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 (60 ^oC, 24 h) sediments with a mixture of concentrated strong acids (HF+HCNO₃+HClO₄) the concentrations for over 50 elements were measured with inductively coupled plasma mass spectrometry. The enrichment factors and the Müller’s geoacumulation index of the analyzed elements were calculated using obtained data to distinguish naturally or anthropogenically enriched PTEs. A principal component analysis was also used to determine the possible associations between elements. The results obtained allow us to establish that there are natural inputs of elements such as Se, Ag, As, Cd and Sb into the sediments, which reflect mainly the lithology of the geological formations surrounding the lagoon. Greatest enrichments of As and Cd were found in the area adjacent to the Mogote peninsula which may reflect litoral transport of phosphatic materials rich in some trace elements, supplied to the sea by arroyos that cut through the Lomas de la Virgen geologic formation. The Pb probably has anthropogenic origin, because its higher concentrations up to 36.8 mg kg^-1 were recorded near the La Paz city. To reconstruct the history of contamination by PTE’s of the lagoon a 46-cm long sediment core was collected and dated in the deep basin aiming to establish also the sedimentation rate in this embayment and then to measure the concentration of trace elements in this core.

Palabras clave: Trace elements; Paralarval assemblages; La Paz Lagoon; sediments

Para obtener una copia del documento contacta la personal de la biblioteca a través del correo bibliocicimar{a}ipn.mx