A study was made in Laguna Carén, a small shallow freshwater system located 20 km from downtown Santiago, Chile, of the behavior of some chemical species in porewater. Manganese, iron, molybdenum, antimony, sulfide and phosphate profile concentrations were determined. Diffusive fluxes through the sediment-water interface were obtained by diffusive dialysis. The behavior of metal species like Fe and Mn was opposite to that of Mo and Sb. Dissolved Fe and Mn showed decreasing concentrations from -6.0 cm to 0.0 cm, while those of Mo and Sb increased at this depth. The results obtained in the sediment-water interface of Laguna Carén indicate the availability of soluble species of Fe(II) and Mn by diffusive transport to the overlying waters, whereas Mo and Sb species are not available in this zone. The fluxes were (in pmol cm -2 s-1) as follows: Fe(II): 0.05; Mn: 0.28; Mo: -1.2 x 10-4; Sb: -3.9 x 10-4.