Part 1: Principles of Matter and Energy To understand how ecosystems function, it is important to first know something about how energy and matter behave - in the universe and in living things. It is also important to understand the basic building blocks of life, starting with cells and organisms, and proceeding to communities and populations.
The scientific study of relationships between organisms and their environment
Examines the life histories, distribution, and behavior of individual species, as well as the structure and function of natural systems at the level of populations , communities , ecosystems , and landscapes
Encourages us to think holistically about interconnections that make whole systems more than just the sum of their individual parts
Examines how and why materials cycle between the living and nonliving parts of our environment
Matter and Energy
Matter and energy are essential constituents of both the universe and living organisms.
Matter - everything that takes up space and has mass
Energy - the capacity to do work
Potential vs. Kinetic Energy
Potential energy - stored energy that is latent but available for use
Kinetic energy - the energy contained in moving object
Figure 2.1 text
Low Quality Energy
Diffused, dispersed, or low in temperature
Difficult to gather and use for productive purposes
Example: heat stored in the oceans
High Quality Energy
Intense, concentrated, or high in temperature
Useful in carrying out work
Example: high-voltage electrical energy
Many of our most common energy sources are low-quality and must be concentrated or transformed into high-quality sources before they are useful to us.
Conservation of Matter
Matter is transformed and combined in different ways, but it doesn't disappear. Everything goes somewhere.
The atoms and molecules in your body have passed through many other organisms, over millions of years.
Under ordinary circumstances, matter is neither created nor destroyed. It is recycled endlessly.
Properties of Energy Energy cannot be recycled. Energy is reused, but it is constantly degraded or lost from the system. Most energy used in ecosystems originates as solar energy. Green plants convert some of this energy to chemical energy, which is then converted to heat or kinetic energy by the animal that eats the plant.
Laws of Thermodynamics First Law of Thermodynamics Energy cannot be created or destroyed, only changed Second Law of Thermodynamics With each successive energy transfer or transformation in a system, less energy is available to do work. Even though the the total amount of energy remains the same, the energy's intensity and usefulness deteriorate. The second law recognizes the principle of entropy , the tendency of all natural systems to move towards a state of increasing disorder.
The Building Blocks of Earth and Life The basic units of matter are called “elements”, which can’t be subdivided chemically into smaller units. Elements make up molecules and compounds. It is important to understand basic chemistry in order to understand the critical role of chemistry in Environmental Science.
Atoms, Molecules, and Compounds
Most material substances can exist in three interchangeable states: solid, liquid, or gas.
Element - substance that cannot be broken down into simpler substances by ordinary chemical reactions
Atom - the smallest particle that exhibits the characteristics of an element
Molecule - a combination of two or more atoms
Compound - a molecule made up of two or more kinds of atoms held together by chemical bonds
Periodic Table of the Elements
Elements and Environmental Science Just four elements - carbon, hydrogen, oxygen, and nitrogen - make up over 96% of the mass of most organisms.
Ionic Bond - Formed when one atom gives up an electron to another atom.
Covalent Bond - Formed when two or more atoms share electrons.
Energy is needed to break chemical bonds.
Energy is released when bonds are formed.
Acids and Bases
Acids are compounds that readily release hydrogen ions (H + ) in water.
Bases are substances that readily take up hydrogen ions (H + ) and release hydroxide ions (OH - ) in solution.
Strength measured by concentration of H + .
Water: A Unique Compound
Sixty to 70 percent of the weight of living organisms
Medium in which all of life's chemical reactions occur
Good electrical conductor
Highest surface tension of any common, natural liquid
Liquid over a wide temperature range
Expands when it crystallizes, unlike most substances
High heat of vaporization
High specific heat
Cells: The Fundamental Units of Life
Microscopic organisms, such as bacteria and protozoa, are composed of single cells.
The human body contains several trillion cells of about two hundred distinct types.
Enzymes – catalysts that speed up the rate of chemical reactions in living systems
Metabolism - all the energy and matter exchanges that occur within a living cell or organism
The Electromagnetic Spectrum The wavelengths of visible light drive photosynthesis.
Light and Dark Reactions of Photosynthesis
Energy Exchange in an Ecosystem
Energy & Matter in the Environment
Food Web: Cross-connected Food Chains
Energy Pyramid Most energy in most ecosystems is stored in the bodies of primary producers . Only about 10 percent of the energy at one energy level passes to the next highest trophic level.
The Water Cycle
The Carbon Cycle
The Nitrogen Cycle
Nitrogen Fixation The nodules on the roots of this plant contain bacteria that help convert nitrogen in the soil to a form the plant can utilize.