Evaluation of soil pollution by heavy metal using index calculations and multivariate statistical analysis.

This study aims to assess the extent of heavy metals (HMs) pollution in soil and identify its potential sources using single and integrated pollution index calculations, and multivariate statistical analysis. The HM concentrations of soil samples were analyzed using ICP-MS. The concentrations (mg/kg) of arsenic (As) ranged from 2.8 to 208.1, cadmium (Cd) from 0.1 to 0.3, cobalt (Co) from 1.9 to 20.5, copper (Cu) from 3.7 to 17.7, nickel (Ni) from 14.7 to 110.6, and lead (Pb) from 6.7 to 37.3. High levels of As contents and physicochemical parameters were found in the northeastern parts of the study area, while levels of other HMs were high in the remaining parts. The HM contents of some soil samples exceeded the average values of basalt and limestone in the study area, as well as the upper, bulk, and lower continental crusts, shale, and soil (worldwide). Multiple index methods were used to assess the pollution risk, and it was determined that some soil samples were moderately to considerably contaminated with varying levels of As, Cd, Co, Ni, and Pb. Multivariate statistical analyses provided that the source of HMs contamination in the soil was a result of geogenic and/or anthropogenic activities. Geogenic sources were associated with weathering rock units, while anthropogenic sources were linked to industrial activities, traffic emissions, and agricultural applications. The findings are useful for detecting contamination by HMs in soil, and they could contribute to future monitoring programs to prevent soil contamination and protect the health of living organisms.

Geochemical investigation of soil quality in terms of toxic elements using an AHP-based index.

In this study, a new Ecological Soil Pollution Index (ESPI) and the associated classification system for this index have been proposed to determine the pollution potential of soil. ESPI was designed using eight elements, namely arsenic, lead, cadmium, nickel, copper, zinc, chromium and cobalt. ESPI, calculated based on the AHP method, is categorized into four classes inspired by the recommendation of some international organizations such as World Health Organization and the Food and Agriculture Organization. ESPI classes based on performance scores of samples are "No pollution," "Low pollution risk," "Medium pollution risk" and "High pollution risk." According to ESPI calculations, the element with the highest efficiency in the hierarchy is arsenic with a weight ratio of 32%, whereas the lowest values are 3.4% and 2.4% for chromium and cobalt, respectively. 5.5% of the soil samples have a high pollution risk, 5.5% medium pollution and 40.7% low pollution risk, whereas 48.3% do not have a pollution risk. Based on the distribution maps, the areas with high pollution potential are located in the north, northwest and southeast of the study area, which is due to the high arsenic, lead and cadmium weight values in the model hierarchy. The correlation coefficients between ESPI and some other indexes indicate that ESPI can produce similar results to them. As a result, ESPI is a user-friendly method that can produce reliable results by combining large numbers of data under a single score.