Inorganic nutrients and organic matter tidal time-scale variation in estuaries from Argentina

MARCOVECCHIO JORGE; SPETTER CARLA; DE MARCO SILVIA; BELTRAME ORNELLA; AMIN OSCAR; COMOGLIO, LAURA; FREIJE R.H; BOTTÉ SANDRA; DELUCCHI FEDERICO; ARIAS A

Bahia Blanca

Simposio; Science and Management of Estuaries and Coasts: A tile of two hemispheres. ECSA44; 2008

ECSA

Land-derived materials are regulated by coastal and shelf environmental conditions before being transported to the open sea. It is of great concern to understand these processes and to establish the extent in which they modify terrestrial compounds fluxes to the oceans, such as nutrients. At present, one of the topics of highest interest within environmental coastal studies is the direction and magnitude of inorganic nutrients and the organic matter exchange fluxes between the water column and the associated tidal plains during the dairy tidal cycle. These processes, together with the local hydrographic conditions, define the key role of this type of environments: its functioning as nutrient and organic matter reservoir and/or as a source. A research program including three estuaries with different tidal amplitude levels were developed in Argentine coastal system: Mar Chiquita Coastal Lagoon (microtidal) and Bahía Blanca Estuary (mesotidal) both in Buenos Aires Province littoral, and Rio Chico Estuary (macrotidal) in Tierra del Fuego. Levels of DIN (nitrate + nitrite + ammonium), DIP, DISi, and organic matter were measured in estuarine water column and tidal plain porewater in a tidal time-scale along a year. Results showed no significant variations during the tidal cycle neither in the macrotidal estuary nor in the mesotidal one. In the opposite, the studied microtidal estuary presented strong variations on nutrients and organic matter concentrations along the tidal cycle. Particular conditions within the systems (sediment characteristics, porewater chemical environment, hydrodynamics, anthropogenic sources, etc) were considered to understand these results.