Estuaries are complex environments that need to be understood, where environmental issues, e.g. pollution, hypoxia, and salinization, have become an increasing cause of concern in recent decades. In this context, this work focuses on investigating the dissolved silicate (DSi) and total suspended solids in a macro-tidal region (northeastern Brazil), considering seasonal, spatial, and tidal variations. Water samples were collected in 9 sites, under spring and neap tides, during the rainy and dry seasons. The salinity ranged from 9.81 to 31.28 g kg-1, and the pH and temperature remained almost constant throughout the study. The dissolved oxygen (DO) varied from 0.40 to 6.21 mg L-1. The total suspended solids (TSS) ranged from 27.60 to 6,268.50 mg L-1 and the DSi from 2.62 to 107.16 µmol L-1. Statistical analysis showed evidence of the seasonality and tidal conditions in observed parameters. These results improved the knowledge of macro-tidal estuaries located in the Amazon-semiarid interface.