Preprints
https://doi.org/10.5194/bg-2021-318
https://doi.org/10.5194/bg-2021-318

  29 Nov 2021

29 Nov 2021

Review status: this preprint is currently under review for the journal BG.

Linking sediment biodegradability with its origin in shallow coastal environments

Justine Louis1,3, Anniet M. Laverman1, Emilie Jardé2, Alexandrine Pannard1, Marine Liotaud2, Françoise Andrieux-Loyer3, Gérard Gruau2, Florian Caradec3, Emilie Rabiller3, Nathalie Lebris1, and Laurent Jeanneau3 Justine Louis et al.
  • 1Centre National de la Recherche Scientifique (CNRS), ECOBIO – UMR 6553, Université de Rennes 1, 35042 Rennes, France
  • 2Centre National de la Recherche Scientifique (CNRS), Géosciences Rennes – UMR 6118, Université de Rennes 1, 35042 Rennes, France
  • 3Ifremer, DYNECO PELAGOS, ZI Pointe du Diable, 29280 Plouzané, France

Abstract. In coastal areas and estuaries, such as those encountered in the western part of France (Brittany region), the recycling of carbon and nutrients from sediments can participate in the development of micro and macro-algal blooms with harmful consequences for these ecosystems. One of the main processes controlling this recycling is the microbial mineralization of sedimentary organic matter (SOM). Mineralization is controlled by the origin, quantity and accessibility of the SOM, three factors whose relative importance remain, however, poorly quantified, mainly due to the great diversity of OM sources in coastal areas. The first objective of the present work was to assess the variability of the SOM origin at the regional scale representative of the complexity of the sources likely to be involved. The second objective was to determine the link between the SOM origin and its biodegradability, and how the OM sources can drive nutrient dynamics at the sediment-water interface. To this end, a broad sediment sampling campaign was carried out on Brittany mudflats, particularly affected by the eutrophication, during the spring period. A total of 200 samples were collected at 45 sites. They were characterized by their porosity and grain-size, as well as their chemical composition through elemental, isotopic and molecular biomarker analysis. A wide range of OM sources were identified in the sediments, including both natural (bacteria, algae, macrophytes, terrestrial plants), and anthropogenic (combustion products, crude oil, petroleum products – e.g. from the processing of crude oil at refineries- and fecal matter) sources. Sediment slurry incubations were carried out to determine the spatial variability of potential mineralization rates under oxic conditions. In addition, the measurements of NH4+ and PO4 fluxes at the sediment-water interface were made from sediment core incubations under realistic redox conditions of sediment. The physical and chemical sedimentary characteristics explained 58 % of the variability of mineralization rates under oxic conditions, with a negligible independent effect of the SOM origin (3 %). Conversely, under insitu redox conditions, the prevalent role of SOM origin over quantity/accessibility on the sediment biodegradability was highlighted with a significant effect 5 and 1.5 fold higher on the PO4 and NH4+ fluxes respectively. The anthropogenic inputs from the watershed to the coastal sediment, through agricultural runoff and/or sewages discharge, seem to significantly drive the nutrient dynamics at the sediment-water interface. Higher values of NH4+ and PO4 fluxes were measured for the sediment with a chemical composition impacted by human activities.

Justine Louis et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2021-318', Wytze Lenstra, 07 Dec 2021
    • AC1: 'Reply on RC1', Justine Louis, 18 Jan 2022
  • RC2: 'Comment on bg-2021-318', Anonymous Referee #2, 21 Dec 2021
    • AC2: 'Reply on RC2', Justine Louis, 18 Jan 2022
  • RC3: 'Comment on bg-2021-318', Anonymous Referee #3, 29 Dec 2021
    • AC3: 'Reply on RC3', Justine Louis, 18 Jan 2022

Justine Louis et al.

Justine Louis et al.

Viewed

Total article views: 401 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
302 86 13 401 28 1 3
  • HTML: 302
  • PDF: 86
  • XML: 13
  • Total: 401
  • Supplement: 28
  • BibTeX: 1
  • EndNote: 3
Views and downloads (calculated since 29 Nov 2021)
Cumulative views and downloads (calculated since 29 Nov 2021)

Viewed (geographical distribution)

Total article views: 338 (including HTML, PDF, and XML) Thereof 338 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 24 Jan 2022
Download
Short summary
This work has described the variability in sedimentary organic matter composition through a broad sampling campaign of marine mudflats at the regional scale (Brittany Region), and made the link with sediment potential biodegradability and nutrient release. In these coastal ecosystems affected by the eutrophication, the potential impact of human activities on the nutrient dynamics at the sediment-water interface was highlighted.
Altmetrics