Evaluating the Levels of Heavy Metals Pollution in the Water and Sediments of Khor Al-Zubair, Southern Iraq, Using Heavy Metal Pollution Index (HPI)

The present study aimed to assess the levels of heavy metal contamination in the water and sediments of Khor Al-Zubair using the Heavy Metal Pollution Index (HPI). Three stations were selected: the first at the Mangrove, the second at the Army Canal, and the third at the Free Zone. Samples were collected quarterly from January to December 2024, at low tide, with one sample taken from each station per sampling period. The pH values of the water were in the alkaline range, and the soil texture at all stations was silty and clayey. The results indicated that the region was particularly rich in nickel, followed by lead in both water and sediments, cobalt in the water, cadmium in the sediments, and then cadmium in the water and cobalt in the sediments. Copper was the least abundant metal in both water and sediments. When compared with global environmental guidelines (WHO) and the local River Conservation System (2011), the concentrations of all measured metals in both water and sediments exceeded the permissible limits and were higher than previously recorded concentrations in the region. Sediment samples consistently showed higher metal concentrations than water samples. This is attributed to the silty clayey soil, which has a high capacity to retain heavy metals, as well as to the elevated sedimentation rates of these metals in the study area.