IADO   05364
INSTITUTO ARGENTINO DE OCEANOGRAFIA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
The role of salt-marsh sediments on nutrients, organic matter and pollutants transference to the estuarine system: sources or sinks?
Reunión:
Encuentro; 2010 The Meeting of the Americas- AGU; 2010
Resumen:
Wetlands
play a significant role within biogeochemical cycles considering that valuable
biological, chemical and sedimentary processes are performed there. In
addition, salt-marshes largely developed in coastal marine and estuarine
systems are usually highly productive environments, acting as source or sink of
materials, depending on different factors including tidal energy, salinity,
oxygen release, etc. Global climate change, with the consequent sea level rise,
could threaten salt marshes and their ecological roles.
Bahía Blanca Estuary, which is our study case, includes many salt-marshes
associated to large tidal flats ; these salt-marshes have different exposure
time to tidal flood within the semidiurnal tide regime which characterizes the
estuary. The production of halophyte vegetation, important (specially the
belowground one) to determine retention capacity of these environments as well
as the transference processes of nutrients, organic matter and several
pollutants from salt-marshes sediments to the estuarine water are analyzed in
the present communication, highlighting the influence of physical-chemical
parameters (i.e. Eh and pH, salinity, dissolved oxygen) on the final direction
of the process.
Bahía Blanca
salt-marshes show low production rates and seasonal differences in biomass of
the macrophytes. The content of nutrients and heavy metals in plant tissues is
a similar range as observed in other salt-marshes. The sediments are highly
reduced and rich in organic matter and nutrients. Several heavy metals (i.e.
Cu, Ni, Fe, Zn) showed to be accumulated in the aboveground tissues of the
halophytes, while others (i.e. Cd, Pb, Mn) do it on aerated ones.
The analyzed data set allows sustaining that it is not possible to define just
a permanent role of these sub-systems within the estuary, considering that
these functions could be modified according to the corresponding environmental
changes in the estuarine conditions, as well as seasonal changes in vegetation.
Consequently, the ability of several physical-chemical processes as indicators
of the transference dynamics within the estuary is fully discussed.