IB Science: Environmental Science Key Points Review | IB 科学：环境科学考点精讲

📚 IB Science: Environmental Science Key Points Review | IB 科学：环境科学考点精讲

Environmental Science in the IB curriculum integrates concepts from biology, chemistry, physics, and geography to address complex environmental issues. This revision guide distills key topics that frequently appear in assessments, helping students understand systems thinking, sustainability, and the interdependence of natural and human systems.

IB 课程中的环境科学融合了生物学、化学、物理学和地理学的概念，以解决复杂的环境问题。本复习指南精炼了考试中频繁出现的核心主题，帮助学生理解系统思维、可持续发展以及自然与人类系统的相互依存关系。

---

1. Environmental Value Systems (EVS) | 环境价值体系

Environmental Value Systems (EVS) are worldviews that shape the way individuals and societies perceive and evaluate environmental issues. They range from ecocentric perspectives, which prioritize nature’s intrinsic value, to technocentric views that believe technology can solve environmental problems, with anthropocentric stances placing human needs at the center.

环境价值体系（EVS）是塑造个人和社会如何看待和评估环境问题的世界观。其范围从生态中心主义（优先考虑自然的内在价值）到科技中心主义（相信技术可以解决环境问题），再到人类中心主义（将人类需求置于中心）。

An ecocentric viewpoint emphasizes the importance of preserving entire ecosystems and advocates minimal human interference. In contrast, technocentrics trust in economic growth and scientific innovation to manage resources sustainably. Anthropocentrics may support environmental protection but primarily for human benefit, such as clean air and water.

生态中心主义观点强调整体生态系统的保护并主张最小的人为干预。相比之下，科技中心主义者相信经济增长和科学创新能够可持续地管理资源。人类中心主义者可能支持环境保护，但主要是为了人类的利益，例如清洁的空气和水。

Understanding different EVSs is essential for analyzing environmental conflicts and policies. For instance, a debate over rainforest clearing may reflect clashing ecocentric and anthropocentric values.

理解不同的环境价值体系对于分析环境冲突和政策至关重要。例如，关于砍伐雨林的争议可能反映了生态中心主义与人类中心主义价值观的冲突。

---

2. Systems and Models | 系统与模型

Systems thinking is fundamental in IB Environmental Science. A system is a set of interconnected parts that form a complex whole. They can be open (exchanging both energy and matter), closed (exchanging energy but not matter), or isolated (no exchange). Earth itself is a closed system for matter but open for energy.

系统思维是 IB 环境科学的基础。系统是由相互关联的部分组成的复杂整体。系统可以是开放的（能量和物质均可交换）、封闭的（交换能量但不交换物质）或孤立的（无交换）。地球本身是一个物质上的封闭系统，但能量上是开放的。

Models are simplified representations of reality used to predict and understand environmental processes. Feedback loops are crucial: positive feedback amplifies changes (e.g., melting ice reduces albedo, causing further warming), while negative feedback dampens changes (e.g., predator-prey relationships stabilize populations).

模型是对现实的简化表示，用于预测和理解环境过程。反馈循环至关重要：正反馈会放大变化（例如，冰融化降低反照率，导致进一步变暖），而负反馈会抑制变化（例如，捕食者-猎物关系稳定种群数量）。

Transfers transform energy and matter flows without changing their form, whereas transformations involve a change in state or chemical nature. In a food chain, consumption is a transfer, whereas photosynthesis is a transformation.

转移是能量和物质流动但不改变其形态，而转化涉及状态或化学性质的改变。在食物链中，取食是一种转移，而光合作用是一种转化。

---

3. Energy, Equilibria, and Thermodynamics | 能量、平衡与热力学

The first law of thermodynamics states that energy cannot be created or destroyed, only transformed. In ecosystems, solar energy is converted to chemical energy through photosynthesis. The second law explains that energy transformations are never 100% efficient, with some energy lost as heat, increasing entropy.

热力学第一定律指出，能量既不能被创造也不能被消灭，只能转化。在生态系统中，太阳能通过光合作用转化为化学能。第二定律解释能量转化永远不会 100% 有效率，一部分能量以热量形式散失，从而增加熵。

Ecosystems maintain a steady-state equilibrium through negative feedback mechanisms. However, tipping points can lead to a regime shift, where the system moves to a new equilibrium. Understanding the concept of carrying capacity is vital: it is the maximum population size an environment can sustain indefinitely.

生态系统通过负反馈机制维持稳态平衡。然而，临界点可能导致系统转换到新的平衡状态。理解承载力的概念至关重要：它是环境能够无限期维持的最大种群规模。

Entropy explains why energy flows are unidirectional and why ecological pyramids of energy are always upright. Only about 10% of energy is passed from one trophic level to the next, limiting food chain length.

熵解释了为什么能量流动是单向的，以及为什么能量金字塔总是直立的。只有大约 10% 的能量从一个营养级传递到下一营养级，这限制了食物链的长度。

---

4. Biomes and Productivity | 生物群落与生产力

Biomes are large ecological areas characterized by distinct climate, flora, and fauna. Major terrestrial biomes include tropical rainforests, deserts, grasslands, and tundra. Their distribution is primarily determined by temperature and precipitation. Aquatic biomes are classified by salinity, depth, and flow.

生物群落是以独特气候、植物和动物为特征的大面积生态区域。主要的陆地生物群落包括热带雨林、沙漠、草原和冻原。它们的分布主要由温度和降水决定。水生生物群落根据盐度、深度和流动性进行分类。

Primary productivity measures the rate of energy conversion by producers. Gross Primary Productivity (GPP) is the total energy fixed; Net Primary Productivity (NPP) is GPP minus respiration (R): NPP = GPP – R. NPP represents the energy available to consumers. Tropical rainforests have the highest NPP.

初级生产力衡量生产者将能量转化的速率。总初级生产力（GPP）是固定的总能量；净初级生产力（NPP）是 GPP 减去呼吸消耗（R）：NPP = GPP – R。NPP 代表可供消费者使用的能量。热带雨林的 NPP 最高。

In aquatic systems, productivity is limited by light and nutrients. Coastal upwellings and estuaries are highly productive. Understanding NPP helps calculate the sustainable yield of fisheries and forests.

在水生系统中，生产力受到光照和营养物的限制。沿海上升流区域和河口生产力很高。理解 NPP 有助于计算渔业和林业的可持续产量。

---

5. Biodiversity and Conservation | 生物多样性与保护

Biodiversity encompasses species diversity, genetic diversity, and ecosystem diversity. Species richness is the number of species present, while evenness describes their relative abundance. The Simpson’s Diversity Index (D = Σ(n/N)²) quantifies diversity; a higher value indicates lower diversity and greater dominance by few species.

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。物种丰富度是指存在的物种数，均匀度描述它们的相对丰度。辛普森多样性指数（D = Σ(n/N)²）可量化多样性；高值表示低多样性和少数物种的优势。

Conservation strategies include in-situ conservation (protecting species in their natural habitat) and ex-situ conservation (zoos, seed banks). Hotspots are regions with exceptional endemism and high threat. Protected areas and international agreements like CITES help preserve biodiversity.

保护策略包括就地保护（在自然栖息地保护物种）和迁地保护（动物园、种子库）。热点地区是具有特殊特有性和高威胁性的区域。保护区以及诸如《濒危野生动植物种国际贸易公约》（CITES）等国际协议有助于保护生物多样性。

Island biogeography theory informs reserve design: larger, closer reserves support more species. Habitat fragmentation reduces biodiversity by creating edge effects and isolating populations.

岛屿生物地理学理论为保护区设计提供依据：面积更大、距离更近的保护区能支持更多物种。栖息地破碎化通过产生边缘效应和隔离种群降低了生物多样性。

---

6. Pollution and Waste Management | 污染与废物管理

Pollution can be classified as point source (single identifiable source) or non-point source (diffuse, e.g., agricultural runoff). Air pollutants include SO₂, NOₓ, particulate matter, and tropospheric ozone. Water pollution is assessed using indicators like biochemical oxygen demand (BOD), which measures oxygen used by decomposers.

污染可分为点源（单一可识别来源）和非点源（扩散源，如农业径流）。大气污染物包括 SO₂、NOₓ、颗粒物和对流层臭氧。水质污染通过诸如生化需氧量（BOD）等指标进行评估，BOD 衡量分解者消耗的氧气量。

Eutrophication results from excess nutrients (N, P) entering water bodies, causing algal blooms and hypoxia. Solid waste management follows the hierarchy: reduce, reuse, recycle, recover (energy), and dispose. Landfills can generate methane, a potent greenhouse gas.

富营养化是由于过量营养物（氮、磷）进入水体，导致藻类大量繁殖和缺氧。固体废物管理遵循层级：减量、再利用、回收、能量回收和处置。填埋场可能产生甲烷，一种强效温室气体。

Ozone depletion in the stratosphere, caused by CFCs, has been successfully addressed by the Montreal Protocol. The recovery of the ozone layer demonstrates that coordinated international action can resolve global environmental threats.

平流层臭氧层损耗由氯氟碳化合物（CFCs）引起，但《蒙特利尔议定书》已成功应对。臭氧层的恢复表明协调的国际行动可以解决全球环境威胁。

---

7. Climate Change and Atmospheric Systems | 气候变化与大气系统

The natural greenhouse effect is essential for life, as greenhouse gases (GHGs) like CO₂, CH₄, and water vapor trap heat. Human activities have enhanced this effect, leading to global warming. The main anthropogenic sources are fossil fuel combustion, deforestation, and agriculture.

天然温室效应对生命至关重要，因为 CO₂、CH₄ 和水蒸气等温室气体（GHGs）捕获热量。人类活动增强了这种效应，导致全球变暖。主要的人为排放源是化石燃料燃烧、森林砍伐和农业。

Impacts include sea-level rise, more frequent extreme weather, ocean acidification, and shifts in biomes. Mitigation strategies aim to reduce GHG emissions (renewable energy, carbon capture), while adaptation involves adjusting to changes (sea walls, drought-resistant crops). International agreements like the Paris Accord set targets.

影响包括海平面上升、更频繁的极端天气、海洋酸化和生物群落转移。缓解策略旨在减少温室气体排放（可再生能源、碳捕获），而适应则涉及调整以应对变化（海堤、耐旱作物）。《巴黎协定》等国际协议设定了目标。

Ocean acidification, caused by increased CO₂ absorption, lowers pH and harms calcifying organisms such as corals and shellfish. This disrupts marine food webs and fisheries.

海洋酸化由 CO₂ 吸收增加引起，导致 pH 值降低，危害珊瑚和贝类等钙化生物。这破坏了海洋食物网和渔业。

---

8. Human Population and Carrying Capacity | 人口与承载力

The world population follows an exponential growth curve, currently exceeding 8 billion. Demographic transition model (DTM) describes changes in birth and death rates as societies develop. Age-sex pyramids illustrate population structure and predict future growth.

世界人口遵循指数增长曲线，现已超过 80 亿。人口转变模型（DTM）描述了随着社会发展出生率和死亡率的变化。年龄-性别金字塔展示人口结构并预测未来增长。

Carrying capacity is affected by resource consumption. Ecological footprint measures the land area required to sustain a population’s lifestyle. If the footprint exceeds biocapacity, an ecological deficit occurs. IPAT equation (Impact = Population × Affluence × Technology) highlights drivers of environmental impact.

承载力受资源消耗的影响。生态足迹衡量维持一个种群生活方式所需的土地面积。如果足迹超过生物承载力，就会出现生态赤字。IPAT 方程（影响 = 人口 × 富裕程度 × 技术）突出了环境影响的驱动因素。

Populations can overshoot carrying capacity, leading to a crash. The introduction of family planning, education, and women’s empowerment are effective strategies for achieving demographic transition and reducing growth rates.

人口可能超过承载力，导致崩溃。推行计划生育、教育和妇女赋权是实现人口转变和降低增长率的有效策略。

---

9. Resource Use and Energy Choices | 资源使用与能源选择

Resources are classified as renewable (solar, wind) or non-renewable (fossil fuels, minerals). Energy security depends on availability, accessibility, and affordability. Energy density (energy per unit mass) and specific energy (energy per unit volume) are key factors in fuel choice.

资源分为可再生（太阳能、风能）和不可再生（化石燃料、矿物）。能源安全取决于可用性、可获取性和可负担性。能量密度（单位质量能量）和比能量（单位体积能量）是燃料选择的关键因素。

Life cycle analysis (LCA) assesses environmental impacts from extraction to disposal. Fossil fuels have high energy density but cause significant pollution. Renewable energy sources reduce GHG emissions but may have intermittency and land-use challenges. Nuclear power offers low-carbon baseload but raises waste and safety concerns.

生命周期分析（LCA）评估从开采到处置的环境影响。化石燃料能量密度高但造成严重污染。可再生能源可减少温室气体排放，但可能面临间歇性和土地利用挑战。核电提供低碳基础负荷，但引起废物和安全问题。

Energy strategies must balance the energy trilemma: security, equity (affordability and access), and environmental sustainability. The transition to a low-carbon mix is a central goal of many national policies.

能源战略必须平衡

Published by TutorHao | IB Science Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）