Ecological risk assessment and potential source of As, Cd, Co, and Ni in Al Qunfudhah seawater, Red Sea coast, Saudi Arabia

Abstract

The rapid economic expansion of the worldwide coastal settlements has resulted in the discharge of substantial amounts of heavy metals (HMs), posing a considerable risk to marine organisms. The present work aims to evaluate the HM contamination of seawater and determine their potential sources in Al Qunfudhah seawater, Red Sea coast utilizing contamination factor (CF), degree of contamination (C_d), modified contamination factor (mC_d), heavy metal pollution index (HPI), and multivariate analysis. A total of twenty-nine samples of surface seawater were gathered and the analysis of HMs was conducted using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The average concentration of dissolved HMs follows the following order: As (5.83 μg/L) ˃ Ni (0.990 μg/L) ˃ Co (0.168 μg/L) ˃ Cd (0.090 μg/L). The average concentrations of As, Co, Ni, and Cd were below the maximum admissible concentration (MAC) set by the World Health Organization (WHO), as well as the criterion continuous concentration (CCC) and criterion maximum concentration (CMC) set by the environmental protection agency. This suggests that the levels of these substances are within the acceptable limits for protecting aquatic life, both in the short-term and long-term exposures. The results of the analysis for CF, C_d, mC_d, and HPI suggested clean and uncontaminated seawater in most sites. Few individual samples obtained elevated values, which might be attributed to natural source, mostly from chemical weathering of rock forming minerals from the Arabian Shield, as well as agricultural and coastal activities.