Hidroquímica do aquífero costeiro do município de Itarema - Ceará

Abstract

The study area covers the coastal area of the county of Itarema, 230 km from Fortaleza, West coast of the State of Ceará. In this area, rare are the works aimed at the study of both surface water and groundwater. Although the exploitation of groundwater tends to increase in the area, due to the increase in population density, bringing with it potential risks of water contamination. Therefore it is important to assess the quality of the water and recharge mechanisms for the preservation and rational use of these resources. We collected samples of surface water and groundwater and carried out measurements of physical, chemical and bacteriological variables for all nine (9) sampling campaigns, using titrimetry, spectrophotometric, potenciometric and atomic absorption spectrometry methods. Groundwater is predominantly fresh water. And surface waters, according to the IQA-CETESB classification are good for public supply. Nitrate contamination in groundwaters, even at low concentrations, shows anthropic actions, not featuring seasonal effect. The study of trace elements sometimes presented some elements with higher levels than the VMP estipulated expected in the current legislation. However, these are not related to possible contamination by agrochemicals, according to the results of the analyses for quantification and qualification of organophosphates. Such results can be associated with the construction of the wells, their depth, waste deposition of various materials and even rock formations in the area. With respect to the study of isotopes, prevail lighter waters during the rainy periods than those collected during periods of drought, which characterizes the amount effect in rainfall. Through the water balance was estimated that, on average, about 31% of the total annual precipitation recharge the aquifers. Finally, the study of vulnerability to contamination of the aquifer, through the DRASTIC method, showed that in 79% of the area prevail moderate and high vulnerability. This requires great care with the use and occupation of the soil, in order to prevent damage to groundwater resources.