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Investigaciones marinas

On-line version ISSN 0717-7178

Abstract

AHUMADA, Ramón; GONZALEZ, Elizabeth; MEDINA, Valentina  and  RUDOLPH, Anny. Analysis of mayor zinc sources in marine sediments of the estuarine zone in Ay sen Fjord, Chile. Investig. mar. [online]. 2007, vol.35, n.2, pp. 5-14. ISSN 0717-7178.  http://dx.doi.org/10.4067/S0717-71782007000200001.

The present study determined the main sources of Zn enrichment at the head of Aysén Fjord. The study considered the analysis of the river sediments that enter the fjord (fluvial record), the marine sediments at the head of the fjord (estuarine area record), and the sediments from stations along the fjord (horizontal concentration gradient). The Zn content was analyzed, as were Cd, Cu, and Pb as references. A different chemical attack was performed in order to estimate the total Zn and a sequential extraction techniques to estimate the "species" or fractions. The quantification was done using a polarographic analyzer (POL 150) coupled to a Trace Lab 50TM with square wave voltammetry and standard addition. Moreover, the sediment grain size, total organic matter, total organic carbon, and total phosphorus were analyzed. The results confirmed the highest zinc concentrations in the surface sediments at the head of the fjord. The profiles showed the highest concentrations of Zn at the surface. The fractional chemical attack indicated that residual Zn (60-80%) was the most abundant fraction. The Zn fractions associated with oxy-hydroxides and organo-metallics were similar (10-20%) and greater than the exchangeable fractions (5-10%). The residual Zn was associated with the lithogenic fraction and the rest corresponded to fluvial contributions main baseline components, whereas the remaining inflow corresponded to contributions associated with fluvial, advective, and anthropogenic components at the head of the fjord. The identification of the sources of Zn enrichment provides information relevant for implementing management policies to protect the area and indicates the changes due to anthropogenic sources

Keywords : estuaries; sediments; Zn; anodic redissolving voltammetry; Aysén Fjord.

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