Environmental Systems:Chapter 2-

Objectives• Define System within the context of environmental science• Explain the components and states of matter• Distinguish between various forms of energy and the first and

second laws of thermodynamics• Understand systems inputs, outputs and distinguish between

positive and negative feedback loops

I. Earth is a single interconnected system

• A set of components connected in such a way that a change in one part of the system affects one or more other parts of the system

• Approximate representations or simulations of real systems

• Limitations of Enviro Science-Most enviro problems involve many variables and complex interactions that models are not useful/have not been developed.Example: Climate models-Global Warming

II. All Environmental SystemsConsist of Matter•Atom, Elements, Ions, Compounds, Mixtures, Molecules

•Atomic Number, Mass Number, Isotopes

• Ionic vs. Molecular Substances

• Ionic bonds, Covalent Bonds, Hydrogen bonds

Chemical Reaction: atoms separate from molecules they are a part of and recombine to form other molecules

Law of Conservation of Matter: Matter can not be created or destroyed; it can change from one form to another

• Organic : Covalently bonded molecules.

Have carbon-carbon and carbon-hydrogen bonds. May contain oxygen and other elements.Examples: Hydrocarbons (fuels), Chlorinated Hydrocarbons, Carbohydrates, Lipids, Proteins, Nucleic Acids.

• Inorganic: Ionic Compounds. Do not contain carbon or have carbon bound to other elements than hydrogen (CO2), NaCl, NH3, H2O

III. Acids, Bases and pH• Acid: H+ ion donator;

contributes H+ ion to solution

• Base: OH-ion donator; accepts H+ ion

• pH: Indicates strength of acids and bases; logarithmic

IV. Energy is a Fundamental Component of Environmental Systems

• Energy: The ability to do work or transfer heat• Power: The rate at which work is done• Potential Energy: Energy that is stored but has not yet been

released.• Kinetic: Energy of motion

Example: Water behind a dam has potential energy; when it is released and flows downstream where it can turn a turbine it is kinetic. Potential energy stored in chemical bonds is chemical energy; Captain Crunch!

Ultimately most energy derived from the sun, which emits electromagnetic radiation.

• First Law of Thermodynamics: Energy is Conserved• Second Law of Thermodynamics: when energy is transformed,

the quantity remains the same but it is of lower qualityExample: When converting from electrical to light energy some energy is converted to low quality heat

• Energy Efficiency: ratio of the amount of work that is done to the total energy input. Example: an incandescent and compact fluorescent both produce 100 watts of light but the incandescent used more electricity; it is less efficient.

• Energy Quality: the ease at which an energy source can be used for work. Example: coal vs wood for running a car.

Heat Transfer:

Convection: lighter molecules rise, heavy ones sink to bottom. Heat is transferred through gas and liquidConduction: Vibrating molecules collide with others and heat is transferred from one substance to another that are in direct contact. Radiation: Electromagnetic waves travel through air; when they collide with an object heat is transferred

V. Systems Analysis: Flow of Matter and Energy in the Environment

• Inputs/Outputs: Salt content of Mono Lake

• Open System/Closed System

• Feedback Loop: results of a process feed back into the system to change the rate of that process.

• Negative Feedback: a system responds to a change by returning to its original state or decreasing the rate at which change is occuring; resists change

• Positive: Causes the system to change further in same direction; amplifies a change

• Natural OR Anthropogenic factors lead to a breakdown in a negative feedback loop and drive an environmental system away from its steady state.

• Time Delays• Synergy• Unintended Results of Human Activity-you never do just one

thing!

Positive and Negative Feedback Loop