Late Holocene Radiocarbon Variability in Northwest Atlantic Slope Waters [electronic resource]
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 dep...
Saved in:
| Online Access: |
Online Access |
|---|---|
| Corporate Author: | |
| Format: | Government Document Electronic eBook |
| Language: | English |
| Published: |
Washington, D.C. : Oak Ridge, Tenn. :
United States. Department of Energy. ; distributed by the Office of Scientific and Technical Information, U.S. Department of Energy,
2008.
|
| Subjects: |
| Summary: | 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-¹⁴C eras. In Labrador Slope Water (LSW), convective mixing homogenizes the pre-bomb Δ¹⁴C signature (-67 ± 4{per_thousand}) to at least 1000 m depth. Surface water bomb-¹⁴C signals were lagged and damped (peaking at ≈ +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 Δ¹⁴C is much stronger. In surface water, pre-bomb Δ¹⁴C averaged -75 ± 5{per_thousand}. At 250-475 m depth, prebomb Δ¹⁴C 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 Δ¹⁴C gradients over the last 1200 years. |
|---|---|
| Item Description: | Published through SciTech Connect. 08/15/2008. "llnl-jrnl-406417" Earth and Planetary Science Letters, vol. 275, no. 1-2, October 30, 2008, pp. 146-153 275 1-2 ISSN 0012-821X; EPSLA2 FT. Ghaleb, B; Sherwood, O; Guilderson, T P; Scott, D B; Risk, M J; Edinger, E. |
| Physical Description: | PDF-file: 34 pages; size: 0.4 Mbytes. |