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Sediments in Southern Part of Great Slave Lake’s Main Basin, Canada

62.6N 110.5W

June 25th, 2013 Category: Lakes, Sediments MODISTerra

Canada – June 24th, 2013

The Great Slave Lake is an enormous, complex body of water. It is the fourth largest lake in Canada and was formed as a result of glacial scouring. The lake has a large, open western basin and a narrow eastern arm with many islands.

Great Slave Lake is drained by the MacKenzie River and has many inflows, of which the Slave River from Lake Athabasca is the largest. Each day in the summer, the Slave River dumps 54,000 metric tons of dissolved minerals and 36,000 metric tons of silt into the southern part of the main lake basin, as can be seen here, which has a mineral content of 160 ppm.

The eastern arm and northern shore of the main basin have a lower dissolved mineral content (22-82 ppm) as a result of dilution by stream inflow off the Pre-Cambrian Shield. The large bays of the eastern arm are extremely deep (e.g. Christie Bay 614 m) and permafrost covers most of the north shore.

This extremely oligotrophic lake has low standing planktonic crops, a limited benthic invertebrate community (six species), and sparse populations of fish. The short summer in this subarctic climate is reflected by the condensed two-week period of yearly growth in whitefish during August (click here for more information).

Sediments and Melting Ice in James Bay, Canada – June 24th, 2013

52.6N 80.1W

June 24th, 2013 Category: Image of the day, Sediments MODISTerra

Canada – June 22nd, 2013

James Bay and Hudson Bay constitute a large, shallow, inland sea connected to the Atlantic Ocean by Hudson Strait and the Labrador Sea, and to the Arctic Ocean by the Foxe Basin, and Fury and Hecla Strait. Currents are strongly affected by influxes of fresh water from rivers and, during the open-water season, by wind stress. Cold saline water enters Hudson Bay and James Bay from the northwest. Less saline surface outflows occur along the eastern shores of James Bay and Hudson Bay north to Hudson Strait.

These two “bays” are the largest bodies of water in the world that seasonally freeze over each winter and become ice-free each summer. In Hudson Bay, the ice cover starts to form in northern areas by late October and continues to grow until a maximum cover is reached at he end of April. Polynya (open water leads in the ice which are known to be important biologically throughout the Arctic) are found predominantly along the north-west and east coasts of Hudson Bay, both coasts of James Bay, and in the vicinity of the Belcher Islands. In James Bay, the ice cover begins to decay in late May, and the area becomes ice-free by the end of July.

The watershed of Hudson Bay and James Bay covers well over one-third of Canada, from southern Alberta to central Ontario to Baffin Island, as well as parts of North Dakota and Minnesota in the United States. The rivers flowing into Hudson Bay and James Bay discharge more than twice the flow of either the Mackenzie or St. Lawrence rivers. The seasonal timing of this freshwater discharge is a major factor governing the productivity and JSC of the region. Hydro developments that change the timing and rate of flow of fresh water may cause changes in the nature and duration of ice-cover; habitats of marine mammals, fish, and migratory birds; currents into and out of Hudson Bay/James Bay; seasonal and annual loads of sediments and nutrients to marine ecosystems (likely leading to lower biological productivity of estuaries and coastal areas); and anadromous fish populations (click here for more information).

Large Plumes of Smoke from Wildfires Near James Bay, Canada – June 22nd, 2013

51.9N 78W

June 22nd, 2013 Category: Fires, Image of the day, Sediments MODISTerra

Canada – June 22nd, 2013

Several large fires can be seen burning in Quebec, east of James Bay (left edge), in Canada. The fires are releasing thick plumes of white smoke that blow mostly towards the east. James Bay appears brown in color due to sediment washed in from numerous rivers.

How Deforestation Impacts the Amazon River, Brazil – June 15th, 2013

0.4N 50.2W

June 15th, 2013 Category: Deforestation, Image of the day, Sediments MODISAqua

Brazil – June 15th, 2013

The Amazon Basin is the largest drainage basin in the world, covering over 7,049,947km2 of land, supplying the Amazon River with all of its water. The Amazon forest is an extremely important habitat containing 30.7% of the world’s rainforest and is the most species-rich biome in the entire world.

Deforestation has been a major problem in the Amazon since 1970s with the forest now 17.1% smaller than it originally was, which equates to 699,746km2 of forest lost. The Amazon has lost more forest than the total amount of forest India has, standing at around 440,000km2. The rate of deforestation has been and still is increasing every year.

The drastic amounts of deforestation obviously have a large impact, especially on the Amazon River itself, whose mouth is visible here. Forest cover anchors the soil, acting as a resistance to erosion, and when an area is cleared of forest erosion rates sky rocket. In a study done on the Ivory Coast a forested slope lost 0.03 hectares of soil per year, while a deforested slope lost up to 90 hectares per year, an increase of 3000%. All of this eroded sediment seeps into the river and is carried along its entire length to the delta on the east coast of Brazil.

An increase in sediment load has many adverse impacts: it can smother fish eggs, diminishing fish populations and hurting the ecosystem as well as the fishing industry, it can damage the infrastructure of a country by destroying bridges and dams which may hurt the economy, and it can increase flood rates and sizes by raising the river bed (click here for more information).

Fires East of James Bay, Canada – June 14th, 2013

51.6N 78.2W

June 14th, 2013 Category: Fires, Image of the day, Sediments VIIRSSuomi-NPP

Canada – June 14th, 2013

Three large fires can be seen east of James Bay, Canada, releasing thick plumes of smoke that fan outwards as they blow south. In the bay, which is part of the larger Hudson Bay, melting ice and the influx of dark brown and tan sediments give the waters a variety of different tones.

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