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Posts tagged Caspian Sea

Sediments in Karabogas Bay and Southeastern Caspian Sea

38.5N 51.6E

September 28th, 2012 Category: Lakes, Sediments

Caspian Sea – September 26th, 2012

Sediments, possibly mixed with phytoplankton growth, color the southeastern shores of the Caspian Sea. Some are also visible in Karabogas Bay, a shallow inundated depression in the northwestern corner of Turkmenistan that forms a lagoon of the Caspian Sea. Linked to the sea via a very narrow opening in a rocky ridge, the salinity of the bay is about 35%, compared to the Caspian Sea’s 1.2% and 3.5% for the world’s oceans. Because of the exceptionally high salinity it has practically no marine vegetation.

Algal Growth Near Volga River Delta, Caspian Sea

45.9N 49.9E

September 23rd, 2012 Category: Phytoplankton, Rivers, Sediments

Caspian Sea – September 17th, 2012

The Volga Delta is the largest river delta in Europe, and occurs where Europe’s largest river system, the Volga River, drains into the Caspian Sea in Russia’s Astrakhan Oblast, north-east of the republic of Kalmykia. The delta is located in the Caspian Depression—the far eastern part of the delta lies in Kazakhstan. The delta drains into the Caspian approximately 60 km downstream from the city of Astrakhan.

Industrial and agricultural modification to the delta plain has resulted in significant wetland loss. Between 1984 and 2001, the delta lost 277 km² of wetlands, or an average of approximately 16 km² per year, from natural and human-induced causes. The Volga discharges large amounts of industrial waste and sediment into the relatively shallow northern part of the Caspian Sea. The added fertilizers nourish the algal blooms that grow on the surface of the sea, clearly visible in the upper half of this image, allowing them to grow larger.

Water Level Changes in Caspian Sea

42.0N 50.0E

August 14th, 2012 Category: Lakes

Caspian Sea – August 13th, 2012

The Caspian Sea is a landlocked sea between Asia and Europe. It is the world’s largest inland body of water, with a surface area of 371,000 km² (143,000 sq. mi.), and therefore has characteristics common to both seas and lakes.

The Caspian Sea is bordered by Russia (Dagestan, Kalmykia, Astrakhan Oblast), Republic of Azerbaijan, Iran (Guilan, Mazandaran and Golestan provinces), Turkmenistan, and Kazakhstan, with the central Asian steppes to the north and east. On its eastern Turkmen shore is a large embayment, the Kara Bogaz Gol (or Karabogas Bay), which here appears lighter blue in color by the right edge of the image.

The Volga River (about 80% of the inflow, visible in the upper left corner) and the Ural River (east of the former) discharge into the Caspian Sea, but it is endorheic, i.e. there is no natural outflow (other than by evaporation). Thus the Caspian ecosystem is a closed basin, with its own sea level history that is independent of the eustatic level of the world’s oceans. The level of the Caspian has fallen and risen, often rapidly, many times over the centuries.

Over the centuries, Caspian Sea levels have changed in synchronicity with the estimated discharge of the Volga, which in turn depends on rainfall levels in its vast catchment basin. Precipitation is related to variations in the amount of North Atlantic depressions that reach the interior, and they in turn are affected by cycles of the North Atlantic Oscillation. Thus levels in the Caspian sea relate to atmospheric conditions in the North Atlantic thousands of miles to the north and west. These factors make the Caspian Sea a valuable place to study the causes and effects of global climate change.

 

Green Sediments and Algal Growth in Northern Caspian Sea

45.2N 50.1E

August 6th, 2012 Category: Sediments

Indonesia – August 5th, 2012

The Volga River, the largest in Europe, drains 20% of the European land area and is the source of 80% of the Caspian Sea’s freshwater inflow. Here, the river’s delta can be seen in the upper left quadrant.  Water entering the sea through the delta contributes to the sediments and algal growth in the northern part of the sea. The river’s lower reaches are heavily developed with numerous unregulated releases of chemical and biological pollutants.

Although existing data are sparse and of questionable quality, there is ample evidence to suggest that the Volga is one of the principal sources of transboundary contaminants into the Caspian. The magnitude of fossil fuel extraction and transport activity constitute risks to water quality. Underwater oil and gas pipelines have been constructed or proposed, increasing potential environmental threats

 

Sediments and Phytoplankton in Caspian and Black Seas

44.4N 48.4E

July 26th, 2012 Category: Rivers

Caspian Sea- July 25th, 2012

The bright colors in the northern part of the Caspian Sea are due partly to sediments from rivers such as the Volga, easily recognizable by its large, green delta, and the Ural, to the east of the former. They are also due in part to phytoplankton growth, which is likely encourages by the influx of nutrients from the two rivers. Upon opening the full image, the Black Sea  can be observed to the west. The phytoplankton bloom that has been flourishing there over the last month (click here for previous images) has now almost completely waned.

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