British scientists find the world's sixth-largest river... at the bottom of the SEA
By Daily Mail Reporter
Last updated at 10:46 AM on 2nd August 2010
Immense rivers that dwarf the Thames have been found at the bottom of the ocean by British scientists.
巨大的河流令泰晤士河顯得矮小，已被英國科學家發現在海洋的底部。
Like those on land, the submarine waterways carve out channels, tributaries, flood plains, rapids and even waterfalls.
像那些在陸地上的，水下航道開拓渠道、支流、洪水平原、險灘、甚至瀑布。
One river, discovered underneath the Black Sea, is up to 115ft deep in places and more than half a mile wide.
一河流被發現在黑海下，某些地方深達115呎和超過半哩寬。
The underwater giant: The river, shown with a 3D scan using false colour, flows along the bed of the Black Sea
水下巨人：這條河，用偽彩色三維掃描顯示，流竄沿黑海床
If found on land, scientists estimate the so-far unnamed waterway would be the world's sixth largest river in terms of the amount of water flowing through it.
The flow – carrying highly salty water and sediment - is 350 times greater than the Thames, according to a Leeds University team who used a robotic submarine to scan the seabed near Turkey.
The undersea river - the only active one to have been found so far - stems from salty water spilling through the Bosphorus Strait from the Mediterranean into the Black Sea, where the water has a lower salt content.
This causes the dense water from the Mediterranean to flow like a river along the sea bed, carving a channel and deep banks.
The discovery could help explain how life manages to survive in the deep ocean far out to sea away from the nutrient rich waters that are found close to land, as the rivers carry sediment and nutrients with them.
Dr Dan Parsons, who led a team from the university's school of earth and environment, told the Sunday Telegraph: ‘The water in the channels is denser than the surrounding seawater because it has higher salinity and is carrying so much sediment.
Watershed discovery: The river - with 350 times the flow of the Thames - has channels, rapids and waterfalls
流域發現：這條河 - 泰晤士河流量的350倍 - 有渠道、急流和瀑布
‘It flows down the sea shelf and out into the abyssal plain much like a river on land.
The abyssal plains of our oceans are like the deserts of the marine world, but these channels can deliver nutrients and ingredients needed for life out over these deserts.
‘This means they could be vitally important, like arteries providing life to the deep ocean.
‘The key difference we found from terrestrial rivers was that as the flow goes round the bend, the water spirals in the opposite way to rivers on land.’
Scientists have long suspected seabed rivers can form, after sonar scans revealed meandering channels in many of the world's oceans.
But none have been found before to be have currents of water flowing through them
Find: The seabed river flows from Turkey's Bosporus
發現：海底河流自土耳其的博斯普魯斯海峽
Among the largest of these channels is off the coast of Brazil where the Amazon enters the Atlantic Ocean.
Most are believed to have formed when sea levels were much lower and the channels have been found to be up to 2,500 miles long and be several miles wide.
The channel in the Black Sea, although much smaller, is the only one to be found still flowing and proves that these mysterious channels are formed by underwater rivers.
Unlike ocean trenches, which are geological formations that form at the deepest parts of the ocean due to movements of the tectonic plates, the undersea river channels meander like rivers on land and form banks in the same way by eroding the silt from the bottom of the channel and building it up at the edges.
Dr Parsons found that the Black Sea river is flowing at around four miles per hour with 22,000 cubic metres of water passing through the channel every second – 10 times greater than Europe's biggest river, the Rhine.
The Black Sea river flows only for around 37 miles until it reaches the edge of the sea shelf and dissipates into the deep sea.
Dr Parsons said data from the research will also be important for oil companies looking to drill in areas where these rivers exist.
http://www.dailymail.co.uk/sciencetech/article-1299348/British-scientists-worlds-sixth-largest-river--the-sea.html
黑海海底發現世界第六大河流
發布時間：2010年8月3日
作者：劉霞
來源：科技日報
本報訊（記者劉霞）據英國“每日郵報”8月2日（北京時間）報導，英國科學家首次在黑海海底約 350米深處的海床發現了可以讓泰晤士河相形見絀的海底河流，其流量大小是泰晤士河的350倍，流程約 2500公里，寬幾公里。
同陸地上的河流一樣，該海底河流也擁有航道，支流，沖積平原，急流甚至瀑布。科學家表示，如果這條河流在陸地上被發現，以流經它的水量來計算，將是世界第六大河流。
聲納掃描顯示，世界上的很多海洋中都存在彎曲航道，因此，科學家一直認為海底河流是有可能形成的。而這次發現的河流，是科學家首次發現的海底河流。
英國利茲大學的研究團隊使用一個海底機器人掃描了土耳其附近的海床，結果顯示，這些河道蜿蜒曲折，河道中水分的鹽度要高於海水的鹽度，同時含有大量泥沙。研究人員表示，從地中海出發的高鹽度海水在流向黑海（其中的海水鹽度很低），經過博斯普魯斯海峽時，飛濺的鹽水像河流一樣沿著海床流動，開闢出一條航道以及很多深深的堤岸，形成了該海底河流。
新發現的這條海底河流或許可以幫助科學家解釋生命如何在深海水域中存活。利茲大學地球和環境學院的丹帕森斯解釋說，這條河流攜帶著沉積物和生命生存所需要的營養物質，生命因此得以存活。
研究人員表示，這條海底河流同陸地上河流的主要區別是，水流在彎道四周流動，水採用螺旋狀的方式前進，與陸地上河流的行進方式相反。
海底河流的航道同海溝不一樣。在地質學上，海溝被認為是海洋板塊和大陸板塊相互作用的結果。密度較大的海洋板塊以30度上下的角度插到大陸板塊的下面，兩個板塊相互摩擦，形成長長的“V”形字形凹陷地帶，這就是海溝。而海底河流緩慢而彎曲地流動，並且通過侵蝕航道底部的淤泥並讓其堆積，從而像陸地上的河流一樣形成了堤岸。
帕森斯發現，黑海海底的河流流速約為每小時 6.4公里，航道水流量每秒約有 22000立方米，是歐洲最大河流萊茵河的10倍多。該海底河流的發現對於試圖在這些區域進行開採的石油公司也非常重要。
本篇文章來源於科技網 www.stdaily.com
http://www.stdaily.com/kjrb/content/2010-08/03/content_214797.htm
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