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Email the author (Login required) Grain size, total organic matter, organic carbon, inorganic carbon and organic nitrogen in surface marine sediments from Puerto Montt to Boca del Guafo (Chilean North Patagonia)
DOI: https://doi.org/10.3856/vol38-issue1-fulltext-1
Abstract
The horizontal distribution of the organic matter, organic and inorganic carbon, organic nitrogen content, and surface sediment texture was determined between Puerto Montt and Boca del Guafo using samples collected during the cruises CIMAR 10 Fiordos (2004), CIMAR 11 Fiordos (2005) and CIMAR 12 Fiordos (2006). Two zones were identified: the northern zone (from Puerto Montt to the Desertores-ApiaoQuehui-Lemuy island group) had mostly high concentrations (TOM >5%; C-org >1.6%; C-inorg >0.4% and N-org > 0.2%) the southern zone (from the same island group to Boca del Guafo) had mostly low concentrations (TOM < 5.0%, C-org <1.6%, C-inorg <0.4% and N-org <0.2%). This segregation is attributed to the effect of oceanographic conditions (estuarine versus oceanic; nutrient contribution, currents, tides, primary and secondary planktonic production), and contributions of terrigenous material from the adjacent area. The terrigenous sediment from the edges of four continental rivers (Petrohué, Cochamó, Puelo, Reñihue, Yelcho) presented mostly high concentrations of TOM > 7.5%, C-org > 2.4%, C-inorg > 0.4% and N-org > 0.2%. The texture of the marine sediments was mostly sand and silt + clay; gravel was scarce and less than 4% in some samples. The terrigenous sediment from the river edges was mostly sandy. The sediment origins (marine versus terrigenous), as a first approach, were inferred from the values of the C:N ratio. The sediments were mostly marine in origin, except in the continental fjords, where the terrigenous component was important.
