📚 GCSE WJEC Science: Environmental Science Key Points | GCSE WJEC 科学：环境科学 考点精讲
Environmental science is a core component of the WJEC GCSE Science specification, linking biology, chemistry, and physics to explore how living organisms interact with their surroundings and the impact of human activities. This revision guide distils the essential topics you need to master for the exam, from ecosystems and cycles to pollution and sustainability.
环境科学是 WJEC GCSE 科学课程的核心组成部分，它将生物学、化学和物理学联系起来，探索生物体如何与环境互动以及人类活动的影响。这份复习指南提炼了你考试必须掌握的核心主题，从生态系统和循环到污染与可持续性。
1. Ecosystems and Habitats | 生态系统与栖息地
An ecosystem is a natural unit consisting of all living organisms (biotic factors) in a specific area interacting with each other and with their non-living environment (abiotic factors) such as light, temperature, water, and soil minerals.
生态系统是一个自然单元，由特定区域内的所有生物（生物因素）组成，它们彼此之间以及与光、温度、水和土壤矿物质等非生物环境（非生物因素）相互作用。
A habitat is the place where an organism lives; it provides food, shelter, and conditions suitable for reproduction. A population is a group of individuals of the same species living in a habitat, while a community includes all the populations of different species in an ecosystem.
栖息地是生物生活的地方，提供食物、住所和适宜繁殖的条件。种群是生活在某个栖息地的同一物种个体的集合，而群落则包括一个生态系统中所有不同物种的种群。
Key terms to remember: individual → population → community → ecosystem → biome → biosphere.
需要记住的关键术语：个体 → 种群 → 群落 → 生态系统 → 生物群系 → 生物圈。
2. Food Chains and Food Webs | 食物链与食物网
A food chain shows the linear sequence of who eats whom in an ecosystem. Energy is transferred from one organism to another. For example: grass (producer) → rabbit (primary consumer) → fox (secondary consumer).
食物链显示了一个生态系统中谁吃谁的线性序列。能量从一个生物体传递到另一个。例如：草（生产者）→ 兔子（初级消费者）→ 狐狸（次级消费者）。
Producers (plants and algae) make their own food via photosynthesis. Consumers eat other organisms. Decomposers (bacteria, fungi) break down dead material, returning nutrients to the soil.
生产者（植物和藻类）通过光合作用制造自己的食物。消费者以其他生物为食。分解者（细菌、真菌）分解死去的物质，将养分归还土壤。
A food web is a network of interconnected food chains, showing the complex feeding relationships in an ecosystem. It provides a more realistic picture because most organisms eat more than one type of food.
食物网是相互连接的食物链网络，展示了一个生态系统中复杂的摄食关系。它提供了更真实的图景，因为大多数生物不止吃一种食物。
Arrows in a food chain or web always point in the direction of energy flow, towards the eater.
食物链或食物网中的箭头始终指向能量流动的方向，即指向取食者。
3. Energy Transfer and Trophic Levels | 能量传递与营养级
Each step in a food chain is called a trophic level. Producers occupy the first level, primary consumers the second, and so on. Energy is lost at every level through respiration, movement, heat, and undigested wastes (egestion).
食物链中的每一步称为一个营养级。生产者占据第一级，初级消费者第二级，依此类推。能量在每一级都会通过呼吸作用、运动、热量和未消化的废物（排遗）而损失。
Typically, only about 10% of the energy is transferred from one trophic level to the next. This inefficiency limits the length of food chains—rarely more than 4 or 5 trophic levels.
通常，只有大约10%的能量从一个营养级传递到下一个。这种低效率限制了食物链的长度——很少超过4或5个营养级。
Ecologists use pyramids to represent these relationships: pyramids of numbers simply count organisms; pyramids of biomass show the total mass of living material at each level; pyramids of energy transfer are always upright and most informative.
生态学家用金字塔表示这些关系：数量金字塔简单统计生物个数；生物量金字塔显示每个营养级活物质的总质量；能量传递金字塔总是正立且信息量最丰富。
4. The Carbon Cycle | 碳循环
Carbon is a fundamental element in all organic compounds and cycles between the atmosphere, living things, oceans, and rocks. The main processes are photosynthesis, respiration, combustion, decomposition, and fossil fuel formation.
碳是所有有机化合物中的基本元素，在大气、生物、海洋和岩石之间循环。主要过程包括光合作用、呼吸作用、燃烧、分解和化石燃料形成。
Photosynthesis removes CO₂ from the atmosphere and converts it into glucose:
光合作用从大气中吸收 CO₂ 并将其转化为葡萄糖：
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Respiration, combustion, and decomposition return CO₂ to the atmosphere. When living things die and are compressed over millions of years, they form fossil fuels (coal, oil, natural gas).
呼吸作用、燃烧和分解将 CO₂ 重新释放到大气中。当生物死亡并被压缩数百万年，就形成化石燃料（煤、石油、天然气）。
Burning fossil fuels releases stored carbon rapidly, disrupting the balance of the cycle. Oceans also act as carbon sinks by absorbing CO₂.
燃烧化石燃料会迅速释放储存的碳，破坏循环的平衡。海洋通过吸收 CO₂ 也充当碳汇。
5. The Nitrogen Cycle | 氮循环
Nitrogen is essential for making proteins and DNA, but plants cannot use atmospheric nitrogen (N₂) directly. The nitrogen cycle converts N₂ into forms plants can absorb, such as ammonium ions (NH₄⁺) and nitrate ions (NO₃⁻).
氮对于制造蛋白质和 DNA 至关重要，但植物不能直接利用大气中的氮（N₂）。氮循环将 N₂ 转化为植物可吸收的形式，如铵离子（NH₄⁺）和硝酸根离子（NO₃⁻）。
Key processes: Nitrogen fixation (by Rhizobium bacteria in root nodules of legumes, and by lightning), which converts N₂ into ammonia (NH₃). Nitrification (by nitrifying bacteria) oxidises ammonia to nitrites (NO₂⁻) then to nitrates (NO₃⁻). Assimilation is when plants take up nitrates to make proteins.
关键过程：固氮作用（由豆科植物根瘤中的根瘤菌以及闪电完成），将 N₂ 转化为氨（NH₃）。硝化作用（由硝化细菌完成）将氨氧化为亚硝酸盐（NO₂⁻）再转换为硝酸盐（NO₃⁻）。同化作用是植物吸收硝酸盐来制造蛋白质。
Ammonification: decomposers break down protein from dead organisms and waste into ammonia. Denitrification: denitrifying bacteria convert nitrates back into N₂ gas, returning it to the atmosphere, often in waterlogged soils.
氨化作用：分解者将死生物和废物中的蛋白质分解为氨。反硝化作用：反硝化细菌将硝酸盐转化回 N₂ 气体，归还大气，常发生在渍水土壤中。
The role of legumes and crop rotation in maintaining soil nitrogen is a common exam question.
豆科植物和轮作在维持土壤氮素方面的作用是常见的考试题目。
6. The Water Cycle | 水循环
Water cycles continuously between the land, oceans, and atmosphere. Energy from the Sun drives the cycle. The main stages are evaporation, transpiration, condensation, precipitation, and runoff.
水在陆地、海洋和大气之间不断循环。太阳的能量驱动这一循环。主要阶段有蒸发、蒸腾、凝结、降水与径流。
Evaporation: liquid water turns into water vapour from surfaces (lakes, rivers, oceans). Transpiration: the loss of water vapour from plant leaves through stomata. Together they are often called evapotranspiration.
蒸发：液态水从湖、河、海洋表面转变成水蒸气。蒸腾：水蒸气从植物叶片的气孔散失。两者合起来常称为蒸散。
Condensation: water vapour cools and turns back into liquid droplets, forming clouds. Precipitation: water falls back to Earth as rain, snow, sleet, or hail. Surface runoff and groundwater flow return water to the oceans, completing the cycle.
凝结：水蒸气冷却变回小液滴，形成云。降水：水以雨、雪、雨夹雪或冰雹的形式返回地面。地表径流和地下水流动将水送回海洋，完成循环。
Drinking water is often obtained from groundwater sources and must be treated to remove pollutants and microbes.
饮用水常取自地下水源，必须经过处理以去除污染物和微生物。
7. Pollution: Causes, Effects, and Solutions | 污染：原因、影响及解决方案
Pollution is the introduction of harmful substances or energy into the environment. It can be local, regional, or global. The table below summarises key air and water pollutants on the WJEC specification.
污染是指有害物质或能量进入环境。它可以是局部的、区域性的或全球性的。下表总结了 WJEC 考纲中关键的空气和水污染物。
| Pollutant 污染物 |
Source 来源 |
Effects 影响 |
|---|---|---|
| Sulfur dioxide (SO₂) 二氧化硫 |
Burning coal and oil in power stations 发电厂燃烧煤和石油 |
Acid rain, respiratory problems 酸雨, 呼吸问题 |
| Nitrogen oxides (NOₓ) 氮氧化物 |
Vehicle engines, furnaces 汽车引擎, 熔炉 |
Acid rain, smog, asthma 酸雨, 烟雾, 哮喘 |
| Carbon monoxide (CO) 一氧化碳 |
Incomplete combustion in cars 汽车中不完全燃烧 |
Toxic, binds to haemoglobin 有毒, 与血红蛋白结合 |
| Particulates (PM) 颗粒物 |
Diesel engines, industry, dust 柴油机, 工业, 灰尘 |
Lung damage, global dimming 肺损伤, 全球变暗 |
| Fertilisers (nitrates, phosphates) 化肥 (硝酸盐, 磷酸盐) |
Agricultural runoff 农业径流 |
Eutrophication of aquatic ecosystems 水生生态系统的富营养化 |
Eutrophication sequence: excess nutrients → algal bloom → blocks light → aquatic plants die → decomposers use oxygen → death of fish and other life.
富营养化顺序：养分过量 → 藻类大量繁殖 → 阻挡光照 → 水生植物死亡 → 分解者消耗氧气 → 鱼类和其他生物死亡。
Solutions include catalytic converters (reduce CO and NOₓ), wet scrubbers in chimneys (remove SO₂), using renewable energy, treating wastewater, and controlling fertiliser use.
解决方案包括催化转化器（减少 CO 和 NOₓ）、烟囱湿式洗涤器（去除 SO₂）、使用可再生能源、处理废水以及控制化肥使用。
8. Greenhouse Effect and Climate Change | 温室效应与气候变化
The greenhouse effect is a natural process where certain gases in the atmosphere (CO₂, CH₄, water vapour) trap heat, keeping Earth warm enough for life. However, human activities have intensified this effect, leading to global warming.
温室效应是一个自然过程，大气中的某些气体（CO₂、CH₄、水蒸气）捕获热量，使地球保持足够温暖的温度以维持生命。然而，人类活动加剧了这一效应，导致了全球变暖。
Enhanced greenhouse gases come from burning fossil fuels (CO₂), deforestation (less CO₂ absorbed), agriculture (CH₄ from cattle, rice paddies), and landfill (CH₄ from decomposing waste).
增强的温室气体来自化石燃料的燃烧（CO₂）、森林砍伐（减少 CO₂ 吸收）、农业（牛和水稻田产生 CH₄）以及垃圾填埋场（废物分解产生 CH₄）。
Consequences of global warming include rising sea levels (thermal expansion and melting ice caps), more frequent extreme weather events (storms, droughts), changes in species distribution, and loss of biodiversity.
全球变暖的后果包括海平面上升（热膨胀和冰盖融化）、更频繁的极端天气事件（风暴、干旱）、物种分布变化以及生物多样性丧失。
Mitigation strategies: reducing fossil fuel use, increasing renewable energy, improving energy efficiency, afforestation, and international agreements like the Kyoto Protocol and Paris Agreement.
缓解策略：减少化石燃料使用、增加可再生能源、提高能源效率、植树造林以及《京都议定书》和《巴黎协定》等国际协议。
9. Deforestation and Biodiversity Loss | 森林砍伐与生物多样性丧失
Deforestation is the large-scale removal of forests, often for timber, agriculture (e.g., palm oil, cattle ranching), mining, or urban expansion. It has severe environmental consequences.
森林砍伐是大规模移除森林的行为，通常为了木材、农业（如棕榈油、养牛）、采矿或城市扩张。它带来严重的环境后果。
Forests are important carbon sinks. When cut and burned, stored carbon is released as CO₂. Deforestation also disrupts the water cycle, causes soil erosion, and destroys habitats, reducing biodiversity.
森林是重要的碳汇。当被砍伐和焚烧时，储存的碳以 CO₂ 的形式释放。森林砍伐还会破坏水循环、造成土壤侵蚀并破坏栖息地，降低生物多样性。
Biodiversity is the variety of life in an area. High biodiversity makes ecosystems more stable and resilient. Conservation methods include establishing national parks and protected areas, captive breeding programmes, seed banks, and sustainable forestry.
生物多样性是一个区域内生命的多样性。高生物多样性使生态系统更加稳定和有复原力。保护方法包括建立国家公园和保护区、圈养繁殖计划、种子库以及可持续林业。
One exam tip is to link deforestation to both the carbon cycle and habitat destruction. Be able to suggest balanced solutions that consider economic needs of local communities.
应试提示：将森林砍伐同时与碳循环和栖息地破坏联系起来。要能提出兼顾当地社区经济需求的平衡解决方案。
10. Sustainability and Resource Management | 可持续性与资源管理
Sustainable development meets the needs of the present without compromising the ability of future generations to meet their own needs. In WJEC Science, this concept is applied to energy, water, waste, and food resources.
可持续发展在满足当代人需求的同时，不损害后代满足自身需求的能力。在 WJEC 科学中，这一概念应用于能源、水、废弃物和粮食资源。
Renewable energy sources (solar, wind, hydroelectric, tidal, wave, geothermal, biomass) are more sustainable than finite fossil fuels. However, they may have limitations such as intermittency, high initial costs, or visual impact.
可再生能源（太阳能、风能、水力、潮汐能、波浪能、地热、生物质）比有限的化石燃料更可持续。但它们可能存在间歇性、初始成本高或视觉影响等局限。
Waste management follows the waste hierarchy: reduce, reuse, recycle. Recycling metals, glass, paper, and plastics saves energy and raw materials. Landfill sites can produce methane, which can be captured for energy; incineration reduces volume but may release pollutants.
废物管理遵循废物层级：减量、再利用、回收。回收金属、玻璃、纸张和塑料可节约能源和原材料。垃圾填埋场会产生甲烷，可捕获用于发电；焚烧可减少体积但可能释放污染物。
Sustainable fishing uses quotas and net designs to prevent overfishing. In agriculture, organic farming, crop rotation, and biological pest control reduce chemical inputs and protect ecosystems.
可持续渔业使用配额和渔网设计防止过度捕捞。在农业中，有机耕作、轮作和生物害虫防治减少化学品投入，保护生态系统。
Treating wastewater (sewage) before releasing it into rivers prevents eutrophication and waterborne diseases. Providing clean drinking water is a global challenge that requires filtration, chlorination, and distribution systems.
在将废水（污水）排入河流前进行处理，可防止富营养化和水媒疾病。提供清洁饮用水是一项全球挑战，需要过滤、加氯消毒和输配系统。
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