Distribution of pharmaceuticals in marine surface sediment and macroalgae (ulvophyceae) around Mombasa peri-urban creeks and Gazi Bay, Kenya

Pollution in marine creeks has been increasing due to anthropogenic activities and has been a global concern. Limited research has been conducted on pharmaceuticals in marine sediment and macroalgae in African countries. In the present study, the levels of pharmaceuticals were assessed in surface sediment and different species of macroalgae (ulvophyceae; Cladophora sudanensis, Chaetomorpha crassa, Chaetomorpha indica, Enteromorpha kylinii, Ulva reticulate, Ulva lactuca and Cladophora sibugae) in Mombasa peri-urban creeks (Tudor, Makupa and Mtwapa creek) and Gazi bay during dry and wet seasons. The concentration of pharmaceuticals in the surface sediment during dry and wet seasons ranged between 0.04–686.8 ng/g and 0.01–2580.6 ng/g, respectively. The highest concentration of pharmaceuticals was observed in Tudor creek in dry and wet seasons, with a sum concentration of ∑1013 ng/g and ∑3111 ng/g, respectively. Gazi Bay was used as a reference environment for this study, and pharmaceuticals were detected in dry and wet seasons with a concentration of 0.10–686.8 ng/g and 0.18–93.5 ng/g, respectively. There was no seasonal variation in the pharmaceutical concentration during the dry and wet seasons. For macroalgae of ulvophyceae species, pharmaceutical concentration ranged below the detection limit (DL)–11059 ng/g. Compared to surface sediment, macroalgae showed a high concentration of pharmaceuticals in Tudor, Makupa and Mtwapa creeks. Tetracycline was higher in sediment and macroalgae in all the creeks than other pharmaceutical compounds. A high concentration of pharmaceuticals confirms sewage effluent into the marine environment of Mombasa peri-urban creek. Pharmaceuticals (acetaminophen, sulfamethoxazole, trimethoprim, carbamazepine and nevirapine) in sediment posed a medium (− 1 < Log10 RQ < 0) to higher risk (Log10 RQ > 0) to algae, invertebrates and fish in the dry and wet seasons. There is a need to sensitise the residents of coastal cities on the impact of sewage effluent into the marine environment and enact strict measures to limit the discharge of sewage effluents containing these contaminants into the marine environment. Nevertheless, it is recommended to conduct further research on the distribution of pharmaceuticals in the marine environment and the long-term combined impacts of these substances of these compounds on marine biota.