Resumen del producto

The study of the biogeochemical cycles of the elements is important because they regulate the functioning of marine coastal ecosystems. To determine the factors that control the distribution of potentially toxic elements (PTE) in surface sediments of the La Paz Lagoon and their possible sources, 91 sediment samples were collected by free diving. After a total digestion of oven-dried sediments with a mixture of concentrated strong acids the total concentrations for over 50 elements were measured with inductively coupled plasma mass spectrometry (ICP-MS). The enrichment factors (EF) and the Müller’s geoacumulation index (Igeo) of the analyzed elements were calculated using obtained data. A principal component analysis (PCA) was also used to determine the possible associations between elements. The results obtained allow us to establish that there are natural enrichments of elements such as Se, As, Cd and Sb, which reflect mainly the lithology of the geological formations surrounding the lagoon. It is important to mention that the greatest enrichment of As and Cd were found in the area adjacent to the Mogote peninsula which may reflect littoral transport of phosphatic materials rich in trace elements (Piper, 1991), supplied to the sea by arroyos that cut through the Lomas de la Virgen geologic formation. The Pb probably has as its source the anthropogenic activity, because its higher concentrations up to 36.8 mg kg-1 were recorded near the La Paz city.

Palabras clave: Laguna de la Paz; Elementos traza; distribución vertical; sedimentos

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