Considering the data for all the rivers at the continental level, there has been little change in nitrate (NO3-N) concentrations between the two decades under comparison. Changes in the median value were not statistically significant. European rivers showed the highest nitrate loads transported to the marine environment. Comparing data from the two decades, North American and European rivers have remained fairly stable, while major river basins i...

This graphic shows the average calcium levels, in milligrams per litre, at major river mouths for the time periods 1976 to 1990 and 1991 to 2000. The graphic also shows the changes in average calcium levels between these two time periods.

This graphic shows the average calcium levels, in milligrams per litre, at major river mouths for the time periods 1976 to 1990 and 1991 to 2000. The graphic also shows the changes in average calcium levels between these two time periods.

Rivers form a hydrological mosaic, with an estimated 263 international river basins covering 45.3% of the land surface area of the earth, excluding Antarctica. This graphic shows the locations of 26 of the world's major river basins. A basin is defined as the land area (watershed) where all surface water drains to a certain river.

Estimates of global water resources based on several different calculation methods have produced varied estimates. This graphic illustrates the proportions of saltwater and freshwater that make up the earth's water resources. It also shows what percentage of the world's freshwater is located in lakes and river storage; in groundwater, including soil moisture, swamp water and permafrost, and in glaciers and permanent snow cover.

Estimates of global water resources based on several different calculation methods have produced varied estimates. This graphic illustrates the proportions of saltwater and freshwater that make up the earth's water resources. It also shows what percentage of the world's freshwater is located in lakes and river storage; in groundwater, including soil moisture, swamp water and permafrost, and in glaciers and permanent snow cover.

Kazakhstan is located in Central Asia, northwest of China; a small portion west of the Ural River in eastern-most Europe, comprising of 2,717,300 sq km. It has a population of 15,185,844 (2005). Major environmental concerns are: radioactive or toxic chemical sites associated with former defense industries and test ranges scattered throughout the country pose health risks for humans and animals; industrial pollution is severe in some cities; becau...

The Caspian Sea runs north and south, extending over 1,200 km, with an average width of 320 km. It covers approximately 400,000 sq km (an area slightly larger than Germany). The population of the region is about 14 million, distributed over the coastal provinces of five countries: 6.5 million in Iran, 3.9 million in Russia, 2.2 million in Azerbaijan, 0.8 million in Kazakhstan and 0.4 million in Turkmenistan.

The Caspian Sea runs north and south, extending over 1,200 km, with an average width of 320 km. It covers approximately 400,000 sq km (an area slightly larger than Germany). The population of the region is about 14 million, distributed over the coastal provinces of five countries: 6.5 million in Iran, 3.9 million in Russia, 2.2 million in Azerbaijan, 0.8 million in Kazakhstan and 0.4 million in Turkmenistan.

The Himalayas–Hindu Kush, Kunlun Shan, Pamir and Tien Shan mountain ranges function as water towers, providing water to people through much of Asia. The glacier-fed rivers originating from the Himalaya mountain ranges surrounding the Tibetan Plateau comprise the largest river run-off from any single location in the world. While the mountains are homes to some 170 million people, the rivers that drain these mountains influence the lives of about 4...

The icebreaking date for the Tornio River in Finland has been recorded since 1693. With the increased greenhouse effect, impacts on the cryosphere are likely. One impact will be less ice on rivers and lakes. Freeze-up dates will be delayed, and break-up will begin earlier. The period of river-ice could be shortened by up to a month. Many rivers within the temperate regions could become ice-free or develop only intermittent or partial ice coverage...

The icebreaking date for the Tornio River in Finland has been recorded since 1693. With the increased greenhouse effect, impacts on the cryosphere are likely. One impact will be less ice on rivers and lakes. Freeze-up dates will be delayed, and break-up will begin earlier. The period of river-ice could be shortened by up to a month. Many rivers within the temperate regions could become ice-free or develop only intermittent or partial ice coverage...

The icebreaking date for the Tornio River in Finland has been recorded since 1693. With the increased greenhouse effect, impacts on the cryosphere are likely. One impact will be less ice on rivers and lakes. Freeze-up dates will be delayed, and break-up will begin earlier. The period of river-ice could be shortened by up to a month. Many rivers within the temperate regions could become ice-free or develop only intermittent or partial ice coverage...

The icebreaking date for the Tornio River in Finland has been recorded since 1693. With the increased greenhouse effect, impacts on the cryosphere are likely. One impact will be less ice on rivers and lakes. Freeze-up dates will be delayed, and break-up will begin earlier. The period of river-ice could be shortened by up to a month. Many rivers within the temperate regions could become ice-free or develop only intermittent or partial ice coverage...

The construction of a large number of dams and industrial facilities on the rivers feeding the Caspian has caused a significant change in the quantity of water inflow. The creation of a succession of large reservoirs, especially on the lower and middle Volga, has led to significant losses in flow rate due to additional evaporation from the surface of the water.

The construction of a large number of dams and industrial facilities on the rivers feeding the Caspian has caused a significant change in the quantity of water inflow. The creation of a succession of large reservoirs, especially on the lower and middle Volga, has led to significant losses in flow rate due to additional evaporation from the surface of the water.

The construction of a large number of dams and industrial facilities on the rivers feeding the Caspian has caused a significant change in the quantity of water inflow. The creation of a succession of large reservoirs, especially on the lower and middle Volga, has led to significant losses in flow rate due to additional evaporation from the surface of the water.

The Caspian Sea runs north and south, extending over 1,200 km, with an average width of 320 km. It covers approximately 400,000 sq km (an area slightly larger than Germany). The population of the region is about 14 million, distributed over the coastal provinces of five countries: 6.5 million in Iran, 3.9 million in Russia, 2.2 million in Azerbaijan, 0.8 million in Kazakhstan and 0.4 million in Turkmenistan.

The Caspian Sea runs north and south, extending over 1,200 km, with an average width of 320 km. It covers approximately 400,000 sq km (an area slightly larger than Germany). The population of the region is about 14 million, distributed over the coastal provinces of five countries: 6.5 million in Iran, 3.9 million in Russia, 2.2 million in Azerbaijan, 0.8 million in Kazakhstan and 0.4 million in Turkmenistan.

The Caspian Sea runs north and south, extending over 1,200 km, with an average width of 320 km. It covers approximately 400,000 sq km (an area slightly larger than Germany). The population of the region is about 14 million, distributed over the coastal provinces of five countries: 6.5 million in Iran, 3.9 million in Russia, 2.2 million in Azerbaijan, 0.8 million in Kazakhstan and 0.4 million in Turkmenistan.