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Reconciling drainage and receiving basin signatures of the Godavari River system

Usman, Muhammed Ojoshogu and Kirkels, Frédérique Marie Sophie Anne and Zwart, Huub Michel and Basu, Sayak and Ponton, Camilo and Blattmann, Thomas Michael and Ploetze, Michael and Haghipour, Negar and McIntyre, Cameron and Peterse, Francien and Lupker, Maarten and Giosan, Liviu and Eglinton, Timothy Ian (2018) Reconciling drainage and receiving basin signatures of the Godavari River system. Biogeosciences, 15 (11). pp. 3357-3375. ISSN 1726-4170. https://resolver.caltech.edu/CaltechAUTHORS:20180620-095745641

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Abstract

The modern-day Godavari River transports large amounts of sediment (170 Tg per year) and terrestrial organic carbon (OC_(terr); 1.5 Tg per year) from peninsular India to the Bay of Bengal. The flux and nature of OC_(terr) is considered to have varied in response to past climate and human forcing. In order to delineate the provenance and nature of organic matter (OM) exported by the fluvial system and establish links to sedimentary records accumulating on its adjacent continental margin, the stable and radiogenic isotopic composition of bulk OC, abundance and distribution of long-chain fatty acids (LCFAs), sedimentological properties (e.g. grain size, mineral surface area, etc.) of fluvial (riverbed and riverbank) sediments and soils from the Godavari basin were analysed and these characteristics were compared to those of a sediment core retrieved from the continental slope depocenter. Results show that river sediments from the upper catchment exhibit higher total organic carbon (TOC) contents than those from the lower part of the basin. The general relationship between TOC and sedimentological parameters (i.e. mineral surface area and grain size) of the sediments suggests that sediment mineralogy, largely driven by provenance, plays an important role in the stabilization of OM during transport along the river axis, and in the preservation of OM exported by the Godavari to the Bay of Bengal. The stable carbon isotopic (δ^(13)C) characteristics of river sediments and soils indicate that the upper mainstream and its tributaries drain catchments exhibiting more ^(13)C enriched carbon than the lower stream, resulting from the regional vegetation gradient and/or net balance between the upper (C_4-dominated plants) and lower (C3-dominated plants) catchments. The radiocarbon contents of organic carbon (Δ^(14)C_(OC)) in deep soils and eroding riverbanks suggests these are likely sources of old or pre-aged carbon to the Godavari River that increasingly dominates the late Holocene portion of the offshore sedimentary record. While changes in water flow and sediment transport resulting from recent dam construction have drastically impacted the flux, loci, and composition of OC exported from the modern Godavari basin, complicating reconciliation of modern-day river basin geochemistry with that recorded in continental margin sediments, such investigations provide important insights into climatic and anthropogenic controls on OC cycling and burial.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.5194/bg-15-3357-2018DOIArticle
Additional Information:© Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. Published by Copernicus Publications on behalf of the European Geosciences Union. Received: 12 Jan 2018 – Discussion started: 08 Feb 2018. Revised: 18 May 2018 – Accepted: 24 May 2018 – Published: 07 Jun 2018. Data availability: All underlying research data associated with this study are available in the Supplement. The authors declare that they have no conflict of interest. We thank the associate editor Markus Kienast and two anonymous reviewers for their comments. This project was supported by the Swiss National Science Foundations (“CAPS LOCK” grant no. 200021-140850 and “CAPS-LOCK2” grant no. 200021-163162). Francien Peterse received funding from NWO-Veni grant (grant no. 863.13.016). Liviu Giosan thanks colleagues and crew from the NGHP-01 expedition for intellectual interactions leading to pursuing work on fluvial–continental margin systems of Peninsular India and to grants from the National Science Foundation (OCE-0841736) and Woods Hole Oceanographic Institution. We also wish to thank Daniel Montluçon for laboratory assistance, and we acknowledge the logistical support of Prasanta Sanyal and Chris Martes with sampling. Further thanks to Michael Strupler for help with grain size measurements. This paper benefitted from discussions with Chantal Freymond.
Funders:
Funding AgencyGrant Number
Swiss National Science Foundation (SNSF)200021-140850
Swiss National Science Foundation (SNSF)200021-163162
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)863.13.016
NSFOCE-0841736
Woods Hole Oceanographic InstitutionUNSPECIFIED
Issue or Number:11
Record Number:CaltechAUTHORS:20180620-095745641
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180620-095745641
Official Citation:Usman, M. O., Kirkels, F. M. S. A., Zwart, H. M., Basu, S., Ponton, C., Blattmann, T. M., Ploetze, M., Haghipour, N., McIntyre, C., Peterse, F., Lupker, M., Giosan, L., and Eglinton, T. I.: Reconciling drainage and receiving basin signatures of the Godavari River system, Biogeosciences, 15, 3357-3375, https://doi.org/10.5194/bg-15-3357-2018, 2018
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:87255
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:20 Jun 2018 17:11
Last Modified:03 Oct 2019 19:54

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