Effects of seawater-pH and biomineralization on the boron isotopic composition of deep-sea bamboo corals ...

• Main Authors: Farmer, Jesse Robert, Hoenisch, Baerbel, Robinson, Laura F., Hill, Tessa M.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Columbia University 2015
• Subjects: Paleoclimatology; Chemical oceanography; Pacific; North Atlantic; Ocean acidification
• Online Access: https://dx.doi.org/10.7916/d8z03716; https://academiccommons.columbia.edu/doi/10.7916/D8Z03716

The ocean is currently absorbing excess carbon from anthropogenic emissions, leading to reduced seawater-pH (termed ‘ocean acidification’). Instrumental records of ocean acidification are unavailable from well-ventilated areas of the deep ocean, necessitating proxy records to improve spatio-temporal understanding on the rate and magnitude of deep ocean acidification. Here we investigate boron, carbon, and oxygen isotopes on live-collected deep-sea bamboo corals (genus Keratoisis) from a pHtot range of 7.5–8.1. These analyses are used to explore the potential for using bamboo coral skeletons as archives of past deep-sea pH and to trace anthropogenic acidification in the subsurface North Atlantic Ocean (850–2000 m water depth). Boron isotope ratios of the most recently secreted calcite of bamboo coral skeletons are close to the calculated isotopic composition of borate anion in seawater (δ11Bborate) for North Atlantic corals, and 1–2‰ higher than δ11Bborate for Pacific corals. Within individual coral ...