Resumen del producto

The objective of this study was to determine the influence of shallow hydrothermal vents in Mapachitos, Bahía Concepción, on the composition of surficial sediments of surrounding area of this bay. The following elements Al, As, Ba, Ca, Cd, Co, Cs, Cu, Fe, Hg, Li, Mn, Mo, Ni, Rb, S, Ti, U, V, Zn, C_org , and C_inorg were determined in sediment samples. The calculated CaCO₃ values in the sediments within some spots of the study area were as high as 90% (with an average of 61 %). The concentration of organic carbon in the sediments was approximately 1%. The total element contents in the sediments were compared with earth’s crustal average and enrichment factors (EF’s) were calculated using Al as normalizing element. The results showed that the majority of elements (Ba, Co, Cs, Cu, Fe, Li, Mn, Ni, Rb, Ti, U, V, and Zn) are conservative, with average EFs close to unity. The lithium, Mo, and U were enriched in the sediments with average values of EF between two and 10. The highest average EFs determined in the study were for the following elements: As, Ca, Cd, and Hg. The average concentrations of potentially toxic elements in the sediments from the Mapachitos vents were 60 mg kg^-1 for As, and 21849 µg kg^-1 for Hg. The surface sediments of the adjacent area, however, have low average concentrations for As and Hg: 3.7 mg kg^-1 and 52 µg kg^-1, respectively. Other elements such as Cd (0.9 mg kg^-1) and Ca (28.3%) are highly enriched in the sediments of the study area, comparing to their average crustal abundances. The results of principal component analysis allowed to determine three factors which explain 91% of data variance, as well as to differentiate four associations including terrigenous elements, calcareous components, elements of the hydrothermal origin and redox-sensitive elements in the surface sediments in front of the Mapachitos in the north-western portion of Bahía Concepción. Furthermore, the results confirmed the influence of the hydrothermal inputs of some trace elements on the sediments of the area surrounding the vents. In particular, As and Hg, and to a lesser extent Al, Fe, and Mn at the venting site.

Palabras clave: Bahía Magdalena; Bahía Concepción; Trace elements; marine sediments; Shallow hydrothermal vents; Flaccisagitta enflata

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