Volcanic arsenic and boron pollution of Ilopango Lake, El Salvador

Volcanic arsenic and boron pollution of Ilopango Lake, El Salvador

More than 200,000 inhabitants live in the drainage basin of Ilopango lake, El Salvador, even though high concentrations of boron (B) and arsenic (As) make this water unsuitable for human consumption. The water and sediments of Ilopango lake have been sampled and analyzed for trace elements and major ions, including As, nutrients (NO-3, PO3−4), SO2−4 , Cl− and B. For the waters, B concentrations range from 1.5 to 8.7 mg/l and As concentrations from 0.15 to 0.77 mg/l with the higher values to the south and lower values close to Cerros Quemados islands (at the lake center), where the last volcanic activity happened in 1880. Arsenic concentrations in the sediments were elevated at Cerros Quemados (86 mg/kg sediment), which also has the lowest concentration of organic matter. Sulfate and Cl− concentrations and the pH of Ilopango lake indicate
that it is in a quiet phase when compared with other volcanic lakes of the world. However, fluxes of volcanic gases seem to occur to the south of the caldera, where seismic activity is higher, and anomalous concentrations of soil gases, especially radon, are evident. Concentrations of As, Cl−, B, PO3−4 , and SO2−4 in the water are also higher to the south, but the sediment concentrations of As, B, and Li are lower. Interaction of volcanic-hydrothermal fluids discharged to the south of the caldera,
with the lake sediments could be generating the high element concentrations observed in the water.

Files associated with this item cannot be displayed due to copyright restrictions.