Scientia Marina, Vol 80, No 3 (2016)

Grain size, morphometry and mineralogy of airborne input in the Canary basin: evidence of iron particle retention in the mixed layer

Alfredo Jaramillo-Vélez
Grupo de Estudios Oceánicos “Luis Fernando Vásquez-Bedoya” (GEOc), Escuela Ambiental, Facultad de Ingeniería, Universidad de Antioquía , Colombia

Inmaculada Menéndez
Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria , Spain

Ignacio Alonso
Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria , Spain

José Mangas
Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria , Spain

Santiago Hernández-León
Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria , Spain


Aeolian dust plays an important role in climate and ocean processes. Particularly, Saharan dust deposition is of importance in the Canary Current due to its content of iron minerals, which are fertilizers of the ocean. In this work, dust particles are characterized mainly by granulometry, morphometry and mineralogy, using image processing and scanning northern Mauritania and the Western Sahara. The concentration of terrigenous material was measured in three environments: the atmosphere (300 m above sea level), the mixed layer at 10 m depth, and 150 m depth. Samples were collected before and during the dust events, thus allowing the effect of Saharan dust inputs in the water column to be assessed. The dominant grain size was coarse silt. Dominant minerals were iron oxy-hydroxides, silicates and Ca-Mg carbonates. A relative increase of iron mineral particles (hematite and goethite) was detected in the mixed layer, reflecting a higher permanence of iron in the water column despite the greater relative density of these minerals in comparison with the other minerals. This higher iron particle permanence does not appear to be explained by physical processes. The retention of this metal by colloids or microorganisms is suggested to explain its long residence time in the mixed layer.


textural analysis; Saharan dust; iron particles; Canary Islands

Full Text:



Alonso-González I., Arístegui J., Lee C., et al. 2010a. Role of slowly settling particles in the ocean carbon cycle. Geophys. Res. Lett. 37: L13608.

Alonso-González I., Arístegui J., Lee C., et al. 2010b. Regional and temporal variability of sinking organic matter in the subtropical northeast Atlantic Ocean: a biomarker diagnosis. Biogeosciences 7: 2101-2115.

Baker A., Jickells T. 2006. Mineral particle size as a control on aerosol iron solubility. Geophys. Res. Lett. 33: L17608.

Barbeau K., Moffett J. 2000. Laboratory and field studies of colloidal iron oxide dissolution as mediated by phagotrophy and photolysis. Limnol. Oceanogr. 45: 827-835.

Barbeau K., Moffett J., Caron D., et al. 1996. Role of protozoan grazing in relieving iron limitation of phytoplankton. Nature 380: 61-64.

Barcelona Supercomputing Center. 2011. (n.d.). Mineral Dust | BSC-CNS. [online] Available at: earth-sciences/mineral-dust-forecast-system [Accessed 27 Mar and 3 Apr. 2011].

Benavides M., Arístegui J., Agawin N., et al. 2013. Enhancement of nitrogen fixation rates by unicellular diazotrophs vs. Trichodesmium after a dust deposition event in the Canary Islands. Limnol. Oceanogr. 58: 267-275.

Blott S., Pye K. 2001. Gradistat: A grain size distribution and statistics package for the analysis of unconsolidated sediments. Earth Surf. Process. Landforms 26: 1237-1248.

Blott S., Pye K. 2008. Particle shape: A review and new methods of characterization and classification. Sedimentology 55: 31-63.

Bory A., Dulac F., Moulin C., et al. 2002. Atmospheric and oceanic dust fluxes in the northeastern tropical Atlantic Ocean: How close a coupling? Ann. Geophys. 20: 2067-2076.

Bronne G., Chauve J.J. 1979. Precambrian banded iron-formations of the Ijil Group (Kediat Ijil, Reguibat Shield, Mauritania). Econ. Geol. 74: 77-94.

Brust J., Waniek J. 2010. Atmospheric dust contribution to deep-sea particle fluxes in the subtropical Northeast Atlantic. Deep-Sea Res. Part I 57: 988-998.

Brust J., Schulz-Bull D., Leipe T., et al. 2011. Descending particles: From the atmosphere to the deep ocean-A time series study in the subtropical NE Atlantic. Geophys. Res. Lett. 38: L06603.

Chase Z., Price N.M. 1998. Metabolic consequences of iron deficiency in heterotrophic marine protozoa. Limnol. Oceanogr. 42: 1673-1684.

De la Rocha C., Passow U. 2007. Factors influencing the sinking of POC and the efficiency of the biological carbon pump. Deep- Sea Res. Part II 54: 639-658.

Delgado J. 2010. Origin and SEM analysis of aerosols in the high mountain of Tenerife (Canary Islands). Engineering 2: 1119-1129.

Ersoy O. 2010. Surface area and volume measurements of volcanic ash particles by SEM stereoscopic imaging. J. Volcanol. Geotherm. Res. 190: 290-296.

Fahl K., Nöthig, E. 2007. Lithogenic and biogenic particle fluxes on the Lomonosov Ridge (central Arctic Ocean) and their relevance for sediment accumulation: Vertical vs. lateral transport. Deep-Sea Res. Part I 54: 1256-1272.

Gelado-Caballero M., López-García P., Prieto S., et al. 2012. Long-term aerosol measurements in Gran Canaria, Canary Islands: Particle concentration, sources and elemental composition. J. Geophys. Res. D: 117.

González-Dávila M., Santana-Casiano M., Millero F. 2005. Oxidation of iron (II) nanomolar with H2O2 in sea water. Geochim. Cosmochim. Acta 69: 83-93.

Goossens D. 2005. Quantification of the dry aeolian deposition of dust on horizontal surfaces: An experimental comparison of theory and measurements. Sedimentology 52: 859-873.

Goudie A., Middleton N. 2001. Saharan dust storms: Nature and consequences. Earth-Sci. Rev. 56: 179-204.

Henderiks J., Freudenthal T., Meggers H., et al. 2002. Glacial-interglacial variability of particle accumulation in the Canary Basin: A time-slice approach. Deep-Sea Res. Part II 49: 3675-3705.

Hurlbut C., Sharp W. 1998. Dana's minerals and who to study them. 4th ed. John Wiley and Sons, Inc., 328 pp.

Iwamoto Y., Yumimoto K., Toratani M., et al. 2011. Biogeochemical implications of increased mineral particle concentrations in surface waters of the northwestern North Pacific during an Asian dust event. Geophys. Res. Lett. 38: L01604.

Jickells T., An Z., Andersen K., et al. 2005. Global iron connections between desert dust, ocean biogeochemistry, and climate. Science 308: 67-71. PMid:15802595

Journet E., Desboeufs K., Caquineau S., et al. 2008. Mineralogy as a critical factor of dust iron solubility. Geophys. Res. Lett. 35: L07805.

Kaufman Y., Tanré D., Boucher O. 2002. A satellite view of aerosols in the climate system. Nature 419: 215-223. PMid:12226676

Klaver A., Formenti P., Caquineau S., et al. 2011. Physico-chemical and optical properties of sahelian and saharan mineral dust: In situ measurements during the gerbils campaign. Q.J.R. Meteorol. Soc. 137: 1193-1210.

Lázaro F., Gutiérrez L., Barrón V., et al. 2008. The speciation of iron in desert dust collected in Gran Canaria (Canary Islands): Combined chemical, magnetic and optical analysis. Atmos. Environ. 42: 8987-8996.

Lehbib S., Arribas A., Melgarejo J. 2009. Depósitos de Hierro de Tipo BIF en la Región del Tiris, Sáhara Occidental. Macla 11: 111-112 .

Levine I. 2001. Physical Chemistry (5th ed.). McGraw-Hill, Boston. ISBN 978-0072534955. 955 pp.

Lide D. 1996. Handbook of chemistry and Physics. CRC Press. Special student edition. 77 ed., 2608 pp.

Mahowald N., Engelstaedter S., Luo C., et al. 2009. Atmospheric iron deposition: global distribution, variability, and human perturbations. Ann. Rev. Mar. Sci. 1: 245-278. PMid:21141037

Menéndez I., Díaz-Hernández J., Mangas J., et al. 2007. Airborne dust accumulation and soil development in the North-East sector of Gran Canaria (Canary Islands, Spain). J. Arid Environ. 71: 57-81.

Menéndez I., Derbyshire E., Engelbrecht J., et al. 2009. Saharan dust and the aerosols on the Canary Islands: past and present. In: Cheng M., Liu W. (eds.), Airborne Particulates. Nova Science Publisher, New York, 39-80 pp.

Mills M., Ridame C., Davey M., et al. 2004. Iron and phosphorus co-limit nitrogen fixation in the eastern tropical North Atlantic. Nature 429: 292-294. PMid:15152251

Neuer S., Torres-Padrón M., Gelado-Caballero M., et al. 2004. Dust deposition pulses to the eastern subtropical North Atlantic gyre: Does ocean's biogeochemistry respond? Global Biogeochem. Cycles 18: 1-10.

Nodwell L., Price N. 2001. Direct use of inorganic colloidal iron by marine mixotrophic phytoplankton. Limnol. Oceanogr. 46: 765-777.

Okada K., Heintzenberg J., Kai K., et al. 2001. Shape of atmospheric mineral particles collected in three Chinese arid-regions. Geophys. Res. Lett. 28: 3123-3126.

Parekh P., Joos F., Müller S.A. 2008. Modeling assessment of the interplay between aeolian iron fluxes and iron-binding ligands in controlling carbon dioxide fluctuations during Antarctic warm events. Paleoceanography 23: PA4202.

Prospero J., Carlson T. 1980. Saharan air outbreaks over the tropical North Atlantic. Pure Appl Geophys. 119: 677-691.

Ratmeyer V., Balzer W., Bergametti G., et al. 1999. Seasonal impact of mineral dust on deep-ocean particle flux in the eastern subtropical Atlantic Ocean. Mar. Geol. 159: 241-252.

Rawle A. 2003. Basic principles of particle-size analysis. Surf. Coat. Int. 86: 58-65.

Red de Control y Vigilancia de la Calidad del Aire de Canarias. 2011. Formulario de datos históricos. Retrieved March and April 2011, Database available in:

Reid E., Reid J., Meier M., et al. 2003. Characterization of African dust transported to Puerto Rico by individual particle and size segregated bulk analysis. J. Geophys. Res. D. 108: 8591.

Rocci G., Bronner G., Deschamps M. 1991. Crystalline basement of the West Africa Craton. In: Dallmeyer R. and Lecorche J. (eds) The West African Orogens and Circum-Atlantic Correlatives. Springer, Berlin, 31-61.

Rubin M. 2011. Dust- and mineral-iron utilization by the marine dinitrogen-fixer Trichodesmium. Nat. Geosci. 4: 529-534.

Sahara Airmass Outbreak Model. 2011- HYSPLIT - Hybrid Single Particle Lagrangian Integrated Trajectory model. Hysplit.uhu. es. Retrieved March and April 2011, from:

Scheuvens D., Schütz L., Kandler K., et al. 2013. Bulk composition of northern African dust and its source sediments — A compilation. Earth-Sci. Rev. 116: 170-194.

Schmincke H., Sumita M. 2010. Geological evolution of the Canary Islands: a young volcanic archipelago adjacent to the old African Continent. Ed. Görres, Koblenz. 200 pp. PMid:21196746

Shi Z., Bonneville S., Krom M.D., et al. 2011. Iron dissolution kinetics of mineral dust at low pH during simulated atmospheric processing. Atmos. Chem. Phys. 11: 995-1007.

Shi Z., Krom M., Jickells T., et al. 2012. Impacts on iron solubility in the mineral dust by processes in the source region and the atmosphere: A review. Aeolian Res. 5: 21-42.

Sohm J. 2011. Nitrogen fixation by Trichodesmium spp. and unicellular diazotrophs in the North Pacific Subtropical Gyre. J. Geophys. Res.-Biogeo. 116.

Soulaimani A., Burkhard M. 2008. The Anti-Atlas chain (Morocco): the southern margin of the Variscan belt along the edge of the West African Craton. Geol. Soc. London Spec. Publ. 297: 433-452.

Torres O., Bhartia P.K., Herman J.R., et al. 2002. A long-term record of aerosol optical depth from TOMS observations and comparison to AERONET measurements. J. Atmos. Sci. 59: 398-413.<0398:ALTROA>2.0.CO;2

Wilson S., Steinberg D., Buesseler K. 2008. Changes in fecal pellet characteristics with depth as indicators of zooplankton repackaging of particles in the mesopelagic zone of the subtropical and subarctic North Pacific Ocean. Deep-Sea Res. Part II 55: 1636-1647.

Zingg T. 1935. Beitrag zur Schotteranalyse. Mineral. Petrogr. 15: 39-140.

Copyright (c) 2016 Consejo Superior de Investigaciones Científicas (CSIC)

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Contact us

Technical support