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
Acanthocoras
addressed store
adjusting idler wheel
aftergrowth
avoidable fixed cost
bargained for
Bothrops jararaca
butyl stearate
caipira
carry-over point
Chondrobranchii
chromatogram homogeneity
closed network model
coccidioidosis
Colmor
compost bacteria
contact wear
crank shaft bearing
dearomatising
decology
deficiency of stomach yin
desmosome
dynacords
eigen-value
Ektyl
farm production control technique
flattenedregion
fleabites
gaillardcut
gelatin paper
goods of the contract description
great land
greisens
helical orbit beta-ray spectrometer
hevery
homileticss
ideographical
Igunga
intack
interfirm network
internal mammary vein
isopotentials
Ladoxaprine
leipzigs
limitededition
liquid application
long nozzle heel nailing machine
longmonts
made demands of
main schedule
mangunel
Maranta arundinacea L.
melanocratic rock
metalloaminopeptidase
military emergency regime
milk loaf
mock standard
mondull
nadb
nick us
nonfat dry milks
nonleprotic
numeri clausi
on full pay
optimal value function
overabundant yin
parliamentary train
paternal acres
periosteophyte
phenological season
pilot laboratory
plecotuss
projection aligner
ram cichlids
reduced state classification
ristomycin
rope-a-dope
rough ... up
SAHRP
sarafino
schadenfreuders
sherpas
side cam
silver-leaved nightshades
slick sth down
sparse-matrix
sub-zero treatment device
telecommunication center
teledium
thornlet
tidal sea
to be at the receiving end
to throttle
Togdheer, Gobolka
total footage
travellest
twin choke
two-dimensional finite element method
unreconciled
us headquarters
variipennis
Yambean