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叶子变色的原因 – 译学馆
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叶子变色的原因

The Real Reason Leaves Change Color In the Fall

You’ve probably heard that leaves of deciduous trees change color in autumn
你应该听说过落叶树的叶子会在秋天变色
because they lose their green chlorophyll molecules
是因为它们失去了绿色的叶绿素分子
allowing the underlying yellow-orange pigments to shine through.
从而露出了下层的黄橙色色素
However, this doesn’t explain why the leaves change color in the first place.
但这并没有解释为什么叶子到秋天就一定要变色
Deciduous trees drop their leaves each year to avoid the high cost of winterizing them
落叶树每年落叶是为了降低冬天防冻的消耗
but this seasonal shedding would be too wasteful to be worth doing
但如果树木把它们每年从土壤里辛苦汲取出来
if the trees lost all of the valuable nutrients they laboriously extracted from the soil
用于长出新叶子的营养全扔了的话
to build their leaves earlier in the year.
这种季节性脱叶未免太过浪费
So each fall, deciduous trees recycle their leaves before dropping them.
所以每年秋天 落叶树会在叶子落下前进行营养回收
That means taking apart cells and photosynthetic apparatus
也就是说会分解树叶的细胞和光合器官
from the inside out in order to recoup their nitrogen
来从中回收氮和磷
and phosphorus and store it in twigs and branches until next spring.
并将它们储在树枝中等待来年春天
This is actually really tricky
这过程非常困难
because as the disassembly starts
因为随着分解开始
the chlorophyll molecules that absorb sunlight for photosynthesis
叶绿素为了光合作用
are still absorbing the sun’s energy.
仍然在吸收太阳能
But with no photosynthesis happening
但却不再进行光合作用
they end up passing the unused energy along to oxygen molecules
最后它们将多余的能量给了氧分子
which become dangerously reactive when energized.
此时氧分子一旦被激发会变得非常危险
These molecules wreak havoc
这些氧分子横行肆虐
damaging the parts of the leaf
破坏了树叶的部分机能
that are in the process of recovering and transporting nutrients back to the rest of the tree.
阻止它们向树的其他部分回收并输送营养物质
To keep this destruction to a minimum
为了使损失最小化
leaves break down their chlorophyll into less dangerous molecules
树叶会把叶绿素变成低危险的分子
that are typically transparent, though sometimes yellow.
它们通常是透明的 也有些是黄色的
Either way, with the bright green molecules gone
无论如何 亮绿色的分子消失了
yellow and orange pigments that were there all along helping with photosynthesis
一直默默帮助光合作用的黄色和橙色色素
are no longer overshadowed,
就都显现了出来
and ta-da! Yellow and orange leaves.
于是 就有了黄色和橙色的叶子
Some trees take an extra autumnal precaution against
有些树木还有一套额外的秋季预防措施
chlorophyll-induced-destruction:
来防止叶绿素引发的破坏
as the leaf dismantling starts
随着树叶开始分解
they build new special pigments to shade chlorophyll from sunlight
它们会形成新的特殊色素来遮挡阳光
until it can be broken down.
直到叶绿素被分解
These new pigments tend to be red or purple in color
这些新色素通常是红色或紫色
so trees that use them have red leaves in the fall –
所以这些树的叶子看上去是红的了
sometimes insanely bright red.
有时会是鲜红色
In the end, these exquisite gold and russet displays
最终 这些美丽的金色和黄褐色树叶
help deciduous trees recover
帮助落叶乔木回收了
as much as 50% of the nitrogen and phosphorus from their old leaves
老叶中多达50%的氮和磷
to help grow fresh new green ones in the spring.
令大树可以在新春中焕发新绿
They are perhaps the world’s prettiest recycling plants.
它们大概是世上最漂亮的回收站

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叶子为什么会变色,来听一下解释叭

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收集自网络

翻译译者

玛卡•巴卡

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审核员BY

视频来源

https://www.youtube.com/watch?v=JWva5AaDkXw

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