Transposição das águas do braço Taquacetuba da represa Billings para a represa Guarapiranga: aspectos relacionados à qualidade de água para abastecimento / Water transposition from Billings reservoir s Taquacetuba branch to Guarapiranga reservoir: aspects related to water quality for water supply.

AUTOR(ES)

Mayla Matsuzaki

DATA DE PUBLICAÇÃO

2007

RESUMO

Objective. The Taquacetuba-Guarapiranga productive system consists of water transposition from Billings reservoir s Taquacetuba branch to Guarapiranga Reservoir in order to increase water supply to the population in São Paulo Metropolitan Area. Due to the risks to public health involving such procedure, a study aiming to evaluate the sanitary aspects of Guarapiranga Reservoir water after the transposition was carried out. Method. The present work was based on secondary data obtained from SABESP in the period between March 2001 and February 2003, in sampling stations located in Guarapiranga and Billings Reservoirs. The environmental, biological and toxicological variables studied were: rainfall, water and air temperature, turbidity, pH, nutrients, E. coli, cyanobacterial cell counting and microcystin concentration. The results were analyzed using Spearman s correlation test. Results. High densities of Microcystis, Cylindrospermopsis and Oscillatoriales were obtained in periods of intense rainfall. The variables showing significant correlation to cyanobacteria density were: temperature, pH, turbidity, nutrients and microcystin. During the period studied herein, nonconformities to CONAMA s Resolution 357/05 for class 2 waters were verified, concerning total phosphorous and total nitrogen. Conclusions. Some environmental variables favored the development of potentially toxic cyanobacteria in the reservoirs. Water transposition from Taquacetuba branch may be influencing the water quality in Guarapiranga reservoir, mainly in what concerns cyanobacteria densities. It is recommended that a continuing monitoring of water used to public supply is performed, as well as risk management related to cyanobacteria and the periodic revision of contingency plans.

ASSUNTO(S)

reservoirs cianobactérias water supply cyanobacteria reservatórios abastecimento de água

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