Estudo geoquímico da bacia do ama e avaliação da qualidade de água

AUTOR(ES)

Luiz Henrique Amorim Moura

DATA DE PUBLICAÇÃO

2008

RESUMO

The quality of water in a drainage basin reflects the natural processes of a water catchment and the changes of environmental conditions reflect on physical and chemical water chemistry. The present work was realized in two drainages on Gama Catchment, Gama brook and Cedro stream, whose waters discharge into Paranoá Lake (Brasília, Federal District). The aim of the study was to identify the influences of catchment land use and human occupation, focusing on water quality disturbance, separating the impacts caused by human settling from natural processes. The geochemistry study used pH, temperature, conductivity, dissolved oxygen, alkalinity, turbidity, color, hardness, nitrate, nitrite, ammonia, suspended solids, dissolved solids, total solids, BOD, COD, discharge, Ca, Mg, Fe, Al, Si, P, Na, K, Mn and Cu data sets. This data analysis was aimed to study two aspects: descriptive, that associates water quality and disturbances with the land use and man-made occupation impact, and statistic, which propose a water quality assessment model through multivariate statistics techniques. The water quality results displays that the disturbance are associated with human settlement and riparian vegetation maintenance. Ca and Mg are related to civil building materials, Al and Si to the soil clay minerals and, nitrogenous compounds with organic material degradation at Cedro Stream and fertilizers used on a farm site in the Gama Brook medium course. Turbidity and color are linked with the riparian tree cover maintenance, ammonia and BOD to wastewater pollution. Principal components technique, allied with cluster analysis, separated parameters such those linked to rock geochemistry and water quality. The water quality assessment model, proposed by discriminant analysis, allows a quick interpretation using only nitrate, ammonia, suspended solids and Al. The used statistics techniques proposed a model based only in some parameters variability, discarding any theoretical importance of the others variables. Thus, it is important to emphasize that other basic parameters like pH, conductivity, dissolved oxygen, alkalinity, turbid, color, dissolved solids, nitrate, ammonia and chloride, Ca, Mg, Si, Fe, Na and K, must be included because they are important indicators of land use and occupation.

ASSUNTO(S)

geologia qualidade de água estatística multivariada região do gama geoquímica

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