墨西哥湾“死亡区”今年面积不到预测一半
<p><span word="U">U</span>.<span word="S">S</span>. <span word="scientists">scientists</span> <span word="have">have</span> <span word="determined">determined</span> <span word="that">that</span> <span word="the">the</span> <span word="Gulf">Gulf</span> <span word="of">of</span> <span word="Mexico">Mexico</span>'<span word="s">s</span> <span word="annual">annual</span> "<span word="dead">dead</span> <span word="zone">zone</span>" — <span word="an">an</span> <span word="area">area</span> <span word="with">with</span> <span word="low">low</span> <span word="oxygen">oxygen</span> <span word="that">that</span> <span word="can">can</span> <span word="kill">kill</span> <span word="fish">fish</span> <span word="and">and</span> <span word="marine">marine</span> <span word="life">life</span> — <span word="is">is</span> <span word="the">the</span> <span word="fourth">fourth</span> <span word="smallest">smallest</span> <span word="since">since</span> <span word="they">they</span> <span word="started">started</span> <span word="mapping">mapping</span> <span word="the">the</span> <span word="area">area</span> <span word="in">in</span> 1985.</p><p><span word="Scientists">Scientists</span> <span word="supported">supported</span> <span word="by">by</span> <span word="the">the</span> <span word="National">National</span> <span word="Oceanic">Oceanic</span> <span word="and">and</span> <span word="Atmospheric">Atmospheric</span> <span word="Administration">Administration</span> (<span word="NOAA">NOAA</span>) <span word="said">said</span> <span word="in">in</span> <span word="a">a</span> <span word="report">report</span> <span word="Tuesday">Tuesday</span> <span word="that">that</span> <span word="the">the</span> <span word="area">area</span> <span word="is">is</span> <span word="only">only</span> <span word="about">about</span> 40 <span word="percent">percent</span> <span word="the">the</span> <span word="average">average</span> <span word="size">size</span> <span word="predicted">predicted</span> <span word="earlier">earlier</span> <span word="this">this</span> <span word="year">year</span> <span word="based">based</span> <span word="on">on</span> <span word="nitrogen">nitrogen</span> <span word="and">and</span> <span word="other">other</span> <span word="nutrients">nutrients</span> <span word="flowing">flowing</span> <span word="down">down</span> <span word="the">the</span> <span word="Mississippi">Mississippi</span> <span word="river">river</span>.</p><p><span word="This">This</span> <span word="year">year</span>'<span word="s">s</span> <span word="dead">dead</span> <span word="zone">zone</span> <span word="off">off</span> <span word="Louisiana">Louisiana</span> <span word="is">is</span> <span word="about">about</span> 7,040 <span word="square">square</span> <span word="kilometers">kilometers</span>, <span word="rather">rather</span> <span word="than">than</span> <span word="the">the</span> 15,000 <span word="square">square</span> <span word="kilometers">kilometers</span> <span word="predicted">predicted</span> <span word="by">by</span> <span word="the">the</span> <span word="NOAA">NOAA</span>.</p><p><span word="Every">Every</span> <span word="year">year</span> <span word="the">the</span> <span word="oxygen">oxygen</span> <span word="depletion">depletion</span> <span word="begins">begins</span> <span word="as">as</span> <span word="snow">snow</span> <span word="melt">melt</span> <span word="and">and</span> <span word="spring">spring</span> <span word="rains">rains</span> <span word="bring">bring</span> <span word="fresh">fresh</span> <span word="water">water</span> <span word="to">to</span> <span word="the">the</span> <span word="gulf">gulf</span>. <span word="Fresh">Fresh</span> <span word="water">water</span> <span word="is">is</span> <span word="lighter">lighter</span> <span word="than">than</span> <span word="salt">salt</span> <span word="water">water</span> <span word="causing">causing</span> <span word="two">two</span> <span word="layers">layers</span> <span word="to">to</span> <span word="develop">develop</span>. <span word="Nitrogen">Nitrogen</span> <span word="and">and</span> <span word="other">other</span> <span word="nutrients">nutrients</span> <span word="in">in</span> <span word="the">the</span> <span word="fresh">fresh</span> <span word="water">water</span> <span word="feed">feed</span> <span word="a">a</span> <span word="growth">growth</span> <span word="spurt">spurt</span> <span word="of">of</span> <span word="algae">algae</span> <span word="and">and</span> <span word="microorganisms">microorganisms</span> <span word="at">at</span> <span word="the">the</span> <span word="top">top</span>.</p><p><span word="The">The</span> <span word="microorganisms">microorganisms</span> <span word="die">die</span> <span word="and">and</span> <span word="fall">fall</span> <span word="to">to</span> <span word="the">the</span> <span word="bottom">bottom</span>, <span word="where">where</span> <span word="their">their</span> <span word="decay">decay</span> <span word="consumes">consumes</span> <span word="oxygen">oxygen</span> <span word="from">from</span> <span word="the">the</span> <span word="bottom">bottom</span> <span word="up">up</span>, <span word="creating">creating</span> <span word="the">the</span> <span word="dead">dead</span> <span word="zone">zone</span>.</p><p>美国科学家认定，墨西哥湾里由于含氧过低导致鱼和海洋生物死亡的所谓“死亡区”今年是1985年开始测量记录以来第四小的面积。</p><p>为美国国家海洋与大气管理局工作的科学家在星期二发布的一份报告中说，这片死亡区的面积只有今年早些时候预计的40%。对死亡区面积的预测基于密西西比河流入墨西哥湾水中的氮和其它营养素含量。</p>
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