Behaviour of heavy metals in the estuarine area of the Capibaribe River in the Northeast of 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 Pernambuco, with a high population density and many heavy industries dealing with metal including 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 from 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 estuary, 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 analyse to determine the distribution of the soil fractions, x-ray diffractomety to determine the mineral composition of the clay fraction and lithium metaborate fusion to determine the total metal concentration using ICP-AES method. Eight metallic elements were studied (Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn) in 16 (sixteen) sediment samples collected. The results 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 the other hand, only the determination 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 metals what can be due to other factor like predominat kind of clay mineral, amount of humic substances, hidrodinamic regime among others.