The Nitrogen Cycle · 氮循环
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| nitrogen fixation/ˈnaɪtrədʒn fɪkˈseɪʃn/ | 固氮作用 | gù dàn zuò yòng |
| nitrifying bacteria/ˈnaɪtrɪfaɪɪŋ bækˈtɪərɪə/ | 硝化细菌 | xiāo huà xì jūn |
| denitrification/diːˌnaɪtrɪfɪˈkeɪʃn/ | 反硝化作用 | fǎn xiāo huà zuò yòng |
The locked-up gas
- The air is mostly nitrogen — about 78% of every breath.
- Nitrogen is essential for proteins and DNA.
- Yet almost no living thing can use the nitrogen gas directly.
- Getting nitrogen into life takes a special journey: the nitrogen cycle.
被锁住的气体
- 空气大部分是氮——每一口呼吸的约 78%。
- 氮对蛋白质和 DNA 是必需的。
- 然而几乎没有生物能直接使用这种氮气。
- 让氮进入生命需要一段特殊的旅程:氮循环。
Why nitrogen must be fixed
- Nitrogen gas (N2) has a very strong triple bond, hard to break.
- So plants and animals cannot use it straight from the air.
- Nitrogen fixation 固氮作用 turns N2 into ammonia and nitrates.
- This job is done mainly by special bacteria in soil and roots.
氮为什么必须被固定
- 氮气(N2)有一个非常强的三键,难以打破。
- 所以植物和动物不能直接从空气中使用它。
- 固氮作用(nitrogen fixation)把 N2 变成氨和硝酸盐。
- 这项工作主要由土壤和根里的特殊细菌完成。
Why can most living things not use the nitrogen gas in the air directly? · 为什么大多数生物不能直接使用空气中的氮气?
N2 has a very strong triple bond, so it must first be fixed · 固定的 into usable forms. · N2 有一个非常强的三键,所以它必须先被固定成可用的形式。
Nitrogen fixation · 固氮 is carried out mainly by… · 固氮主要由……进行。
Nitrogen fixation · 固氮 by bacteria turns N2 into ammonia and nitrates plants can use. · 细菌的固氮把 N2 变成植物能用的氨和硝酸盐。
Nitrogen enters the food chain
- Plants absorb the fixed nitrates through their roots.
- They use the nitrogen to build proteins and DNA.
- Animals get their nitrogen by eating plants.
- So fixed nitrogen passes up through the whole food chain.
氮进入食物链
- 植物通过它们的根吸收固定好的硝酸盐。
- 它们用氮来构建蛋白质和 DNA。
- 动物通过吃植物获得它们的氮。
- 所以固定的氮沿整条食物链向上传递。
The nitrogen cycle · 氮循环
Step around the cycle - nitrogen gas is fixed into usable forms, used by life, then returned to the air. · 绕这个循环走——氮气被固定成可用的形式,被生命使用,然后还给空气。
Plants use fixed nitrogen to build , and animals get it by eating plants. · 植物用固定的氮来构建,动物通过吃植物获得它。
Nitrogen is essential for proteins and DNA; animals get theirs by eating plants. · 氮对蛋白质和 DNA 是必需的;动物通过吃植物获得它们的氮。
Back to the air
- When living things die, decomposers release their nitrogen into the soil.
- Nitrifying bacteria 硝化细菌 convert it into nitrates plants can reuse.
- Finally, denitrification 反硝化作用 returns nitrogen to the air as N2 gas.
- The loop is closed, ready to begin again.
回到空气
- 当生物死去,分解者把它们的氮释放进土壤。
- 硝化细菌(nitrifying bacteria)把它转化成植物能重新使用的硝酸盐。
- 最后,反硝化作用(denitrification)把氮作为 N2 气体还给空气。
- 循环闭合,准备重新开始。
Denitrifying bacteria return nitrogen to the air, completing the cycle. · 反硝化细菌把氮还给空气,完成循环。
Denitrification · 反硝化 converts nitrates back to N2 gas, closing the loop. · 反硝化把硝酸盐转回 N2 气体,闭合这个循环。
Select all · 所有 true statements about the nitrogen cycle. · 选出关于氮循环的所有正确说法。
Most life cannot use N2 gas directly — it must be fixed first. The other three are correct. · 大多数生命不能直接使用 N2 气体——它必须先被固定。其余三条正确。
The whole cycle depends on bacteria, not big organisms. Without nitrogen-fixing and denitrifying bacteria, the nitrogen in the air could never reach living things or return. These tiny microbes are the hidden engine of the entire nitrogen cycle.
整个循环依赖细菌,而不是大型生物。没有固氮和反硝化细菌,空气中的氮就永远无法到达生物或返回。这些微小的微生物是整个氮循环隐藏的引擎。
Farmers and the nitrogen cycle:
- Crops strip nitrogen from the soil as they grow.
- Farmers restore it — by planting legumes whose root bacteria fix nitrogen, or by adding fertiliser.
- Both put usable nitrogen back into the soil so the next crop can build its proteins.
农民与氮循环:
- 作物在生长时从土壤里夺走氮。
- 农民恢复它——通过种植根部细菌能固氮的豆科植物,或通过施肥。
- 两者都把可用的氮放回土壤,这样下一茬作物就能构建它的蛋白质。
The nitrogen cycle moves nitrogen from air to life and back. Because N2 gas is hard to use, nitrogen fixation by bacteria turns it into usable nitrates. Plants use these for proteins; animals get theirs by eating plants; and denitrification returns nitrogen to the air. Bacteria drive every key step.
氮循环把氮从空气移到生命再移回来。因为 N2 气体难以使用,细菌的固氮作用把它变成可用的硝酸盐。植物用这些来制造蛋白质;动物通过吃植物获得它们的;而反硝化作用把氮还给空气。细菌驱动每一个关键步骤。