环境英语证书考试(PEC)-环境经济学词汇.doc

环境英语证书考试（PEC）-环境经济学词汇 Afforestation: Planting trees where there were none before. Agroforestry: The integration of tree growing with crop and livestock production. Agroforestry offers a way of tackling the combined problems of wood storages, poor agricultural production and environmental degradation. Acid rain: When strong acids fall from the atmosphere in the form of rain, snow, fog or dry particles. The acid is the result of pollution caused mostly by sulphur oxides and nitrogen oxides that are discharged into the atmosphere by industry. It also is created by burning coal and oil, from the operation of smelting industries and from transportation. In the atmosphere, these gases combine with water vapour to form acids, which then fall back to Earth. The result often kills forests and sterilizes lakes. Anthropogenic: Human-induced or human-caused, derived from the Greek root anthropos meaning man. Algae blooms: The rapid growth of algae on the surface of lakes, streams, or ponds; stimulated by nutrient enrichment; an explosive increase in the density of phytoplankton within an area. Algae: Rootless plants that grow in sunlit waters in relative proportion to the amounts of nutrients available. They can affect water quality adversely by lowering the dissolved oxygen in the water. They are food for fish and small aquatic animals. However, when algae exists in excess, it takes away oxygen from the water, thus killing all life. Aquifer: A porous, water-saturated layer of sediment and bedrock under the Earths surface; also described as artesian (confined) or water table (unconfined). Arid: Regions where precipitation is insufficient in quantity for most crops and where agriculture is impractical without irrigation. Atmosphere: The envelope of air surrounding the Earth. Most of the total mass of the atmosphere lies within the troposphere and the stratosphere. Most weather events are confined to the troposphere, the lower eight to 12 km of the atmosphere. The ozone layer i