Abstract
In recent years, the process of urbanization has been growing in Iguatu, important city of the semi-arid region of Brazil. This process has influenced the quality of aquatic environments due to effluent discharge and the emission of pollutants. Iguatu has modern and efficient sewage treatment system, but only 15% of the population benefits. This paper aimed at the determination of 9 metals and 12 physical-chemical parameters to characterize of Bastiana Lake-CE and to evaluate the influence of effluent discharge. The results of the analysis of toxic metals showed presence of Zinc (Zn) and manganese (Mn) at levels above of maximum limits established by Brazilian legislation. Exposure to Mn can affect the IQ (Intellectual quotient). Water samples showed high concentration of organic matter (BOD), nitrogen, phosphorus, soluble substances hexane and presence of floating materials. The level of nutrients (N and P) classified the lake as eutrophic and hypereutrophic and may cause risk to human health. Results suggest that actions must be taken by government agencies to prevent the complete degradation of Lake Bastiana (Ceará, Brazil).
Highlights
The northeastern semiarid region's main characteristic is the shortage or high spatial and temporal variability of rainfall
The results indicated that Lake Koumoundourou was contaminated with heavy metals in a moderate degree
Researchers conducted in Mexico and Brazil indicated that exposure to manganese can affect the IQ (Intellectual quotient) (Menezes-Filho et al, 2009; Riojas-Rodríguez et al, 2010)
Summary
The northeastern semiarid region's main characteristic is the shortage or high spatial and temporal variability of rainfall. These weather conditions make the regional society to seek better use of water resources for carrying out their economic activities related to agriculture and livestock. Urban development has produced a cycle of contamination caused by the discharged wastewaters and residues (Tucci 2008; Dsikowitzky & Schwarzbauer 2014). Contamination of aquifers is one of the major public health problems nowadays (Milhome et al, 2015; Mazoud et a.l, 2016). The collection of sewage is still not widespread service in most of Brazil and the treatment is scarce, causing serious consequences to the environment and public health. In Brazil, the sewer system covers about 55% of the municipalities, but only a portion of 29% own treatment system (IBGE, 2008)
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