Abstract:
Windblown transport and deposition of dust is widely recognized as an important physical and chemical
concern to climate, human health and ecosystems. Sistan is a region located in southeast Iran with extensive
wind erosion, severe desertification and intense dust storms, which cause adverse effects in regional
air quality and human health. To mitigate the impact of these phenomena, it is vital to ascertain the physical
and chemical characteristics of airborne and soil dust. This paper examines for the first time, the mineralogical
and chemical properties of dust over Sistan by collecting aerosol samples at two stations
established close to a dry-bed lake dust source region, from August 2009 to August 2010. Furthermore,
soil samples were collected from topsoil (0–5 cm depth) at several locations in the dry-bed Hamoun lakes
and downwind areas. These data were analyzed to investigate the chemical and mineralogical characteristics
of dust, relevance of inferred sources and contributions to air pollution. X-ray Diffraction (XRD)
analysis of airborne and soil dust samples shows that the dust mineralogy is dominated mainly by quartz
(30–40%), calcite (18–23%), muscovite (10–17%), plagioclase (9–12%), chlorite ( 6%) and enstatite ( 3%),
with minor components of dolomite, microcline, halite and gypsum. X-ray Fluorescence (XRF) analyses of
all the samples indicate that the most important oxide compositions of the airborne and soil dust are
SiO2, CaO, Al2O3, Na2O, MgO and Fe2O3, exhibiting similar percentages for both stations and soil samples.
Estimates of Enrichment Factors (EFs) for all studied elements show that all of them have very low EF
values, suggesting natural origin from local materials. The results suggest that a common dust source
region can be inferred, which is the eroded sedimentary environment in the extensive Hamoun dry lakes
lying to the north of Sistan.
