Contamination, Source Apportionment and Health Risk Assessment of Potentially Toxic Elements in Soil of Park-e-Shahr and Park-e-Laleh, Tehran City

The soil quality of urban parks is of vital importance as the children playing in the parks get themselves easily contaminated. This study aimed to investigate the concentrations, sources, pollution levels and human health risk of potentially harmful elements in the soil of two urban parks present in Tehran. For this purpose, the soil samples (n=26) were collected from shahr and lale parks analyzed for total potentially toxic elements concentration (As, Cd, Co, Cr, Cu, V, Pb, Ni and Zn) using an Inductively Coupled Plasma Spectroscopy and Optical Emission Spectroscopy. The degree of pollution by potentially toxic elements was assessed with respect to the background concentration by calculation and comparison of the geo-accumulation index (Igeo), enrichment factor (EF), pollution index (PI) and integrated pollution index (IPI).Sources of different elements in the soils were identified by employing principal component analysis (PCA). The results of EF and Igeo analysis showed about 50% of the soil samples to be enriched in heavy metals Cd, Cr, Cu, Pb and Zn compared with background levels, suggesting heavy metals contamination of soil two urban parks are from anthropogenic sources. Based on the PI values, Cd, Cr, Cu, Pb and Zn in the soil of two parks were higher than their background concentrations. IPI decreased in the order of Shahr and Lale parks. Geochemical indicators and PCA confirmed that the main pollution source of soil was traffic, fertilizers, waste, corrosion of metal surfaces of cars, fuel additives and corrosion of building materials. Health risk assessment indicated that the potentially toxic element contamination in the Shahr and Lale parks, were below the acceptable threshold for carcinogenic and non-carcinogenic risks. However, the carcinogenic risk from Cr due to oral ingestion of soil exceeded the value of 1×10−6, in both parks. It indicates that the exposure to Cr-contaminated soil may cause adverse health effects in humans, especially in children. The Hazard Quotient (HQ) and Hazard Index (HI) for different metals through ingestion, inhalation and dermal pathways was also found to be less than 1, indicating no health risk exists in present condition.