Étude de la remontée relative des niveaux d'eau de l'estuaire du Saint-Laurent

1992 ◽  
Vol 19 (2) ◽  
pp. 252-259 ◽  
Author(s):  
François Anctil ◽  
Jean-Pierre Troude
Keyword(s):  
High Water ◽  
Water Levels ◽  
Freshwater Input ◽  
Relative Variation ◽  
Lawrence Estuary ◽  
High Discharge ◽  
Mean Water Level ◽  
Stability Of Water ◽  
St Lawrence Estuary ◽  
St Lawrence River

Data available on water levels in the St. Lawrence Estuary were used to evaluate the relative variation of mean water levels in this area. Only measurements taken at Pointe-au-Père could be used to evaluate this parameter with the required precision; a relative stability of water levels (−0.3 ± 0.5 mm/year) was observed. Upstream stations, especially the ones in the estuary, are highly influenced by the freshwater input of the St. Lawrence River. The high discharge of the river has been identified as the main cause of high water levels observed between 1970 and 1988 and, consequently, of bank erosion at the limit of the St. Lawrence estuary. Key words: discharge, erosion, estuary, mean water level, relative variation.

Le Panache du Saguenay

1983 ◽  
Vol 40 (1) ◽  
pp. 52-60 ◽  
Author(s):  
J. Lebel ◽  
E. Pelletier ◽  
M. Bergeron ◽  
N. Belzile ◽  
G. Marquis
Keyword(s):  
Surface Layer ◽  
Deep Water ◽  
High Tide ◽  
Lawrence Estuary ◽  
Fresh Waters ◽  
Saguenay Fjord ◽  
Region Data ◽  
Saguenay River ◽  
St Lawrence Estuary ◽  
St Lawrence River

The large difference between the alkalinity of the fresh waters of the St. Lawrence River (1.475 mmol∙kg−1) and the Saguenay River (0.134 mmol∙kg−1) was used to locate the region on the St. Lawrence estuary which is under the influence of the Saguenay River. This method has the advantage over classical measurements such as salinity and temperature that it is independent of the upwelling of deep water in this region. Data was obtained in the St. Lawrence estuary near the mouth of the Saguenay fjord using a network of 33 stations at slack low tide and 23 stations at slack high tide. The results show that, at low tide, Saguenay water forms a plume which extends more than 10 km from the mouth of the fjord into the estuary. At high tide the plume is restricted to the surface layer as the Saguenay waters are pushed back into the fjord.

Distribution, Transport, and Composition of Suspended Matter in the St. Lawrence Estuary

1973 ◽  
Vol 10 (9) ◽  
pp. 1380-1396 ◽  
Author(s):  
Bruno F. d'Anglejan ◽  
Eric C. Smith
Keyword(s):  
Suspended Matter ◽  
Large Time ◽  
Total Suspended Matter ◽  
Quebec City ◽  
Lawrence Estuary ◽  
Tidal Circulation ◽  
Saguenay River ◽  
St Lawrence Estuary ◽  
Vertical Gradients ◽  
St Lawrence River

The distribution of total suspended matter in the estuary of the St. Lawrence River was studied by quantitative filtration through membrane filters. Tidal fluctuations in the vertical gradients of suspensoids were followed at fixed stations along the estuary. The concentrations varied from nearly 40 mg/1 below near Ile d'Orléans, to values less than 1 mg/1 at the downstream end of the upper estuary near the Saguenay River entrance. The tidal mean concentrations for the fixed stations ranged from 20 mg/1 to 2 mg/1. A turbidity maximum, which develops because of entrapments of particles by the tidal circulation, extends for 100 km below Quebec City. In this zone large vertical gradients changing in intensity with the tide by resuspension of settled material exist above the bottom. The total suspended matter is 60% to more than 90% inorganic by weight, and has a mean particle size between 5 and 7 μ. The annual rate of transport of suspended material out of the upper estuary at a section near the Saguenay River is estimated at less than 1 × 106 metric tons.Chemical and mineralogical analyses were performed on 23 suspensoid samples collected by centrifuging large volumes of water. The clay mineral composition of the less than 2 μ fraction is on the average 1.5% montmorillonite, 8% kaolinite, 31% chlorite, and 60% illite. However, large time and space variations are found both in the chemistry and mineralogy of the suspended matter.

scholarly journals Tumors in St. Lawrence Beluga Whales (Delphinapterus leucas)

1994 ◽  
Vol 31 (4) ◽  
pp. 444-449 ◽  
Author(s):  
S. De Guise ◽  
A. Lagacé ◽  
P. Béland
Keyword(s):  
Small Population ◽  
Delphinapterus Leucas ◽  
Carcinogenic Effect ◽  
Lawrence Estuary ◽  
Beluga Whales ◽  
High Prevalence ◽  
Endangered Population ◽  
High Concentrations ◽  
St Lawrence Estuary ◽  
St Lawrence River

A population of 450–500 belugas ( Delphinapterus leucas) resides in the polluted estuary of the St. Lawrence River. Stranded carcasses of this endangered population were recovered and necropsied. High concentrations of organochlorines, heavy metals, and benzo-a-pyrene exposure were demonstrated in tissues of these whales. Between 1988 and 1990, 21 tumors were found in 12 out of 24 carcasses. Among these tumors, six were malignant and 15 were benign. The animals were between 1.5 and >29 years of age, and the ages of animals with and without tumors did not differ when two juvenile animals (1.5 and 3.5 years of age) were excluded. Seven other neoplasms had been reported previously in six out of 21 well-preserved carcasses examined in the same laboratory between 1982 and 1987. Overall, 28 of the 75 confirmed tumors reported so far in cetaceans (37%) were from this small population of beluga whales in the St. Lawrence Estuary. Such a high prevalence of tumors would suggest an influence of contaminants through a direct carcinogenic effect and/or a decreased resistance to the development of tumors in this population.

The Limnological Units of the Lower Great Lakes - St. Lawrence River Corridor and Their Role in the Source and Aquatic Fate of Toxic Contaminants

1986 ◽  
Vol 21 (2) ◽  
pp. 168-186 ◽  
Author(s):  
R.J. Allan
Keyword(s):  
Great Lakes ◽  
Residence Time ◽  
Control Strategies ◽  
Salt Water ◽  
Transport Systems ◽  
Long Term Effects ◽  
Lawrence Estuary ◽  
St Lawrence Estuary ◽  
St Lawrence River

Abstract The waterways of the lower Great Lakes and St. Lawrence River, between Sarnia and the Saguenay Fiord, are made up of four limnological units. The first comprises the high discharge, rapid flow rivers, namely the St. Clair, Detroit, Niagara and St. Lawrence. Second are the four shallow, short residence time, riverine lakes, namely St. Clair, St. Francois, St. Louis and St. Pierre. Third are the two, relatively deep, long residence time, lower Great Lakes Erie and Ontario. Lastly, there is the freshwater-salt water mixing zone of the upper St. Lawrence Estuary. The rivers are essentially sources and transport systems of toxic contaminants on a grand scale. The riverine lakes provide only temporary storage or sinks even for contaminants associated with sediments because these are eventually resuspended and moved on downstream. The major sinks, where long-term effects are most evident are the two lower Great Lakes and the St. Lawrence Estuary. These sites are also where sediment associated contaminants can be permanently removed by deep burial in bottom sediments. However, even here, a proportion of the contaminant load passes on downstream and eventually out to the Gulf of St. Lawrence. The distinctive characteristics of the four limnological units are discussed in relation to sources and fate of toxic contaminants. Understanding the role of the units is critical to development of toxic chemicals control strategies and reduction in aquatic ecosystem contamination.

The Saguenay Fjord: A Third Factor in the Toxic Chemical Contamination of the St. Lawrence River Estuary

1990 ◽  
Vol 25 (1) ◽  
pp. 1-14
Author(s):  
R.J. Allan
Keyword(s):  
Toxic Metals ◽  
River Estuary ◽  
Organic Chemical ◽  
Organic Chemicals ◽  
Chemical Contamination ◽  
Lawrence Estuary ◽  
The Past ◽  
Saguenay Fjord ◽  
St Lawrence Estuary ◽  
St Lawrence River

Abstract The Saguenay Fjord enters the north shore of the St. Lawrence River estuary. The St. Lawrence River is one source of a variety of toxic metals and organic chemicals to its estuary. Some of these chemicals are transported by the river from its source in Lake Ontario and others are added along its course. However, the second major source of water inflow to the St. Lawrence Estuary is the Saguenay Fjord, which is by no means free of contamination. This paper overviews the types of toxic metals and organic chemical contamination and sources in the fjord proper and upstream in its drainage basin. The principal contaminants recorded in bottom sediments are polyaromatic hydrocarbons and mercury. An extensive forest products industry may also be a source of toxic chlorinated organic chemicals. The combined (peak) inputs of these chemicals to the Saguenay Fjord system was in the past and may have continued for many years, even decades. The relationship between the type of contaminants introduced in the past to the St. Lawrence estuary by the St. Lawrence River and the Saguenay Fjord may have implications concerning contamination of the beluga whale population which is located most frequently in the estuary near the fjord inflow.

Submarine Sand Dunes in the St. Lawrence Estuary

1971 ◽  
Vol 8 (11) ◽  
pp. 1480-1486 ◽  
Author(s):  
B. F. d'Anglejan
Keyword(s):  
Water Waves ◽  
Seismic Reflection ◽  
Sand Dunes ◽  
Wave Length ◽  
Quebec City ◽  
Lawrence Estuary ◽  
Seismic Reflection Profiling ◽  
St Lawrence Estuary ◽  
High Degree ◽  
St Lawrence River

Areas of sand dunes and ripples have been observed in the estuary of the St. Lawrence River below Quebec City. A train of dunes 18 km long is present in the channel of Ile-aux-Coudres. Symmetrical dunes as high as 12 m and reaching 120 m in wave-length are abundant. Symmetrical subsurface crests are also revealed by seismic reflection profiling. The mode of origin of these dunes is not yet established. However, because of the high degree of stratification present in the water column, the possible role played by internal water waves in their formation should be considered.

Geochemistry of zinc, copper and lead in the sediments of the estuary and Gulf of St. Lawrence

1978 ◽  
Vol 15 (5) ◽  
pp. 757-772 ◽  
Author(s):  
D. H. Loring
Keyword(s):  
Organic Material ◽  
Lower Estuary ◽  
Lawrence Estuary ◽  
Fine Grained ◽  
Elemental Concentrations ◽  
Suspended Particulate ◽  
Fine Grained Material ◽  
St Lawrence Estuary ◽  
Total Sedimentation ◽  
St Lawrence River

Total elemental concentrations (Zn, 8–215 ppm; Cu, 3–76 ppm; Pb, 9–66 ppm) vary texturally and regionally in the sediments of the St. Lawrence estuary and open Gulf of St. Lawrence.Chemical and mineralogical analyses indicate that 8–39% of the total Zn, 7–20% of the total Cu and 15–26% of the total Pb are weakly held by fine-grained organic material, oxide grain coatings, ion exchange positions and carbonates in the sediments. These concentrations are potentially available to the biota. The remaining concentrations (61–93% of the total) are not readily available but are locked up in fine-grained sulphide, oxide and silicate minerals.The highest concentrations of the detrital and non-detrital contributions occur in the pelites or muds of the upper estuary. Seaward these concentrations decrease as the natural and anthropogenic supply of dissolved and suspended particulate matter from the St. Lawrence River diminishes. The upper estuary acts as a sink for these elements because most of the non-detrital Zn, Pb and Cu supplied are removed here by adsorption onto fine-grained suspended terrestrial organic material from solution or before entry (Cu) and transferred to the bottom along with other fine-grained material in response to the present depositional conditions. Decreasing concentrations of these elements are deposited seaward and the sedimentation intensities of the non-detrital elements remain constant with fluctuations in total sedimentation intensity in the lower estuary and open Gulf of St. Lawrence.Biogeochemically, Zn is a contaminant and Pb and Cu are potential contaminants of the upper estuary sediments. Zn and Pb are potential contaminants in the lower estuary but all the elements are at or near natural levels in the open gulf sediments.

Hunting for Quaternary Faults in Eastern Canada: A Critical Appraisal of Two Potential Candidates

2020 ◽  
Author(s):  
Nicolas Pinet ◽  
Maurice Lamontagne ◽  
Mathieu J. Duchesne ◽  
Virginia I. Brake
Keyword(s):  
River Estuary ◽  
Seismic Profile ◽  
Fault Scarp ◽  
Seismic Zone ◽  
Eastern Canada ◽  
Lawrence Estuary ◽  
Surface Ruptures ◽  
St Lawrence Estuary ◽  
Fault Scarps ◽  
St Lawrence River

Abstract This study documents two potential neotectonic features in the seismically active St. Lawrence estuary and western part of the Gulf of St. Lawrence of Quebec, Canada. Historically, the region is the locus of series of damaging earthquakes, including the 1663 M 7 earthquake, which suggests the occurrence of coseismic surface ruptures beneath the St. Lawrence River. In the western Gulf of St. Lawrence (Lower St. Lawrence seismic zone), a potential fault scarp identified on a vintage seismic profile has been investigated through high-resolution seismic and multibeam bathymetry data. On the seafloor, the scarp corresponds to an ∼1.8  m high (maximum) feature that is located above a buried escarpment of the Paleozoic bedrock. Holocene units are draping over the escarpment on one profile, but are possibly cut on two others. The scarp meets several of the criteria generally associated with neotectonic features. However, a close look at the data indicates that the staircase geometry of the top of the bedrock and its expression at the surface is linked, at least partially, with the presence of an erosion-resistant unit. This makes a neotectonic reactivation possible but not proven. In the Tadoussac area, ∼40  km north of the Charlevoix seismic zone, the offshore extension of the St. Laurent fault corresponds to an ∼110  m high bathymetric escarpment with well-preserved triangular facets. Such “fresh” morphology is unique in the St. Lawrence River Estuary and may attest to Quaternary displacements, yet other interpretations may also explain the unusual preservation of the escarpment. These two case studies illustrate the difficulty to unambiguously document Holocene fault scarps, even in the marine domain in which the sedimentary succession is generally continuous.

Nutrient Distribution in the St. Lawrence Estuary

1977 ◽  
Vol 34 (11) ◽  
pp. 2104-2116 ◽  
Author(s):  
Paul Greisman ◽  
Grant Ingram
Keyword(s):  
Intermediate Layer ◽  
Internal Tide ◽  
Horizontal Distribution ◽  
Estuarine System ◽  
Nutrient Distribution ◽  
Surface Distribution ◽  
Lawrence Estuary ◽  
Freshwater Source ◽  
St Lawrence Estuary ◽  
St Lawrence River

The horizontal distribution of nutrients in the St. Lawrence estuary during early July of 1975 is presented. The major sources of nutrients to the estuarine system appeared to be from the St. Lawrence River and the intermediate layer of the Laurentian Channel. By the assumption of simple mixing and conservation, the surface distribution of nutrients has been calculated. Differences between the calculated and observed values may be attributable to consumption, variability of the freshwater source and of the internal tide amplitude. Key words: nutrient distribution, estuarine circulation, mixing

Seaward Nutrient Transport in the Lower St. Lawrence Estuary

1976 ◽  
Vol 33 (6) ◽  
pp. 1271-1277 ◽  
Author(s):  
Michael Sinclair ◽  
Mohammed El-Sabh ◽  
Jean-Rock Brindle
Keyword(s):  
Nutrient Transport ◽  
Volume Transport ◽  
Published Data ◽  
Annual Data ◽  
Freshwater Input ◽  
Nitrogen And Phosphorus ◽  
Lawrence Estuary ◽  
Annual Variability ◽  
Total Dissolved Nitrogen ◽  
St Lawrence Estuary

A transect across the lower St. Lawrence estuary was occupied to estimate volume transport and nutrient distributions (total dissolved nitrogen and phosphorus, and silicate) during February and May through September. Seaward transport was restricted to the upper 50 m and varied from 17 × 103 m3/s (August) to 129 × 103 m3/s (May). Nutrient and volume transport data are combined to estimate seasonal variability in monthly surface nutrient transport towards the Gulf of St. Lawrence. The estimates vary as follows: 0.72–6.72 × 103 tons N/mo, 0.05–0.48 × 103 tons P/mo and 0.50–6.73 tons Si/mo. Ratios between monthly freshwater input into the estuary and the corresponding values for net seaward transport, which varied from 1.1 to 9.4, are combined with annual data (1960–73) on monthly freshwater input into the estuary to estimate potential annual variability in seaward transport for each of the above months. Observed nutrient data, with the above transport estimates, suggest the possible range in monthly seaward nutrient transport that would be associated with the annual variability in monthly freshwater input into the estuary. Seaward nitrogen transport from May through September, estimated at 2.3 × 104 tons, is considered in relation to published data on the primary production in the western part of the Gulf of St. Lawrence. The estuary supplied a smaller amount of nutrients to the Gulf than has previously been assumed.

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