Water Quality of Underground Wells in Limoeiro do Norte, Brazilian Northeast

The objective of this work was to assess the physicochemical and microbiological characteristics, as well as the potential of salinization and sodification of groundwater wells in Limoeiro do Norte, Ceará states, Brazil. Six water wells were selected for the study, all of them used for irrigation and human consumption. The ionic classification was performed by Piper Diagram and the salinity risk using the U.S.S.L. (United States Salinity Laboratory) Diagram using Qualigraf software. Based on the average chemical element concentration (mmolc L-1) in the groundwater, the following quantification is obtained- Na+ > Ca2+ > Mg2+ > K+ for cations. For anions there was a change in the the wells, for the 1, 3 and 4 Cl- > HCO3- > SO42- > CO32- and wells 2, 5 and 6 HCO3- > Cl- > SO42- > CO32-. The wells 1, 2 and 3 have severe restrictions for use by SAR (sodium absorption ratio) and Na+ content. Water from wells 1, 3 and 5 were classified as sodium chloride, 2 and 6 were classified as sodium bicarbonate and well 4 as calcium magnesium sulfate. With the exception of well 6 classified as freshwater, all other wells were classified as brackish water. Groundwater samples fall in C3S1 or C3S2 category with high salinity and low or medium sodium hazard. With the exception of Na+, whose value was above the limit allowed, no well with groundwater was detected chemical hazard for human consumption. There was the detection of Total coliforms, but in well 5 the presence of Thermotolerant coliforms was detected.