Spatial trend and source apportionment of metals in wet atmospheric precipitation: a study on drying Urmia Lake implications, NW Iran

ABSTRACT

During this decade, the drying of Urmia Lake resulted in devastating tragedies in the region, resulting in the emission of toxic metals into the atmosphere. Urmia city’s wet atmospheric depositions were analysed to assess the quantity and spatial trends of numerous heavy metals and sodium (Na), as well as their sources. Wet precipitation was collected as rainwater, and the concentration of metals was determined using an Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). The mean concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), zinc (Zn), and sodium (Na) were 0.14, 0.18, 1, 3.7, 2.9, 5.6, 6.3 µg/L, and 2.6 mg/L, respectively, following the sequence Na > Zn > Ni > Cu > Pb > Cr > Cd > As. To identify the sources of these metals, enrichment factor analysis and principal component analysis (PCA) were employed. The enrichment factor analysis revealed that Na and As exhibited relatively low enrichment factors suggesting natural sources, whereas Zn, Cd, Cr, Cu, Ni, and Pb were highly enriched, indicating significant contributions from anthropogenic sources. The distribution map of Urmia City demonstrated that the northern and western parts of the city were highly polluted with As, Ni, Cr, and Zn. PCA analysis revealed that the emissions from vehicles and fuel combustion were the primary sources of Cd, Cr, Cu, Ni, and Pb, whereas the drying of the Urmia lake is the primary source of Na, As, and Zn. The process of the lake bottom drying likely releases these metals into the atmosphere, leading to their deposition in the surrounding areas.

KEYWORDS:

• Atmospheric deposition
• elemental composition
• principal component analysis
• Urmia city

Acknowledgments

This study was financially supported by grant number 5628. The authors would like to thank the Shahid Sadoughi University of Medical Sciences (student research committee) and Urmia University of Medical Sciences, and all those who helped during the study period.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Shahid Sadoughi University of Medical Sciences. [grant number 5628 and Research Ethics Certificate IR.SSU.REC.1396.149]. This grant was received by Dr. Amir Mohammadi.