Distribution and sources of bulk organic matter (OM) on a tropical intertidal mud bank in French Guiana from elemental and isotopic proxies

Gontharet, S.; Mathieu, Olivier; Lévêque, Jean; Milloux, Marie-Jeanne; Lesourd, Sandric; Philippe, Sylvie; Caillaud, Jacinthe; Gautier, Antoine; Sarrazin, Max; Proisy, Christophe

doi:10.1016/j.chemgeo.2014.03.009

Cited by 25 publications

(20 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In all samples, the OM derived from SPM was the main OM source for sediments, with minor inputs from mangrove plants and MPB. These calculated results are in agreement with those found in a previous study of sedimentary cores collected from the same mud bank …”

Section: Resultssupporting

confidence: 92%

“…Relationships between the atomic [TN/TOC] ratios, and the δ 13 C and δ 15 N values of sedimentary OM and the three vegetation end‐members. Typical atomic [TN/TOC] ratios, and δ 13 C and δ 15 N value ranges for C 3 terrestrial plants, microphytobenthos (MPB), freshwater phytoplankton (FP) and marine phytoplankton (MP) are also represented (data used from Gontharet et al …”

Section: Resultsmentioning

confidence: 99%

“…The relative contribution of the three OM sources to sediments can be calculated using three end‐member mixing equations based on [TOC/TN] atomic ratios, δ 13 C values and mass balance as:

\begin{matrix} left \\ {([], normalT normalO normalC true/ normalT normalN)}_{S e d} = {normalf}_{Mang} \times {([], normalT normalO normalC true/ normalT normalN)}_{Mang} + {normalf}_{M P B} \times {([], normalT normalO normalC true/ normalT normalN)}_{M P B} + {normalf}_{S P M} \times {([], normalT normalO normalC true/ normalT normalN)}_{S P M} \\ δ^{13} {normalC}_{S e d} = {normalf}_{Mang} \times δ^{13} {normalC}_{Mang} + {normalf}_{M P B} \times δ^{13} {normalC}_{M P B} + {normalf}_{S P M} \times δ^{13} {normalC}_{S P M} \\ 1 = {normalf}_{Mang} + {normalf}_{M P B} + {normalf}_{S P M} \end{matrix}

where [TOC/TN] and δ 13 C are the atomic elemental ratio and carbon isotopic composition of sediments (Sed), mangrove leaves (Mang), microphytobenthos (MPB) and suspended particulate matter (SPM) (Fig. (a) and Table ).…”

Section: Resultsmentioning

confidence: 99%

“…In various marine environments, many studies have focused on the simultaneous use of two or more geochemical proxies (including total organic carbon and total nitrogen ([TOC/TN]) ratios, and stable carbon and nitrogen isotope ratios) as natural tracers to identify the origin and fate of OM. [5][6][7][8][9][10][11] Their application relies on the existence of source-specific signatures between terrigenous, marine and fluvial inputs, and also on the preservation of each OM source signal after burial. However, early diagenetic processes, mainly composed of microbial OM mineralization at the surface sediments, might significantly alter the chemistry and isotopic composition of sedimentary OM and, consequently, limit the usefulness of these geochemical tracers as OM source indicators.…”

Section: Rationalementioning

confidence: 99%

mentioning

confidence: 99%

See 4 more Smart Citations

Effect of emersion/immersion cycles on the elemental and isotopic compositions of the organic matter from surface sediments of an intertidal mud bank (French Guiana): a preliminary study

Gontharet

Artigas

Mathieu

et al. 2015

Rapid Commun. Mass Spectrom.

View full text Add to dashboard Cite

The [TOC/TN]atomic ratios and the δ(13)C values, indicating the primary signal of OM sources, represented the most reliable geochemical proxies for calculating the relative contribution of OM sources to sediments in environments characterized by variable air exposure duration. The use of δ(15)N values in such environments is limited by OM degradation processes but their variation might enable the nature and the degree of these processes to be identified.

show abstract

Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

“…The relative contribution of the three OM sources to sediments can be calculated using three end‐member mixing equations based on [TOC/TN] atomic ratios, δ 13 C values and mass balance as:

\begin{matrix} left \\ {([], normalT normalO normalC true/ normalT normalN)}_{S e d} = {normalf}_{Mang} \times {([], normalT normalO normalC true/ normalT normalN)}_{Mang} + {normalf}_{M P B} \times {([], normalT normalO normalC true/ normalT normalN)}_{M P B} + {normalf}_{S P M} \times {([], normalT normalO normalC true/ normalT normalN)}_{S P M} \\ δ^{13} {normalC}_{S e d} = {normalf}_{Mang} \times δ^{13} {normalC}_{Mang} + {normalf}_{M P B} \times δ^{13} {normalC}_{M P B} + {normalf}_{S P M} \times δ^{13} {normalC}_{S P M} \\ 1 = {normalf}_{Mang} + {normalf}_{M P B} + {normalf}_{S P M} \end{matrix}

Section: Resultsmentioning

confidence: 99%

Section: Rationalementioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Effect of emersion/immersion cycles on the elemental and isotopic compositions of the organic matter from surface sediments of an intertidal mud bank (French Guiana): a preliminary study

Gontharet

Artigas

Mathieu

et al. 2015

Rapid Commun. Mass Spectrom.

View full text Add to dashboard Cite

show abstract

Nutrient Biogeochemistry

2021

Tropical Marine Ecology

View full text Add to dashboard Cite

The Amazon shelf sediments, a reactor that fuels intense nitrogen cycling at the seabed

Choisnard

Burtscher

Förster

et al. 2023

Limnology & Oceanography

View full text Add to dashboard Cite

Large river plumes such as the Amazon River Plume are known as regions of intense biological, chemical, and physical forcing affecting the delivery and speciation of nutrients. On the shelf, sediments may act as a net source or sink of dissolved inorganic nitrogen (DIN) for the water column depending on the preservation of organic matter (OM) and its remineralization pathways in benthic environments. Previous studies on sediments of the Amazon shelf suggested that the seabed mainly acted as a sink of DIN, with denitrification as the main loss process. However, the Amazon Basin faced drastic changes over the past decades, with climate change, deforestation, and damming potentially impacting the DIN and OM loads to the estuary. These perturbations might have led to changes in benthic remineralization, calling for updates of previously studied benthic remineralization processes on the Amazon shelf. Our analysis of eight short cores confirmed the occurrence of intense recycling of mostly terrestrial material (> 60%) in the river mouth, and little organic carbon was remaining in shelf sediments. We measured a sediment oxygen demand of ~ 23 mmol m−2 d−1, which can explain the ammonification and nitrification of all the organic nitrogen (N) reaching the sediment, underlining the importance of the seabed as a sink for organic N species. Therefore, in spite of the changes in the Amazon Basin, nitrification still seems to be balanced by denitrification, as, similarly to previous results, no DIN diffused out of the sediment.

show abstract

Distribution and sources of bulk organic matter (OM) on a tropical intertidal mud bank in French Guiana from elemental and isotopic proxies

Cited by 25 publications

References 53 publications

Effect of emersion/immersion cycles on the elemental and isotopic compositions of the organic matter from surface sediments of an intertidal mud bank (French Guiana): a preliminary study

Effect of emersion/immersion cycles on the elemental and isotopic compositions of the organic matter from surface sediments of an intertidal mud bank (French Guiana): a preliminary study

Nutrient Biogeochemistry

The Amazon shelf sediments, a reactor that fuels intense nitrogen cycling at the seabed

Contact Info

Product

Resources

About