欧洲现在有17个海上风力发电厂在运转。距离爱尔兰东海岸8英里（13公里）的阿克罗银行海上风力园就是这样的一个项目，它的七个涡轮机产生的电力足够为16000户家庭供电。尽管目前鲜有美国家庭利用风能自己发电，但是许多电力公司允许消费者选择风力供电或者其他可再生能源供电。
On Tuesday, Colorado voters will consider a ballot initiative that would requires power companies to provide 10 percent of their electricity from wind and other renewable sources by 2015.
周二科罗拉多州的选民将考虑举行一次公民投票，要求至2015年电力公司为他们提供的电力中的有10%是来自于可替代能源。
“If that passes, power companies will offer more rebates to homeowners to encourage renewable energy production,” said Sheila Hayter, an NREL senior engineer.
美国可再生能源实验室的一位高级工程师希拉?海特说：“如果该投票表决能够通过，电力公司将能够给房主提供更多折扣，鼓励他们使用可再生能源。” Ground Heat 地热
Tapping into the ground offers another option to regulate household heating and cooling. 开发地下能源为调节家庭供暖和降温提供了另一种选择。
In most areas of the United States, the ground below the frost line maintains an average temperature between 50 and 54 degrees Fahrenheit (10 to 12 degrees Celsius).
在美国的大部分地区,冰冻线以下地面的平均温度保持在50至54华氏度(10至12℃)。 Ground-source heat pumps, also called geo-exchange systems, use this relatively constant temperature to keep homes at comfortable temperatures. The devices employ a series of underground, liquid-filled tubes or wells. Liquid flows through the pipes into the home, where a heat exchanger either adds or subtracts heat from indoor air, depending on the season. In winter, that means added warmth captured from the ground. “If you can (do that), your furnace doesn’t have to work so hard,” Hayter said.
地热泵系统，也称为地热交换系统，采用这种相对恒定的温度保证家中的室温维持在舒适的温度。这种装置使用一系列地下液体管或液体井。液体流经这个管道进入家中,通过一个热交换器根据季节增减室内空气的热度。在冬天,这意味着增加了从地面获得的温度。海特说，“如果能够这样，家中的火炉就不必如此辛苦了”。
A U.S. Environmental Protection Agency study found that geo-exchange systems can save up to 70 percent of home-heating costs.
美国环保局的研究发现，地热交换系统可节省高达百分之七十的家庭供暖成本。
Unit 3 Plants and Animals Plant Adaptation 植物的适应性
Like a human being or an animal, a plant must adapt to its environment in order to survive. Survival usually means struggle. It may be hard to think of a plant as “struggling,” yet that is often the case.
像人类和动物一样，植物为了生存也必须适应周边的环境。生存就意味着竞争，我们很难想象植物之间的竞争。但也就那么回事。
A plant, first, must compete with other plants for light, air, soil and water. Second, it must contend with people and animals, who may eat it or make the environment unfit for it to live in.
Third, the physical environment itself may be hostile or inadequate to a plant’s need. Is there enough light, water, air and soil? Is it warm and cool enough for a given plant species?
首先，不同的植物之间会争夺阳光、空气、土壤和水分。其次，植物也会与那些吃它或者威胁到它生存环境的人类和动物竞争。再次，植物所处的环境也可能也是有敌对性的或者不利于其生长的。怎样才能有足够的阳光、水分、空气和土壤？气温的冷热就是植物生长的主要因素吗？
Light is vital to a plant, especially a green one. Green plants manufacture foodstuffs in sunlight—a process known as photosynthesis. Light also affects the rate of water absorption and flower formation.
光对于植物来说是最基本的，尤其是对于绿色植物来说。绿色植物在光照下能制造养分—这是一种被称为光合作用的过程，而光也能影响水分蒸发的速率和花蕾的形成。
Temperature must also be taken into account. If it falls below 1°Celsius or rises above 43°Celsius, serious injury or death results for most vegetation. Temperature also directly influences the formation of seeds and the production of blossoms. It also helps determine the geographic distribution of plants.
温度也是必须考虑的因素。对于大多数植物来说，温度低于一度或者高于四十三度都会对其造成严重的损伤甚至死亡。而温度也直接影响了种子的萌芽以及开花。当然温度也会决定植物在地理上的分布。
Plants cannot survive without water. Many need immense quantities for their development. Therefore, the humidity of atmosphere, the amount of precipitation and the presence of streams, lakes and soil moisture are important to plants.
没有水植物也是无法生存的。有些植物的生长过程需要大量的水分，因此潮湿的空气、大量的降水以及溪流湖泊和湿润的土壤对于植物都是重要的。
Most plants need plenty of air. The atmosphere contains gases that are essential to their life: oxygen, carbon dioxide, water vapor, and nitrogen.
大多数植物需要有足够空气。大气中包含一些对其生命所必要的气体，包括：氧气、二氧化碳、水蒸气和氮气。
Not only the air itself, but its movement—the wind—affects plants greatly. Wind spreads pollen, spores and certain seeds, enabling plants to grow in many places. But a powerful wind may distort or even kill vegetation, particularly trees. It may below away needed soil. Also, wind increases the rate of evaporation and so may create a water shortage for plants.
空气移动所产生的风对于植物也有很大影响。风有助于传播花粉、孢子和种子从而将它们播种在各种地方。但强风也有可能折断或者损害植物，尤其是大树。而大风吹走了一些有养分的土壤，也会加快水分的蒸发从而使植物处于缺水状态。
Soil is extremely important to land plants. A plant’s development depends in large part on the nature of the soil: its wetness, acidity, minerals and the amount of oxygen it contains.
土壤对于陆生植物来说是必不可少的。植物的生长很大一部分需要依靠其土壤的特性：其中包含它的湿度、酸度、矿物成分、含氧量。
A plant is also influenced by other living things with which it competes. It has to withstand parasites, hungry birds and grazing or gnawing mammals. Yet a plant often needs animals to spread its pollen or scatter its seeds.
植物生长也会受到其他竞争生物的影响。它必须要经受寄生菌、饥饿的鸟类、牛羊等食用叶子的动物对其的影响，但同时植物也需要动物帮助传播花粉以及播洒种子。
The stems and leaves of trees and shrubs show us some of the adaptations that enable a
plant to get the maximum amount of light and air.
有树叶和枝干的树以及灌木向我们展示了它们的适应性，这也告诉了我们植物是怎样获得最大量的光和空气的。
In such trees as beech, elm, oak, apple and chestnut, there may be shoots that are primarily vertical while others are primarily horizontal. To secure a maximum amount of sunlight, the leaves on the vertical shoots are arranged in spirals so that any given leaf does not shade the leaf next below it on the shoot. Though the buds on a horizontal shoot of these trees may be arranged spirally, the leaves commonly arrange themselves alternately in a common plane on either side of the shoot.
和那些山毛榉树、榆树、橡树、苹果树和栗子树一样，它们有一些枝芽主要是垂直生长的，另一些是水平生长。为了能获得最多的阳光，一些垂直生长的枝芽会螺旋缠绕生长以不至于遮挡到自己下边的叶子。虽然那些水平生长的枝芽上的花蕾有可能被其他枝芽缠绕着，但树叶会根据自身环境的变化调整自己的生长方向。
In many trees that have their leaves placed opposite to each other, each pair occupies the space between the pair immediately below. You can see this by looking down on a shoot of the horse chestnut. Similar very perfect arrangements will be noted in many climbers. The arrangement of the leaves in the horse chestnut, when examined at the end of a shoot and vertically, has been termed a leaf mosaic, because of the variegated pattern that the leaves of this tree present. Another common device for a similar purpose is the fringelike dividing of the leaf. The carrot plant has this type of leaf. Such a leaf obtains good sunlight but does not shade to a great extent the leaves below it. Moreover, it is in less danger from strong winds.
许多树的叶子会在树枝上相反的方向生长，这样就能让它能迅速占领空间。要是从上往下看七叶树你就能看到这个现象。像这种非常完美的缠绕方式在许多攀岩植物身上能看见。由于树叶分布的多样性，无论你从枝芽末端或者垂直看过去，七叶树的树叶就像马赛克一样。出于同样目的的另一种方式就是树叶的分布像流苏一样。如胡萝卜的叶子就是这种类型。这也是为了能尽可能的获得最大限度的眼光又不至于遮挡到下方的树叶，并且这样的树叶分布更能让它抵御强风。
There are numerous plants that live in environments where light never penetrate. Many of these plants are fungi. They have no chlorophyll, but subsist on organic matter, produced by animals or other plants, that may be found whatever the fungi flourish. Rains washing into the underground nooks and crannies may be one of the agents responsible for getting organic matter into these places.
有大量的植物生长在光线渗透不到的环境中。这些植物大多是一些真菌类植物。真菌类植物他们自身没有叶绿素，但他们却可以寄生在其他动物或植物产生的有机物中。而雨水冲入地下的隐蔽处或者裂缝也会带来一些有机物。
In caves and underground mines, or in pits and wells, where there is a certain amount of light penetration—even if very little—we find that the plants are principally green. Not only is this so, but the green coloring of vegetation in caves is often luxuriantly brilliant. In fact, it may appear even more vivid than that of a plant in the open air. This is true of liverworts, many mosses and some of the ferns that flourish abundantly in these situations. In such cases the chlorophyll granules are developed in a very special way. The light falling on the plant cells is concentrated on the chlorophyll granules themselves, which thus receive a sufficient supply for food-making.
在一些凹陷处、地下矿山、深坑或者矿井只要有甚至非常少的光线射入，我们都能发现这些植物都是很绿的。不仅如此，那些矿井中的植物还有丰富的叶绿素，甚至它们比外面那
些能接触到充足阳光的植物颜色更艳丽。像欧龙牙草、许多蘑菇、一些蕨类植物也能在这种环境中大量生长。在这种环境下叶绿色粒子都按照很特殊的形式在运动。落在植物细胞上的光线聚焦在叶绿色分子上就能提供它足够的能量制造食物。
Plants also receive a minimum of light in the depths of the sea or at the bottom of lakes and pools, since sunlight is weak or absent there. The light under water diminishes in proportion to the depth. It is also greatly influenced by the amount of sediment in suspension and consequently varies before and after storms and at different distances from the mouths of rivers and streams.
即使在光线很弱或者稀薄的深海或者湖泊和水塘的底部，植物也能得到少量的光线。而光线在水下的削弱程度和水深是成正比的，它会被水下大量的悬浮颗粒所影响。在暴风雨前后这个比例关系也是不停变化，甚至离小河和溪流的入口处不同距离的比例也是不同的。
Complete darkness reigns at depths greater than 200 meters below the surface of clear sea water. At a depth of 170 meters, the illumination is about equal to that at the surface of the water during moonlight. Under such conditions, plants possessing chlorophyll cannot manufacture the sugars ordinarily formed by green plants in sunlight. This explains why plants possessing green coloring matter are rarely seen at depths of more than 60 meters. As a matter of fact, by far the greatest part of the vegetation of the sea is found within about 30 meters of the surface.
在海平面下方两百多米深度几乎是黑暗的区域。在170米处水下的光线强度和夜晚月光的强度差不多。在这样的情况下，这里的植物就不能像原始的植物通过叶绿素来制造糖类了。这也就解释了为什么在60米水深以下植物含有的叶绿色就很少了。所以，海里大部分的植物还是生活在水深三十米以上的。
In the process of photosynthesis the leaves of plants do not absorb all the colors of the spectrum to the same degree. The red, orange and yellow rays of light that reach the leaves are absorbed much more effectively than the rest. In deep marine water, vegetation receives more blue to green light than it does red to yellow. This is another reason why conditions are particularly unfavorable for plant growth at considerable depths below the surface of the sea.
在光合作用的过程当中，植物对各种颜色光谱的吸收程度是不同 的。红、橙、黄光谱比其他颜色的光谱更容易被吸收。植物在深水里吸收的蓝色光谱比绿色光谱更多，这也是深水为什么不适宜植物生长的原因了。
A striking adaptation is found in red algae. These plants contain, in addition to chlorophyll, pigments known as carotenoids and phycoerythrins. These pigments are present in considerable quantities and give the red algae their characteristic color. They also absorb blue to green colors of light more than chlorophyll does. It is suspected that after they absorb light, they transmit the energy from this light to chlorophyll, for photosynthesis.
红藻有很强的适应性，因为这类植物除了叶绿素以外还有如类胡萝卜素和藻红蛋白。这些色素大量的存在于红藻当中并使它们具有特定的颜色。它们也能比叶绿色吸收更多的蓝光和绿光。令人不可思议的是吸收阳光后它们能利用光合作用把光能存到叶绿素当中。
In tropical forests the tree growth is often so profuse that sunlight may never reach the ground. In these hot and humid climates there are a great many epiphytes—plants such as Spanish moss, orchids and staghorn fern—that grow on other plants.
热带雨林中的植物通常茂密到能遮挡住所有的光线。在这种又热又潮湿的气候条件下生长着大量的附生植物，例如寄生藤、兰花和鹿角蕨。
The epiphytes grow on upper limbs of trees and on poles. Their roots are suspended in air and they absorb moisture and gases from the humid atmosphere. The cells of epiphytes are not
directly parasitic, for they contain chlorophyll and they manufacture their own food. However, they may injury trees by their sheer weight.
那些附生植物生长在一些树木的枝干上，它们将自己的根暴露在空气中来吸收这潮湿空气中的水分和空气。这些寄生植物也并不需要直接寄生，它们含有自己的叶绿色能制造食物，但它们自身的重量可能损伤到大树。
The liana is a vine with a woody stem, which encircle the trunk of a tree as it climbs to the highest branches. In this way, though the liana is rooted in the soil, it can reach the sunlight.
那些有着木质藤条的藤本植物缠绕着树干生长，似乎想爬到最高的树枝去一样。就这样即使它扎根在土里也能照射到阳光。
Unit 4 Landscaping and Homes
Landscaped Roofs Have Chicago Mayor Seeing Green 芝加哥的屋顶绿化
When cities run out of valuable real estate, planners look up. The search for green space is no exception. Europe’s green roofs have long provided environmental, aesthetic and economic benefits. Is the idea growing in the United States?
由于当城市中宝贵的房屋建筑用地已所剩无几，城市规划者开始将目光转向空中。寻找绿色空间也不例外。欧洲的绿色屋顶长期以来为人们提供了环境、审美和经济方面的利益。这种想法是否也会根植在美国呢？
Mayor Richard Daley began a green roof initiative in Chicago, Illinois, after he saw the gardenlike roofs in Europe.
在伊利诺伊州芝加哥市，当市长理查德?戴利看到了欧洲花园般的屋顶之后，便开始了绿色屋顶的创意。
“I thought, with all the flat roofs in Chicago, you could reclaim thousands of acres for the environment and also help buildings with heating and cooling and controlling rainwater going into the sewer system,” he said during a recent telephone interview.
在最近的一次电话采访时他说：“我认为，如果把芝加哥所有平坦的屋顶都利用起来，可以开辟数千英亩的土地用于美化环境，还有利于建筑物供暖、降温，以及进入排污系统的雨水控制。”
“When you look out over the city, instead of steel and concrete, you see something for the environment,” he continued. “So I just thought that was the way for us to go”
他继续说：“当你透过窗户眺望看这个城市时，你看到的不是钢筋混凝土，而是一些美化的环境。所以我想，这就是我们应该做的到事情。”
绿色屋顶通常是由无需经常维护的抗旱植物组成（如景天属暑天景植物）。这些屋顶的厚度均小于4英寸（10厘米），可直接在上面种植或制作成已有植物预先栽种在上面的种植垫。即使斜屋顶也可以进行绿色屋顶处理。
利用率较高的绿色屋顶系统可以包括多种植物和园林要素，如树木，但只有在平坦的屋顶上才行。这种绿色屋顶需要更深的种植材料或土壤替代物，它们更重，更昂贵，并且需要更多的维护。
绿化屋顶的最大好处之一是水资源管理。它们能吸收落在屋顶上的大约50%-60%的雨水，这些雨水一部分通过植物蒸发（或“呼气”）回到大气中而消耗掉了，另一部分水保留在土壤中或其他培养媒介中，。其余的则缓慢地、在人们的控制下缓慢地流入城市雨水排水系统，这个过程有助于抑制城市供水系统中大量雨水激增的现象，而要扩充该系统的费用是很昂贵的。