Sediment Organic Matter

Meyers, Philip A; Teranes, Jane L.

doi:10.1007/0-306-47670-3_9

Cited by 378 publications

(437 citation statements)

References 93 publications

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“…They are significantly lower than those reported from a number of other studies in lowland South America (e.g. Sifeddine et al, 2003;Cordeiro et al, 2011) Where algae use dissolved CO 2 in equilibrium with the atmosphere, their δ 13 C organic values are approximately the same as those of C3 land plants (Meyers and Teranes, 2001), however high productivity may lead algae to use dissolved bicarbonate from the water column, resulting in higher δ 13 C organic values. Jacob et al (2004) report algal values of around -20‰ from a site in northern Brazil.…”

Section: Results and Interpretation: Stratigraphy Diatoms And Sedimementioning

confidence: 58%

“…Used together, the combination of C/N and δ 13 C organic ( Fig. 2) can provide a powerful tool to identify sources of organic matter (Meyers and Teranes, 2001). However, the C/N values here are all within the range for algal or mixed algal/terrestrial plant sources, with no values (> 20) clearly indicative of higher land plant inputs only.…”

Section: Results and Interpretation: Stratigraphy Diatoms And Sedimementioning

confidence: 99%

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Hydrology and climatology at Laguna La Gaiba, lowland Bolivia: complex responses to climatic forcings over the last 25 000 years

Metcalfe

Whitney

Fitzpatrick

et al. 2014

J Quaternary Science

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Diatom, geochemical and isotopic data provide a record of environmental change in Laguna La Gaiba, lowland Bolivia, over the last ca. 25,000 years. High-resolution diatom analysis around the last glacial -interglacial transition provides new insights into this period of change. The full and late glacial lake was generally quite shallow, but with evidence of periodic flooding. At about 13,100 cal a BP, just prior to the start of the Younger Dryas chronozone, the diatoms indicate shallower water conditions, but there is a marked change at about 12,200 cal a BP indicating the onset of a period of high variability, with rising water levels punctuated by periodic drying. From ca. 11,800 to 10,000 cal a BP stable, deeper water conditions persisted. There is clear evidence for drying in the early to mid Holocene, but not as pronounced as that reported from elsewhere in the southern hemisphere tropics of South America. This was followed by the onset of wetter conditions in the late Holocene consistent with insolation forcing. Conditions very similar to present were 2 established about 2,100 cal a BP. A complex response to both insolation forcing and millennial scale events originating in the North Atlantic is noted.

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Section: Results and Interpretation: Stratigraphy Diatoms And Sedimementioning

confidence: 58%

Section: Results and Interpretation: Stratigraphy Diatoms And Sedimementioning

confidence: 99%

Hydrology and climatology at Laguna La Gaiba, lowland Bolivia: complex responses to climatic forcings over the last 25 000 years

Metcalfe

Whitney

Fitzpatrick

et al. 2014

J Quaternary Science

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“…2E). Sediment ␦ 13 C is positively correlated with lake productivity, because algal photosynthetic demand for C is the dominant fractionation pathway (27), and it has been declining for the past several decades (Fig. 2C).…”

Section: Resultsmentioning

confidence: 99%

Changes in nitrogen cycling during the past century in a northern hardwood forest

McLauchlan

Craine

Oswald

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

113

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Nitrogen (N) availability, defined here as the supply of N to terrestrial plants and soil microorganisms relative to their N demands, limits the productivity of many temperate zone forests and in part determines ecosystem carbon (C) content. Despite multidecadal monitoring of N in streams, the long-term record of N availability in forests of the northeastern United States is largely unknown. Therefore, although these forests have been receiving anthropogenic N deposition for the past few decades, it is still uncertain whether terrestrial N availability has changed during this time and, subsequently, whether forest ecosystems have responded to increased N deposition. Here, we used stable N isotopes in tree rings and lake sediments to demonstrate that N availability in a northeastern forest has declined over the past 75 years, likely because of ecosystem recovery from Euro-American land use. Forest N availability has only recently returned to levels forecast from presettlement trajectories, rendering the trajectory of future forest N cycling uncertain. Our results suggest that chronic disturbances caused by humans, especially logging and agriculture, are major drivers of terrestrial N cycling in forest ecosystems today, even a century after cessation.15 N ͉ land-use history ͉ Mirror Lake ͉ nitrogen availability ͉ paleoecology

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“…Periods of increased flood frequency (~1930-1932, ~1937-1947, ~1961-1962, ~1968-1974, ~1976-1981, and ~1992-1998, shown as grey bars on Figure 5) generally have low water, organic carbon and nitrogen contents, while δ 15 N and C/N values are high. River floodwaters are associated with high C/N ratios, which may reflect organic matter derived from terrestrial sources (Meyers and Teranes, 2001). However, high C/N ratios may also be due to the influx of C-rich, N-poor hydrocarbons (i.e., bitumen) derived from upstream oil sand deposits, as has been suggested for similar geochemical signatures in the stratigraphic records of oxbow lakes in the PAD (Wolfe et al, 2006;Jarvis, 2008).…”

Section: Physical and Geochemical Proxiesmentioning

confidence: 99%

“…However, high C/N ratios may also be due to the influx of C-rich, N-poor hydrocarbons (i.e., bitumen) derived from upstream oil sand deposits, as has been suggested for similar geochemical signatures in the stratigraphic records of oxbow lakes in the PAD (Wolfe et al, 2006;Jarvis, 2008). During non-flood intervals, increases in autochthonous production generate sediment that is more organic-rich with higher water content, and possesses lower δ 15 N values and C/N ratios, the latter typical of aquatic organic matter (Meyers and Teranes, 2001). The lack of clear oscillations in δ 13 C org values that can be correlated to the other physical and geochemical proxies suggests this parameter is less sensitive to fluctuating hydrological conditions at SD2.…”

Section: Physical and Geochemical Proxiesmentioning

confidence: 99%

Flood Frequency Variability During the Past 80 Years in the Slave River Delta, NWT, as Determined from Multi-Proxy Paleolimnological Analysis

Brock¹,

Martin²,

Mongeon³

et al. 2010

Canadian Water Resources Journal

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A paleolimnological approach was employed to reconstruct variations in the frequency of spring break-up flooding in the Slave River Delta during the past ~80 years based on multi-proxy analyses (geochemistry, diatoms, plant macrofossils) of a sediment core from a shallow, flood-prone lake in the active delta. Results reveal oscillating decadal-scale intervals of high and low flood frequency. The post-1960 reconstruction of Slave River flood frequency parallels variations in measured Slave River discharge and corresponds to the flood history derived from observations of land users. Notably, the interval of lowest water levels inferred from a peak sedimentary abundance of Sagittaria cuneata seeds pre-dates upstream regulation of the Peace River in 1968. Multi-proxy records reveal that the onset of river regulation coincided with a period of increased flood frequency beginning in the early 1960s and ending in the early 1980s. It is therefore unlikely that river regulation is the primary factor causing declines in the frequency of spring break-up floods at the study site. Furthermore, the flood record developed in the Slave River Delta parallels similar changes in flood frequency from an oxbow lake in the northern Peace sector of the upstream Peace-Athabasca Delta. This suggests that climate-driven change in the runoff regime of the upper Mackenzie River Basin is likely the principle driver of variability in flood frequency in both deltas. Continued reductions in snowpacks and headwater runoff are therefore likely to reduce the frequency of flooding in the Slave River Delta.Résumé : Une approche paléolimnologique a été employée pour reconstituer les variations dans la fréquence des inondations attribuables aux débâcles du printemps dans le delta de la rivière Slave au cours des 80 dernières années, plus ou moins, en fonction d'analyses « multi-proxy » de diverses données indirectes (géochimie, diatomées, macrofossiles de plantes) d'une carotte de sédiments provenant d'un lac peu profond et sujet aux inondations dans le delta actif. Les résultats révèlent des intervalles à l'échelle décadaire oscillant entre une fréquence de crue élevée et faible. La reconstitution postérieure à 1960 de la fréquence de crue de la rivière Slave permet d'établir un parallèle avec les variations dans le débit mesuré 282 Canadian Water Resources Journal/Revue canadienne des ressources hydriques

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Sediment Organic Matter

Cited by 378 publications

References 93 publications

Hydrology and climatology at Laguna La Gaiba, lowland Bolivia: complex responses to climatic forcings over the last 25 000 years

Hydrology and climatology at Laguna La Gaiba, lowland Bolivia: complex responses to climatic forcings over the last 25 000 years

Changes in nitrogen cycling during the past century in a northern hardwood forest

Flood Frequency Variability During the Past 80 Years in the Slave River Delta, NWT, as Determined from Multi-Proxy Paleolimnological Analysis

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