Reconstructing organic matter sources and rain rates in the southern West Pacific Warm Pool during the transition from the deglaciation period to early Holocene

Chen, Linying, Luo, Min, Dale, Andrew W., Rashid, Harunur, Lin, Gang and Chen, Duofu (2019) Reconstructing organic matter sources and rain rates in the southern West Pacific Warm Pool during the transition from the deglaciation period to early Holocene Chemical Geology, 529 (Article number 119291). DOI 10.1016/j.chemgeo.2019.119291.

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Supplementary data:

Abstract

Highlights

• δ13C, δ15N, and TOC/TN of POM suggest that the POM is characterized by a mixture of marine and terrestrial origins.
• Hindcast model results revealed a major decrease in POC rain rate during the deglaciation–early Holocene transition.
• The decrease in POC rain rate was induced by the decline in the terrestrial OM input associated with rapid sea level rise.

Abstract

Transient features in the organic carbon content of deep-sea sediment cores resulting from changes in the flux and/or quality of organic matter input are not uncommon. We examined the geochemical characteristics of sediments retrieved with a gravity core from the northwestern Solomon Sea (3908 m water depth), southern West Pacific Warm Pool (WPWP). δ13C and δ15N of sedimentary organic matter, together with TOC/TN data suggest that the organic material is characterized by a mixture of marine and terrestrial origins with a higher contribution from marine algae. The data were analyzed with an inverse non-steady-state reaction-transport model to examine the magnitude and variability of particulate organic carbon (POC) flux to the seafloor during the transition between the deglaciation period and early Holocene. Measured POC content and porewater NO3−, NH4+, DIC and SO42− concentrations were used to constrain the model. Hindcast results revealed that POC flux decreased from 75 to 37.5 μg cm−2 yr−1 during the deglaciation–early Holocene transition. The rate of POC degradation in the present setting is slightly lower compared to that in the pre-Holocene setting. The synchronous decline in the relative contribution of terrestrial organic matter input and rapid sea level rise during this transition suggest that sea level, rather than surface productivity, is the dominant factor controlling the POC deposition flux in the Solomon Sea. This is conceivable because the sampling site is proximal to high-relief islands with high rainfall, a well-developed submarine canyon system and narrow and steep continental margins. Consequently, we suggest that deep-water basins in proximity to similar high-relief mountainous islands in the tropical Pacific may represent important sinks for terrestrial organic material, especially during sea level lowstands.

Document Type: Article
Keywords: Organic carbon burial, Particulate organic matter, Reaction-transport model, Transient state, West Pacific Warm Pool, RV Zhangjian
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
Refereed: Yes
DOI etc.: 10.1016/j.chemgeo.2019.119291
ISSN: 0009-2541
Date Deposited: 20 Sep 2019 06:51
Last Modified: 20 Sep 2019 06:51
URI: http://eprints.uni-kiel.de/id/eprint/47790

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