Heavy-metal behavior during mixing of river and sea waters: Diurnal variability in heavy-metal contents in water and suspensate in the tidal estuary of the Saigon River, South China Sea

Data are given on the diurnal variation in the dissolved and suspended forms of Zn, Mn, Cu, Fe, Co and Sb in the river and sea parts of the Saigon estuary in the South China Sea. For Zn and Cu dissolved forms predominate at both diurnal stations; the dissolved Zn fraction shows conservative behavior when seawater mixes with fresh. Fe migrates in the Saigon R. and Mn, Co and Fe migrate in the coastal zone in a way determined by their suspended forms, so the interaction between the river runoff and the tidal currents is particularly important, as it regulates the amount of suspended material in the estuary. For Zn, Mn and Cu in the Saigon River (S = 6.0-10.5‰) a negative correlation is observed between their specific contents in the suspensate and the concentrations of suspended material, which may be due to the mobile forms predominating (reversibly sorbed). Approximate equilibrium between the suspended and dissolved forms occurs for Sb.