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

Abstract

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.