Open AccessCalibration of the carbon isotope composition (δ 13 C) of benthic foraminifera
Author(s) -
Schmittner Andreas,
Bostock Helen C.,
Cartapanis Olivier,
Curry William B.,
Filipsson Helena L.,
Galbraith Eric D.,
Gottschalk Julia,
Herguera Juan Carlos,
Hoogakker Babette,
Jaccard Samuel L.,
Lisiecki Lorraine E.,
Lund David C.,
MartínezMéndez Gema,
LynchStieglitz Jean,
Mackensen Andreas,
Michel Elisabeth,
Mix Alan C.,
Oppo Delia W.,
Peterson Carlye D.,
Repschläger Janne,
Sikes Elisabeth L.,
Spero Howard J.,
Waelbroeck Claire
Publication year - 2017
Publication title -
paleoceanography
Language(s) - English
Resource type - Journals
eISSN - 1944-9186
pISSN - 0883-8305
DOI - 10.1002/2016pa003072
Subject(s) - foraminifera , benthic zone , seawater , oceanography , carbonate , carbon cycle , isotopes of carbon , carbon fibers , water column , environmental science , geology , total organic carbon , chemistry , environmental chemistry , ecology , biology , ecosystem , mathematics , organic chemistry , composite number , algorithm
The carbon isotope composition (δ 13 C) of seawater provides valuable insight on ocean circulation, air‐sea exchange, the biological pump, and the global carbon cycle and is reflected by the δ 13 C of foraminifera tests. Here more than 1700 δ 13 C observations of the benthic foraminifera genus Cibicides from late Holocene sediments (δ 13 C Cibnat ) are compiled and compared with newly updated estimates of the natural (preindustrial) water column δ 13 C of dissolved inorganic carbon (δ 13 C DICnat ) as part of the international Ocean Circulation and Carbon Cycling (OC3) project. Using selection criteria based on the spatial distance between samples, we find high correlation between δ 13 C Cibnat and δ 13 C DICnat , confirming earlier work. Regression analyses indicate significant carbonate ion (−2.6 ± 0.4) × 10 −3 ‰/(μmol kg −1 ) [CO 3 2− ] and pressure (−4.9 ± 1.7) × 10 −5 ‰ m −1 (depth) effects, which we use to propose a new global calibration for predicting δ 13 C DICnat from δ 13 C Cibnat . This calibration is shown to remove some systematic regional biases and decrease errors compared with the one‐to‐one relationship (δ 13 C DICnat = δ 13 C Cibnat ). However, these effects and the error reductions are relatively small, which suggests that most conclusions from previous studies using a one‐to‐one relationship remain robust. The remaining standard error of the regression is generally σ ≅ 0.25‰, with larger values found in the southeast Atlantic and Antarctic ( σ ≅ 0.4‰) and for species other than Cibicides wuellerstorfi . Discussion of species effects and possible sources of the remaining errors may aid future attempts to improve the use of the benthic δ 13 C record.