International Journal of Earth Sciences

, Volume 98, Issue 2, pp 281–298 | Cite as

Mineral ballast and particle settling rates in the coastal upwelling system off NW Africa and the South Atlantic

  • G. Fischer
  • G. Karakas
  • M. Blaas
  • V. Ratmeyer
  • N. Nowald
  • R. Schlitzer
  • P. Helmke
  • R. Davenport
  • B. Donner
  • S. Neuer
  • G. Wefer
Original Paper


The ocean off NW Africa is the second most important coastal upwelling system with a total annual primary production of 0.33 Gt of carbon per year (Carr in Deep Sea Res II 49:59–80, 2002). Deep ocean organic carbon fluxes measured by sediment traps are also fairly high despite low biogenic opal fluxes. Due to a low supply of dissolved silicate from subsurface waters, the ocean off NW Africa is characterized by predominantly carbonate-secreting primary producers, i.e. coccolithophorids. These algae which are key primary producers since millions of years are found in organic- and chlorophyll-rich zooplankton fecal pellets, which sink rapidly through the water column within a few days. Particle flux studies in the Mauretanian upwelling area (Cape Blanc) confirm the hypothesis of Armstrong et al. (Deep Sea Res II 49:219–236, 2002) who proposed that ballast availability, e.g. of carbonate particles, is essential to predict deep ocean organic carbon fluxes. The role of dust as ballast mineral for organic carbon, however, must be also taken into consideration in the coastal settings off NW Africa. There, high settling rates of larger particles approach 400 m day−1, which may be due to a particular composition of mineral ballast. An assessment of particle settling rates from opal-production systems in the Southern Ocean of the Atlantic Sector, in contrast, provides lower values, consistent with the assumptions of Francois et al. (Global Biogeochem Cycles 16(4):1087, 2002). Satellite chlorophyll distributions, particle distributions and fluxes in the water column off NW Africa as well as modelling studies suggest a significant lateral flux component and export of particles from coastal shelf waters into the open ocean. These transport processes have implications for paleo-reconstructions from sediment cores retrieved at continental margin settings.


Ballast Particle settling rates Particle fluxes Lateral advection Coccolithophorids Diatoms Modelling Dust Mauretania Upwelling 



We would like to thank the masters and crew of RV METEOR, RV POLARSTERN and RV POSEIDON for their competent assistance during the deployments and recoveries of the moorings. For logistical support, we are very much grateful to G. Ruhland. For laboratory analysis, we are indebted to V. Diekamp, M.Scholz and M. Klann and H. Buschhoff. We also like to thank the reviewers for helpful comments and the editors of this volume. A large number of data were collected during the SFB 261 programme conducted in the Atlantic Ocean (1989–2001) and we would like to thank the Deutsche Forschungsgemeinschaft for funding. This is publication of the Research Center Ocean Margins (RCOM), No. 519, funded by the Deutsche Forschungsgemeinschaft.


  1. Antia AN et al (2001) Basin-wide particulate carbon flux in the Atlantic Ocean: regional export patterns and potential for atmospheric CO2 sequestration. Global Biogeochem Cycles 15(4):845–862CrossRefGoogle Scholar
  2. Antoine D, Jean-Michel A, Morel A (1996) Ocean primary production: 2. Estimation at global scale from satellite (Coastal Zone Colour Scanner) chlorophyll. Global Biogeochem Cycles 10:57–69CrossRefGoogle Scholar
  3. Ariathurai R, Arulanandan K (1978) Erosion rates of cohesive soils. J Hydr Div ASCE 104(2):279–282Google Scholar
  4. Armstrong RA, Lee C, Hedges JI, Honjo S, Wakeham SG (2002) A new, mechanistic model of organic carbon fluxes in the ocean based on the quantitative association of POC with ballast minerals. Deep Sea Res II 49:219–236CrossRefGoogle Scholar
  5. Barton ED et al (1998) The transition zone of the Canary Current upwelling region. Prog Oceanogr 41:455–504CrossRefGoogle Scholar
  6. Behrenfeld MJ, Falkowski PG (1997) Photosynthetic rates derived from satellite-based chlorophyll concentration. Limnol Oceanogr 42:1–20CrossRefGoogle Scholar
  7. Berelson WM (2002) Particle settling rates increase with depth in the ocean. Deep Sea Res II 49:237–251CrossRefGoogle Scholar
  8. Berger WH, Wefer G (1990) Export production: seasonality and intermittency, and paleoceanographic implications. Palaeogeogr Palaeoclimatol Palaeoecol 89:245–254CrossRefGoogle Scholar
  9. Berger WH, Smetacek V, Wefer G (1989) Ocean productivity and paleoproductivity : an overview. In: Berger WH, Smetacek V, Wefer G (eds) Productivity in the ocean: present and past. Wiley, New York, pp 1–34Google Scholar
  10. Blaas M, Dong C, Marchesiello P, McWilliams JC, Stolzenbach KD (2007) Sediment transport modeling on Southern Californian Shelves: A ROMS case study. Cont Shelf Res 27:832–853CrossRefGoogle Scholar
  11. Bory A, Newton PP (2000) Transport of airborne lithogenic material down through the water column in two contrasting regions of the eastern subtropical North Atlantic Ocean. Global Biogeochem Cycles 14(1):297–315CrossRefGoogle Scholar
  12. Bory A et al (2001) Downward particle flux within different productivity regimes off the Mauretanian upwelling zone (EUMELI program). Deep Sea Res II 48:2251–2282CrossRefGoogle Scholar
  13. Boyer TP, Stephens C, Antonov JI, Conkright ME, Locarnini RA, O’Brian TD, Garcia HE (2002) World Ocean Atlas 2001. Salinity. In: Levitus S (ed) NOAA Atlas NESDIS 50, vol 1. U.S. Government Printing Office, Washington, DC, pp 1–165Google Scholar
  14. Carr M-E (2002) Estimation of potential productivity in Eastern Boundary Currents using remote sensing. Deep Sea Res II 49:59–80CrossRefGoogle Scholar
  15. Chen C-TA, Liu K-K, MacDonald R (2003) Continental margin exchanges. In: Fasham MJR (ed) Ocean biogeochemisty, international geosphere-biosphere programme book. Springer, Berlin, pp 53–97Google Scholar
  16. Davenport R, Neuer S, Helmke P, Perez-Marrero J, Llinás O (2002) Primary productivity in the northern Canary Islands region as inferred from SeaWiFS imagery. Deep Sea Res II 49:3481–3496CrossRefGoogle Scholar
  17. da Silva A, Young C, Levitus S (1994) Atlas of surface marine data 1994, vols. 1–5, NOAA Atlas NESDIS 6–10. US Government Printing Office, Washington, DCGoogle Scholar
  18. de Menocal PB, Ruddiman WF, Pokras EM (1993) Influences of high- and low-latitude processes on African terrestrial climate: pleistocene eolian records from equatorial Atlantic ocean-drilling program site 663. Paleoceanography 8(2):209–242CrossRefGoogle Scholar
  19. Dierks AR, Asper VL (1987) In situ settling speeds of marine snow aggregates below the mixed layer: Black Sea and Gulf of Mexico. Deep Sea Res 44:385–398CrossRefGoogle Scholar
  20. Drake DE, Cacchione DA (1989) Estimates of the suspended sediment reference concentration (ca) and resuspension coefficient (γ0) from near-bed observations on the California shelf. Cont Shelf Res 9:51–64CrossRefGoogle Scholar
  21. Dugdale RC, Wilkerson FP, Minas HJ (1995) The role of a silicate pump in driving new production. Deep Sea Res 42(5):697–719CrossRefGoogle Scholar
  22. Fischer G, Wefer G (1996) Long-term observations of particle fluxes in the Eastern Atlantic: seasonality, changes of flux with depth and comparison with the sediment record. In: Wefer G, Berger WH, Siedler G, Webb DJ (eds) The South Atlantic: present and past circulation. Springer, Berlin, pp 325–344Google Scholar
  23. Fischer G, Donner B, Ratmeyer V, Davenport R, Wefer G (1996a) Distinct year-to-year flux variations off Cape Blanc during 1988–1991: relationship to δ18O-deduced sea-surface temperatures and trade winds. J Mar Res 54:73–98CrossRefGoogle Scholar
  24. Fischer G, Neuer S, Wefer G, Krause G (1996b) Short-term sedimentation pulses recored with a fluorescence sensor and sediment traps at 900 m depth in the Canary Basin. Limnol Oceanogr 41(6):1354–1359CrossRefGoogle Scholar
  25. Fischer G, Kalberer M, Donner B, Wefer G (1999) Stable isotopes of pteropod shells as recorders of sub-surface water conditions: comparison with the record of G. ruber and measurements. In: Fischer G, Wefer G (eds) Use of proxies in paleoceanography: examples from the South Atlantic. Springer, Berlin, pp 191–206Google Scholar
  26. Fischer G, Ratmeyer V, Wefer G (2000) Organic carbon fluxes in the Atlantic and the Southern Ocean: relationship to Primary Production compiled from satellite radiometer data. Deep Sea Res 47(2):1961–1997Google Scholar
  27. Fischer G, Gersonde R, Wefer G (2002) Organic carbon, biogenic silica and diatom fluxes in the marginal winter sea–ice zone and in the Polar Front Region: interannual variations and differences in composition. Deep Sea Res II 49:1721–1745CrossRefGoogle Scholar
  28. Fischer G et al. (2003) Transfer of particles into the deep Atlantic and the global ocean: control of nutrient supply and ballast production. In: Wefer G, Mulitza S, Ratmeyer V (eds) The South Atlantic in the Late Quaternary: Reconstruction of material budgets and current systems. Springer, Berlin, pp 21–46Google Scholar
  29. Fischer G, Neuer S, Davenport R, Romero O, Ratmeyer V, Donner B, Freudenthal T, Meggers H, Wefer G (2007) Control of ballast minerals on organic carbon export in the Eastern Boundary Current System (EBCs) off NW Africa. In: Liu K K et al (eds) CMTT volume, Springer, BerlinGoogle Scholar
  30. Fowler SW, Small LF (1972) Sinking rates of euphausiid fecal pellets. Limnol Oceanogr 17:293–296CrossRefGoogle Scholar
  31. Francois R, Honjo S, Krishfield R, Manganini S (2002) Factors controlling the flux of organic carbon in the bathypelagic ocean. Global Biogeochem Cycles 16(4):1087. doi: 10.1029/2001GB001722 Google Scholar
  32. Garcia M, Parker G (1991) Entrainment of bed sediment into suspension, J Hydr Eng 117(4):414–435CrossRefGoogle Scholar
  33. Hamm CE (2002) Interactive aggregation and sedimentation of diatoms and clay-sized lihtogenic material. Limnol Oceanogr 47(6):1790–1795CrossRefGoogle Scholar
  34. Hebbeln D, Marchant M, Wefer G (2000) Seasonal variations of the particle flux in the Peru-Chile current at 30°S under “normal” and El Nino conditions. Deep Sea Res II 47:2101–2128CrossRefGoogle Scholar
  35. Helmke P, Romero O, Fischer G (2005) Northwest African upwelling and its effect on off-shore organic carbon export to the deep sea. Global Biogeochem Cycles 19. doi: 10.1029/2004GB002265
  36. Hernández-Guerra A, Arístegui J, Cantón M, Nykjaer L (1993) Phytoplankton pigment patterns in the Canary Islands area as determined using Coastal Zone Colour Scanner data. Int J Remote Sensing 14(7):1431–1437CrossRefGoogle Scholar
  37. Honjo S, Doherty KW (1988) Large scale aperture time-series sediment traps; design, objectives, construction and application. Deep Sea Res 35:133–149CrossRefGoogle Scholar
  38. Honjo S, Manganini S J (1993) Annual biogenic particle fluxes to the interior of the North Atlantic Ocean; studies at 34°N 21°W and 48°N 21°W. Deep Sea Res I 40(1/2):587–607CrossRefGoogle Scholar
  39. Honjo S, Francois R, Manganini S, Dymond J, Collier R (2000) Particle fluxes to the interior of the Southern Ocean in the Western Pacific sector along 170°W. Deep Sea Res II 47:3521–3548CrossRefGoogle Scholar
  40. Ittekkot V (1993) The abiotically driven biological pump in the ocean and short-term fluctuations in atmospheric CO2 contents. Global Planet Change 8:17–25CrossRefGoogle Scholar
  41. Inthorn M, Mohrholz V, Zabel M (2006) Nepheloid layer distribution in the Benguela upwelling area offshore Namibia. Deep Sea Res I 53:1423–1438CrossRefGoogle Scholar
  42. Jahnke R (2003) Floor as a sediment trap: contributions to JGOFS from benthic flux studies. In: Final JGOFS conference in Washington DC, May 2003Google Scholar
  43. Jickells TD et al (2005) Global iron connections between desert dust, ocean biogeochemistry, and climate. Science 308:67–71CrossRefGoogle Scholar
  44. Karakas G et al (2006) High-resolution modelling of sediment erosion and particle transport across the NW African shelf. J Geophys Res 111(C06025). doi: 10.1029/2005JC003296
  45. Kaufman YJ et al (2005) Dust transport and deposition from the Terra-Moderate Resolution Imaging Spectroradiometer (MODIS) spacecraft over the Atlantic Ocean. J Geophys Res 110. doi: 10.1029/2003/JD004436
  46. Klaas C, Archer DE (2002) Association of sinking organic matter with various types of ballast in the deep sea: Implications for the rain ratio. Global Biogeochemical Cycles 16 (4):1116. doi: 10.1029/2001GB001765 Google Scholar
  47. Kremling K, Lentz U, Zeitzschel B, Schulz-Bull DE, Duinker JC (1996) New type of time-series sediment trap for the reliable collection of inorganic and organic trace chemical substances. Rev Scient Instr 67(12):4360–4363CrossRefGoogle Scholar
  48. Levitus S, Burgett R, Boyer T (1994) World Ocean Atlas 1994. NOAA Atlas NESDIS 3, vol 3: Nutrients, Department of Commerce, Washington DCGoogle Scholar
  49. Marchesiello P, McWilliams JC, Shchepetkin A (2001) Open boundary conditions for long-term integration of regional oceanic models. Ocean Model 3:1–20CrossRefGoogle Scholar
  50. Martin JH, Knauer GA, Karl DM, Broenkow WW (1987) VERTEX: carbon cycling in the northeast Pacific. Deep Sea Res 34(2):267–285CrossRefGoogle Scholar
  51. Martin JH, Fitzwater SE, Gordon RM (1990) Iron deficiency limits phytoplankton growth in Antarctic waters. Global Biogeochem Cycles 4(1):5–12CrossRefGoogle Scholar
  52. Milliman J et al (1999) Biologically mediated dissolution of calcium carbonate above the chemical lysocline. Deep Sea Res I 46:1653–1669CrossRefGoogle Scholar
  53. Mittelstaedt E (1991) The ocean boundary along the northwest African coast. Prog Oceanogr 26:307–355CrossRefGoogle Scholar
  54. Müller PJ, Fischer G (2001) A 4-year sediment trap record of alkenones from the filamentous upwelling region off Cape Blanc, NW Africa and a comparison with distributions in underlying sediments. Deep Sea Res I 48:1877–1903CrossRefGoogle Scholar
  55. Müller PJ, Fischer G (2003) C37-alkenones as paleotemperature tool: fundamentals based in sediment traps and surface sediments from the South Atlantic Ocean. In: Wefer G, Mulitza S, Ratmeyer V (eds) The South Atlantic in the Late Quaternary: reconstruction of material budgets and current systems. Springer, Berlin, pp 167–193Google Scholar
  56. Müller PJ, Schneider R (1993) An automated leaching method for the determination of opal in sediments and particulate matter. Deep Sea Res I 40(3):425–444CrossRefGoogle Scholar
  57. Neuer S, Ratmeyer V, Davenport R, Fischer G, Wefer G (1997) Deep water particle flux in the Canary Island region: seasonal trends in relation to long-term satellite derived pigment data and lateral sources. Deep Sea Res 44:1451–1466CrossRefGoogle Scholar
  58. Neuer S, Freudenthal T, Davenport R, Llinás O, Rueda M-J (2002) Seasonality of surface water properties and particle flux along a productivity gradient off NW Africa. Deep Sea Res II 49:3561–3576CrossRefGoogle Scholar
  59. Neuer S, Torres-Padron ME, Gelado-Caballeo MD, Rueda MJ, Hernandez-Brito J, Davenport R, Wefer G (2004) Dust deposition to the eastern subtropical North Atlantic gyre: Does ocean’s biogeochemistry respond? Global Biogeochemical Cycles 18. doi: 10.1029/2004GB002228
  60. Nowald N, Karakas G, Ratmeyer V, Fischer G, Schlitzer R, Davenport R, Wefer G (2006) Distribution and transport processes of marine particulate matter off Cape Blanc (NW-Africa): results from vertical camera profiles. Ocean Sci Disc 3:903–938CrossRefGoogle Scholar
  61. Passow U (2004) Switching perspectives: do mineral fluxes determine particulate organic fluxes or vice versa. Geochem, Geophys, Geosys 5(4): Q04002. doi: 10.1029/2003GC000670
  62. Pilskaln CH, Lehmann C, Padaun JB, Silver MW (1998) Spatial and temporal dynamics in marine aggregate abundance, sinking rate and flux: Monterey Bay, California. Deep Sea Res II 45:1803–1837CrossRefGoogle Scholar
  63. Prospero JM (1996) The atmospheric transport of particles to the ocean. In: Ittekkot V et al (eds) Particle Flux in the Ocean, SCOPE. Wiley, Chichester, pp 19–52Google Scholar
  64. Ragueneau O et al (2000) A review of the Si cycle in the modern ocean: recent progress and missing gaps in the application of biogenic opal as a paleoproductivity proxy. Global Planet Change 26:317–365CrossRefGoogle Scholar
  65. Ramaswamy V, Gaye B (2006) Regional variations in the fluxes of foraminifera carbonate, coccolithophorid carbonate and biogenic opal in the northern Indian Ocean. Deep Sea Res I 53:271–293CrossRefGoogle Scholar
  66. Ratmeyer V, Fischer G, Wefer G (1999) Lithogenic particle fluxes and grain size distributions in the deep ocean off northwest Africa: Implications for seasonal changes of aeolian dust input and downward transport. Deep Sea Res II 46:1289–1337CrossRefGoogle Scholar
  67. Romero OE, Fischer G, Lange CB, Wefer G (2000) Siliceous phytoplankton of the western equatorial Atlantic: sediment traps and surface sediments. Deep Sea Res II 47:1939–1959CrossRefGoogle Scholar
  68. Romero OE, Lange CB, Wefer G (2002) Interannual variability (1988–1991) of siliceous phytoplankton fluxes off northwest Africa. J Plankton Res 24(10):1035–1046CrossRefGoogle Scholar
  69. Romero OE, Dupont L, Wyputta U, Jahns S, Wefer G (2003) Temporal variability of fluxes of eolian-transported freshwater diatoms, phytoliths, and pollen grains off Cape Blanc as reflection of land-atmosphere-ocean interactions in northwest Africa. J Geophys Res 108(C5):22/1–22/11CrossRefGoogle Scholar
  70. Rühlemann C, Müller PJ, Schneider RR (1999) Organic carbon and carbonate as paleoproductivity proxies: examples from high and low latititude productivity areas of the tropical Atlantic. In: Fischer G, Wefer G (eds) Proxies in paleoceanography: Examples from the South Atlantic. Springer, Berlin, pp 315–344Google Scholar
  71. Sarnthein M, Tetzlaff G, Koopmann B, Wolter K, Pflaumann U (1981) Glacial and interglacial wind regimes over the eastern subtropical Atlantic and North-West Africa. Nature 293:193–196CrossRefGoogle Scholar
  72. Schemainda R, Nehring D, Schulz S (1975) Ozeanologische Untersuchungen zum Produktionspotential der nordwestafrikanischen Wasserauftriebsregion 1970–1973. Geodätische Geophysikalische Veröff 4:1–88Google Scholar
  73. Scholten JC et al (2001) Trapping efficiencies of sediment traps from the deep Eastern North Atlantic: the 230Th calibration. Deep Sea Res II 48:2383–2408CrossRefGoogle Scholar
  74. Shchepetkin AF, McWilliams JC (2005) The regional oceanic modeling system (ROMS): a split-explicit, free-surface, topography-following-coordinate oceanic model. Ocean Model 9(4):347–404CrossRefGoogle Scholar
  75. Siegel DA, Granata TC, Michaels AF ,Dickey TD (1990) Mesoscale Eddy Diffusion, Particle Sinking, and the Interpretation of Sediment Trap Data. J Geophys Res 95(C4):5305–5311CrossRefGoogle Scholar
  76. Smith JD, McLean SR (1977) Spatially averaged flow over a wavy bed. J Geophys Res 82:1735–1746CrossRefGoogle Scholar
  77. Smith WHF, Sandwell DT (1997) Global seafloor topography from satellite altimetry and ship depth soundings. Science 277:1957–1962Google Scholar
  78. Stephens C, Antonov JI, Boyer TP, Conkright ME, Locarnini RA, O’Brian TD, Garcia HE (2002) World Ocean Atlas 2001. Volume 1: Temperature. In: Levitus S (eds) NOAA Atlas NESDIS 49. U.S. Government Printing Office, Washington, DC, pp 1–167Google Scholar
  79. Stein R, Ten Haven HL, Littke R, Rullkötter J, Welte DH (1989) Accumulation of marine and terrigenous organic carbon at upwelling site 658 and non-upwelling Sites 657 and 659: Implications for the reconstruction of paleoenvironments in the eastern subtropical Atlantic through late Cenozoic times. Proc ODP Sci Results 108:361–386Google Scholar
  80. Takahashi K, Bé AWB (1984) Planktonic foraminfera: factors controlling sinking speeds. Deep Sea Res I (31):1477–1500Google Scholar
  81. Tsunogai S, Noriki S (1991) Particulate fluxes of carbonate and organic carbon in the ocean. Is the marine biological activity working as a sink of atmospheric carbon ? Tellus Ser A 43(2):256–266CrossRefGoogle Scholar
  82. Van Camp L, Nykjaer L, Mittelstadt E, Schlittenhardt P (1991) Upwelling and boundary circulation off Northwest Africa as depicted by infrared and visible satellite observations. Prog Oceanogr 26:357–402CrossRefGoogle Scholar
  83. Wefer G, Fischer G, Fütterer D, Gersonde R (1988) Seasonal particle flux in the Bransfield Strait, Antarctica. Deep Sea Res 35(6):891–898CrossRefGoogle Scholar
  84. Xu JP, Noble M, Eittreim SL (2002) Suspended sediment transport on the continental shelf near Davenport, California. Mar Geol 181:171–193CrossRefGoogle Scholar
  85. Yu EF, Francois R, Honjo S, Fleer AP, Manganini SJ, Rutgers van der Loeff MM, Ittekkot V (2001) Trapping efficiency of bottom-tethered sediment traps estimated from the intercepted fluxes of 230Th and 231Pa. Deep Sea Res I 48:865–889CrossRefGoogle Scholar
  86. Žarić S, Donner B, Fischer G, Mulitza S, Wefer G (2005) Sensitivity of planktic foraminifera to sea surface temperature and export production as derived from sediment trap data. Mar Micropaleont 55:75–105CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • G. Fischer
    • 1
  • G. Karakas
    • 3
  • M. Blaas
    • 4
  • V. Ratmeyer
    • 1
  • N. Nowald
    • 1
  • R. Schlitzer
    • 3
  • P. Helmke
    • 2
  • R. Davenport
    • 1
  • B. Donner
    • 1
  • S. Neuer
    • 2
  • G. Wefer
    • 1
  1. 1.Geosciences Department and Research Center Ocean Margins (RCOM), Klagenfurter StrasseUniversity of BremenBremenGermany
  2. 2.School of Life SciencesArizona State UniversityTempeUSA
  3. 3.Alfred-Wegener-Institute for Polar and Marine ResearchBremerhavenGermany
  4. 4.Delft HydraulicsDelftThe Netherlands

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