Baseline survey of sediment contamination with 210Polonium in three peri-urban creeks of Mombasa, Kenya

210Po in marine sediment from three peri-urban creeks in Mombasa was analyzed by alpha spectrometry in order to determine its baseline contamination levels. The mean 210Po activity in marine sediment from Mtwapa, Tudor and Makupa creeks were 18.67 ± 1.8, 21.17 ± 2.2 and 13.09 ± 1.6 Bq Kg−1 dw, for surface sediment and 37.56 ± 2.14, 28.64 ± 2.86 and 30.42 ± 2.1 Bq Kg−1 dw respectively, for sediment cores. Comparison of 210Po activity in surface sediment indicated that 210Po in the creeks could be originating from the same source. However, comparison of activities in the entire cores from the three creeks indicated that 210Po sources could have been different in the past. 210Po activities in this study were relatively elevated compared to marine environments under similar anthropogenic influence and there is need to understand its source and fate. •Sediment from the three peri-urban creeks showed 210Po contamination.•Mtwapa sediment had higher 210Po contamination compared to the sediment from the other two creeks.•The activity concentration of 210Po in the three creeks were relatively higher compared to the levels reported in other coastal systems under similar anthropogenic activities.