Revista Ambiente & Água (Dec 2009)
Heterogeneidade espacial e temporal da qualidade da água no reservatório Rio das Pedras (Complexo Billings, São Paulo)
Abstract
The objective of the present study was to evaluate spatial and temporal patterns of limnological characteristics of the Rio das Pedras Reservoir (Billings Complex, São Bernardo do Campo, São Paulo – Brazil). Profile samples were taken at three stations during two periods (March and October, 2004). The variables analyzed were: temperature, electrical conductivity, pH, with multiparameter probe; concentration of ammonium, nitrite, nitrate, phosphate, orthosilicate, total phosphorus, chlorophyll-a and phaeophytin, by spectrophotometric method; dissolved oxygen by titrimetric method; beyond concentrations of total solids and suspended material. PCA (Principal Components Analyses) was applied for the statistical analyses. The temporal heterogeneity observed was a consequence of differences in temperature observed in the month of March, which generated thermal, chemical and biological stratification. The vertical spatial differences also resulted from the thermal stratification. The largest discrepancies in the limnological characteristics, in relation to the pattern of horizontal spatial distribution, were obtained in station 1, and are directly related to the influence of the incoming waters of the Billings reservoir. According to CONAMA 357/05, for the month of October, 2004, the waters of the reservoir were in accordance with Class 3. In March, the values for station 3 were below the standards established, indicating non-conformity with Class 3.
