Flora diatomácea do reservatório de Tanque Grande, município de Guarulhos SP como indicadora da qualidade de água

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The Tanque Grande Reservoir is responsible for supplying 10% of the total population of the city of Guarulhos, State of São Paulo, Brazil. It was constructed in order to dam the Tanque Grande River waters, an affluent of the Baquirivu-Guaçu River, which flows to the Tietê River, within the Greater São Paulo Metropolitan area. The reservoir is located within the upper Tanque Grande microbasin which is monitored by CETESB - the Environmental Company of the State of São Paulo. According to the CETESBs water control reports, the water of the Tanque Grande Reservoir is classified as belonging to the Special Category. However, SAAE, the water treatment company of the city of Guarulhos, considers its water as belonging to the Class I category, which by definition can be supplied to the population after a simple treatment. This study analyses the water quality of the reservoir, by using diatom planctonic and perifitic algal communities as bioindicators. The montly sampling period occurred between May 2006 and June 2007. Qualitative and quantitative diatom analyses indicate the presence of 69 species which allow the following conclusions: in terms of trophy, the waters are in general mesotrophic; in relation to acidity the waters appear to have neutral pH, whereas as far as salt concentrations are concerned the diatom assemblages suggest mesohalobic conditions. These results are in accordance with the historical series of physic/chemical/biological data obtained by CETESB and used in its Water Quality Index for the Tanque Grande Reservoir. According to CETESB the water is classified as requiring only a simple treatment (ranging from good to excellent), with pH varying between 6.5 and 7.5 During the analysis, it became clear that the water quality tends to lower during the rainy months with high precipitation levels, as diatoms considered as indicators of eutrophication became common. On the other hand, during the dry winter months water quality varied between oligotrophic to mesotrophic.

ASSUNTO(S)

eutrofização abastecimento de água water supply eutrophicaton geociencias oligotrophy diatomáceas oligotrofia diatoms

ACESSO AO ARTIGO

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