Publication Date:
2022-05-26
Description:
Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Continental Shelf Research 31 (2011): 315-329, doi:10.1016/j.csr.2010.05.013.
Description:
We investigated the provenance of organic matter in the inner fjord area of northern
Patagonia, Chile (~44–47° S), by studying the elemental (organic carbon, total nitrogen),
isotopic (δ13C, δ15N), and biomarker (n–alkanoic acids from vascular plant waxes)
composition of surface sediments as well as local marine and terrestrial organic matter.
Average end–member values of N/C, δ13C, and δ15N from organic matter were 0.127 ±
0.010, –19.8 ± 0.3‰, and 9.9 ± 0.5‰ for autochthonous (marine) sources and 0.040 ±
0.018, –29.3 ± 2.1‰, 0.2 ± 3.0‰ for allochthonous (terrestrial) sources. Using a mixing
equation based on these two end–members, we calculated the relative contribution of
marine and terrestrial organic carbon from the open ocean to the heads of fjords close to
river outlets. The input of marine–derived organic carbon varied widely and accounted for
13 to 96% (average 61%) of the organic carbon pool of surface sediments. Integrated
regional calculations for the inner fjord system of northern Patagonia, which encompasses
an area of ~ 4,280 km2, suggest that carbon accumulation may account for between 2.3 and
7.8 x 104 ton C yr–1. This represents a storage capacity of marine–derived carbon between
1.8 and 6.2 x 104 tons yr–1, which corresponds to an assimilation rate of CO2 by marine
photosynthesis between 0.06 and 0.23 x 106 tons yr–1. This rate suggests that the entire fjord
system of Patagonia, which covers an area of ~ 240,000 km2, may represent a potentially
important region for the global burial of marine organic matter and the sequestration of
atmospheric CO2.
Description:
J. Sepúlveda was funded by a
M.S. scholarship from the Graduate School at UDEC and by Fundación Andes through the
Woods Hole Oceanographic Institution (WHOI)/UDEC agreement during a research visit at
WHOI. This research was funded by the Ministerio de Hacienda de Chile and the Comité
Oceanográfico Nacional (CONA) through the CIMAR–7 FIORDO Program (Grant C7F
01–10 to SP), CONICYT/NSF Grant 2001–120, Fundación Andes–Chile, and the Center
for Oceanographic Research in the eastern South Pacific (COPAS) and COPAS Sur–
Austral (PFB–31/2007).
Keywords:
Organic matter sources
;
Carbon cycling
;
CO2
;
Fjords
;
Northern Patagonia
;
Chile
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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