Variability of particulate flux over the Mid-Atlantic Ridge

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• 作者：Richard E. Abell ; Tim Br ; Andrew C. Dale ; Gavin H. Tilstone ; Christine Beveridge
• 关键词：Primary production ; Carbon export ; Sediment traps ; Mid-Atlantic Ridge ; Particle tracking ; Particle flux
• 刊名：Deep Sea Research Part II: Topical Studies in Oceanography
• 出版年：15 December, 2013
• 年：2013
• 卷：98
• 期：Complete
• 页码：257-268
• 全文大小：3012 K

文摘

The magnitude and composition of the sinking-particle flux were studied over the northern Mid-Atlantic Ridge (MAR) from June 2007 to July 2010. Four moorings equipped with dual sediment traps, 100 m and 1000 m above the sea floor, sampled regions north and south of the Charlie Gibbs Fracture Zone (between 49掳N and 54掳N) and east and west of the MAR. Biogenic data were coupled with satellite estimates of primary production and modelled particle source to assess the variability in export flux. Large variations were found in the seasonality, chemical composition, magnitude and source of sinking particulate material between mooring sites. The northern moorings recorded both greater mean primary production and greater particle mass flux than the southern moorings, although, the large inter-annual variability within the sites exceeded inter-site differences. While estimates of primary production and organic carbon fluxes are comparable to other investigations of this type, they are notably lower than previous estimates for the abyssal plain of the North Atlantic. The deeper traps consistently recorded a higher mass flux compared to the shallower traps. However, we suggest that the overall flux recorded by the shallower traps was reduced by trapping inefficiency, which in the light of the low current velocities, may largely be due to the physical nature of the sinking material. Although deep-trap flux estimates may be more susceptible to errors due to re-suspended and advected material from nearby topography, mass flux and current velocity are not linked. In addition, the relatively low aluminium concentration of the deep-trap material indicates that this contribution is relatively small. The organic carbon flux to the NE, NW, SE and SW station was 0.8, 1.2, 1.1 and 1.1 g m^鈭? y^鈭? respectively, corresponding to an export flux of 0.6% over this region of the MAR.