Spatial analysis of total mercury concentration in surface sediments in Sulaibikhat Bay, Kuwait

Abstract

Sulaibikhat Bay, a shallow estuarine embayment in the southern part of Kuwait Bay, has undergone substantial anthropogenic impacts over the past decade, resulting in altered sediment quality and mercury (T-Hg) contamination. This bay, bordered by the Doha Power Plant and Shuwaikh Port, receives untreated sewage and industrial waste through 17 outfalls, nine of which remain active. To assess the extent of contamination, 44 surface sediment samples were analyzed for T-Hg concentrations and fluxes. T-Hg concentrations ranged from 8 to 800 ng g⁻¹, averaging 74 ng g⁻¹. Elevated levels were observed predominantly on the eastern side of the bay, with a maximum of 800 ng g⁻¹ near Outfall 3. In contrast, the western side exhibited lower concentrations, ranging from 17 to 50 ng g⁻¹. Mercury fluxes mirrored this spatial pattern, with the highest flux recorded at 250 ng cm⁻² yr⁻¹. Assessment using enrichment factors and the geoaccumulation index indicated that western bay sediments are uncontaminated to moderately contaminated, while the eastern side is moderately to strongly contaminated, with some areas classified as extremely contaminated. Although most T-Hg concentrations were below Interim Sediment Quality Guideline (ISQG) thresholds, location H41 exceeded the Probable Effect Level (PEL) at 800 ng g⁻¹. These findings, consistent with previous studies, raise concerns about higher mercury levels in deeper sediments, which could resuspend during dredging or coastal development, increasing risks to the marine ecosystem. This study highlights the urgent need for a strategic management plan to mitigate contamination, protect the bay, and guide future monitoring and conservation efforts.