Tracing the Agulhas leakage with lead isotopes

The transport of warm and salty waters from the Indian Ocean to the South Atlantic by the Agulhas Current constitutes a key return route of the meridional overturning circulation. Despite the importance of the Agulhas Leakage on interoceanic exchange, its role on biogeochemical cycles is poorly documented. Here we present the first lead (Pb) concentration and isotope data for surface seawater collected during the GEOTRACES cruise D357 in the Agulhas current system. Lead in surface waters of the Cape Basin is described by three distinct end‐members: the South African coast, open South Atlantic seawater, and Indian Ocean seawater. The latter stands out in its Pb isotopic composition and can be tracked within two distinct Agulhas rings. High Pb concentrations in the Agulhas rings further corroborate an Indian Ocean provenance of waters and suggest that the Agulhas Leakage represents a major conduit not only for heat but also for trace metals.

[1]  E. Boyle,et al.  Impact of anthropogenic Pb and ocean circulation on the recent distribution of Pb isotopes in the Indian Ocean , 2015 .

[2]  Peer Bork,et al.  Environmental characteristics of Agulhas rings affect interocean plankton transport , 2015, Science.

[3]  M. Rehkämper,et al.  High-precision measurements of seawater Pb isotope compositions by double spike thermal ionization mass spectrometry. , 2015, Analytica chimica acta.

[4]  E. Boyle,et al.  Coral-based history of lead and lead isotopes of the surface Indian Ocean since the mid-20th century , 2014 .

[5]  E. Boyle,et al.  Anthropogenic Lead Emissions in the Ocean: The Evolving Global Experiment , 2014 .

[6]  P. Worsfold,et al.  Biogeochemical cycling of dissolved zinc along the GEOTRACES South Atlantic transect GA10 at 40°S , 2014 .

[7]  L. Reisberg,et al.  Behavior of osmium at the freshwater–saltwater interface based on Ganga derived sediments from the estuarine zone , 2011 .

[8]  H. McGowan,et al.  Comment on "Lead isotopic evidence for an Australian source of aeolian dust to Antarctica at times over the last 170,000 years" by P. De Deckker, M. Norman, , 2010 .

[9]  R. Zahn,et al.  Contrasting multiproxy reconstructions of surface ocean hydrography in the Agulhas Corridor and implications for the Agulhas Leakage during the last 345,000 years , 2010 .

[10]  M. Norman,et al.  Lead isotopic evidence for an Australian source of aeolian dust to Antarctica at times over the last 170,000 years , 2010 .

[11]  E. Bard,et al.  Migration of the subtropical front as a modulator of glacial climate , 2009, Nature.

[12]  Ben C. Reynolds,et al.  The double spike toolbox , 2009 .

[13]  M. Ferrat,et al.  Stable lead isotope compositions in selected coals from around the world and implications for present day aerosol source tracing. , 2009, Environmental science & technology.

[14]  W. D. Ruijter.  The Agulhas Current , 2008 .

[15]  N. Mahowald.  Anthropocene changes in desert area: Sensitivity to climate model predictions , 2007 .

[16]  S. Goldstein,et al.  Reduced Agulhas Leakage during the Last Glacial Maximum inferred from an integrated provenance and flux study , 2006 .

[17]  T. Jickells,et al.  Atmospheric trace metals over the Atlantic and South Indian Oceans: Investigation of metal concentrations and lead isotope ratios in coastal and remote marine aerosols , 2006 .

[18]  C. Jeandel,et al.  Neodymium isotopes as a new tool for quantifying exchange fluxes at the continent-ocean interface , 2005 .

[19]  R. Schneider,et al.  Vigorous exchange between the Indian and Atlantic oceans at the end of the past five glacial periods , 2004, Nature.

[20]  A. Bollhöfer,et al.  The temporal stability in lead isotopic signatures at selected sites in the Southern and Northern Hemispheres , 2002 .

[21]  E. Maier‐Reimer,et al.  Advection and removal of 210Pb and stable Pb isotopes in the oceans: a general circulation model study , 2002 .

[22]  S. Rintoul,et al.  Circulation, Renewal, and Modification of Antarctic Mode and Intermediate Water , 2001 .

[23]  Andreas Bollhöfer,et al.  Isotopic source signatures for atmospheric lead: the Northern Hemisphere , 2000 .

[24]  Wilbert Weijer,et al.  Indian‐Atlantic interocean exchange: Dynamics, estimation and impact , 1999 .

[25]  Y. Erel,et al.  Leakage of industrial lead into the hydrocycle , 1994 .

[26]  M. L. Gründlingh,et al.  Eddy fluxes of heat and salt from the southwest Indian Ocean into the southeast Atlantic Ocean : a case study , 1994 .

[27]  E. Helmers,et al.  Lead and aluminum in Atlantic surface waters (50°N to 50°S) reflecting anthropogenic and natural sources in the Eolian transport , 1993 .

[28]  R. Weiss,et al.  Thermocline and intermediate water communication between the south Atlantic and Indian oceans , 1992 .

[29]  P. Richardson,et al.  Seasonal cycle of velocity in the Atlantic North Equatorial Countercurrent as measured by surface drifters, current meters, and ship drifts , 1987 .

[30]  P. Gabrielli,et al.  Lead isotopic compositions in the EPICA Dome C ice core and Southern Hemisphere Potential Source Areas , 2010 .

[31]  R. Schlitzer.  Ocean Data View , 2007 .

[32]  F. Monnaa,et al.  Origin of atmospheric lead in Johannesburg , South Africa , 2006 .

[33]  B. Hamelin,et al.  Role of oceanic circulation on contaminant lead distribution in the South Atlantic , 2001 .

[34]  B. Hamelin,et al.  Isotopic evidence of contaminant lead in the South Atlantic troposphere and surface waters , 2001 .