Determination of heavy metal contamination in surface and deep water samples from Lake Ilopango, El Salvador

Abstract

This article describes the results of evaluating the concentrations of heavy metals such as Lead, Arsenic and Chromium, in water samples extracted from different points of Ilopango lake, on the surface and at a depth of 20 m, and comparing them with reference standards for water, in order to determine the degree of contamination present in the collected samples. It is an initial monitoring that will establish the possibility of making its water adequate for human consumption and other uses. The results were obtained through the application of the Total Reflection X-ray Fluorescence (TXRF) technique, which allows to quantify elemental concentrations with a sensitivity of less than one part per million in optimal cases, and a maximum error of 10 % in determining concentrations. In addition, the gradient of the concentrations of heavy metals as Cr, As and Pb present in the lake, was geographically determined, applying QGIS and the first neighbor’s method. The initial results indicate a strong contamination by Arsenic and Lead, up to 27 and 38 times higher, respectively, than the limit established in the guide value of the code, in addition to some physical-chemical parameters outside of acceptable limits, so that the purification of lake water with conventional methods is not recommended.