ASSESSMENT OF DISSOLVED INORGANIC NUTRIENT LEVELS IN WATER AND POREWATER OF BAHIA BLANCA ESTUARY, ARGENTINA

SPETTER, CARLA VANESA; ASTEASUAIN, RAÚL; ARLENGHI, JAVIER; FREIJE, HUGO; MARCOVECCHIO, JORGE

Buzios

Simposio; 4th International Symposium Environmental Geochemistry In Tropical Countries; 2004

Universidad de Brasil

The process of modification of the nutritional status on an aquatic system by nutrient level increase is so called eutrophication. The impact of the eutrophication process, originated by alteration of primary compounds of nitrogen and phosphorous, is important keeping in mind they regulate the biological processes development within aquatic environments, as well as they behave on all compartments of the whole ecosystem (sediments, water, porewater, etc) ; this fact means that the eutrophication process supports the occurrence of significant variations in the biogeochemical cycles of N and P within these environments. In addition, the coastal zone acts as a buffer area inserted between land and ocean systems, and retaining suspended material and nutrients from land origin. The main aim of the present study is to understand the behavior of the select inorganic nutrients (nitrite, nitrate, ammonium, phosphate and silicate) in the water column and porewater at the inner zone of the Bahia Blanca estuary, looking for a characterization of this environment from its potential biological development viewpoint. Corresponding samples were taken during a year, in a two-a-month frequency basis. Temperature, salinity, pH, turbidity and dissolved oxygen were in situ measured in each sampling.- Besides, other samples for the determination of water column and porewater inorganic nutrients, as well as water column chlorophyll a and phaeopigments concentrations, were obtained. in the water column (0.10 fi 3.63 ØM) was higher than in the porewater (0.01fi0.98 (DM, surface and 0.05-0.92 olVI, sub-surface); has showed a similar trend (n.d.-21.58 øM, n.d.-4.19 øM and 0.08 2.83 øM, respectively). Unlike this, NH4+ has presented an inverse trend, with higher levels in the porewater (2.96-50.66 øM and 103.44-241.82 øM, surface and sub-surface respectively) than in the water column (5.47-41.74 22M). P043- concentrations were between n.d. and 4.3 øM. Finally, Si02- levels were higher in the porewater (71.60 -406.22 oM and 103.44 - 888.35 oM, surface and sub-surface respectively) than in the water column (57.79 - 270.37 ØM). Furthermore maximum Chlorophyll a values has varied between 38.93 and 23.74 og.L-1 in winter and 21.90 and 22.470911 in summer.