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V1:
还有一个是某种温室气体会由植物排放出来，而远古时代某时段应为海底冰层一下子释放出了很多这种气体而导致大气变暖......(也就是说这种气体的几个来源)，后来又说植物虽然排放这种气体，但是植物能够吸收其他温室气体如二氧化碳等气体，所以大家应该保护植被...
V2:
地球温室效应的研究：提到一个s物质会导致北半球温度降低，但在1870年后，反而北半球温度上升，第一段的学者认为此现象与温室效应相反。第二段的学者说，本来造成温室效应的因素就不是这种物质，而是南半球海洋多，而北半球主要是陆地造成的差异，所以s物质只是短暂现象。
以上是我的理解，不过不确定是否有完整表达，大家还是以原文文章为主吧。
第三篇讲的是气候变化。说空气里的二氧化碳会和水结合会生成酸，腐蚀了石头后流入海底，并且封存在海底很久，所以空气里的二氧化碳减少，能够导致气候变冷。而近400万年的地质变化导致更多的石头暴露出来，因而这个过程加剧，所以近 400万年的气候比以前寒冷干燥。
V3:
地球水(或冰层)的来源。首先提出疑问，再提出两种theory 一种说来源于存在于A和B之间的陨石坠落到地球 另一种说来源于...忘记了 但其中包含了关于水(或冰层)出现年代的问题.carbon dioxide 被remove, 然后climate从以前的wet,cool,not regional extreme（不知道什么意思，但是考到了。定位原文第一段。）问题是问以前是怎样的。（还是现在是怎样的？？应该是以前，反正如果现在就取非。）这篇文章都考了第二段，但是我匆匆忙忙，颠三倒四得看只有浪费了时间，而且不知道讲什么。所以，如果碰到，建议先仔细阅读第二段。
V4:
关于地球突然降温的问题。一段说之前的理论认为地球在一段时间突然降温是怎样怎样。
二段说不是。一个V调查了说是有种石头之类的东东可以吸收co2然后变成液体被植物和动物固定。当然，这些c最终可以转化成co2再到空气中，但是需要更长的时间。这样的话，大气中没有了co2温度就降低了。还说旧石头和新石头都可以吸收，所以加快降温速度。
二段全部划线，问题都挺搞。
V5 (By smile7728)
It is about the effect of the methane甲烷on global warming. It was thought that the methane emission comes from the fuel fossil burn, fire and other. However, the recent study finds that the methane also comes from plants. The article listed two studys to demonstrate that the plants really emit the methane.
V6:
第一段说甲烷和二氧化碳一样是一种温室气体；第二段说，新发现甲烷由plant释放出来，尤其是tropical forest; 第三段继续说这一发现可以用于解释ice age前后甲烷的变化；第四段说，虽然发现了plant会释放甲烷，但是tropical forest也吸收很多二氧化碳，所以减少甲烷还是应该减少fuel.
V7 By pinpink)
1P 关于某M物质向其它温室气体一样，也会造成global warming。列举了造成大气中M物质增加的原因，如燃烧石化燃料等。(有题考这段的作用，我认为是提供背景资料)
2P “Surprisingly”(转折)科学家发现植物也会释放M，提出如卫星空照的证据，说热带地区因为有较密集的丛林，所以大气中的Ｍ特别集中。
3P (有些地方没读通) 似乎是说植物释放M也可以解释古老的冰块中的气泡浬为何也有M… 可能是说随着冰河入到海洋，海底也沉积了很多Ｍ，上一个冰河时期的结束可能就是这些储存在海底的Ｍ被释放的结果。但是证据显示海底大概四万年都没有剧烈变动，所以这个应该不是导致冰河期结束的原因。推测应该是植物大量的繁衍，释放出Ｍ才使得冰河期结束。
4P 虽然植物会释放M，但是希望藉由减少植物来阻止溫室效应仍然是不对的，因为植物可以吸收其它更多的温室气体。想要缓和温室效应还是应该从减少石化原料的使用下手。
有考一题问文章”主题”
V8By marimomo)
（长）M（长单词，M开头，不认识）是一种温室气体。温室气体造成地球变暖。汽车尾气等都会排放M。但最近的研究发现植物也会释放出M。由于植物在地球上 广泛存在，它们甚至可能是最主要的M制造者。卫星照片发现，热带雨林上空就聚集了大量的M。植物排放M的事实也解释了另一个科学谜题，即为什么古老的冰层 取样中有小气泡含有S（又一个不认识的单词）。。。。（之后是一段关于冰河期、小气泡和植物的故事，没完全看懂，大意包括4000年前上一个冰河期结束时 没有过S大爆发。植物在冰河期结束后越来越多，排放的M越来越多，导致平均气温越来越高,blabla）
考题:
有题考这段的作用，我认为是提供背景资料
有考一题问文章”主题”
V9:
科学家发现最近40million years，地球不再是原来那么warm和wet了（此处有题），先给出了一个流派的若干解释：随着二氧化碳的增多，大气的降水中融解了二氧化碳，这些水降到海面，被各种过程吸收，然后沉积到海底，虽然到海底这些c最终还是要回到大气中，但是这个过程需要hundreds of millions of years（隐含40百万年对它来说是相对短的过程，此处有题），另外陆面也对二氧化碳的吸收起到一定作用，而且随着内海的面积逐渐减少，陆面的面积越来越大因而吸收c也越多。第一段的末尾说这个解释不错，但作为唯一的解释未免不让人信服。下一段是讲好像叫M R的人提出一种观点，对第一段的解释起到支持作用，他说地质演变抬高了陆地某些位置，高了之后会有更多的fresh岩石吸收c，而且因为抬高了后这些位置比较陡，降水可以更好的冲走这些吸收了c的岩石。4个问题，比较长。
V10:
第一段：Aerosol导致了温室效应不明显，让空气的温度变低
第二段：说了三个problem，第一个是对海洋的影响比对海洋上的冰的影响大，有题（希望牛牛补充）。第三个影响最严重。
V11 (By VVBV)
又是篇超长文章，开头忘了，因为整个第二段被highlight了。。。题目基本是第二段的，考了好几题逻辑。。。无语了。。。哦！想起来！是讲气候变冷的，第二段讲的是由于大气中的carbon dioxide收支不平衡之类的导致气候变冷，然后讲了具体过程，说是石头之类的东东里的CO2被一种叫weathering process的东东给弄出来了，然后到海里，然后被植物和动物吸收，最后变成化石被掩埋。然后说是一种updrift的地壳运动之类的东东会加速weathering process。可能记忆有误差，大家斟酌一下，文章没什么单词，我主要一下子碰到2道长题有点慌了。基本上认真看第二段是可以做题了，题目也好想有6道。
参考阅读 http://www.columbia.edu/~vjd1/carbon.htm
The Carbon Cycle and Earth's Climate
Carbon dioxide is an atmospheric constituent that plays several vital roles in the environment. It is a greenhouse gas that traps infrared radiation heat in the atmosphere. It plays a crucial role in the weathering of rocks. It is the carbon source for plants. It is stored in biomass, organic matter in sediments, and in carbonate rocks like limestone.
The Carbon Cycle
The primary source of carbon/CO2 is outgassing from the Earth's interior at midocean ridges, hotspot volcanoes, and subduction-related volcanic arcs. Much of the CO2 released at subduction zones is derived from the metamorphism of carbonate rocks subducting with the ocean crust. Much of the overall outgassing CO2, expecially as midocean ridges and hotpot volcanoes, was stored in the mantle when the Earth formed. Some of the outgassed carbon remains as CO2 in the atmosphere, some is dissolved in the oceans, some carbon is held as biomass in living or dead and decaying organisms, and some is bound in carbonate rocks. Carbon is removed into long term storage by burial of sedimentary strata, especially coal and black shales that store organic carbon from undecayed biomass and carbonate rocks like limestone (calcium carbonate).
[attachimg=500,357]74884[/attachimg]
Photosynthesis
Plants and photosynthetic algae and bacteria use energy from sunlight to combine carbon dioxide (C02) from the atmosphere with water (H2O) to form carbohydrates. These carbohydrates store energy. Oxygen (O2) is a byproduct that is released into the atmosphere. This process is known as photosynthesis.
CO2 + H2O + sunlight -> CH2O + O2
Respiration
Plants (and photosynthetic algae and bacteria) then use some of the stored carbohydrates as an energy source to carry out their life functions. Some of the carbohydrates remain as biomass (the bulk of the plant, etc.). Consumers such as animals, fungi, and bacteria get their energy from this excess biomass either while living or dead and decaying. Oxygen from the atmosphere is combined with carbohydrates to liberate the stored energy. Water and carbon dioxide are byproducts.
oxygen + carbohydrate -> energy + water + carbohydrate
O2 + CH2O -> energy + H2O + CO2
Notice that photosynthesis and respiration are essentially the opposite of one another. Photosynthesis removes CO2 from the atmosphere and replaces it with O2. Respiration takes O2 from the atmosphere and replaces it with CO2. However, these processes are not in balance. Not all organic matter is oxidized. Some is buried in sedimentary rocks. The result is that over geologic time, there has been more oxygen put into the atmosphere and carbon dioxide removed by photosynthesis than the reverse.
Weathering
Carbon dioxide and the other atmospheric gases dissolve in surface waters. Dissolved gases are in equilibrium with the gas in the atmosphere. Carbon dioxide reacts with water in solution to form the weak acid, carbonic acid. Carbonic acid disassociates into hydrogen ions and bicarbonate ions. The hydrogen ions and water react with most common minerals (silicates and carbonates) altering the minerals. The products of weathering are predominantly clays (a group of silicate minerals) and soluble ions such as calcium, iron, sodium, and potassium. Bicarbonate ions also remain in solution; a remnant of the carbonic acid that was used to weather the rocks.
[attachimg=445,249]74885[/attachimg]
Carbonate Rocks
1. Carbon dioxide is removed from the atmosphere by dissolving in water and forming carbonic acid
CO2 + H2O -> H2CO3 (carbonic acid)
2. Carbonic acid is used to weather rocks, yielding bicarbonate ions, other ions, and clays
H2CO3 + H2O + silicate minerals -> HCO3- + cations (Ca++, Fe++, Na+, etc.) + clays
3. Calcium carbonate is precipitated from calcium and bicarbonate ions in seawater by marine organisms like coral
Ca++ + 2HCO3- -> CaCO3 + CO2 + H2O
the carbon is now stored on the seafloor in layers of limestone
Metamorphism of Carbonates
Some of this carbon is returned to the atmosphere via metamorphism of limestone at depth in subduction zones or in orogenic belts
CaCO3 + SiO2 -> CO2 + CaSiO3
followed by outgassing at the volcanic arc.
[attachimg=577,212]74886[/attachimg]
The Greenhouse Effect
Most of the sun's energy that falls on the Earth's surface is in the visible light portion of the electromagnetic spectrum. This is in large part because the Earth's atmosphere is transparent to these wavelengths (we all know that with a functioning ozone layer, the higher frequencies like ultraviolet are mostly screened out). Part of the sunlight is reflected back into space, depending on the albedo or reflectivity of the surface. Part of the sunlight is changed into infrared (lower frequency than visible light). While the dominant gases of the atmosphere (nitrogen and oxygen) are transparent to infrared, the so-called greenhouse gasses, primarily water vapor (H2O), carbon dioxide, and methane (CH4), absorb the infrared radiation. They collect this heat energy and hold it in the atmosphere. While we worry about possible global warming from the additional CO2 we put into the atmosphere by burning fossil fuels, if there was no CO2 in the atmosphere the global climate would be significantly cooler.
[attachimg=551,361]74883[/attachimg]
The Climate Buffer
Because of the role of CO2 in climate, feedbacks in the carbon cycle act to maintain global temperatures within certain bounds so that the climate never gets too hot or too cold to support life on Earth. The process is a large-scale example of LeChatelier's Principle. This chemical principle states that if a reaction at equilibrium is perturbed by the addition or removal of a product or reactant, the reaction will adjust so as to attempt to bring that chemical species back to its original concentration. For example, as carbonic acid is removed from solution by weathering of rocks, the reaction will adjust by producing more carbonic acid. And since the dissolved CO2 is in equilibrium with atmospheric CO2, more CO2 is removed from the atmosphere to replace that removed from solution by weathering.
some examples:
If CO2 concentration increases in the atmosphere because of an increased rate of outgassing, global temperature will rise. Rising temperature and more dissolved CO2 will lead to increased weathering of crustal rocks as a result of faster reaction rates (temperature effect) and greater acidity. Enhanced weathering will use up the excess CO2 thereby cooling the climate.
If global temperature cools as a result of some astronomical forcing or tectonic/ocean circulation effect, the lower temperatures will result in lower rates of chemical weathering. Decreased weathering means less CO2 being drawn from the atmosphere by weathering reactions, leaving more CO2 in the atmosphere to increase temperatures.
If more rocks become available for rapid weathering as a result of mountain uplift the enhanced weathering will draw down atmospheric CO2 and decrease global temperatures. But the decreased temperatures will slow reaction rates, thereby using less CO2, thus allowing temperatures to moderate. |
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发表于 2010-1-7 19:29:57
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