Contamination and source apportionment of iron, zinc, cadmium and chromium elements in surface soil of Khorramabad county, Iran

Soil contamination with heavy metals is the most important challenge and common environmental, economic, and public health issue in the world. Therefore, this research was conducted to evaluate the contamination and source identification of Fe, Zn, Cd, and Cr in the surface soils of Khorramabad county, west of Iran in 2020.

In this descriptive study, after dividing the study area into 11 homogeneous units, a total of 65 surface soil samples were collected. After preparing the samples, the content of the elements was determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Also, enrichment factor (EF), pollution factor (CF), and Nemrow integrated pollution index (NIPI) were calculated. Statistical analyses of the data were performed using SPSS statistical software.

The results showed that the average content of Fe, Zn, Cd, and Cr (mg/kg) in soil samples were 3.14, 1.13, 0.021, and 0.529, respectively. The EF values showed that the enrichment of Zn, Cd, and Cr was "extremely severe" and the average values of EF for the elements followed the descending order of Cd > Cr > Zn. The average values of CF and NIPI varied from 3.30×10-5 to 0.182 and 0.043-0.136, respectively, indicating the level of "low pollution" and quality conditions of "no pollution" in all the studied stations. Based on the results of multivariate statistical analysis (PCC, PCA and HCA), Fe has a geological origin; while, Zn, Cd, and Cr mainly originated from a combination of geological processes and anthropogenic activities.

Although the average values of CF and NIPI showed that the study area has an acceptable soil quality, the values of EF indicated the impact of anthropogenic activities on soil contamination. Therefore, regular and periodic monitoring of soil samples as well as management and control of pollutant emission sources is recommended for maintaining environmental and human health.