Study of Physical, Geochemical and Mineralogical Properties of Dust in Lorestan Province (Case Study: Kuhdasht Constituency)

The phenomenon of dust is one of the biggest serious environmental problems in arid and semi-arid regions. More than two thirds of Iran is located in this climate. This phenomenon can damage infrastructure and agricultural products and cause a lot of economic damage. Therefore, since the study area is in the western part of Iran and is highly exposed to dust. On the other hand, so far no comprehensive study has been conducted in this field in the region, so this research is a necessity. Scientific and practical objectives of the research include: Investigating the diversity of soils in the region and their relationship with landforms in the region, Investigating the temporal distribution of dust characteristics in the region, Investigating the soil characteristics of the study area and Hur al-Azim wetland in Khuzestan This is a phenomenon.

For this study, Kuhdasht basin with an area of 456 square kilometers located in western Iran and southwestern Lorestan province was considered. 12 glass traps with dimensions of one square meter were installed in the area to trap dust at a height of about 2.5 meters above the ground. And seasonal dust samples were prepared during 2015. Sampling was performed for origin from the surface soil of the region and Hur al-Azim wetland. To determine the concentration of heavy metals, the chemical digestion step was performed by the ETHOS 1 microwave device made in Italy. Then, to determine the concentration of elements, atomic absorption apparatus (Perkin Elmer Analyst, 3030) with detection limit of ppm and ppb and flame technique was used and for cadmium metal concentration through graphite furnace technique. Meanwhile, the region's flower was drawn by WRPLOT software, 7.0.0.

The highest rate of dust subsidence is in spring and the lowest in autumn. The average annual subsidence rate of the region is 11.51 tons per square kilometer per year. The textile class of silt sludge dust particles and the particle transfer index from areas with medium to high distances. The average concentration of heavy metals in dust is higher than the soil of the region. In general, the results showed that cadmium and zinc elements have very high pollution factor, nickel and lead have significant pollution and manganese and copper elements have low pollution. The elements cadmium, zinc and nickel, which have an enrichment factor of more than 10, are of human origin, but the element lead is of natural and human origin together, and the elements manganese and copper are of natural origin in the region. The similarity of minerals and the presence of evaporative minerals in fine dust reinforces the hypothesis that it is part of the origin of wetland and offshore particles. However, the study of chemical properties indicates the role of local resources in the generation of dust.

The main flow of dust in all seasons in the study area is from cross-border areas. The amount of dust is highest in spring and lowest in other seasons, which is lowest in autumn. The particle size distribution class is silty loam, which indicated the presence of resources at medium to relatively close distances to the area. The rate of subsidence in the region indicates the type of regional dust. The concentration of heavy metals in dust is high in winter and the element zinc has the highest amount. The level of pollution index of all elements indicates the spread of pollution in the region. Clay mineralogy showed that the presence of evaporative minerals strengthens the hypothesis of wetland origin and transboundary. In general, this study showed that the deserts of the mentioned neighboring countries and dust sources of Khuzestan province (located in the south of the region) are the main sources of dust in the region.