Chemical assessment of water prospects for direct applications in Nicaragua

Abstract

The chemical water quality of 30 samples from Nicaragua and 8 samples from Iceland were used to evaluate the potential for different direct-use applications. All the samples were classified according to the ternary Cl-SO4-HCO3 plot for chloride, sulphate, and bicarbonate water types. These samples showed a very variable chemical composition, influenced by water-rock interaction and geothermal alteration. Different water quality guidelines were used for the assessment of the prospect water according to different cascading applications. The water quality of the data sets were compared with the WHO (2008) drinking water standards; with many samples exceeding the optimum levels for parameters such as Na, Cl, SO4, and TDS, and some samples breaching the drinking water guideline in trace elements such as arsenic. The European Union mineral water classification was used for balneological purposes, as well as a classification basis on pH and temperature; all the samples were compared with ten times the drinking water standards (applicable for recreational waters) and only a few samples were above these limits. For aquacultural purposes, the samples were evaluated according to physicochemical parameters such as temperature, pH, alkalinity and hardness, and to the inorganic toxicant constituents. Many samples exceeded the generally recommended values for fish culture in H2S, Zn, Fe, Mn, and Al; and some exhibited higher Cr and As levels than the recommended limits. The water sample data were also classified on the basis of salinity and boron toxicity, and evaluated with respect to the minor and trace elements. The main problem in the samples was the high boron concentrations which limited the water’s usefulness as irrigation water. Finally, the samples were chemically assessed for industrial uses, for example the pulp and paper industry; according to US EPA (2004) water quality guidelines, with many samples not being suitable for this purpose.