1 2009 International Nuclear Atlantic Conference - INAC 2009 Rio de Janeiro, RJ, Brazil, September 27 to October 2, 2009 ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR – ABEN ASSESSMENT OF SEDIMENTS FROM THE TIETÊ RIVER –TOXICITY, METALS AND TRACE ELEMENTS - FROM SALESÓPOLIS TO SUZANO COUNTIES, SÃO PAULO, BRAZIL Gabriel F. Alegre 1 , Sueli Borrely 1 , Thuany M. Nascimento 2 , Deborah I.T. Favaro 2 1 Centro de Tecnologia das Radiações, CTR, IPEN/CNEN - SP Av. Professor Lineu Prestes 2242 05508-000 São Paulo, SP gabrielfonseca@usp.br 2 Neutron Activation Analysis Laboratory, LAN/CRPQ, IPEN/CNEN - SP, Av. Professor Lineu Prestes 2242 05508-000 São Paulo, SP defavaro@ipen.br ABSTRACT In the present study, sediment samples from the Tietê River were evaluated for toxicity and metals (5 sampling sites). The studied region includes Salesópolis to Suzano and surroundings, a highly industrialized area. The study involved two scientific areas: whole toxicity evaluation (sediment, elutriate and pore-water) and the distribution of some major, trace and rare earth elements on sediments. Multielemental analysis was carried out by instrumental neutron activation analysis (INAA) and total mercury by cold vapor atomic absorption technique (CV AAS). The concentration values obtained for the metals As, Cr, Hg and Zn in the sediment samples were compared to the Canadian Council of Minister of the Environment (CCME) oriented values (TEL and PEL). Regarding toxicity, whole sediments and elutriate fractions were evaluated using chronic assays for Ceriodaphnia dubia, while the pore water was carried out for Vibrio fischeri toxicity assays. These assays followed Brazilian Standardized Methods (ABNT). Whole sediments and elutriate evidenced negative biological effects, even at Salesópolis county, the control site (less impacted area). The worst effects were obtained at Mogi das Cruzes and Suzano counties (sampling stations 3 and 4). The elutriate fractions collected at the same stations showed acute toxicity in two of three samples (C. dubia). When pore water was evaluated, a toxicity gradient which increased as the river flowed through Mogi das Cruzes county was obtained. Regarding toxic metal contents in the sediment samples points 3 and 4 exceeded the TEL oriented values for As, Cr, Hg and Zn and point 4 also exceeded the PEL values for all these elements. 1. INTRODUCTION Substantial part of São Paulo Metropolitan Region (SPMR) is included at Tietê Hydrographic Basin (Alto Tietê). Tietê river flows from Salesópolis through Barragem do Rasgão, totalizing 5.985 Km² draining basin area. The region includes 35 municipalities: part is agriculture area and most is urban area. The region is important for water supply once