📚 IGCSE AQA Science: Environmental Science Key Points Explained | IGCSE AQA 科学：环境科学 考点精讲
Environmental Science is a core topic across the AQA IGCSE Science specifications, blending biology, chemistry and physics to explore how living organisms interact with their surroundings and how human activities are shaping the planet. This article summarises the key points you need to master for the exam, from ecosystems and energy flow to pollution, climate change and sustainable solutions.
环境科学是 AQA IGCSE 科学课程中的核心主题，融合了生物学、化学和物理学知识，探讨生物如何与环境相互作用以及人类活动如何改变地球。本文总结了你必须掌握的所有关键考点，涵盖生态系统、能量流动、污染、气候变化和可持续解决方案。
1. Ecosystems and Interdependence | 生态系统与相互依赖
An ecosystem is a self-contained unit including all the living organisms (biotic factors) and the non-living conditions (abiotic factors such as light, temperature, water and soil) in a given area. The organisms form a community, and the place where a particular species lives is its habitat. The role it plays within the ecosystem is its ecological niche.
生态系统是一个独立的单元，包括特定区域内所有生物（生物因素）和非生物条件（非生物因素，如光照、温度、水和土壤）。生物种群构成群落，一个物种生活的地方就是它的栖息地，它在生态系统中扮演的角色就是生态位。
Interdependence describes the way species rely on one another for food, shelter, pollination and seed dispersal. If one species is removed, it can affect the entire food web and reduce ecosystem stability.
相互依赖指物种之间彼此依赖来获取食物、庇护、传粉和种子传播。如果移除了某个物种，可能会影响整个食物网，降低生态系统的稳定性。
2. Food Chains and Trophic Levels | 食物链与营养级
A food chain shows the transfer of energy from one organism to the next, starting with a producer (usually a green plant or alga that carries out photosynthesis). Primary consumers eat producers, secondary consumers eat primary consumers, and so on. Each feeding level is called a trophic level.
食物链表示能量从一个生物传递到下一个生物的过程，起点是生产者（通常是能进行光合作用的绿色植物或藻类）。初级消费者吃生产者，次级消费者吃初级消费者，以此类推。每一个取食层级叫做营养级。
Food chains are usually short because energy is lost at each trophic level through respiration, movement and undigested material. In reality, organisms feed on more than one species, forming a complex food web.
食物链通常很短，因为能量在每一营养级都会因呼吸作用、运动以及未被消化的物质而损失。现实中，生物取食不止一种物种，形成了复杂的食物网。
| Trophic level | Example |
|---|---|
| Producer | Grass |
| Primary consumer | Rabbit |
| Secondary consumer | Fox |
| Tertiary consumer | Eagle |
3. Pyramids of Biomass and Energy Loss | 生物量金字塔与能量损失
A pyramid of biomass represents the total mass of living material at each trophic level. The bar for producers is always the widest, and it narrows towards the top because energy is lost at every transfer. On average, only about 10% of the energy is passed on to the next level; the rest is used for life processes or lost as heat.
生物量金字塔展示了各营养级的生物总质量。生产者的柱形总是最宽，越往上越窄，因为能量在每次传递中都有损失。平均而言，仅有大约 10% 的能量传递到下一营养级，其余能量用于生命过程或以热的形式散失。
Energy available at next trophic level ≈ 10% of previous level
下一营养级可用的能量 ≈ 前一级能量的 10%
The loss of energy explains why food chains rarely have more than five trophic levels and why there are far fewer top predators than herbivores. Efficiency of energy transfer can be calculated as (energy transferred / energy input) × 100%.
能量损失解释了为什么食物链很少超过五个营养级，以及顶级捕食者的数量为何远少于食草动物。能量传递效率可用公式（传递的能量 ÷ 输入的能量）× 100% 计算。
4. Bioaccumulation and Biomagnification | 生物累积与生物放大
Some pollutants, such as pesticides (e.g. DDT) or heavy metals, do not break down easily in the body and instead build up in the tissues of organisms. This is bioaccumulation. When these toxic substances pass along a food chain, their concentration increases at each successive trophic level—a process called biomagnification.
一些污染物，如杀虫剂（例如 DDT）或重金属，不易在体内分解，而是逐渐积累在生物体组织中，这就是生物累积。当这些有毒物质沿食物链传递时，它们的浓度在每一营养级不断升高，这一过程称为生物放大。
Top predators are most severely affected, often suffering reproductive failure or death. This is a key example of how human actions can have far-reaching effects on ecosystems.
顶级捕食者受到的危害最为严重，往往出现繁殖失败甚至死亡。这是人类行为对生态系统产生深远影响的一个关键实例。
5. The Carbon Cycle | 碳循环
Carbon is recycled constantly through the environment. Photosynthesis removes CO2 from the atmosphere and converts it into organic compounds in plants. Feeding passes carbon through food chains, while respiration by all living organisms releases CO2 back into the air.
碳通过环境持续循环。光合作用从大气中吸收 CO2 并将其转化为植物体内的有机化合物。取食行为让碳沿着食物链传递，而所有生物的呼吸作用又将 CO2 释放回到空气中。
Photosynthesis: 6CO2 + 6H2O → C6H12O6 + 6O2
光合作用：6CO2 + 6H2O → C6H12O6 + 6O2
Decomposers (bacteria and fungi) break down dead organisms and waste, returning carbon to the soil as organic matter and releasing CO2 through their own respiration. Combustion of fossil fuels and wood also emits CO2, and over geological timescales carbon becomes locked away in sedimentary rocks and fossil fuels.
分解者（细菌和真菌）分解死去的生物和废物，将碳以有机物形式归还土壤，并通过自身的呼吸作用释放 CO2。化石燃料和木材的燃烧也会释放 CO2，在漫长的地质时间里碳被储存在沉积岩和化石燃料中。
6. The Water Cycle | 水循环
The water cycle describes how water moves between the atmosphere, land and oceans. The key processes are evaporation (from water bodies), transpiration (from plant leaves), condensation (forming clouds) and precipitation (rain, snow or hail).
水循环描述了水如何在大气、陆地和海洋之间移动。关键过程包括蒸发（来自水体）、蒸腾作用（从植物叶片）、凝结（形成云）和降水（雨、雪或冰雹）。
Most water returns directly to the oceans, but some falls on land and is taken up by plants, flows across the surface as runoff, or infiltrates into the ground to become groundwater. Human activities, such as deforestation and urbanisation, alter the water cycle by reducing infiltration and increasing runoff, which can lead to flooding.
大部分水直接返回海洋，但一部分降落在陆地并被植物吸收，以表面径流形式流动，或渗入地下成为地下水。人类活动，如森林砍伐和城市化，会减少入渗、增加径流，从而改变水循环，可能引发洪水。
7. Human Population Growth and Resource Demands | 人口增长与资源需求
The global human population is increasing rapidly, leading to a higher demand for food, fresh water, timber, energy and land. To meet these needs, more land is converted for farming and housing, often at the expense of natural habitats.
全球人口正在快速增长，导致对食物、淡水、木材、能源和土地的需求不断增加。为满足这些需求，更多的土地被开垦为农田和建设用地，通常以牺牲自然栖息地为代价。
This expansion can cause habitat destruction, a decline in biodiversity and increased pollution from agriculture and industry. Managing resources sustainably is therefore a major challenge for modern science and society.
这种扩张可能导致栖息地破坏、生物多样性下降以及农业和工业污染的加剧。因此，可持续地管理资源是当代科学和社会面临的一大挑战。
8. Pollution – Air, Water and Land | 污染：空气、水与土地
Air pollution arises from the combustion of fossil fuels and industrial processes. Key pollutants include carbon monoxide (CO) – a poisonous gas, sulfur dioxide (SO2) and nitrogen oxides (NOx) which cause acid rain, and particulates (PM) that damage respiratory systems.
空气污染来自化石燃料的燃烧和工业过程。主要污染物包括一氧化碳（CO）——一种有毒气体；导致酸雨的二氧化硫（SO2）和氮氧化物（NOx）；以及危害呼吸系统的颗粒物（PM）。
Water pollution can be caused by untreated sewage, agricultural runoff containing nitrates and phosphates, and toxic chemicals from industry. Excess nutrients cause eutrophication, where algal blooms deplete oxygen levels and kill aquatic life.
水污染可能由未处理的污水、含有硝酸盐和磷酸盐的农业径流以及工业有毒化学物质引起。过剩的营养物质导致富营养化，藻类大量繁殖耗尽水中氧气，使水生生物死亡。
Land pollution includes the dumping of solid waste and the accumulation of harmful substances in soil, which can enter food chains and contaminate groundwater.
土地污染包括固体废物的倾倒以及有害物质在土壤中的积累，这些物质会进入食物链并污染地下水。
9. Greenhouse Effect and Climate Change | 温室效应与气候变化
The natural greenhouse effect keeps the Earth warm enough for life. Greenhouse gases such as carbon dioxide (CO2), methane (CH4) and water vapour trap infrared radiation from the Sun, preventing it from escaping back into space. Without this effect, the Earth’s average temperature would be about −18 °C.
天然的温室效应使地球保持适合生命存在的温度。温室气体如二氧化碳（CO2）、甲烷（CH4）和水蒸气会捕获来自太阳的红外辐射，阻止其返回太空。如果没有温室效应，地球的平均温度会低至 −18 °C。
Human activities, especially the burning of fossil fuels, deforestation and agriculture, have dramatically increased the concentration of these gases, enhancing the greenhouse effect and causing global warming. This is linked to climate change – rising sea levels, more extreme weather events and changes to ecosystems.
人类活动，尤其是化石燃料燃烧、森林砍伐和农业生产，极大地提高了这些气体的浓度，增强了温室效应，导致全球变暖。这与气候变化密切相关——海平面上升、极端天气事件增多以及生态系统变化。
10. Acid Rain, Deforestation and Biodiversity Loss | 酸雨、森林砍伐与生物多样性丧失
Sulfur dioxide and nitrogen oxides dissolve in moisture in the atmosphere to form sulfuric acid and nitric acid. These acids fall as acid rain, damaging trees, eroding buildings and lowering the pH of lakes and rivers, which harms aquatic organisms.
二氧化硫和氮氧化物溶解在大气中的水汽里，形成硫酸和硝酸。这些酸以酸雨的形式降落，损害树木，侵蚀建筑物，降低湖泊和河流的 pH 值，危害水生生物。
2SO2 + O2 + 2H2O → 2H2SO4
2SO2 + O2 + 2H2O → 2H2SO4
Large-scale deforestation, often for timber or to clear land for agriculture, destroys habitats and reduces biodiversity. It also disrupts the carbon and water cycles, as fewer trees are available to absorb CO2 and release water vapour.
大规模的森林砍伐，通常是为了获取木材或开垦农田，会破坏栖息地并降低生物多样性。它还会扰乱碳循环和水循环，因为可吸收 CO2 并释放水蒸气的树木减少了。
Biodiversity is the variety of different species, genetic variation within species and the range of ecosystems. High biodiversity makes ecosystems more resilient to change, so its loss is a serious concern.
生物多样性是指物种的多样化、物种内的遗传变异以及生态系统的多样性。较高的生物多样性使生态系统对变化更具适应力，因此其丧失是一个重大关切。
11. Sustainability and Conservation | 可持续性与保护
Sustainability means meeting the needs of the present population without compromising the ability of future generations to meet their own needs. Strategies include reforestation, sustainable fishing quotas, using renewable energy and reducing waste through the ‘three Rs’ – reduce, reuse, recycle.
可持续性意味着满足当代人的需求，同时不损害未来世代满足其自身需求的能力。相关策略包括重新造林、设定可持续的捕捞配额、使用可再生能源以及通过“3R”原则——减少使用、重复利用和回收——来减少废物。
Conservation programmes aim to protect species and their habitats. This can be done by setting up nature reserves, captive breeding programmes and enforcing laws against poaching and deforestation. Protecting a keystone species often helps to maintain the structure of an entire ecosystem.
保护计划旨在保护物种及其栖息地。可以通过建立自然保护区、实施圈养繁殖计划以及执行打击偷猎和滥伐森林的法律来实现。保护关键物种通常有助于维持整个生态系统的结构。
12. Renewable and Non-Renewable Energy Resources | 可再生与不可再生能源资源
Non-renewable energy resources include fossil fuels (coal, oil, natural gas) and nuclear fuels. They are finite and release CO2 or other pollutants when used. Burning fossil fuels is the largest contributor to the enhanced greenhouse effect.
不可再生能源包括化石燃料（煤、石油、天然气）和核燃料。它们是有限的，并且在使用时会释放 CO2 或其他污染物。燃烧化石燃料是增强温室效应的最大贡献者。
Renewable resources are naturally replenished and typically produce far less pollution. Examples include solar, wind, tidal, wave, hydroelectric and geothermal energy, as well as biofuels. However, they can be intermittent and may require specific geographical conditions, and some, like biofuels, can compete with food production for land.
可再生资源可自然补充，通常产生的污染要少得多。实例包括太阳能、风能、潮汐能、波浪能、水力发电和地热能，以及生物燃料。然而，这些能源可能是间断性的，需要特定的地理条件，而且其中一些如生物燃料可能会与粮食生产争夺土地。
| Energy resource | Renewable? | Key advantage | Key disadvantage |
|---|---|---|---|
| Coal | No | Reliable, high energy output | Releases CO2 and SO2 |
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