Evaluating Soil Contamination Risks Using a Novel Combined Pollution Quality Index (CPQI) in Sulaymaniyah, Iraq

Volume 11 , Issue 3 , August 2025 , Pages 30-53

Authors

MIDYA ABDALRAHMAN 1 ; Zeren Ghafour 1 ; Nihad Salih 1

1 University of Sulaimani , College of Engineering , Water Resources Department

DOI logo 10.17656/sjes.10195

Keywords

Abstract

Soil is a great reservoir of nutrients and pollutants, and as such plays an important role in health and socio-ecological sustainability. Contaminants from agriculture, urbanization and industrial activities enter the soil which increases soil pollution and impose a big risk on human health. This study introduces a novel Combined Pollution Quality Index (CPQI) that integrates six weighted indices-Nutrient Index, Salinity Index, Organic Matter Index, Sodium Adsorption Ratio (SAR) Index, Heavy Metal Risk Index, and Pollution Quality Index (PQI). Analytic Hierarchy Process (AHP) used to find weight values for each index. Soil samples from two different locations in Sulaymaniyah city were examined. The areas are two agricultural farms irrigated    by water from stream and by wastewater respectively. Different points were selected at each area with two depths (surface and at 60 cm).  Chemical, physical and biological tests were carried for all samples such as; heavy metals, organic matter, nutrients, PH, TDS, EC. The results showed that the heavy metal concentration in all samples (surface and 60 cm depth) are within the allowable range. Generally higher levels of most heavy metals observed at 60 cm depth compared to surface samples. CPQI (combined pollution quality index) derived from all indices together to realize pollution index for each location, consequently all the CPQI values founded are below 1, meaning they fall under "Low Pollution" condition according to the limitations values, the highest value taken by the first location 60 cm deep result about 0.49578 and lowest value 0.34348 for the first location surface sample. this result is due to the high probability of absorption by plant roots and vegetables.

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