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| Farmer, Jesse; Hertzberg, Jennifer; Cardinal, Damien; Fietz, Susanne; Hendry, Katharine; Jaccard, Sam; Paytan, Adina; Rafter, Patrick; Ren, Haojia; Somes, Christopher; Sutton, Jill; Geotraces Pages Biological Productivity Working Group Members,. |
| Biological productivity in the ocean directly influences the partitioning of carbon between the atmosphere and ocean interior, thereby controlling the distributions of many elements and their isotopes in the ocean. Through this carbon cycle feedback, changing ocean productivity has long been hypothesized as a key pathway for modulating past atmospheric carbon dioxide levels and hence global climate. To reconstruct climate impacts from temporal changes in paleoproductivity, robust proxies are needed to test the connection between past ocean productivity, nutrient biogeochemistry, ocean circulation and climate. Here we compile water column carbon (C), nitrogen (N) and silicon (Si) stable isotopes from GEOTRACES-era data in four key ocean regions to review... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00649/76114/77076.pdf |
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| Ren, Haojia; Sigman, Daniel M.; Chen, Min-te; Kao, Shuh-ji. |
| We report a new foraminifera-bound delta N-15 (FB-delta N-15) record from the South China Sea (SCS) extending back to 42 ka. This record shows a similar to 1.2 parts per thousand glacial-to-interglacial delta N-15 decrease, with a deglacial delta N-15 maximum similar to that observed in many bulk sedimentary delta N-15 records and in a Caribbean FB-delta N-15 record. The glacial-to-interglacial delta N-15 decrease is smaller than in the Caribbean record, indicating that at least half of the Caribbean delta N-15 decrease into the Holocene was regional, not global, supporting the interpretation of a Holocene increase in Atlantic nitrogen fixation. At the same time, the glacial-to-interglacial delta N-15 decrease observed in the SCS may also be explained as a... |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00265/37670/36834.pdf |
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| Wang, Tingting; Ravelo, Ana Christina; Ren, Haojia; Dang, Haowen; Jin, Haiyan; Liu, Jingjing; Jian, Zhimin. |
| We report the differences between δ15N of organic nitrogen bound in foraminifera tests (foraminifera‐bound δ15N, or FB‐δ15N), which is considered an effective recorder of thermocline nitrate δ15N in the oligotrophic areas, and bulk sedimentary δ15N (δ15Nbulk) of core MD12‐3433, located in the northern South China Sea (SCS), to explore possible causes of the offset between these two proxies in the SCS. The offset can be best explained by the influence of the terrigenous input on δ15Nbulk, as evidenced by its general correlation with sea level changes, C:N ratios, and inorganic nitrogen contribution to total nitrogen. Moreover, our new record is compared to six previously published δ15Nbulk records of the SCS based on their geographical proximity to the... |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00441/55238/56719.pdf |
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| Serno, Sascha; Winckler, Gisela; Anderson, Robert F.; Hayes, Christopher T.; Mcgee, David; Machalett, Bjoern; Ren, Haojia; Straub, Susanne M.; Gersonde, Rainer; Haug, Gerald H.. |
| Eolian dust is a significant source of iron and other nutrients that are essential for the health of marine ecosystems and potentially a controlling factor of the high nutrient-low chlorophyll status of the Subarctic North Pacific. We map the spatial distribution of dust input using three different geochemical tracers of eolian dust, He-4, Th-232 and rare earth elements, in combination with grain size distribution data, from a set of core-top sediments covering the entire Subarctic North Pacific. Using the suite of geochemical proxies to fingerprint different lithogenic components, we deconvolve eolian dust input from other lithogenic inputs such as volcanic ash, ice-rafted debris, riverine and hemipelagic input. While the open ocean sites far away from... |
| Tipo: Text |
Palavras-chave: Eolian dust; Subarctic North Pacific; INOPEX; Helium-4; Th-232; REE. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00291/40196/38719.pdf |
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| Meckler, A. Nele; Ren, Haojia; Sigman, Daniel M.; Gruber, Nicolas; Plessen, Birgit; Schubert, Carsten J.; Haug, Gerald H.. |
| Constraining variations in marine N(2)-fixation over glacial-interglacial timescales is crucial for determining the role of the marine nitrogen cycle in modifying ocean productivity and climate, yet paleo-records from N2-fixation regions are sparse. Here we present new nitrogen isotope (delta(15)N) records of bulk sediment and foraminifera test-bound (FB) nitrogen extending back to the last ice age from the oligotrophic Gulf of Mexico (GOM). Previous studies indicate a substantial terrestrial input during the last ice age and early deglacial, for which we attempt to correct the bulk sediment delta(15)N using its observed relationship with the C/N ratio. Both corrected bulk and FB-delta(15)N reveal a substantial glacial-to-Holocene decrease of delta(15)N... |
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| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00227/33786/32567.pdf |
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