ABSTRACT
The objective of present study was to evaluate variation of ionic composition of water from cristalline region of the northeast Brazil, utilising data bank of 557 results of chemical analysis, with electrical conductivity up to 5,000 µS cm-1, belonging to different rural farms, in the states of Paraiba, Rio Grande do Norte and Ceara. The chemical composition of water in terms of percentage, lithology of place of origin and water salinity level was evaluated. The study was made with graphs and regression analysis between salinity and contents of Cl-, Na+, Ca2+ + Mg2+ and SAR. The results show that in general, the water from cristalline Brazilian northeast has lot of sodium chloride and it varies with the lithology place and for prediction purposes regression equations based on local data perform ed better than global equation except for Ca2+ + Mg2+ for nucleus of Pau dos Ferros-RN.
Index terms:
water quality; salinity; irrigation; chemical composition