Open AccessReproducibility of Ba/Ca variations recorded by northeast Pacific bamboo corals
Author(s) -
Serrato Marks G.,
LaVigne M.,
Hill T. M.,
Sauthoff W.,
Guilderson T. P.,
Roark E. B.,
Dunbar R. B.,
Horner T. J.
Publication year - 2017
Publication title -
paleoceanography
Language(s) - English
Resource type - Journals
eISSN - 1944-9186
pISSN - 0883-8305
DOI - 10.1002/2017pa003178
Subject(s) - coral , geology , transect , oceanography , aragonite , calcite , reproducibility , barium , biogeochemical cycle , scleractinia , mineralogy , environmental chemistry , chemistry , cnidaria , chromatography , inorganic chemistry
Trace elemental ratios preserved in the calcitic skeleton of bamboo corals have been shown to serve as archives of past ocean conditions. The concentration of dissolved barium (Ba SW ), a bioactive nutrientlike element, is linked to biogeochemical processes such as the cycling and export of nutrients. Recent work has calibrated bamboo coral Ba/Ca, a new Ba SW proxy, using corals spanning the oxygen minimum zone beneath the California Current System. However, it was previously unclear whether Ba/Ca coral records were internally reproducible. Here we investigate the accuracy of using laser ablation inductively coupled plasma mass spectrometry for Ba/Ca coral analyses and test the internal reproducibility of Ba/Ca among replicate radial transects in the calcite of nine bamboo corals collected from the Gulf of Alaska (643–720 m) and the California margin (870–2054 m). Data from replicate Ba/Ca transects were aligned using visible growth bands to account for nonconcentric growth; smoothed data were reproducible within ~4% for eight corals ( n = 3 radii/coral). This intracoral reproducibility further validates using bamboo coral Ba/Ca for Ba SW reconstructions. Sections of the Ba/Ca records that were potentially influenced by noncarbonate bound Ba phases occurred in regions where elevated Mg/Ca or Pb/Ca and coincided with anomalous regions on photomicrographs. After removing these regions of the records, increased Ba/Ca coral variability was evident in corals between ~800 and 1500 m. These findings support additional proxy validation to understand Ba SW variability on interannual timescales, which could lead to new insights into deep sea biogeochemistry over the past several centuries.