DOI : 10. 1051/jp4 : 20030283 Behaviour of heavy metals in the estuarine area of the Capibaribe River in the Northeast of Brazil F. M. M. Brayner, A. M. Freitas Barbosa, H. K. Phillipini da Silva and L. Vieira de Melo Instituto Tecnologico do Estado de Pemambuco-Brazil, Av. Prof Luiz Freire 700, Ciudade Universitaria, Recife/PE, Brazil Abstract. The Capibaribe river estuary extends more than 15 km, mostly within urban areas in the city of Recife, capital of the state of Pemambuco, with a high population density and many heavy industries dealing with me(iliincluding platting. For this reason the river receives many different forms of pollution such as wastewater, litter or industrial effluents without treatments as well as sediments derived fron the degradation of its borders or from hills erosion located around the city. To study the behaviour of the heavy metal along the Capibaribe river estuarv, sixteen sediment samples were collected in different waterlogged areas : eight from the right border of the river and eight from the left, each one in front of the other. Sediment superficial samples were collected with a plastic manual sampler and submitted to granulometric analse to determine the distribution of the soil fractions, x-ray diffractomety to détermine thé minera ! composition of the clay fraction and lithium metaborate fusion to détermine thé total metal concentration using ICP-AES method. Eight metallic clements were studied (Cd, Co, Cr. Cu, Mn, Ni, Pb and Zn) in 16 sediiment samples collected. The resuüts indicated that the concentration of total heavy metal along the Capibaribe estuary was influenced by sediment granulometric composition. with a trend to high total heavy metal concentration in samples with high percentage of clay. On thé other hand, onty thé deternination of the granulometric composition wasn't sufficient to analyse this behaviour because some points with high percentage of sand presented high concentration of total heavy metais what can be due to other factor like predominat kind of clay minerai, amont of humic substances, hidrodinamic régime, among others. L INTRODUCTION In the last decades tbe industrîalization and urbanization process have increased the pressure above the coastal ecosystems. In tropical regions a great nurnber of cities are located in estuarine areas, zones of complex interaction between fluvial and marine processes that may act as a geochemical trap for heavy metals immobilízing them in fine-grained sédiments. Thé heavy metals have significantly contributed to air, water and soil pollution, producing great damage to the environment and human health. The mixing of continental ffesh and marine sait waters that occurs in the coastal and estuarine systems leads to floculation and accumulation pro cesses of suspended sediments, which are controlled by hydrodynamic and chemistry gradients and some phisyco-chemical properties of clay minerais, such as specific surface and exchange capacity. This way, clay minerais play an important role as a natural tracer of pollutants in estuarine environments [1] and [2]. Furtherrrore, the input of material in the estuarine and coastal zones is mainly determined by rivers discharge and the amount of sediment transported can be strongly affected by human activities. reported that in s-mali rivers with highty urbanized drainage areas, thé input ofmateriat by man