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This kills off marine life or forces it to leave the area, removing life from the area and giving it the name dead zone. Hypoxic zones or dead zones can occur naturally, but nutrient pollution from human activity has turned this natural process into an environmental problem. [29] There are five main sources of nutrient pollution.
Sulfidic (or euxinic) conditions, which exist today in many water bodies from ponds to various land-surrounded mediterranean seas [21] such as the Black Sea, were particularly prevalent in the Cretaceous Atlantic but also characterised other parts of the world ocean. In an ice-free sea of these supposed super-greenhouse worlds, oceanic waters ...
The oceanic zone is typically defined as the area of the ocean lying beyond the continental shelf (e.g. the neritic zone), but operationally is often referred to as beginning where the water depths drop to below 200 metres (660 ft), seaward from the coast into the open ocean with its pelagic zone.
The ocean zones can be grouped by light penetration into (from top to bottom): the photic zone, the mesopelagic zone and the aphotic deep ocean zone: The photic zone is defined to be "the depth at which light intensity is only 1% of the surface value". [12]: 36 This is usually up to a depth of approximately 200 m in the open ocean.
Maps exhibiting the world's oceanic waters. A continuous body of water encircling Earth, the World/Global Ocean is divided into a number of principal areas. Five oceanic divisions are usually recognized: Pacific, Atlantic, Indian, Arctic, and Southern/Antarctic; the last two listed are sometimes consolidated into the first three.
The mass of this world ocean is 1.35 × 10 18 metric tons or about 1/4400 of Earth's total mass. The world ocean covers an area of 3.618 × 10 8 km 2 with a mean depth of 3682 m, resulting in an estimated volume of 1.332 × 10 9 km 3. [17] If all of Earth's crustal surface was at the same elevation as a smooth sphere, the depth of the resulting ...
Dead zones are hypoxic (low-oxygen) areas in the world's oceans and large lakes. Hypoxia occurs when dissolved oxygen (DO) concentration falls to or below 2 ml of O 2 /liter. [2] When a body of water experiences hypoxic conditions, aquatic flora and fauna begin to change behavior in order to reach sections of water with higher oxygen levels.
For purposes of this list, "maritime boundary" includes boundaries that are recognized by the United Nations Convention on the Law of the Sea, which includes boundaries of territorial waters, contiguous zones, and exclusive economic zones. However, it does not include lake or river boundaries.