Environmental Science Flashcards

Intro to ENVISCI

• Denis Dyvee Errabo, PhD

Outline of Presentation

• Definition

• Classical and modern views

• Why study the environment

• Tragedy of the commons

• Indicators of environmental stress

Environmental Science

• Is a dynamic, interdisciplinary field that studies the interaction between living and non-living components of the environment.

Dynamics

• Focuses on human impacts on the environment

• Examines the conditions, objects, and circumstances that surround organisms and communities

• Explores the complex interactions within environmental systems

Components of Environmental Systems

• Energy

• $CO_2$

• Water

• Minerals

The Interdisciplinary Nature

1. Hierarchy

   • Organismal, Population, Community, Ecosystem, Global

2. Concept

   • Descriptive, Functional, Evolutionary

3. Taxonomy

   • Plant, Microbial, Fungal, Animal, Avian, Protozoan

4. Time/Place

   • Marine, Terrestrial, Freshwater, Paleoecology, Tropical Ecology

5. Processes

   • Behavioral, Physiological

Hierarchy - Example of Inquiry

• Organism: How does an organism adapt to extremes?

• Population: Is the population increasing or decreasing? Why? What controls population size?

• Community: Who eats whom? What happens to the community when you remove a top predator?

• Ecosystems: What controls the flow of energy and nutrients through an ecosystem?

• Biosphere: How is the biosphere responding to increasing atmospheric carbon dioxide levels?

Modern View

• Environmental Science is at the intersection of Humanities, Social Sciences, and Natural Sciences.

Environmental Components

• Energy

• $CO_2$

• Water

• Minerals

Environmental Components (Repeated)

• Energy

• $CO_2$

• Water

• Minerals

Why Study Environmental Science?

• Human behavior directly affects the environment

• Understanding scientific principles behind natural interactions is essential

• Our future depends on our capacity to evaluate and act on environmental evidence

Facing Global Challenges

• Climate change

• Habitat loss

• Population growth

• Rapid development

Complex Environmental Systems

• Interactions between natural and human components

• Links from local to global, short- to long-term

• From individual behavior to collective action

The Tragedy of the Commons (Garrett Hardin, 1968)

• A situation where individuals, acting in their own self-interest, collectively overexploit shared, limited resources—leading to long-term ruin for all.

Why It’s a Tragedy

• A Rational behavior at the individual level

• Irrational outcome at the collective level

• “Freedom in a commons brings ruin to all.”

• Hardin's Conclusion: Without restraints or ethics guiding use, shared resources will inevitably be depleted or destroyed.

Real-World Applications of the Commons

• Overgrazing of public lands

• Deforestation in shared forests

• Overfishing in oceans

• Water pollution from sewage dumping

• Air pollution from shared atmosphere

Questions Regarding Environmental Impacts

• How does deforestation influence the global climate?

• How does deforestation influence the water supply to neighboring towns?

• How does acid rain influence forest productivity?

• What are the biological controls over rock weathering?

The Climate Crisis as a Commons Tragedy

• Commons Affected: The atmosphere

• Issue: $CO_2$ emissions from burning fossil fuels

• Short-term economic gain per country

• Long-term global environmental cost

• Hardin’s Insight: Countries, like the herders, act in their own interest, leading to climate degradation that affects everyone.

Global Environmental Stress — Key Indicators

1. Forests

   • Deforestation: 1 million hectares lost annually (1980–1990)

   • Main driver: Agricultural land clearing by farmers

   • Concern: Forest degradation from overuse and lack of regulation

2. Soil

   • 10% of vegetated land is moderately degraded

   • 20% of irrigated land is losing productivity

   • Issue: Long-term food security and soil sustainability

3. Fresh Water

   • 20% of global population lacks access to safe drinking water

   • 50% lacks safe sanitation

   • By 2025: 2/3 of world population may face water stress

4. Marine Fisheries

   • 25% of fisheries at max capacity; 35% overfished

   • Pressure to increase harvest through aquaculture

   • Risk: Pollution, wetland and mangrove loss

5. Biodiversity

   • Threats: Habitat destruction and pollution

   • Estimated species: ~14 million

   • 1–11% species risk extinction every decade

   • Coastal ecosystems especially at risk

6. Atmosphere

   • Human activity affects climate (IPCC finding)

   • $CO_2$ emissions rising in industrialized nations

   • Countries failed to meet 1990 emission targets by 2000

7. Toxic Chemicals

   • 100,000+ commercial chemicals, mostly untested for impact

   • Persistent organic pollutants (POPs): Found worldwide

   • Risk: Toxicity, long-term ecological harm

8. Hazardous Wastes

   • Heavy metal pollution from mining/industry

   • Radioactive contamination incidents increasing

   • Legacy nuclear waste poses long-term threats

9. Waste Management

   • Domestic/industrial waste increasing globally

   • Developed countries: Per capita waste tripled in 20 years

   • Developing countries: Waste expected to double next decade

   • Poor sanitation still a major cause of illness and death

The Process of Science

• Denis Dyvee Errabo, PhD

Learning Objectives

• Use the scientific method to develop analytical frameworks for environmental issues.

• Analyze ecological, physical, social, and political principles of environmental systems.

• Apply systems thinking in understanding environmental interactions.

Understanding the Scientific Method

Scientific Method

• A structured way of exploring questions through experiments and careful observation.

Hypothesis

• A testable idea or explanation for an event or pattern.

Steps of the Scientific Method

• Make an observation

• Ask a question

• Form a hypothesis that answers the question

• Make a prediction based on the hypothesis

• Do an experiment to test the prediction

• Analyze the results

  • If hypothesis is supported: Try again…

  • If hypothesis is not supported: Report results

Scientific Theory

• A well-tested, widely accepted explanation of natural phenomena, built from many hypotheses and observations.

• Why It Matters: Scientific theories form the foundation of scientific knowledge—they help us understand and predict the world.

Scientific Method as a Process

1. Observation

   • Scientific discovery begins with careful observation.

2. Inquiry

   • Asking questions leads to deeper understanding.

3. Hypothesis

   • A proposed explanation that predicts an outcome and gives a reason why it might be true.

4. Prediction

   • A specific, testable statement that follows from the hypothesis.

5. Testing

   • Both hypotheses and predictions must be testable and measurable to be scientifically valid.

6. Conclusion

   • Iteration of earlier assumptions vis-à-vis with the findings.

7. Communication

   • Relating relevant findings to the stakeholders in the community.

Observational Study

• Scientists observe and compare groups with and without the presumed cause (no manipulation).

Replicates Matter!

• Use of multiple samples helps make results more reliable.

• Ensures the patterns are due to the variable studied, not random chance.

Repeatability is Key

• A study should be repeatable: If done the same way again, it should give similar results.

Multiple Studies, One Hypothesis

• Different researchers may test the same hypothesis in various ways to build stronger evidence.

Lens of Experimental Design

• Response Variable

  • The outcome being measured in the study.

• Explanatory Variable (Treatment)

  • The factor scientists intentionally change to observe its effect.

• Controlled Variables

  • Other factors kept constant to avoid affecting the results (also called confounding variables).

Manipulative Experiment

• The explanatory variable is altered by scientists to test its effect on the response variable.

Control vs. Test Group

• Control Group: Does not receive the treatment.

• Test Group: Receives the treatment.

• Both groups should be as similar as possible to ensure valid results.

Designing a Scientific Experiment

1. Response Variable

   • The outcome being measured (what changes as a result of the experiment).

2. Controlled Variables (Confounding Factors)

   • Other factors that might influence the outcome but are kept constant to ensure fair testing.

3. Manipulative Experiment

   • Scientists change the explanatory variable (the cause) and observe its effect on the response variable.

   • This change is called the treatment.

4. Control Group vs. Experimental Group

   • Control Group: Does not receive the treatment.

   • Experimental Group (or Test Group): Receives the treatment.

   • Both groups should be as similar as possible to make results valid.

5. Purpose

   • To test cause-and-effect relationships in a controlled, measurable way.

Lens of Social Research Design

• Dependent Variable (Response)

  • The social behavior, attitude, or condition being measured.

• Independent Variable (Cause)

  • The factor believed to influence or cause change in the dependent variable (e.g., policy, education level, income).

• Control Variables

  • Other factors that could affect results (e.g., age, gender, culture) and must be accounted for to avoid bias.

Social Inquiry Approach

• Researchers do not always manipulate variables—they often observe, interview, or analyze patterns in real-world settings.

Comparison Groups

• Control Group: Not exposed to the intervention or social condition.

• Experimental/Focus Group: Experiences the condition or receives the intervention.

Ethics & Reflexivity

• Researchers reflect on their own role, avoid harm, and protect participants’ rights and confidentiality.

Basic Science Process Skills

Observing

• Using your senses to gather information about the world (e.g., sight, smell, touch).

Classifying

• Grouping objects or events based on common characteristics (e.g., size, shape, use).

Measuring

• Using tools to collect data in standard units (e.g., length, mass, time, temperature).

Inferring

• Making explanations or interpretations based on your observations.

Predicting

• Stating what you think will happen based on past experiences or patterns.

Communicating

• Sharing findings through writing, talking, drawing, graphs, or charts.

Observation

Classification

• Tropical Rainforest

• Temperate Forest

• Boreal Forest

• Desert

• Savanna

• Grassland

• Marine

• Freshwater

• Tundra

Measurement

• A measurement of earthquake magnitude, based on seismic wave size.

• Richter scale

Inferencing

Prediction

Communication

• Storm surge warning system levels and expected heights:

  • RED (TAKE ACTION): 3 meters above - Storm surge is CATASTROPHIC.

  • ORANGE (ALARM): 1.1-3 meters - Storm surge is EXPECTED.

  • YELLOW (ALERT): 0.5-1 meter - Storm surge is POSSIBLE.

  • GREEN (NO ALERT): No action required.

Environmental Systems

Cultural

• To understand development and process of the physical world.

Civic

• Utilizing scientific processes to create informed decisions, participate in civic movement and cultural affairs, and contribute to economic productivity.

Scientific

• Become active members of society through problem-solving.

Aesthetic

• Promote and sustain beauty of nature.

System Thinking

• A way of understanding how parts of a system are connected and how they affect one another.

• Helps explain complex, real-world problems by seeing the big picture.

• Why It Matters

  • Predicts and adjusts outcomes in complex systems (e.g., ecosystems, societies, economies).

  • Essential in a globalized, tech-driven world where problems are interconnected.

Environmental

Chemistry: Soil, Water, and Atmosphere

• Denis Dyvee Errabo, PhD

Environmental Chemistry

• Study of chemical processes occurring in the environment (natural and human-induced)

• Focus Areas: Lithosphere, Hydrosphere, Atmosphere

• Relevance: Pollution, ecosystem health, resource sustainability

Atoms and Elements

• Everything in the environment is made of atoms

• Atoms consist of protons, neutrons, and electrons

• Elements are pure substances made of one type of atom

• Atomic number = number of protons

• Mass number = protons + neutrons

• Common Environmental Elements: C, O, N, H, P, S

• Role in Ecosystems: Biogeochemical cycles

Molecules and Compounds

• Molecules: Two or more atoms bonded (e.g., $O<em>2$, $H</em>2O$)

• Compounds: Atoms of different elements bonded (e.g., $CO_2$, $NaCl$)

• Environmental Examples: Water ($H<em>2O$), Carbon Dioxide ($CO</em>2$), Nitrogen Dioxide ($NO_2$)

Key Environmental Molecules

Chemical Bonds

• Ionic Bonds: Electron transfer (e.g., $NaCl$)

• Covalent Bonds: Electron sharing (e.g., $H<em>2O$, $CO</em>2$)

• Importance in Stability and Reactivity

Ionic Bonds

• Ionic bonds form between metals and nonmetals, involving the transfer of electrons. This results in the formation of oppositely charged ions (cations and anions) that attract each other.

• Properties:

  • High melting and boiling points

  • Often water-soluble

  • Good conductors when dissolved (electrolytes)

Environmental Relevance of Ionic Compounds

Covalent Bonds

• Covalent bonds form between nonmetal atoms through the sharing of electrons, leading to stable molecules.

• Properties:

  • Lower melting/boiling points than ionic compounds

  • Often insoluble or partially soluble in water

  • Can be polar or nonpolar, affecting how they move through soil or water

Environmental Relevance of Covalent Compounds

Ions

• Charged atoms/molecules

• Ions: Atoms with unequal protons and electrons

  • Cations: lose electrons (+ charge)

  • Anions: gain electrons (– charge)

• Common Ions: $NO<em>3^-$, $SO</em>4^{2-}$, $Ca^{2+}$, $Cl^-$

Ions and Environmental Impact

• Soil fertility depends on the availability of ions like $K^+$, $Mg^{2+}$, and $NH_4^+$.

• Water quality is affected by ions such as $NO<em>3^-$, $PO</em>4^{3-}$, $Pb^{2+}$.

• Air pollution control involves ionic species like $SO<em>4^{2-}$ and $NH</em>4^+$ in aerosols.

Isotopes

• Atoms of the same element with different neutrons

• Use Cases: Tracing pollutants, dating rocks/water, climate history

• Examples: $^{14}C$ (carbon dating), $^{18}O$ (paleoclimate)

Isotope Applications

Acids, Bases, and pH

• pH is a measure of the hydrogen ion concentration $[H^+]$ in a solution.

• Scale ranges from 0 to 14:

  • pH < 7 = Acidic

  • pH = 7 = Neutral

  • pH > 7 = Basic (alkaline)

• Environmental Impact: Acid rain, soil pH, aquatic life

• Examples: $H<em>2SO</em>4$ (acid), $NaOH$ (base), $H<em>2CO</em>3$ (weak acid)

Acids, Bases, and pH Examples

Soil Chemistry

• Ideal soil pH: 6.0–7.5 for nutrient availability

• Acidic soil (pH < 5.5): Limits plant growth, dissolves toxic metals like $Al^{3+}$

• Alkaline soil (pH > 8): Reduces micronutrient availability (Fe, Zn, Mn)

• Acidification sources: acid rain, overuse of ammonium fertilizers

• Remediation: adding lime ($CaCO_3$) to raise pH

Lithosphere

• Key Elements/Compounds: $CaCO<em>3$, $Fe</em>2O<em>3$, $SiO</em>2$

• Issues: Soil acidification, nutrient depletion

• Inorganic: Heavy metals (Pb, Cd, Hg), nitrates from fertilizers

• Organic: Pesticides, herbicides, hydrocarbons from spills

• Management: Fertilizers, lime application

Important Processes in the Lithosphere

• Cation exchange capacity (CEC): Determines nutrient availability, especially for inorganic ions.

• Decomposition: Organic matter breakdown releases $CO<em>2$, $CH</em>4$, and nutrients.

• Complexation: Organic molecules bind heavy metals, affecting mobility and toxicity.

Water Chemistry

• Aquatic life thrives in water with pH 6.5–8.5

• Acidic water increases metal solubility → toxic to fish (e.g., $Al^{3+}$ toxicity)

• Basic water can reduce solubility of nutrients and cause ammonia toxicity

• Causes of pH changes: industrial discharges, mine drainage, acid rain

• Buffer systems: carbonate ($HCO<em>3^- / CO</em>3^{2-}$) buffer helps stabilize aquatic pH

Hydrosphere

• Key Compounds: $H<em>2O$, dissolved $O</em>2$, $CO_2$

• Pollution: Nitrates, phosphates, heavy metals

• Inorganic: Arsenic, lead, nitrates

• Organic: Petroleum hydrocarbons, plasticizers (BPA), pharmaceuticals

• Acidification & Buffers: Carbonate buffering

Hydrogen Bonds

• Form between δ+ hydrogen and δ– atom (often O or N)

• Weaker than ionic or covalent bonds

• Important in water properties and DNA structure

Water and Life

• Water is polar and forms hydrogen bonds

• Stabilizes temperature, dissolves substances, cohesive

• Supports life processes and environments

Important Processes in the Hydrosphere

• Solubility and speciation: How inorganics dissolve and react in aquatic systems.

• Degradation: Biodegradation of organic molecules (aerobic/anaerobic)

• Eutrophication: Caused by inorganic (nitrate, phosphate) and organic waste inputs.

Atmospheric Chemistry

• Acid Rain Formation:

  • $SO<em>2 + H</em>2O \rightarrow H<em>2SO</em>4$

  • $NO<em>2 + H</em>2O \rightarrow HNO_3$

• Resulting precipitation pH: 4.2–5.0

• Consequences:

  • Soil acidification

  • Aquatic ecosystem collapse

  • Corrosion of buildings and cultural heritage

Atmosphere

• Key Gases: $N<em>2$, $O</em>2$, $CO<em>2$, $O</em>3$

• Pollutants: $SO<em>2$, $NO</em>x$ → acid rain

• Inorganic: $SO<em>2$, $NO</em>x$, CO, ozone

• Organic: Methane, VOCs (benzene, toluene)

• Processes: Greenhouse effect, ozone layer

Important Processes in the Atmosphere

• Photochemical reactions: VOCs + $NO<em>x$ + sunlight → tropospheric ozone ($O</em>3$)

• Acid rain formation: $SO<em>2$ and $NO</em>x$ (inorganic) react with water to form $H<em>2SO</em>4$ and $HNO_3$

• Smog formation: Interaction of inorganic oxides and organic vapors

Systems Thinking: Interconnectivity of Soil, Water, and Atmosphere

• Example 1: Acid rain affects soil pH and aquatic life.

• Example 2: Agricultural runoff (nitrates and phosphates) pollutes water bodies and contributes to air pollution via nitrogen compounds.

• Example 3: Wildfires degrade air quality, impact soil nutrients, and alter water cycles.