NÃveis de concentraÃÃes de metais pesados em macroalgas e em sedimentos marinhos do Estado de Pernambuco - Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The strong industrial and agricultural activities in Pernambuco State are contributing heavily to the contamination of the coastal waters with heavy metals and unfortunetly it is increasing constantly. As this subject is explored in many aspects and as there exists already a great production of papers, in order to diagnostic the present situation and to suggest an efficient monitoring of the coast of Pernambuco, we intended in this work, to give specific data on the level of some metals in macroalgae and marine sediments and its interactions with the properties of sea water. For this study, because of their algae banks and the impact of industrial and domestic effluents, the selected areas were, one in the north (Itamaraca Beach â 7o 45âS and 34Â50âW) and another in the south (Piedade Beach 08Â09â17ââS and 34Â55âW). The selected algae were Gracilariopsis lemaneiformis and Hypnea musciformis and the chemical elements were copper, lead, zinc and iron. In each region the samples were collected monthly from May 2000 to April 2001, during the low tides. The metal concentrations in the algae were determined by Atomic Absorption Spectroscopy and in sediments by X-Ray Fluorescence. The areas present a hot and humid climate, Asâ in the Koppen classification, with an annual average temperature of 26ÂC, and a dry season from September to February with an average rain fall of 120 mm and a wet season from March to August with an average rain fall of 415 mm. The hydrological analysis showed that the water temperature ranged from 28o to 31oC, the salinity from 26.38 to 36.88 UPS and the dissolved oxygen from 2.43 to 6.37 mL.L-1. The highest metals contents were detected in algae on the south coast, where the Hypnea musciformis presented the highest retention capacity. In the sediments in all the cases the highest contents were also found in the south, except to the iron. It was also observed that the retention in the sediments was higher than in the algae, except to zinc. So, they were the most appropriate to monitoring the metals of the Pernambuco State Coast. A global exploratory analysis (North and South Coast of Pernambuco) of the metal concentrations in the algae and sediments, of the physical-chemical properties of the water and the pluviometry was performed by multivariable projection analysis of the main components. The main components (wich represented 36,8% of the total variability of the data) showed that the samples from the south coast were more dispersed and presented higher values for the metals in the sediments and in the algae. It was also observed that in the north coast occurred an effluent discharge carried by the rains, presenting an anomalous situation in July with higher metal levels in the sediments. In this area there were positive correlations in the sediments among all the metals, while in the algaes these correlations were observed between lead and copper in the sediment. In the sediment samples from the south area, positive correlations between copper and lead, iron and zinc and between lead and zinc were noticed. The results of the average metal concentrations in the sediments were: in North area the iron (0,078%), lead (6,923mg.Kg-1), copper (38,178mg.Kg-1) and zinc (5,610mg.Kg-1); in South area the iron (0,339%), lead (5,942mg.Kg-1), copper (48,799mg.Kg-1) and zinc (8,388mg.Kg-1). In the algae: Gracilariopsis lemaneiformis in the North area, iron (141μg.g-1), lead (3,50μg.g-1), copper (0,95μg.g-1) and zinc (33,14 μg.g-1); in the South area iron (347μg.g-1), lead (2,99μg.g-1), copper (1,57μg.g-1) and zinc (28,57μg.g-1). The Hypnea musciformis were: in the North area, iron (675μg.g-1), lead (8,90μg.g-1), copper (1,85μg.g-1) and zinc (49,93μg.g-1); in the South area iron (806μg.g-1), lead (5,49μg.g-1), copper (2,35μg.g-1) and zinc (44,57μg.g-1). Between the algaes testeds, the Hypnea musciformis presented higher metal level. The sediments metal level was taken was the parameter of comparison as it was the higher than that one found in both algaes. The seasonal metal changes in the algae and sediments were irrelevant, not presentig a standard regular distribution

ASSUNTO(S)

sedimentos marinhos oceanografia algas metais pesados

ACESSO AO ARTIGO

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