CHAPTER 6 . The Argentina Estuaries: A Review
113
microscales. The 10 d peak corresponds to the frequency of storm passage for the study
zone and the 5.6 d characterizes the synaptic scale. These periods are typical of high
and mid latitudes. The 12 h peak corresponds to the local wind circulation: the sea
breeze. Therefore, the sea level variations of the Quequen River Estuary is mostly due
to the effect of the meteorological forcing.
Furthermore, tidal records also show the presence high frequency oscillations. The
periods for these seiches are between 3 and 25 min, although the later is predominant.
Even though normal oscillations have amplitudes of the order of 10 cm, commonly
appear oscillations of up to 1.5 m. Normally the oscillations increase in size suddenly
and unexplained, but inducing serious consequences for the navigation of large cargo
vessels. At least two vessels departing from the harbour with full load hit the bottom
due to the occurrence of sudden large oscillation, fortunately without damage. The
resonance periods for the harbour calculated using Merian's and Helmholz's equations give theoretical values of 3.3 and 6.4 min, which are well below the typical 25 min.
Most probably the seiches are produced by internal waves generated at the interface.
The foraminiferal and the camoebian biocenosis of the Quequen River Estuary has
been studied by Boltovskoy and Boltovskoy (1968) and Wright (1968). They found
Miliammina fusca, Elphidium excavatum, Rotalia beccarii ex gr. Parkinsoniana,
Bulimina patagonica (f. glabra), Trochammina inflata and small calcareous Miliolidae.
These species can tolerate very large changes in salinity (about 5-28 psu). The Quequen
River Estuary is an interesting area for ecological studies not only on foraminifera,
but for many other group of benthos and plankton.
6.3.3
Bahia Blanca Estuary
The Bahia Blanca area has suffered an accelerated urban expansion due to the presence of a major petrochemical industrial park, a thermoelectric plant, and an important deep-water harbour system from which most of the agricultural products of the
country are exported. All of them are placed on the northern margin of the Principal
Channel of the Bahia Blanca Estuary (Fig. 6.1). Industrial wastes (mainly oil derivates,
pesticides, heavy metals, etc.) and untreated sewage discharges from coastallocalities generate increasing contamination problems. Therefore, the distribution pattern
of chemical parameters in a large populated and industrialized area of this estuary
has received special attention (Freije et al. 1981; Sericano and Pucci 1982; Orozco Storni
et al. 1984; Lara et al. 1985). The levels and ranges of heavy metals in estuarine areas
not associated with anthropogenic activities have also been studied in water and sediments (Villa and Pucci 1985, 1987; Zubillaga and Pucci 1986; Villa 1988). Whereas the
geomorphologic characteristics and hydrography of the Bahia Blanca Estuary has been
extensively studied (Sequeira and Piccolo 1985; Serman 1985; Piccolo et al. 1987; Perillo
et al. 1987a,b; Perillo and Sequeira 1989) and a chapter of this book is devoted to this
estuary; therefore only a brief summary is presented here.
Bahia Blanca Estuary is a geomorphological complex environment derived from a
former Late Pleistocene-Early Holocene delta complex. Tidal flats and channels with
subordinate islands and few salt marsh areas are the main features of the estuary. These
channels are partly closed by modified ebb deltas. The estuary has a general triangular shape with the major channels trending in a NW-SE direction. Dominant sedi-
113
microscales. The 10 d peak corresponds to the frequency of storm passage for the study
zone and the 5.6 d characterizes the synaptic scale. These periods are typical of high
and mid latitudes. The 12 h peak corresponds to the local wind circulation: the sea
breeze. Therefore, the sea level variations of the Quequen River Estuary is mostly due
to the effect of the meteorological forcing.
Furthermore, tidal records also show the presence high frequency oscillations. The
periods for these seiches are between 3 and 25 min, although the later is predominant.
Even though normal oscillations have amplitudes of the order of 10 cm, commonly
appear oscillations of up to 1.5 m. Normally the oscillations increase in size suddenly
and unexplained, but inducing serious consequences for the navigation of large cargo
vessels. At least two vessels departing from the harbour with full load hit the bottom
due to the occurrence of sudden large oscillation, fortunately without damage. The
resonance periods for the harbour calculated using Merian's and Helmholz's equations give theoretical values of 3.3 and 6.4 min, which are well below the typical 25 min.
Most probably the seiches are produced by internal waves generated at the interface.
The foraminiferal and the camoebian biocenosis of the Quequen River Estuary has
been studied by Boltovskoy and Boltovskoy (1968) and Wright (1968). They found
Miliammina fusca, Elphidium excavatum, Rotalia beccarii ex gr. Parkinsoniana,
Bulimina patagonica (f. glabra), Trochammina inflata and small calcareous Miliolidae.
These species can tolerate very large changes in salinity (about 5-28 psu). The Quequen
River Estuary is an interesting area for ecological studies not only on foraminifera,
but for many other group of benthos and plankton.
6.3.3
Bahia Blanca Estuary
The Bahia Blanca area has suffered an accelerated urban expansion due to the presence of a major petrochemical industrial park, a thermoelectric plant, and an important deep-water harbour system from which most of the agricultural products of the
country are exported. All of them are placed on the northern margin of the Principal
Channel of the Bahia Blanca Estuary (Fig. 6.1). Industrial wastes (mainly oil derivates,
pesticides, heavy metals, etc.) and untreated sewage discharges from coastallocalities generate increasing contamination problems. Therefore, the distribution pattern
of chemical parameters in a large populated and industrialized area of this estuary
has received special attention (Freije et al. 1981; Sericano and Pucci 1982; Orozco Storni
et al. 1984; Lara et al. 1985). The levels and ranges of heavy metals in estuarine areas
not associated with anthropogenic activities have also been studied in water and sediments (Villa and Pucci 1985, 1987; Zubillaga and Pucci 1986; Villa 1988). Whereas the
geomorphologic characteristics and hydrography of the Bahia Blanca Estuary has been
extensively studied (Sequeira and Piccolo 1985; Serman 1985; Piccolo et al. 1987; Perillo
et al. 1987a,b; Perillo and Sequeira 1989) and a chapter of this book is devoted to this
estuary; therefore only a brief summary is presented here.
Bahia Blanca Estuary is a geomorphological complex environment derived from a
former Late Pleistocene-Early Holocene delta complex. Tidal flats and channels with
subordinate islands and few salt marsh areas are the main features of the estuary. These
channels are partly closed by modified ebb deltas. The estuary has a general triangular shape with the major channels trending in a NW-SE direction. Dominant sedi-