Determination of heavy metal contamination and pollution indices of atmospheric dust in Dushanbe and Ayvaj, Tajikistan

Abstract

In this paper was studied the content of heavy metals in atmospheric dust of Dushanbe and Ayvaj. Dust samples were taken and analyzed to determine the content of heavy metals (HM): Zn, Pb, Cu, Cr, V, Ni, Co, As, Sr, MnO, TiO2 and Fe2O3 using X-ray fluorescence spectrometry. The pollution levels and environmental risks of HMs were assessed using the geoaccumulation index, contamination factor, pollution load index and potential ecological risk index. The results revealed severe contamination of atmospheric dust from Ayvaj and Dushanbe with particularly hazardous HMs such as As and Pb, the proportion of As is higher in the dust of Dushanbe, and the contribution of Pb is significant in the samples of Ayvaj. The concentrations of As, Pb, Zn, MnO, Sr, TiO2, V, Co in the dust of Dushanbe and As, Pb, Zn, Sr, TiO2, Cu in the dust of Ayvaj showed high variability (CV> 35%), which indicates an intense influence of anthropogenic activity. The results of the pollution factor analysis show that As, Co, V in Ayvaj atmospheric dust samples and Pb, Cr, Ni, V, MnO in Dushanbe samples were assigned to the class of very high pollution (CF>3). According to the results of the geoaccumulation index Ayvaj is heavily polluted with the following elements: V, Pb, Cr (3< Igeo ≤4). Based on the ecological risk index method, As and Pb were found to be priority pollutants in the study areas.