Occurrence, source identification, and implications of human and ecological risks of potentially toxic elements in sediments from Keta Lagoon, Ghana

Keta Lagoon is a major coastal lagoon and an important ecological and socioeconomic asset in the Volta Region of Ghana. Despite its socioeconomic significance, contamination by potentially toxic elements (PTEs) in its sediments remains underexplored. This study aimed to assess the concentrations, potential sources, and associated ecological and human health risk implications of PTE exposure in sediments from the lagoon. Composite sediment samples (n = 12) were obtained from the Keta Lagoon, each formed by homogenizing six individual sediment samples collected from 12 randomly designated sampling sites, and analysed for potentially toxic elements (PTEs) using ICP-MS for Cd, Cu, Cr, Pb, and Zn; Varian AA 240 Hydride Generation AAS for As; and a Mercury Analyzer Model HG-5000 for Hg. Multivariate statistical tools and pollution indices were applied to identify potential sources and the severity of PTE contamination. Human health risks were evaluated using carcinogenic (CR) and noncarcinogenic models (NCR). Ecological risk and pollution indices were assessed using single factor pollution index, Nemerow’s pollution index, ecological risk index, and geoaccumulation index (Igeo). Cd (2.258 mg/kg) and Hg (1.708 mg/kg) concentrations exceeded their recommended default guideline values of 1.500 and 0.150 mg/kg significantly and may pose ecological and human health risks. Multivariate analysis revealed that potential sources of PTE enrichment were largely associated with anthropogenic activities within and around the lagoon, particularly washing bay discharges, domestic wastewater inputs, salt harvesting activities, and agricultural runoff from surrounding coastal settlements. Ecological risk and pollution indices indicated moderate to extreme levels of PTE contamination in sediments, reflecting increased PTE accumulation and potential bioavailability within the aquatic ecosystem. The NCR and CR exceeded the upper reference dose of 1 and 1.00E-04, respectively, indicating potential health challenges and cancer risks in adults and children. This study emphasizes how susceptible children are to PTE contamination and necessitates the need for urgent sediment quality monitoring, pollution control and mitigation around Keta Lagoon to reduce PTE enrichment, protect public health and aquatic biodiversity in the region. Assessment of potentially toxic elements (PTEs) in sediments of Keta Lagoon, Ghana. Hg and Cd exceeded their recommended default guideline values. Multivariate analysis identified sources such as domestic waste and salt-mining activities. Health risk assessment suggests potential non-carcinogenic and carcinogenic risks, particularly for children.