Sources and distribution of organic matter in northern Patagonia fjords, Chile (44–47°S): A multi-tracer approach for carbon cycling assessment

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• 作者：Julio Sep&#xfa ; lveda^a ; ^{juliosep@mit.edu} ; Silvio Pantoja^b ; Konrad A. Hughen^c
• 关键词：Organic matter sources ; Carbon cycling ; CO₂ ; Fjords ; Northern Patagonia ; Chile
• 刊名：Continental Shelf Research
• 出版年：2011
• 出版时间：1 March 2011
• 年：2011
• 卷：31
• 期：3-4
• 页码：315-329
• 全文大小：956 K

文摘

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‰, and 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 13–96 % (average 61 % ) of the organic carbon pool of surface sediments. Integrated regional calculations for the inner fjord system of northern Patagonia covered in this study, which encompasses an area of 4280 km², suggest that carbon accumulation may account for between 2.3 and 7.8×10⁴ ton C yr⁻¹. This represents a storage capacity of marine-derived carbon between 1.8 and 6.2×10⁴ ton yr⁻¹, which corresponds to an assimilation rate of CO₂ by marine photosynthesis between 0.06 and 0.23×10⁶ ton 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.