The sequestration sink of black carbon in the Northern European Shelf.
L. Sánchez-García, I. Cato, Ö. Gustafsson. The sequestration sink of black carbon in the Northern European Shelf. . Global Biogeochemical Cycles. 2012, Vol. 26, p. GB1001, 12 PP-2012.
To test the hypothesis that ocean margin sediments are a key final repository in the large-scale biogeospheric cycling of soot black carbon (soot-BC), an extensive survey was conducted along the ~2,000 km stretch of the Swedish Continental Shelf (SCS). The soot-BC content in the 120 spatially-distributed SCS sediments was 0.18 (0.13-0.25) % dw (median with interquartile ranges), corresponding to ~5% of total organic carbon. Using side-scan sonar constraints to estimate the areal fraction of postglacial clay sediments that are accumulation bottoms (15% of SCS), the soot-BC inventory in the SCS mixed surface sediment was estimated at ~4,000 Gg. Combining this with radiochronological constraints on sediment mass accumulation fluxes, the soot-BC sink on the SCS was ~300 Gg/yr, which yielded an area-extrapolated estimate for the Northern European Shelf (NES) of ~1,100 Gg/yr. This sediment soot-BC sink is ~50 times larger than the river discharge fluxes of soot-BC to these coastal waters, however, of similar magnitude as estimates of atmospheric soot-BC emission from the upwind European continent. While large uncertainties remain regarding the large-scale to global BC cycle, this study combines with two previous investigations to suggest that continental shelf sediments are a major final repository of atmospheric soot-BC. Future progress on the soot-BC cycle and how it interacts with the full carbon cycle is likely to benefit from 14C determinations of the sedimentary soot-BC and similar extensive studies of coastal sediment in complementary regimes such as off heavily soot-BC-producing areas in S and E Asia and on the large pan-Arctic shelf.
To test the hypothesis that ocean margin sediments are a key final repository in the large-scale biogeospheric cycling of soot black carbon (soot-BC), an extensive survey was conducted along the ~2,000 km stretch of the Swedish Continental Shelf (SCS). The soot-BC content in the 120 spatially-distributed SCS sediments was 0.18 (0.13-0.25) % dw (median with interquartile ranges), corresponding to ~5% of total organic carbon. Using side-scan sonar constraints to estimate the areal fraction of postglacial clay sediments that are accumulation bottoms (15% of SCS), the soot-BC inventory in the SCS mixed surface sediment was estimated at ~4,000 Gg. Combining this with radiochronological constraints on sediment mass accumulation fluxes, the soot-BC sink on the SCS was ~300 Gg/yr, which yielded an area-extrapolated estimate for the Northern European Shelf (NES) of ~1,100 Gg/yr. This sediment soot-BC sink is ~50 times larger than the river discharge fluxes of soot-BC to these coastal waters, however, of similar magnitude as estimates of atmospheric soot-BC emission from the upwind European continent. While large uncertainties remain regarding the large-scale to global BC cycle, this study combines with two previous investigations to suggest that continental shelf sediments are a major final repository of atmospheric soot-BC. Future progress on the soot-BC cycle and how it interacts with the full carbon cycle is likely to benefit from 14C determinations of the sedimentary soot-BC and similar extensive studies of coastal sediment in complementary regimes such as off heavily soot-BC-producing areas in S and E Asia and on the large pan-Arctic shelf.