AMANDES research project PI: C. Jeandel-P.Seyler 4 french joint labs IRD/CNRS/Univ. Brasilian cooperations: UnB, UFF, USP (IO, IPEN) Processo CNPq n° / Measures and models Weathered flux, LMTG Exchanged flux, LEGOS CEREGE Measures and models, POC, Legos/LA Amandes Andines OuestEst Impact of the Amazone discharge on the Atlantic chemistry?

AMANDES (AMazone-ANDES): Main questions OUR APPROACH: Coupling dynamic/ geochemistry/ modeling/ satellite data assimilation Continuum continent-estuary-shelf-ocean  Constrain the nature, transformations and dispersion into the ocean of the fluxes of “trace elements and isotopes (TEIs)” weathered from the Andine mountains  Improve the modeling of the dynamical circulation shelf/slope/open ocean In order to better quantify - fresh water transport and its impact on the regional circulation - tidal effects on this transport, re-suspension and sediment re-distribution - impact of these dynamics on the chemical element transformation/dispersion  Quantify the impact of these fluxes on the chemical composition of the open ocean waters off the Amazone mouth, simultaneously constrained by the coastal and western boundary current dynamics

Contribution of the time series HyBAm to AMANDES 1- Temporal variability of the TEIs at Obidos 2 - Propagation of the tide wave in the estuary, down Obidos Institut de Recherche pour le Développement

Area selected for the study of oceanic tide waves propagation. Triangular symbols indicate hydrometric stations. The longer side of the rectangle is about 1200 km long Study Area

Amandes project Hydrodynamics of the shelf/estuary/river system F. Lyard, Y. Le Bars, R. Belmiro LEGOS, CNRS, Toulouse Univ. Sao Paolo

Approach Multi-scale dynamics: from the global ocean circulation to the Amazon river flow and backward 2D/3D hydrodynamic model, unstructured grid modelling 1st step (2D): Tides, storm surges, river flow 2nd step (3D): Shelf circulation, river plume, open ocean outflow

Unstructured grid Necessary to describe the regional, estuary and river channels details

Amazon river’s shelf dynamical issues It is a macro-tidal zone It is connected to the north brazil current system It has the world-largest fresh-water discharge The estuary is 500 km wide, with complex channels connections and semi-permeable shores (mangroves) Tidal waves propagate inside the river up to Obidos (500 km upstream) due to the profound river bed Sediment transport and erosion is responsible for time-varying shorelines and bathymetry at the river mouth Bottom rugosity is strongly affected by sediment transport and re- suspension (mud lens)

 CO 2, nutrients, oxygen: carbonate chemistry of the waters (N. Lefèvre, LOCEAN and T. Meziane, Lille)  Radium isotopes (226Ra, 228Ra and 224Ra, 233Ra): Tracers of continent-shelf-open ocean exchange process, submarine groundwater (Van Beek LEGOS, De Oliveira, USP) Nd and iron isotopes: Tracers of sources and exchange processes (Jeandel, Lacan, LEGOS) Lead isotopes: Tracers of sources and exchange processes (Hamelin, Claude, CEREGE) 210 Pb, 7 Be, 234 Th: Tracers sedimentation rates, coastal/open ocean processes (Radakovitch, CEREGE) 9 Be/ 10 Be: Tracers of weathering processes (Hamelin and Bourlès, CEREGE; Seyler, LMTG) Hg and REE speciation: tracers of processus and contaminants (J. Sonke, L.Maurice-B., P. Seyler, P. Moreira-T, LMTG; UnB, ANA (+ CPRM), UFRJ (COPPE) Which tracers will be measured?

ADCP de fond P1 P3 P4 P6P6 P7P7 P9 1x couranto+S+T 2x couranto+S+T Para-S0 Amaz-S0 Strategy and sampling, on the shelf: 4 cruises Oct-Nov 2007, jan 2008, march 2008, July 2008, R/V ANTEA, IRD  9 mooring lines, including 3 ADCP at the break of the shelf (100m depth)  Bathymetry (historical and new data)  Tide gauges (shelf and estuary)  Water sampling: dissolved and solid phases, filtration and ultra-filtration on board, 3 depths.  Large volumes: numerous TEIs  Multi-coring, interstitial waters  Radiometer

Our wishes, as a follow-up to Amandes …but no research vessel so far! Goal: quantify the impact of the Amazon inputs on the Atlantic ocean chemistry Could be part, or the starting point of a Geotraces section.