 放大圖片
■科學家在加勒比的開曼海溝下發現這個相信是全球最深的海底火山。 資料圖片
科學家利用遙控潛水艇，發現全球已知最深的海底火山口。火山口內的高溫海水可能有未知的海洋生物，甚至可能有助解開地球生命之源。
科研船「詹姆斯庫克號」的專家表示，他們於加勒比的開曼海溝之下逾3英里發現這個火山口。
遙控潛艇的領航員、地質學家默頓表示，該處有螺旋形的多色沉積礦物，一大群熒光藍色的微生物在火山口旁較冷的水溫區內蓬勃生長，探索該地區猶如在「另一世界遊走」，以往從未遇過。
海水會從海底火山口的裂縫滲入地殼，有些海水可深入1英里，那裡的溫度高達攝氏400度，海水溫度高至可溶解鉛。
這些含豐富礦物的熾熱液體會如煙般噴出，造成一個礦物煙囪；那裡的壓力比大氣壓力高500倍，故水分不會被煮沸。
海底火山口附近的環境惡劣，高熱、高壓及有毒的金屬物質，形成一種高酸性的混合物。但這種環境亦可孕育出很多稀有的生物，例如盲蝦、大白蟹，甚至沒有消化系統的紅口管蟲，科學家都難以解釋。這個生態系統的最底層是一些專吃化合物的細菌，它們依靠火山口的硫氫化鈉和甲烷為生。
由於今次的海底火山口地區比以往發現的更深近半英里，科學家猜測這是歷來最熱的火山口。研究這個火山口可解開海洋歷史、超臨界流體的物理現象與深海的化學結構。超臨界流體是指液體過於高溫，開始出現氣體狀態。 ■綜合外電消息/羅國偉 資深翻譯員
World's Deepest Known Undersea Volcanic Vent Found
Scientists using a remote-controlled submarine have discovered the deepest known volcanic vent and say the superheated waters inside could contain undiscovered marine species and perhaps even clues to the origin of life on earth.
Experts aboard the RRS James Cook said that they found the underwater volcanic vent more than 3 miles beneath the surface of the Caribbean in an area known as the Cayman Trough.
Geologist Bramley Murton, the submersible's pilot, said exploring the area was "like wandering across the surface of another world," complete with spires of multicolored mineral deposits and thick collections of fluorescent blue micro-organisms thriving in the slightly cooler waters around the chimneys. The scenes "were like nothing I had ever seen before," Murton said.
Volcanic vents are areas where sea water seaps into small cracks that penetrate deep into the earth's crust-some reaching down more than a mile. Temperatures there can reach 750 degrees Fahrenheit, heating the water to the point where it can melt lead.
The blazing hot mineral-rich fluid is expelled into the icy cold of the deep ocean, creating a smoke-like effect and leaving behind towering chimneys of metal ore. The spectacular pressure-500 times stronger than the earth's atmosphere-keeps the water from boiling.
The environment in volcanic vents may appear brutal: the intense heat and pressure combines with toxic metals to form a highly acidic undersea cocktail. But vents host lush colonies of exotic animals such as blind shrimp, giant white crabs, and even large red-lipped tubeworms whose lack of any apparent digestive system once left scientists scratching their heads. At the base of this ecosystem present are chemical-eating bacteria who draw on the hydrogen sulphide and methane erupting from the vents to make food.
Because the vent area is nearly half a mile deeper than any previously discovered, scientists speculate that it could be the hottest ever found. Study of the vent could yield a variety of new insights into the history of the ocean, the physics of so-called
"supercritical fluids"-liquids so hot they act like gasses-and the chemical makeup of the deep ocean. ■AP
|
放大圖片
