Deep-sea gorgonian corals secrete a 2-part skeleton of calcite, derived from dissolved inorganic carbon at depth, and gorgonin, derived from recently fixed and exported particulate organic matter. Radiocarbon contents of the calcite and gorgonin provide direct measures of seawater radiocarbon at depth and in the overlying surface waters, respectively. Using specimens collected from Northwest Atlantic slope waters, we generated radiocarbon records for surface and upper intermediate water layers spanning the pre- and post bomb-{sup 14}C eras. In Labrador Slope Water (LSW), convective mixing homogenizes the pre-bomb {Delta}{sup 14}C signature (-67 {+-} 4{per_thousand}) to at least 1000 m depth. Surface water bomb-{sup 14}C signals were lagged and damped (peaking at {approx} +45{per_thousand} in the early 1980s) relative to other regions of the northwest Atlantic, and intermediate water signals were damped further. Off southwest Nova Scotia, the vertical gradient in {Delta}{sup 14}C is much stronger. In surface water, pre-bomb {Delta}{sup 14}C averaged -75 {+-} 5{per_thousand}. At 250-475 m depth, prebomb {Delta}{sup 14}C oscillated quasi-decadally between -80 and -100{per_thousand}, likely reflecting interannual variability in the presence of Labrador Slope Water vs. Warm Slope Water (WSW). Finally, subfossil corals reveal no systematic changes in vertical {Delta}{sup 14}C gradients over the last 1200 years.
Sherwood, O, et al. "Late Holocene Radiocarbon Variability in Northwest Atlantic Slope Waters." Earth and Planetary Science Letters, vol. 275, no. 1-2, Aug. 2008. https://doi.org/10.1016/j.epsl.2008.08.019
Sherwood, O, Edinger, E, Guilderson, T P, Ghaleb, B, Risk, M J, & Scott, D B (2008). Late Holocene Radiocarbon Variability in Northwest Atlantic Slope Waters. Earth and Planetary Science Letters, 275(1-2). https://doi.org/10.1016/j.epsl.2008.08.019
Sherwood, O, Edinger, E, Guilderson, T P, et al., "Late Holocene Radiocarbon Variability in Northwest Atlantic Slope Waters," Earth and Planetary Science Letters 275, no. 1-2 (2008), https://doi.org/10.1016/j.epsl.2008.08.019
@article{osti_945532,
author = {Sherwood, O and Edinger, E and Guilderson, T P and Ghaleb, B and Risk, M J and Scott, D B},
title = {Late Holocene Radiocarbon Variability in Northwest Atlantic Slope Waters},
annote = {Deep-sea gorgonian corals secrete a 2-part skeleton of calcite, derived from dissolved inorganic carbon at depth, and gorgonin, derived from recently fixed and exported particulate organic matter. Radiocarbon contents of the calcite and gorgonin provide direct measures of seawater radiocarbon at depth and in the overlying surface waters, respectively. Using specimens collected from Northwest Atlantic slope waters, we generated radiocarbon records for surface and upper intermediate water layers spanning the pre- and post bomb-{sup 14}C eras. In Labrador Slope Water (LSW), convective mixing homogenizes the pre-bomb {Delta}{sup 14}C signature (-67 {+-} 4{per_thousand}) to at least 1000 m depth. Surface water bomb-{sup 14}C signals were lagged and damped (peaking at {approx} +45{per_thousand} in the early 1980s) relative to other regions of the northwest Atlantic, and intermediate water signals were damped further. Off southwest Nova Scotia, the vertical gradient in {Delta}{sup 14}C is much stronger. In surface water, pre-bomb {Delta}{sup 14}C averaged -75 {+-} 5{per_thousand}. At 250-475 m depth, prebomb {Delta}{sup 14}C oscillated quasi-decadally between -80 and -100{per_thousand}, likely reflecting interannual variability in the presence of Labrador Slope Water vs. Warm Slope Water (WSW). Finally, subfossil corals reveal no systematic changes in vertical {Delta}{sup 14}C gradients over the last 1200 years.},
doi = {10.1016/j.epsl.2008.08.019},
url = {https://www.osti.gov/biblio/945532},
journal = {Earth and Planetary Science Letters},
issn = {ISSN EPSLA2},
number = {1-2},
volume = {275},
place = {United States},
year = {2008},
month = {08}}