Influência da salinização em parâmetros de qualidade das águas subterrâneas na região costeira do Baixo Jaguaribe

Abstract

Clean fresh water is increasingly rare in the coastal zone due to how it is being used, reducing its characteristic as renewable resource because of contamination by urbanization, industrialization and agricultural production of recharge areas and reserves. This imbalance becomes increasingly necessary to the sustainable use of groundwater. Groundwaters are also a vulnerable resource due to over-exploitation and contamination. In the coastal region the exploitation coupled with increasing sea level due to climatic changes, intensifies the problem of availability of quality drinking water because of the salinization process. In this context, the evaluation of the water quality of wells from the lower Jaguaribe region (CE) was performed. The region has an increasing population density the river has more than 80% of its flow retained by dams facilitating salt intrusion. Samplings were carried out during the rainy and dry and certain isotopes δ18O and δ2H to identify the source of groundwater, as well as major ions. The levels observed in mg.L-1 were 73.62 to 296.68 for Cl-, 19.29 to 108.99 for Ca2+, 4.64 to 28.52 for Mg2+, 69.25 to 124.75 for Na+, 13.25 to 62.25 for K+, 12.5 to 156.08 for HCO3- and 0.02 to 12 for SO42-. Based on these values, waters were classified as sodium chloride according to the Piper diagram. Isotopic values and relations of δ2H versus δ18O of groundwater showed lines similar to the Straight World Meteoric identifying aquifer recharge through rain. The application of statistical methods shows that the mobility of trace metals (especially chromium) is affected by changes in the salinity of the water making it potentially the most toxic for human consumption. The results suggest that a continuous monitoring of groundwater in the lower Jaguaribe basin is necessary.