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This work aims to investigate the competitive time-dependent desorption rate of heavy metals (lead, zinc, nickel) coexisting with phenanthrene from natural high buffering soil. Two non-ionic surfactants (Tween 80 and Brij 35) combined with disodium ethylene diamine tetraacetate salt (Na2-EDTA) were utilized as the reagents. The contaminants' time-dependent desorption data was fitted with five kinetic models including parabolic diffusion, Elovich, fractional power function, pseudo-first and-secondorder equations. The best removal of contaminants obtained by the mixture of Tween 80/EDTA; desorbing 93% of lead (Pb). The competitive desorption of nickel (Ni) and zinc (Zn) is affected by the stability of Metal-EDTA complexes. Moreover, phenanthrene removal in the soil studied was slow and laborious. The desorption kinetics are well described by parabolic diffusion (for phenanthrene) and pseudo-second-order (for heavy metals of interest). In the soil-surfactant-water system, soil structure changes were negligible; however, Tween 80 influenced the development of crystal faces of CaCO3 during the process.

Rapid industrialization and urbanization have resulted in environmental pollution and unsustainable development of cities. The concentration of 12 potentially toxic metal(loid)s in windowsill dust samples (n = 50) were investigated from different functional areas of Qom city with the highest level of urbanization in Iran. Spatial analyses (ArcGIS 10.3) and multivariate statistics including Principal Component Analysis and Spearman correlation (using STATISTICA-V.12) were adopted to scrutinize the possible sources of pollution. The windowsill dust was very highly enriched with Sb (50 mg/kg) and Pb (1686 mg/kg). Modified degree of contamination (mCd) and the pollution load indices (PLIzone) indicate that windowsill dust in all functional areas was polluted in the order of industrial > commercial > residential > green space. Arsenic, Cd, Mo, Pb, Sb, Cu, and Zn were sourced from a mixture of traffic and industrial activities, while Mn in the dust mainly stemmed from mining activities. Non-carcinogenic health risk (HI) showed chronic exposure of Pb for children in the industrial zone (HI = 1.73). The estimations suggest the possible carcinogenic risk of As, Pb, and Cr in the dust. The findings of this study reveal poor environmental management of the city. Emergency plans should be developed to minimize the health risks of dust to residents.