Atmospheric Fe deposition modes at Bermuda and the adjacent Sargasso Sea

• Published in: Geochemistry, Geophysics, Geosystems
• Main Authors: Tian, Zhenglong, Ollivier, Patrick, Veron, Alain, Church, Thomas
• Other Authors: Bureau de Recherches Géologiques et Minières (BRGM), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), School of Marine Science and Policy, University of Delaware Newark
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2008
• Subjects: Fe deposition; deposition mode; NAO; [SDE]Environmental Sciences; [SDE.MCG]Environmental Sciences/Global Changes; [SDU]Sciences of the Universe [physics]; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; North Atlantic; North Atlantic oscillation
• Online Access: https://hal.science/hal-02116103; https://hal.science/hal-02116103/document; https://hal.science/hal-02116103/file/2007GC001868.pdf; https://doi.org/10.1029/2007GC001868

International audience The atmospheric fluxes of Fe and Al were determined from bulk (wet + dry) plus wet only deposition and aerosol samples collected at Bermuda from 1999 to 2001. During the sampling period, dry deposition accounted for majority (>70%) of total Fe deposition estimated by both modeled and measured means. This contrasts the North Pacific, where generally wet dominates dry deposition. This may be caused by the size and proximity of continental dust sources and seasonal patterns of precipitation to the North Atlantic. Comparing time series measurement of wet soluble Fe deposition indicates that the North Atlantic Oscillation (NAO) may impact the deposition mode of Fe in these areas. The dry deposition velocities of Fe-bearing aerosols (DDV Fe) were estimated from paired averages of measured dry deposition (bulk-wet fluxes) divided by corresponding aerosol concentrations, and a seasonal trend was observed. During the summer months of 1999, the DDV Fe ranged from 0.1 to 0.3 cm s À1 yet, during the fall and winter months, the DDV Fe ranged from 2.0 to 6.0 cm s À1. It is hypothesized that with increased humidity and wind speeds at Bermuda during fall and winter, mineral aerosol particles could be internally mixed with sea salt and gaseous S and N pollutants to increase effective particle sizes. Such marine particle aggregation is reported elsewhere and could seasonally increase the apparent dry deposition velocity of mineral aerosols.