Diagnóstico da qualidade da água do reservatório do Tanque Grande, município de Guarulhos, Estado de São Paulo, no período compreendido entre 1990 e 2005

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The main objective of this research was to evaluate the water quality of the Tanque Grande Reservoir, in the period understood between 1990 and 2005, in function of the population increase in around of this reservoir, as well as of the diversification of the use and occupation of the ground in region. The present work had as objective main to analyze the quality of the water of the Tanque Grande Reservoir, used mainly for public supplying, located in the city of Guarulhos, State of São Paulo, Brazil. The analysis include the period understood between 1990 and 2005. the following physical, chemical and biological parameters had been evaluated provided by the CETESB, in the year of 2006: UV Absorbance, total Colifoms, Coloration, Conductivity, Chemical Oxigen Demand (COD), total Iron, total Manganese, Ammoniac Nitrogen, Kjeldahl Nitrogen, Monthly Precipitation, THM Potential Formation, Temperatures of Air. Additionally, the Water Quality Index IQA was used, that include also the parameters: Thermotolerants Coliforms, Biochemical Oxigen Demand (BOD5,20), total Phosphorous, total Nitrogen, Dissolved Oxygen (DO), pH, total Residue (Solid), Water Temperature and Turbidity, calculated for the CETESB for this exactly period. As it has supported to the interpretation of these parameters, parallel, had become fullfilled studies of correlation of Person and multiple regression, beyond data-collectings regarding the half physicists, biotics and partner-economic of the involved region, as well as of the adjacent urban areas. The reached results show that the verified urban expansion in the city of Guarulhos, from the decade of 70, reached the areas next to the reserves to sources, compromising, in part, the quality of the superficial hídrics resources. With effect, in passed times, the Tanque Grande Reservoir was classified as Special Class, that is, destined to the supplying for human consumption, without disinfection. However, in the current days, the classification of the waters that better is classified is of Class One (1) and, in relation to some parameters, until lower class, therefore has necessity of treatment simplified before to have the use of the population of Guarulhos. The analyses of correlation of Pearson and multiple regression disclose that, of the nine variable used to calculate of the IQA, only four had significantly influenced the variation of the index calculated for the Tanque Grande Reservoir (n = 84, p <0,05): Thermotolerants Coliforms (r2 = 0,50), Turbidity (r2 = 0.21), Dissolved Oxygen (r2 = 0,14) and total Solids (r2 = 0,08). Thus, three hypotheses had been considered: (i) the main source of thermotolerants coliforms is the activity of creation of animals next to the tributaries to the reservoir and the rise of the concentration of this parameter in the summer is associated with the increase of the flow of the tributaries in the period of rains; (II) the main source of thermotolerants coliforms is the activity of recreation of the population next to the reservoir, being that it does not have local sanitary structure to support this type of activity; (III) the two first added hypotheses. In the period considered in this study of case, it was noticed that most of the falls of the IQA was associated with the rainy periods, concomitant to the increase of the concentration of thermotolerants coliforms. The activities of creation of animals gifts to the sum and recreation that occur to the edges of the reservoir represent the main sources of introduction of thermotolerants coliforms in the reservoir. Thus, one concludes that activities of Ambient Education that acquire knowledge the population and guide the adequate use of the Tanque Grande Reservoir and of its areas of around will have to contribute for the maintenance of high values of IQA.

ASSUNTO(S)

reservoirs limnology limnologia guarulhos reservatórios water quality index guarulhos geociencias Índice de qualidade da água

ACESSO AO ARTIGO

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