空气的变化：比例、证据及碳储存库
引入| English | 释义 | 拼音 |
|---|---|---|
| volcanic activity | 火山活动 | huǒ shān huó dòng |
| condensation/kɒndenˈseɪʃn/ | 凝结 | níng jié |
| algae/ˈælɡiː/ | 藻类 | zǎo lèi |
| photosynthesis/ˌfəʊtəʊˈsɪnθəsɪs/ | 光合作用 | guāng hé zuò yòng |
| fossil fuel/ˈfɒsl ˈfjuːəl/ | 化石燃料 | huà shí rán liào |
| limestone/ˈlaɪmstəʊn/ | 石灰岩 | shí huī yán |
| coal/kəʊl/ | 煤 | méi |
| crude oil/kruːd ɔɪl/ | 原油 | yuán yóu |
| natural gas/ˈnætʃərəl ɡæs/ | 天然气 | tiān rán qì |
Why is today's air unlike volcanic gas?
- Today's air is roughly four-fifths nitrogen and one-fifth oxygen, with small amounts of other gases. Water vapour varies; dry-air proportions exclude it.
- Volcanoes release much carbon dioxide, but it is a small component of today's air. Explain the processes that changed the atmosphere rather than treating today's air as a direct volcanic sample.
Convert a gas fraction into a volume
- For a fixed temperature and pressure, gas volume = its fraction × total air volume. Use one consistent dataset: the rough 80/20 model deliberately ignores small components.
- Worked case: 300 cm³ of air in that model contains $\frac45\times300=240$ cm³ nitrogen and $\frac15\times300=60$ cm³ oxygen. A separate supplied 78/21/1 dataset must be calculated with its own fractions.
For a 500 cm³ sample with 78% nitrogen, 21% oxygen and 1% other gases, the nitrogen volume is $0.78\times500=390$ cm³. The other gases total 5 cm³; they are not all carbon dioxide.
一个 500 cm³ 的样本代表 78% 的氮气。请计算其在相同温度和压力下的氮气体积。
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氮气体积 = 氮气分数 × 总体积 = 78 / 100 × 500 cm³ = 390 cm³。请使用 0.78 进行计算，而非 78 或不同的粗略 4/5 模型。
Separate the early-atmosphere theory from certainty
- One theory links the early atmosphere to intense volcanic activity 火山活动 during Earth's first billion years: mainly carbon dioxide, water vapour and nitrogen, with little or no oxygen and small amounts of methane/ammonia.
- Earth formed about 4.6 billion years ago. Direct measurements from then do not exist, and evidence is limited. Modern volcanic gases, rocks and other planets can support a theory; they do not supply an exact ancient percentage. Ice cores record later air, not the first atmosphere.
观察到现代火山释放 CO₂，这一现象支持哪项结论？
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该观察结果支持一种可能的气体来源假说。它既未测量古代的具体百分比，也未确立最早期大气中与现代相同的氧气比例。
古老冰芯直接采样了地球初生时的大气环境。
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冰芯记录的是较晚时期的大气状况，而非约 4.6 十亿年前地球形成时的空气。原始大气必须依据有限的间接证据进行推断。
Follow water and carbon by different routes
- Condensation 凝结 changes water vapour into liquid as Earth cools, forming oceans. It does not change water into carbon dioxide.
- Carbon dioxide dissolves in ocean water; carbonates precipitate and form sediments. These processes remove carbon from the atmosphere. Nitrogen from volcanic activity gradually builds up.
Explain the biological oxygen increase
- Algae 藻类 first produced oxygen by photosynthesis 光合作用 about 2.7 billion years ago; plants evolved later. Oxygen rose gradually over the next billion years to a level that enabled animals to evolve.
- Photosynthesis uses light: $6CO_2+6H_2O\rightarrow C_6H_{12}O_6+6O_2$. Carbon dioxide enters biomass and oxygen is released. Each side has six carbon, twelve hydrogen and eighteen oxygen atoms; respiration has the opposite overall gas effect.
藻类使用哪种过程去除CO₂并释放氧气？
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光合作用利用二氧化碳和水在光照下生成葡萄糖和氧气。藻类在植物进化之前就开始贡献氧气。
Distinguish rock from fossil-fuel 化石燃料 formation
- Limestone 石灰岩 forms from accumulated carbonate sediments, including marine shells/skeletons. Coal 煤 forms from buried plant remains; crude oil 原油 and natural gas 天然气 form mainly from buried small marine organisms changed by heat and pressure over millions of years.
- Burial can store carbon outside the atmosphere for a long time rather than returning all of it by decay. These fossil fuels do not form instantly when carbon dioxide dissolves; burning them returns carbon mainly as carbon dioxide.
将过程或储存库与其含义相匹配。
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凝结改变物理状态；光合作用改变化学物质；石灰岩和化石燃料通过不同的形成途径储存碳。
State what evidence can establish
- A modern volcano releasing carbon dioxide supports a possible volcanic origin. It does not show that Earth's first atmosphere was exactly 90% carbon dioxide. Independent geological evidence and planetary comparisons can strengthen an interpretation.
- Use the pattern “observation → supported explanation → limitation”. Treat the diagram as a qualitative sequence, not measured historical fractions or a time scale.
“Ancient ice directly samples the air when Earth first formed” is false. Ice records much later atmospheres. The earliest composition must be inferred from limited indirect evidence.
Today's proportions, cooling/condensation, ocean carbon removal, photosynthesis and burial explain different parts of the atmospheric change. Name the process and carbon/oxygen route, then state the evidence's limit.
哪两个陈述能使早期大气解释保持合理？
难度 2/5 · 今日首次完成可获 140 金币及少量额外奖励
说明观察内容及支持结论，然后指出缺失的直接证据。精确的历史百分比和普适行星类比夸大了证据效力。