Fractionation, source apportionment, and health risk assessment of selected metals in the soil of public parks of Lahore, Pakistan

The aim of this study is to evaluate the mobility/availability of potentially toxic elements in the soil of public parks to assess the environmental quality and potential health risks. The concentrations of 16 selected metals (Ca, Mg, Sr, K, Na, Li, Fe, Mn, Zn, Cu, Ag, Co, Ni, Cr, Cd and Pb) in the soil samples collected from 20 parks located in Lahore, Pakistan were measured by flame atomic absorption spectrometry using modified BCR sequential extraction during summer and winter season. In the exchangeable soil fraction, highest mean concentration was found for Ca, followed by Mg, K, Na and Mn, while in the reducible soil fraction, relatively higher mean levels were noted for Ca, Fe, Mg, K and Mn. In the case of oxidisable soil fraction, Fe, Mg, K, Na, Ca, Mn and Pb were the dominant contributors among the selected metals. Comparatively higher mobility and bioavailability in the soil was shown by Ca, Sr, Pb, Cd, Na, Ag, Co, Mn, and Zn while Cr, K, Li, Fe and Cu were found mainly in the residual fraction. Cluster analysis demonstrated anthropogenic intrusions of Cd, Pb, Co, Cr, Cu, Li, Zn and Na in the park soil. The pollution assessment revealed that the soil of the public parks was heavily to extremely polluted by Cd, followed by moderate to significant contamination for Pb and Zn. The modified degree of contamination (1.48 and 1.88 in summer and winter, respectively) exhibited an overall low degree of contamination. The health risk assessment showed that the calculated values were within the safe limit thereby indicating no significant non-carcinogenic or carcinogenic heath risk to the exposed population. The study offers more insights to control the environmental and human health risks of trace metals in public parks by reducing the soil pollution and it will provide critical information for policy makers to formulate effective pollution control strategies.