PubH416: Global Issues in Environmental Health

Lecture 1: Introduction to Ecological Principles

No prior ecology or physics class required.
Focus on foundational ecological concepts relevant to environmental health.
Key topics: Ecological principles, Laws of Thermodynamics, Biogeochemical Cycling.

Ecology: Study of organisms' distribution, abundance, and interaction with the environment.
- Humans are part of the ecosystem, affecting and being affected by it.
Environmental Health: How the environment impacts human health.
Importance of maintaining a balance within ecosystems for human survival.

Population: Individuals of the same species in a given area (e.g., humans, rice paddies).
Biotic Community: Interacting organisms of various species in a region.
Ecosystem: Includes living (biotic) and non-living (abiotic) elements.
Biomes: Groups of similar ecosystems (e.g., tropical forests, deserts).
Biosphere: Global ecological system integrating all life forms and their interactions.

Biotic Communities: Support and depend on each species; changes affect the community.
- Example: Beavers affecting flooding by building dams.
Ecological Dominance: Some species have a larger impact (e.g., hardwood trees).

Niche: The role or function of a species within an ecosystem.
Competitive Exclusion Principle: Two species competing for the same resources cannot coexist indefinitely.

First Law: Energy can neither be created nor destroyed; it changes forms.
Second Law: Energy transformation results in a loss of usable energy (entropy increases).
- Usable energy decreases with each transfer (e.g., food chain energy transfer).

Energy Flow: A one-way transfer from the sun through the food chain, ending as heat.
Trophic Levels: Stages in the food chain, from producers to various levels of consumers.
- More usable energy at lower trophic levels; energy decreases with each trophic level.

Macronutrients & Trace Elements: Crucial for organism survival; need to be recycled.
Carbon Cycle: Involves atmosphere, soil, and water through processes like photosynthesis and decomposition.
Phosphorus Cycle: Originates from rocks and soil; no atmospheric component.
Nitrogen Cycle: Involves conversion of non-reactive nitrogen to reactive forms by bacteria.
Sulfur Cycle: Involves atmosphere, hydrosphere, and geosphere; part of proteins and vitamins.

Human Acceleration: Activities like fossil fuel burning and fertilizer use disrupt cycles.
Eutrophication: Caused by excessive nitrogen and phosphorus, leading to algal blooms.

Primary Succession: Starts on bare rock or soil (e.g., after a glacier recedes).
Secondary Succession: Occurs where life has been disrupted but soil remains (e.g., post-fire).
Aquatic Succession: Transformation from lakes to land over time due to sediment buildup.

Energy is non-recyclable, but nutrients must be cycled for sustainability.
Understanding ecosystem dynamics is central to addressing environmental health issues.
Additional lecture materials and quizzes provided for deeper understanding and assessment.