The concentrations of dissolved cadmium, lead, chromium and níquel were determined in surface water column and pore water, collected from the extensive tidal plain at Bahía Blanca estuary, Argentina. Three different polluted areas were selected to study the spatial variation of these metals. The concentration ranges within the water column were slightly variable (Cd: 0.18-2.48 microg L(-1); Pb: 0.38-7.53 microg L(-1); Cr: 0.89-5.83 microg L(-1); Ni: 0.81-3.49 microg L(-1)), and displayed a clear gradient respect to the industrial area. Significant differences (contrast tests) between sites were detected for Cd, Pb and Ni. Very similar concentrations of Cd (0.18-3.41 microg L(-1)), Pb (0.38-5.83 microg L(-1)), Cr (0.89-9.37 microg L(-1)), Ni (0.81-6.56 microg L(-1)) were found in the porewater at all sites. The results suggested that both environmental compartments (water column and tidal flats porewater) may be affected by similar point and non-point heavy metal sources.