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A study on the trace elements transfer from tidal water to mangrove sediments from Guanabara Bay (southeastern Brazil) was performed in laboratory microcosms. Sediment cores were covered with tidal water spiked with Cs, Mn and Co during 5-h experiments, and water samples were taken at regular intervals to measure uptake kinetics at the sediment-water interface. At the end of the experiments, the uptake and diffusional penetration into the sediments was evaluated. Half-removal times from water to sediments were slightly higher for Cs (3.4 ± 1.7 h) than observed for Mn (2.3 ± 0.2 h) and Co (2.6 ± 1.1 h). After these experiments, all radioisotopes presented decreasing activities with increasing sediment depth, being the distribution of Cs indicative of higher diffusion within the upper 2 cm. This study on the removal of Cs, Mn and Co from tidal water by mangrove sediments suggests that while Co and Mn presented closer behaviors, there was a slightly higher mobility of Cs. [ABSTRACT FROM AUTHOR]