Organic carbon fluxes to the ocean from high-standing islands

Lyons, W. Berry; Nezat, Carmen A.; Carey, Anne E.; Hicks, D. Murray

doi:10.1130/0091-7613(2002)030<0443:ocftto>2.0.co;2

Cited by 182 publications

(137 citation statements)

References 25 publications

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“…Relative to tropical mountainous headwater rivers with large carbon fluxes to the ocean 6,8-11 , the headwater rivers described here respond differently to carbon delivery from upland sources and can store substantial quantities of carbon. Global compilations indicate that temperate forest watersheds typically have lower organic carbon export than other environments, including boreal forest, wetlands and tropical forests 8,21 . Work in Glacier Creek, CO indicates that subalpine forests in our study region have low production relative to other temperate coniferous forests 37 , as well as low rates of riverine carbon export 22 .…”

Section: Discussionmentioning

confidence: 99%

“…Although individual headwater floodplains are much narrower and shallower than the extensive floodplains that characterize downstream portions of large river networks, the cumulative length of the many small tributaries in a river network implies that organic carbon storage along these smaller rivers can be important. Further study of mechanisms and patterns of carbon storage in diverse geographic settings is needed to determine regional differences and the relative abundance of headwater rivers characterized by large downstream carbon fluxes 6,[8][9][10][11] versus headwater rivers characterized by the storage mechanisms described here. However, widespread reduction of geomorphic complexity along headwater channels likely has long-term and cumulative global effects on the carbon cycle.…”

Section: Discussionmentioning

confidence: 99%

“…Mountainous rivers contribute disproportionately to delivery of sediment and organic carbon to the oceans [6][7][8] . Research in the mountainous tropics demonstrates that headwater rivers respond to disturbances, such as cyclones, landslides and large floods, by rapidly exporting terrestrial carbon downstream 6,[9][10][11] .…”

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Mechanisms of carbon storage in mountainous headwater rivers

et al. 2012

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Published research emphasizes rapid downstream export of terrestrial carbon from mountainous headwater rivers, but little work focuses on mechanisms that create carbon storage along these rivers, or on the volume of carbon storage. Here we estimate organic carbon stored in diverse valley types of headwater rivers in Rocky Mountain National Park, CO, USA. We show that low-gradient, broad valley bottoms with old-growth forest or active beaver colonies store the great majority of above-and below-ground carbon. These laterally unconfined valley segments constitute o25% of total river length, but store B75% of the carbon. Floodplain sediment and coarse wood dominate carbon storage. Our estimates of riverine carbon storage represent a previously undocumented but important carbon sink. Our results indicate that: not all mountainous rivers rapidly export carbon; not all valley segments are equally important in carbon storage; and historical changes in riverine complexity have likely reduced carbon storage.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Mechanisms of carbon storage in mountainous headwater rivers

et al. 2012

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“…Small, mountainous river systems (SMRS) deliver over half of the global sediment supply to the world's oceans (Milliman and Syvitski 1992) and may account for a similar fraction of the global particulate organic matter (POM) flux (Lyons et al 2002;Gomez et al 2003;Coynel et al 2005). The importance of SMRS has motivated an increasing number of studies focused on determining the characteristics of these systems, which contrast markedly from the fifty or so largest rivers of the world.…”

Section: Introductionmentioning

confidence: 99%

Chemical characteristics of particulate organic matter from a small, mountainous river system in the Oregon Coast Range, USA

2010

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To better understand the transfer of particulate organic matter (POM) by small mountainous river systems (SMRS) to the ocean, we measured the concentration and composition of suspended particles from the Alsea River, a SMRS in the Oregon Coast Range, over a wide range of discharges that included several floods. All particulate constituents measured, including organic carbon, nitrogen and biomarkers such as lignin-derived phenols, cutin acids and amino acid-derived products, displayed concentrations that increased as a power function of discharge. In contrast to other SMRS, virtually all POM in the Alsea River samples was modern and had an average age \60 year. In spite of their similar 14 C ages, marked contrasts in elemental and biomarker compositions were evident in particles collected at low and high discharges. Particles at low flows were primarily composed of organic detritus from non-vegetation sources (e.g., algal cells) whereas mineral-rich particles containing vegetation and soil-derived POM were predominant at elevated flows. Biomarker compositions of these latter particles suggest most of the POM originated from areas if the watershed with measurable hardwood contributions, which include areas affected by shallow landslides and riparian zones. We infer that the low uplift rates, lush vegetation, high net primary production and relatively thick soils that characterize the Alsea watershed are responsible for these trends. Comparison of our results with those from other systems, including the well-studied Santa Clara River (southern California), demonstrates that SMRS are part of a continuum whereby contrasts in hydroclimate, geology and vegetation lead to significant differences in the age and composition of POM exported to the ocean.

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“…[2] Small mountainous rivers draining tectonically active margins have recently received attention as previously overlooked systems that export significant quantities of sediment and particulate organic carbon (POC) to the oceans [Milliman and Syvitski, 1992;Milliman et al, 1999;Lyons et al, 2002]. Contrary to the conventional view that rivers exclusively discharge modern POC [Hedges et al, 1986], it has been recognized that small mountainous rivers discharge fossil POC derived from rapid erosion of bedrock [Kao and Liu, 1996;Masiello and Druffel, 2001;Blair et al, 2003;Komada et al, 2004].…”

Section: Introductionmentioning

confidence: 99%

Sedimentary rocks as sources of ancient organic carbon to the ocean: An investigation through Δ¹⁴C and δ¹³C signatures of organic compound classes

Komada

Druffel

Hwang

2005

Global Biogeochemical Cycles

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Chemical and isotopic variability of particulate organic carbon (POC) was examined in samples from the Santa Clara River watershed and adjacent shelf to investigate the processing of fossil POC derived from bedrock. The Santa Clara is a small coastal river that drains mountainous terrain in southern California, United States. Organic carbon in shale, river suspended sediment, and coastal marine sediment was separated into three operationally defined organic compound classes: total extractable lipids, acid hydrolyzable material, and the nonhydrolyzable residue. In all samples, the nonhydrolyzable fraction was dominant (∼50% of POC), while lipids and acid hydrolyzable moieties were relatively minor (≤22 and ≤13%, respectively). The Δ14C and δ13C signatures of the isolated fractions varied dramatically, not only across different sample types, but also for a given sample. At the shale exposure, low Δ14C values (<−760‰) indicated dominance of ancient C in all three organic compound classes. In downstream samples, the extractable lipids displayed the lowest Δ14C values (<−500‰), while the acid hydrolyzable fraction was predominantly modern (Δ14C > −30‰). The nonhydrolyzable fraction displayed intermediate Δ14C values (<−190‰) that increased steadily downstream with decreasing δ13C values (−22.2 to −25.0‰), possibly from mixing of shale and surface soil POC. Our results indicate that most of the fossil POC discharged by the Santa Clara is composed of non‐acid hydrolyzable material, but its elusive molecular structure and marine‐like δ13C signature may render its detection in the ocean difficult. In contrast, fossil lipids may be more amenable to detection if their resistant components (e.g., asphaltic material) are unique to crustal sources.

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Organic carbon fluxes to the ocean from high-standing islands

Cited by 182 publications

References 25 publications

Mechanisms of carbon storage in mountainous headwater rivers

Mechanisms of carbon storage in mountainous headwater rivers

Chemical characteristics of particulate organic matter from a small, mountainous river system in the Oregon Coast Range, USA

Sedimentary rocks as sources of ancient organic carbon to the ocean: An investigation through Δ¹⁴C and δ¹³C signatures of organic compound classes

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Organic carbon fluxes to the ocean from high-standing islands

Cited by 182 publications

References 25 publications

Mechanisms of carbon storage in mountainous headwater rivers

Mechanisms of carbon storage in mountainous headwater rivers

Chemical characteristics of particulate organic matter from a small, mountainous river system in the Oregon Coast Range, USA

Sedimentary rocks as sources of ancient organic carbon to the ocean: An investigation through Δ14C and δ13C signatures of organic compound classes

Contact Info

Product

Resources

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Sedimentary rocks as sources of ancient organic carbon to the ocean: An investigation through Δ¹⁴C and δ¹³C signatures of organic compound classes