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The river pushes a vast plume of fresh water into the ocean. The plume is about 400 km (250 mi) long and between 100 and 200 km (62 and 124 mi) wide. The fresh water, being lighter, flows on top of the seawater, diluting the salinity and altering the colour of the ocean surface over an area up to 2,500,000 km 2 (970,000 sq mi) in extent. For ...
Out of all the water on Earth, saline water in oceans, seas and saline groundwater make up about 97% of it. Only 2.5–2.75% is fresh water, including 1.75–2% frozen in glaciers, ice and snow, 0.5–0.75% as fresh groundwater and soil moisture, and less than 0.01% of it as surface water in lakes, swamps and rivers.
Most water in Earth's atmosphere and crust comes from saline seawater, while fresh water accounts for nearly 1% of the total. The vast bulk of the water on Earth is saline or salt water, with an average salinity of 35‰ (or 3.5%, roughly equivalent to 34 grams of salts in 1 kg of seawater), though this varies slightly according to the amount of runoff received from surrounding land.
It can be thought of as a list of the biggest rivers on Earth, measured by a specific metric. For context, the volume of an Olympic-size swimming pool is 2,500 m 3 (88,000 cu ft). The average flow rate at the mouth of the Amazon is sufficient to fill more than 83 such pools each second.
Fresh water, which is essential for life, appeared on Earth about four billion years ago – 500 million years earlier than previously thought, research suggests.
Fresh water can easily become polluted by human activities or due to naturally occurring processes, such as erosion. Fresh water makes up less than 3% of the world's water resources, and just 1% of that is readily available. About 70% of the world's freshwater reserves are frozen in Antarctica. Just 3% of it is extracted for human consumption.
In 1960, the Aral Sea was the world's twelfth-largest known lake by volume, at 1,100 km 3 (260 cu mi). However, by 2007 it had shrunk to 10% of its original volume and was divided into three lakes, none of which are large enough to appear on this list. [17]
However, because it is also the deepest lake, [6] with a maximum depth of 1,642 metres (5,387 feet; 898 fathoms), [1] Lake Baikal is the world's largest freshwater lake by volume, containing 23,615.39 km 3 (5,670 cu mi) of water [1] or 22–23% of the world's fresh surface water, [7] [8] more than all of the North American Great Lakes combined. [9]