HEAVY METAL CONCENTRATIONS IN SESTON OF TEN LENTIC SYSTEMS FROM THE NORTHERN OF RIO DE JANEIRO STATE: PARAMETERIZATION WITH C, N, P AND CHLOROPHYLL a

Paulo Pedrosa*, Roberto Amaral da Silva, Cristina Maria Magalhães de Souza, Marina Satika Suzuki & Carlos Eduardo Rezende (Universidade Estadual do Norte Flumenense, Laboratório de Ciências Ambientais, Av. Alberto Lamego 2000, Campos dos Goytacazes, 28.015-620, Rio de Janeiro, Brasil. Email:pedrosa@cbb.uenf.br; Tel: + 55 24 7263819 and Fax: +55 24 7263720)

Ten lentic systems were surveyed for seston heavy metal concentrations. The systems were represented by tropical lakes and lagoons from the northern of Rio de Janeiro State. The overall characteristics of the systems included areas from 0.1 to 102 km2, transparent to turbid water optical state, fresh- to brackish waters, and macrophyte to phytoplankton-based primary production. The aim of this study was to investigate the relationships among heavy metals (e.g., Zn, Cd, Cu, Cr, Pb, Fe), and C, N, P and chlorophyll a (Chl a) pigment in seston from a set of lentic tropical systems. Particulate fraction was obtained by water filtration in Whatman GF/C filters. For heavy metals, samples were acid digested and measured through ICP-AES. Carbon and nitrogen were determined with a CHNS/O analyzer. Phosphorus was determined by colorimetry with ammonium molybdate ascorbic acid reaction. Chlorophyll a was extracted in alkaline acetone 90% and determined spectrophotometrically. Elemental !

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and elemental:Chl a ratios were, thus, applied as biogeochemical indicators of seston quality and to normalize seston heavy metal content on fixed references beyond weight. The implications of our results for diagnosing heavy metal behavior in particulate matter of aquatic systems are potentially applicable for monitoring/management purposes. Finally, a tentative of grouping limnological features, seston quality and heavy metal concentrations is provided.

Key words: seston, aquatic systems, monitoring/management, heavy metals

Financial Support: FENORTE/UENF