Compositions and fluxes of particulate organic material in the Amazon River1

Hedges, John I.; Clark, Wayne A.; Quay, Paul D.; Richey, Jeffrey E.; Devol, Allan H.; Santos, Manoel Luíz dos

doi:10.4319/lo.1986.31.4.0717

Cited by 774 publications

(585 citation statements)

References 56 publications

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“…C/N is an indicator of the type of OM input since N is found mainly in proteins (Müller and Mathesius, 1999 Ertel and Hedges, 1985;Hedges et al, 1986;Meyers, 1994), which are protein-poor (1-10%) and cellulose-rich. Generally, the content of TN is low in Sphagnum spp.…”

Section: Cjnmentioning

confidence: 99%

Biomarkers and inorganic proxies in the paleoenvironmental reconstruction of mires: The importance of landscape in Las Conchas (Asturias, Northern Spain)

Ortíz

Borrego

Gallego

et al. 2016

Organic Geochemistry

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A B S T R A C TWe determined the lipid distributions (n-alkanes, n-alkan-2-ones, n-alkanoic acids), total organic carbon (TOC), total nitrogen (TN), CajMg and ash content in Las Conchas mire, a 3.2 m deep bryophytedominated mire in Northern Spain covering 8000 cal yr BP. Bog conditions developed in the bottom 20 cm of the profile, and good preservation of organic matter (OM) was inferred from n-alkanoic acid distribution, with the exception of the uppermost 20 cm (last ca. 200 yr). Microbial synthesis of long chain saturated fatty acids from primary OM likely produced a dominance of short chain n-alkanoic acids with a bimodal distribution, as well as the lack of correspondence between the n-alkane and n-alkanoic acid profiles in the upper 20 cm. This was accompanied by an increase in ash content, a decrease in TOC and variation in n-alkane ratio s, thereby suggesting significant changes in the mire, namely drainage and transformation to a meadow, in the last ca. 200 yr. The distribution of n-alkan-2-ones indicated an increase in bacterial source from the bottom of the record to 94 cm, whereas their distribution in the upper part could be attributed mainly to plant input andjor the microbial oxidation of n-alkanes. The different n-alkane proxies showed variations, which we interpreted in terms of changes in vegetation (Sphagnum vs. non-Sphagnum dominated phases) during the last 8000 cal yr BP. C 23 was the most abundant homolog throughout most ofthe record, thereby suggesting dominant humid conditions alternating with short drier phases. However, such humid conditions were not linked to paleoclimatic variation but rather to geomorphological characteristics: Las Conchas mire, at the base of the Cuera Range, receives continuous runoff-even during drier periods-which is not necessarily accompanied by additional mineral input to peat, producing the development of Sphagnum moss typical of waterlogged ecotopes and damp habitats. Thus, although geochemical proxies indicated an ombrotrophic regime in the mire, geomorphological characteristics may make a considerable contribution to environmental conditions.

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Section: Cjnmentioning

confidence: 99%

Biomarkers and inorganic proxies in the paleoenvironmental reconstruction of mires: The importance of landscape in Las Conchas (Asturias, Northern Spain)

Ortíz

Borrego

Gallego

et al. 2016

Organic Geochemistry

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“…Furthermore, rivers are generally not passive conduits to the ocean, but rather 56 integrate, process, and remineralize multiple sources of terrestrial and aquatic organic matter 57 (OM) during transit (Aufdenkampe et al, 2011;Cole et al, 2007). Although riverine signals are 58 typically interpreted to reflect a catchment-integrated signal, downstream replacement and/or 59 dilution of headwater POC has been observed in many large basins including the Amazon 60 (Hedges et al, 1986;2000), Ganges-Brahmaputra (Galy et al 2008;2011), and Orange 61 (Herrmann et al, 2016) Rivers. Discerning the controls on POC overprinting is therefore critical 62 in order to accurately assess the ability of rivers to integrate terrestrial signals throughout their 63 catchments.…”

Section: Introduction 51mentioning

confidence: 99%

Hydrologic controls on seasonal and inter-annual variability of Congo River particulate organic matter source and reservoir age

et al. 2017

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“…A strong, linear relationship exists between organic carbon and total nitrogen contents of all surface sediments (r 2 = 0.83). It is noteworthy that the x-intercept (%OC = 0) of this regression is 0.16, therefore close to zero, which indicates that the majority of nitrogen in these sediments is associated with organic matter (e.g., Hedges et al, 1986). …”

Section: Organic Carbon Analysismentioning

confidence: 99%

Shallow gas off the Rhône prodelta, Gulf of Lions

et al. 2006

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In areas unaffected by the high flux of organic matter and rapid/thick flood deposition, or in between flood events, the conditions for methanogenesis and gas accumulation have not been met. In these areas, the physical and biological reworking of the surficial sediment may effectively oxidize and mineralize organic matter and limit bacterial methanogenesis in the subsurface. We propose that in the Rhône prodelta flood deposits deliver significant amounts of terrigenous 1 organic matter that can be rapidly buried, effectively removing this organic matter from aerobic oxidation and biological uptake, and leading to the potential for methanogenesis with burial.

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Compositions and fluxes of particulate organic material in the Amazon River1

Abstract: Lignin, elemental, and stable carbon isotope compositions are reported for local plants and for coarse (>63 pm) and fine (~63 pm) suspended particulate materials collected along a 1,950-km reach of the lower Amazon River during four contrasting stages of the 1982-1983 hydrograph.

Cited by 774 publications

References 56 publications

Biomarkers and inorganic proxies in the paleoenvironmental reconstruction of mires: The importance of landscape in Las Conchas (Asturias, Northern Spain)

Biomarkers and inorganic proxies in the paleoenvironmental reconstruction of mires: The importance of landscape in Las Conchas (Asturias, Northern Spain)

Hydrologic controls on seasonal and inter-annual variability of Congo River particulate organic matter source and reservoir age

Shallow gas off the Rhône prodelta, Gulf of Lions

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