Isotopic composition of carbonate-bound organic nitrogen in deep-sea scleractinian corals: A new window into past biogeochemical change
Journal
Earth and Planetary Science Letters
Journal Volume
400
Pages
243-250
Date Issued
2014
Author(s)
Wang, X.T.
Prokopenko, M.G.
Sigman, D.M.
Adkins, J.F.
Robinson, L.F.
Oleynik, S.
Williams, B.
Haug, G.H.
Abstract
Over the last two decades, the skeletal remains of deep-sea corals have arisen as a geochemical archive of Pleistocene oceanographic change. Here we report the exploration of the isotopic composition of the carbonate-bound organic nitrogen (hereafter, CB-δ15N) in the deep-sea scleractinian coral Desmophyllum dianthus as a possible tool for reconstructing past changes in the ocean nitrogen cycle. The measurement protocol is adapted from a high-sensitivity method for foraminifera shell-bound δ15N. We explored the variability of CB-δ15N within specimens, among corals collected at different depths in a given ocean region, and among different ocean regions. Modern D. dianthus CB-δ15N is strongly correlated with the δ15N of N export as estimated from sediment traps, shallow subsurface nitrate, and surface sediments, suggesting that CB-δ15N is a reliable proxy for δ15N of N export. D. dianthus CB-δ15N is consistently 8-9‰ higher than δ15N of N export, indicating that D. dianthus acquires its nutrition primarily from suspended particulate organic matter (POM) that derives from sinking POM, not directly from sinking POM. © 2014 Elsevier B.V.
SDGs
Type
journal article