时间:2018-12-07 作者:英语课 分类:(科普英语)Earth and Sky


英语课


 


Water Cycle 水循环


All the oceans on earth are salty, while inland water is typically fresh. How does water become salty? We'll answer a listener's question -- today on Earth and Sky.


DB: This is Earth and Sky. We recently visited the Austin Children's Museum in Texas to record your science questions. This one is from Jeana Lungwitz.


Jeana Lungwitz: Why are the oceans salt water and the rivers and lakes typically fresh water?


JB: Jeana, first imagine a tea kettle. If you boil tap water to make tea, some of it evaporates. After a while, you might notice a hard crust of mineral deposits forms on the bottom of your teapot


DB: That crust is there because when tap water evaporates it leaves behind any dissolved salts and minerals. Now take this scenario 1 to the ocean. Most water on Earth evaporates from the surface of the ocean. There it leaves behind dissolved salts. Then, when water precipitates 2 out of the atmosphere, it falls as fresh water.


JB: The freshwater that falls onto land cascades 3 over surfaces like rocks and sediments 4. Here it picks up nutrients 5, chemicals, and salts. The water carries the dissolved salts on its long journey back to sea. If you run this water cycle over and over again, through four and a half billion years, you eventually leave a lot of salt in the ocean.


DB: In fact, if you came back in another billion years, the ocean would be even saltier than it is now. Thanks for your question Jeana. And with thanks to the National Science Foundation, we're Block and Byrd for Earth and Sky.



1 scenario
n.剧本,脚本;概要
  • But the birth scenario is not completely accurate.然而分娩脚本并非完全准确的。
  • This is a totally different scenario.这是完全不同的剧本。
2 precipitates
v.(突如其来地)使发生( precipitate的第三人称单数 );促成;猛然摔下;使沉淀
  • Water precipitates camphor from its alcoholic solution. 水能把樟脑从其酒精溶液中淀析出来。 来自《简明英汉词典》
  • Precipitates are usually collected by centrifugation at intervals. 常常是用离心法分段收集沉淀的。 来自辞典例句
3 cascades
倾泻( cascade的名词复数 ); 小瀑布(尤指一连串瀑布中的一支); 瀑布状物; 倾泻(或涌出)的东西
  • The river fell in a series of cascades down towards the lake. 河形成阶梯状瀑布泻入湖中。
  • Turning into the sun, he began the long, winding drive through the Cascades. 现在他朝着太阳驶去,开始了穿越喀斯喀特山脉的漫长而曲折的路程。 来自英汉文学 - 廊桥遗梦
4 sediments
沉淀物( sediment的名词复数 ); 沉积物
  • When deposited, 70-80% of the volume of muddy sediments may be water. 泥质沉积物沉积后,体积的70-80%是水。
  • Oligocene erosion had truncated the sediments draped over the dome. 覆盖于穹丘上的沉积岩为渐新世侵蚀所截削。
5 nutrients
n.(食品或化学品)营养物,营养品( nutrient的名词复数 )
  • a lack of essential nutrients 基本营养的缺乏
  • Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》
学英语单词
absolute stop
accidental severity
Admiralty
alliate
ambitionist
angulus acromialis scapulae
antenna director
attah
ballet mistress
be all over bar the shouting
blade butt
blindman's bluff
brain disease
bromophenyl
capit-
chancelleries
checking by sampling
chief fireman
Clausena lunulata
closing flag
cold-sore
colo(u)ring problem
compilator
compostability
Cumberland Is.
cytotaxonomically
dam-buster
damper current
dancercise
degree of polymerization
dephosphorized pig iron
duobinary code
eaux de vie
ectoflexid
elmid
endochroic
episodic memories
ex buyer's godown
external malleolus
gaze on
geranium batangense pax et hoffm.
girder work
glacial amphitheater
Gosné
group lubrication
guardman
harbor wall
have trouble doing sth
Hightisone
homonoia riparia lour.
hydromagnocalcite (hydrodolomite)
ILAE
incremental displacement sensitivity
infommercials
iodine consumption
iron by hydrogen
irrorate, irrorated
law-men
leipein
neonic
nonexpert
osgoode
overpublicizes
p-words
phosphate deposit
previtalis
printed-circuit special lacquers
propellant explosive
psychophysical test
public service industry
pump assembly
pyramidology
renovict
residue of function at pole
revolving pan
Rhaphigaster mongolica
ripple through carry
rolling curve
Salians
sand explosion
Sokosho
spaghettoni
stress amplitude ratio
submarginate
suppliants
supra-mutagen
taiahas
thiodine
thread gage
through ball
throughtout
THYRIDIAE
tilt-block mountain
torgersen
TOTAL SCORE
tulgey
tumultus cordis
Twi-tard
unadulterated food
unfreakingbelievable
ventral mediastinal lymph gland
Zetlanders