托福閱讀材料之人類會成“吸血鬼”？

　　An asteroid splashdown in one of Earth's oceans could trigger a destructive chemical cycle that would wipe out half of the ozone layer, according to a new study. The massive loss of protection against the sun's ultraviolet (UV) radiation would likely force humans into a vampire-style existence of staying indoors during daylight hours.

　　最新科學(xué)研究顯示，小行星墜入地球海洋會引發(fā)毀滅性的化學(xué)連鎖反應(yīng)，導(dǎo)致50%的臭氧層消失。缺少了臭氧層對太陽紫外線輻射的抵擋，人類將有可能被迫過起“吸血鬼”般的生活——白天只能躲在屋子里。

　　The worst scenario based on an asteroid 1 kilometer wide would re-create the hole in the ozone layer, which appeared over Antarctica during the 1990s, except this would be worldwide. UV levels in the study's simulation soared beyond anything measured so far on Earth by the UV Index's daily forecasts of overexposure to UV radiation, and remained that way for as long as two years.

　　早在上世紀90年代，南極洲上空就已出現(xiàn)臭氧空洞。此次研究發(fā)現(xiàn)，直徑達1000米的小行星撞擊地球后也會出現(xiàn)臭氧空洞，且危害波及整個地球。研究結(jié)果顯示，模擬太陽紫外線輻射在撞擊后飆升，超過了此前在地球上測量的所有紫外線輻射指數(shù)預(yù)報數(shù)據(jù)，并且會以這種狀態(tài)保持兩年。

　　Researchers tested scenarios with a 0.6-mile asteroid and a 0.3-mile asteroid (500 meters) at a specific location and specific time of year. Models used in the research showed how ozone destruction would result from an asteroid strike launching seawater vapor hundreds of miles up into the highest parts of the atmosphere. Chemical elements such as chloride and bromide that separated from the water vapor could then wreak havoc by destroying the ozone layer that protects life on Earth from UV rays.

　　在實驗中，研究人員測試了特定時間特定地點下直徑分別為1000米和500米的小行星。研究人員通過觀察模型發(fā)現(xiàn)了小行星墜落入地球海洋后的臭氧層破滅過程：巨大的撞擊力量使得海水蒸汽上升至大氣層最高點，隨后氯化物及溴化物等化學(xué)物質(zhì)脫離水汽，毀壞保護人類免受輻射的臭氧層。

　　Long-term effects of such high UV radiation would include skin-reddening, changes in plant growth and genetic mutations for humans and other organisms. And an asteroid has about twice the chance of striking water rather than hitting land. Those odds come from the fact that over 70 percent of the Earth's surface is covered by water.

　　據(jù)悉，長期面臨輻射可導(dǎo)致皮膚紅化、植物生長發(fā)生改變、人類以及其他有機體的基因變異。而且據(jù)了解，小行星落入海洋的幾率是與陸地相撞幾率的兩倍，原因在于地球70%以上的表面被水覆蓋。

　　Asteroid hunters have found about 903 of an estimated 1,050 near-Earth objects (NEOs) with diameters of 1 kilometer or greater as of October 1. That still leaves well over 100 objects in the 1-2 kilometer size undiscovered.

　　據(jù)估計，截至10月初，直徑大于等于1000米的近地小行星約有1050個，行星探測器已發(fā)現(xiàn)903個，而還有100多個直徑為1000到2000米的小行星尚待發(fā)掘。