📚 IB Edexcel Science: Environmental Science Key Points Explained | IB Edexcel 科学：环境科学考点精讲
This article provides a focused revision guide for Environmental Science topics common to IB Environmental Systems and Societies (ESS) and Edexcel A Level Environmental Science. It covers core concepts, key definitions, processes, and exam-relevant examples to strengthen your understanding and recall.
本文为IB环境系统与社会（ESS）和Edexcel A Level环境科学中共同的环境科学主题提供重点复习指南。涵盖核心概念、关键定义、过程以及考试相关实例，以加深理解和记忆。
1. Ecosystems and Energy Flow | 生态系统与能量流动
An ecosystem is a dynamic complex of biotic communities and the abiotic environment they interact with. Energy enters ecosystems primarily through photosynthesis, where producers convert light energy into chemical energy.
生态系统是由生物群落及其相互作用的非生物环境构成的动态复合体。能量主要通过光合作用进入生态系统，生产者将光能转化为化学能。
Energy flows through food chains and food webs, with each trophic level losing about 90% of energy as heat through respiration. This limits the number of trophic levels in an ecosystem.
能量沿食物链和食物网流动，每个营养级通过呼吸作用损失约90%的能量作为热量。这限制了生态系统中营养级的数量。
Gross primary productivity (GPP) is the total energy fixed by producers. Net primary productivity (NPP) equals GPP minus respiration (R) by producers: NPP = GPP − R. NPP represents energy available to consumers.
总初级生产力（GPP）是生产者固定的总能量。净初级生产力（NPP）等于GPP减去生产者的呼吸消耗（R）：NPP = GPP − R。NPP代表可供消费者利用的能量。
Energy pyramids, biomass pyramids, and pyramid of numbers can represent ecosystem structure. An inverted pyramid of biomass may occur in aquatic ecosystems with high phytoplankton turnover.
能量金字塔、生物量金字塔和数量金字塔可表示生态系统结构。在浮游植物周转率高的水生生态系统中可能出现倒置的生物量金字塔。
2. Biogeochemical Cycles | 生物地球化学循环
The carbon cycle involves the movement of carbon among atmosphere, biosphere, hydrosphere, and lithosphere. Photosynthesis and respiration are key biological fluxes; combustion and volcanic activity are geological fluxes.
碳循环涉及碳在大气圈、生物圈、水圈和岩石圈之间的移动。光合作用和呼吸作用是关键的生物通量；燃烧和火山活动是地质通量。
Photosynthesis equation:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
光合作用方程式：6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
The nitrogen cycle includes nitrogen fixation (by lightning or symbiotic bacteria), nitrification, assimilation, ammonification, and denitrification. Nitrifying bacteria convert NH₄⁺ to NO₂⁻ and then to NO₃⁻.
氮循环包括固氮作用（闪电或共生细菌）、硝化作用、同化作用、氨化作用和反硝化作用。硝化细菌将NH₄⁺转化为NO₂⁻，再转化为NO₃⁻。
Human activities such as fertiliser use and fossil fuel combustion have dramatically altered both cycles, leading to eutrophication and enhanced greenhouse effect.
使用化肥和燃烧化石燃料等人类活动极大改变了这两个循环，导致富营养化和增强的温室效应。
3. Biodiversity and Conservation | 生物多样性与保护
Biodiversity encompasses species diversity, genetic diversity, and ecosystem diversity. High biodiversity generally increases ecosystem resilience and stability.
生物多样性包括物种多样性、遗传多样性和生态系统多样性。高生物多样性通常提高生态系统的恢复力和稳定性。
Simpson’s Diversity Index (D) measures the probability that two individuals randomly selected from a sample belong to different species. It is calculated as:
辛普森多样性指数（D）衡量从样本中随机选取的两个个体属于不同物种的概率。计算公式为：
D = 1 − Σ (n/N)²
where n = number of individuals of a species, N = total number of individuals. Higher D values indicate greater diversity.
其中n为某物种个体数，N为总个体数。D值越高，多样性越大。
Conservation strategies include in-situ conservation (protected areas, national parks) and ex-situ conservation (zoos, seed banks). CITES and the IUCN Red List are international tools for protecting species.
保护策略包括就地保护（保护区、国家公园）和迁地保护（动物园、种子库）。CITES和IUCN红色名录是保护物种的国际工具。
4. Population Ecology | 种群生态学
A population is a group of organisms of the same species living in the same area at the same time. Population size is determined by births, deaths, immigration, and emigration.
种群是同一物种在同一时间生活在同一区域的生物群体。种群大小由出生、死亡、迁入和迁出决定。
Exponential growth occurs when resources are unlimited, described by dN/dt = rN, where r is the intrinsic rate of increase. Under limited resources, logistic growth applies: dN/dt = rN((K − N)/K), where K is the carrying capacity.
当资源无限时发生指数增长，可用dN/dt = rN描述，r为内禀增长率。资源有限时符合逻辑斯蒂增长：dN/dt = rN((K − N)/K)，K为环境承载能力。
Carrying capacity is the maximum population size an environment can sustain indefinitely. Factors such as food availability, disease, and predation regulate population around K.
承载能力是环境可无限期维持的最大种群规模。食物供应、疾病和捕食等因素使种群在K附近调节。
Population sampling techniques include quadrats for static organisms and mark-release-recapture for mobile animals. The Lincoln index (N = (M × C)/R) estimates population size, where M=marked, C=captured second time, R=recaptured marked.
种群抽样方法包括用于静止生物的样方法和用于移动动物的标记重捕法。林肯指数（N = (M × C)/R）估算种群大小，M为标记数，C为第二次捕获数，R为重捕标记数。
5. Pollution Types and Effects | 污染类型与影响
Pollution is the introduction of harmful materials into the environment. Major types include air pollution, water pollution, soil pollution, and noise pollution.
污染是将有害物质引入环境。主要类型包括空气污染、水污染、土壤污染和噪声污染。
Primary pollutants are emitted directly (e.g., SO₂ from coal burning). Secondary pollutants form in the atmosphere through reactions (e.g., ozone (O₃) from NOx and VOCs in sunlight).
一次污染物是直接排放的（如燃煤产生的SO₂）。二次污染物在大气中通过反应形成（如阳光下NOx和VOCs生成的臭氧O₃）。
Eutrophication arises from excessive nutrient inputs (nitrates, phosphates) into water bodies, triggering algal blooms, oxygen depletion, and death of aerobic organisms. Its sequence: nutrient influx → algal bloom → death and decomposition → hypoxic conditions.
富营养化由过量营养物（硝酸盐、磷酸盐）进入水体引起，导致藻类大量繁殖、氧气耗尽和好氧生物死亡。过程：营养物输入→藻类暴发→死亡分解→低氧条件。
Bioaccumulation is the build-up of persistent pollutants (e.g., DDT, heavy metals) in an organism. Biomagnification is the increase in concentration along food chains, severely affecting top predators.
生物累积是持久性污染物（如DDT、重金属）在生物体内的积累。生物放大是浓度沿食物链递增，严重影响顶级捕食者。
6. Climate Change Science | 气候变化科学
The greenhouse effect is a natural process where greenhouse gases (GHGs: CO₂, CH₄, H₂O vapour) trap heat in the atmosphere, keeping Earth warm. Enhanced greenhouse effect refers to the additional warming due to human emissions.
温室效应是自然过程，温室气体（GHG：CO₂、CH₄、水蒸气）在大气中捕获热量，使地球保持温暖。增强的温室效应指人为排放导致的额外变暖。
Key evidence for climate change includes rising global temperatures, melting ice caps, sea level rise, increased frequency of extreme weather, and shifts in phenology.
气候变化的关键证据包括全球气温上升、冰盖融化、海平面上升、极端天气频率增加以及物候变化。
Positive feedback loops amplify warming, such as melting permafrost releasing methane, and reduced ice albedo. Negative feedbacks, like increased cloud cover, may offset warming but are less dominant.
正反馈循环加剧变暖，例如永久冻土融化释放甲烷和冰反照率降低。负反馈如云量增加可能抵消变暖但作用较弱。
Mitigation strategies include reducing fossil fuel use, afforestation, and carbon capture. Adaptation strategies involve building sea walls, developing drought-resistant crops, and adjusting agricultural practices.
缓解策略包括减少化石燃料使用、植树造林和碳捕集。适应策略涉及修建海堤、培育抗旱作物和调整农业实践。
7. Sustainability and Resource Management | 可持续发展与资源管理
Sustainability meets present needs without compromising the ability of future generations to meet their own needs. It integrates environmental, social, and economic dimensions (triple bottom line).
可持续发展既满足当代需求，又不损害后代满足其需求的能力。它整合了环境、社会和经济三个维度（三重底线）。
Renewable resources (solar, wind, biomass) can be replenished naturally. Non-renewable resources (fossil fuels, minerals) exist in finite quantities. Sustainable yield is the rate at which a renewable resource can be used without depletion.
可再生资源（太阳能、风能、生物质）可自然补充。不可再生资源（化石燃料、矿产）储量有限。可持续产量是指可再生资源不会耗竭的使用率。
Ecological footprint measures the biologically productive land and water area required to support a population’s consumption and absorb its wastes. If footprint exceeds biocapacity, the region runs an ecological deficit.
生态足迹衡量支撑某人口消费并吸收其废物所需的生物生产性土地和水域面积。若足迹超过生物承载力，该区域出现生态赤字。
Circular economy principles aim to eliminate waste by designing products for reuse, repair, and recycling, minimising resource extraction and environmental impact.
循环经济原则旨在通过设计可重用的产品消除废物，促进再利用、维修和回收，最小化资源开采和环境影响。
8. Environmental Value Systems | 环境价值观体系
An environmental value system (EVS) is a worldview that shapes how individuals or groups perceive environmental issues. IB ESS classifies EVS as ecocentric, anthropocentric, or technocentric.
环境价值观体系（EVS）是一种塑造个人或群体如何看待环境问题的世界观。IB ESS将EVS分为生态中心主义、人类中心主义和技术中心主义。
Ecocentrism sees nature as having intrinsic value, advocates minimal disturbance, and promotes deep ecology and self-reliance. Anthropocentrism values nature for human benefit and supports conservation through laws and management.
生态中心主义认为自然具有内在价值，提倡最小干预，推崇深层生态和自力更生。人类中心主义视自然为人类利益服务，支持通过法律管理进行保护。
Technocentrism believes technology can solve environmental problems, favours economic growth, and trusts in market-based solutions and scientific innovation.
技术中心主义相信技术能解决环境问题，支持经济增长，信赖市场解决方案和科学创新。
Understanding EVS helps explain differing responses to issues like climate change, deforestation, or resource exploitation. Environmental decision-making often involves a clash between these value systems.
理解EVS有助于解释对气候变化、森林砍伐或资源开发等问题的不同反应。环境决策常涉及这些价值观体系的冲突。
9. Fieldwork and Sampling Techniques | 野外考察与取样技术
Environmental investigations rely on robust sampling methods to collect representative data. Random sampling uses random coordinates to place quadrats, minimising bias.
环境调查依赖稳健的取样方法收集代表性数据。随机取样使用随机坐标放置样方，减少偏差。
Systematic sampling with transects (line or belt) is used to study changes across environmental gradients, such as zonation on a rocky shore or along a pollution gradient.
系统取样使用样带（线状或带状样带）研究环境梯度上的变化，如岩岸的分带或沿污染梯度的变化。
For mobile species, mark-release-recapture method and the Lincoln index are standard. Ethical considerations must be addressed, including minimal harm and correct licensing.
对于移动物种，标记重捕法和林肯指数是标准方法。必须处理伦理问题，包括最小伤害和正确的许可。
Water and soil quality can be assessed using physical (turbidity, temperature), chemical (pH, dissolved oxygen, nitrate concentration), and biological (biotic index) indicators. Triangulation of data increases reliability.
水质和土壤质量可通过物理（浊度、温度）、化学（pH、溶解氧、硝酸盐浓度）和生物（生物指数）指标评估。数据三角验证可提高可靠性。
Published by TutorHao | Environmental Science Revision Series | aleveler.com
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