

Dust storm ، Land degradation ، Hamoun wetlands ، Wind of 120 days