Natural and anthropogenic sources of lead, zinc, and nickel in sediments of Lake Izabal, Guatemala.

Sediments in Lake Izabal, Guatemala, contain substantial lead (Pb), zinc (Zn), and nickel (Ni). The lack of historical data for heavy metal concentrations in the sediments makes it difficult to determine the sources or evaluate whether inputs of metals to the lake have changed through time. We measured the relative abundances and concentrations of Pb, Zn, and Ni by X-Ray Fluorescence core scanning and by Inductively Coupled Plasma Optical Emission Spectrometry in three sediment cores to explore stratigraphic distributions of metals in the lake deposits. High amounts of Pb and Zn in the core taken near the Polochic Delta suggest that galena and sphalerite mining increased Pb and Zn delivery to Lake Izabal between ~1945 and 1965 CE. An up-core Ni increase in the core taken near a different mine on the north shore of Lake Izabal suggests that recent nickel mining operations led to an increase in Ni concentrations in the local sediments, but amounts in the other cores indicate that Ni is not widely distributed throughout the lake. Sediment cores from Lake Izabal are reliable recorders of heavy metal input to the lake, and were measured to establish background metal levels, which would otherwise be unavailable. Concentrations of Pb, Zn, and Ni in older, pre-20th-century Lake Izabal sediments reflect input from natural erosion of bedrock. Our results provide previously unavailable estimates of background metal concentrations in Lake Izabal before the onset of mining. These results are necessary for future monitoring related to mining contamination of the lake ecosystem.

Determinación de arsénico y mercurio en agua superficial del lago de Atitlán / Determination of arsenic and mercury levels in superfitial water of Atitlán lake

El lago de Atitlán, considerado uno de los lagos más bellos del mundo, tiene una superficie de 125.7 km2, una profundidad máxima de aproximadamente 350 m, y se encuentra en el departamento de Sololá, en el occidente de Guatemala. Desde 2009 se han observado floraciones extensivas de cianobacterias en el lago, reflejando la contaminación del agua en la cuenca. Se determinaron los niveles dearsénico (As) y mercurio (Hg) en agua superficial del lago de Atitlán, por espectrofotometría de absorción atómica (EAA), en cuatro muestreos realizados en marzo, mayo, agosto y octubre de 2014 en 14 sitios. Diez sitios se encuentran localizados en el lago, habiendo sido definidos en estudios anteriores con base en su cercanía a poblaciones asentadas en la orillas del lago. Dos sitios corresponden a los principales ríos tributarios, y los restantes dos sitios a la entrada y salida de la planta de tratamiento Los Cebollales, ubicada en Panajachel. Los niveles de As encontrados en el lago de Atitlán, tributarios y en la planta de tratamiento, fueron superiores a 20 μg/L. Los resultados indican que la contaminación del lago de Atitlán por As se debe principalmente a la geología de la cuenca, al localizarse en una zona volcánica. Los niveles cuantificables de As, son superiores al nivel máximo permitido para agua potable en la Norma de Agua Potable (NGO 29001:99) de la Comisión Guatemalteca de Normas (COGUANOR), por lo que el agua del lago de Atitlán no se considera apta para el consumo humano.

Lake Atitlan is considered one of the most beautiful lakes in the world. It has 125.7 km2 and 350 m maximum depth. It is located at the western province Sololá in the Guatemalan highlands. Since 2009 several cyanobacterial blooms have occurred at the lake, as consequence of the environmental degradation caused by water contamination into the basin. In this study pollution levels by arsenic (As) and mercury (Hg) in Lake Atitlan, were investigated in collaboration with the Authority for the Sustainable Management of Lake Atitlan and its Surroundings (AMSCLAE). Four samplings were conducted in March, May, August and October 2014, collecting samples of water at 14 sampling sites, including the Wastewater Treatment Plant located at Panajachel. As and Hg in water samples of Lake Atitlan were analyzed by atomic absorption spectrophotometry. Presence of arsenic above 20 μg/L was found in the water of Lake Atitlan, rivers and the wastewater treatment plant. The results indicate that contamination of Lake Atitlan regarding metals, is due majorly to the Basin geology located in a volcanic region. The levels of As are higher than recommended levels for drinking water in different regulations.