1. Environmental Systems: Chapter 2-

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

3. 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
Climate models are computer programs that simulate the processes that govern the Earth’s climate. Global climate models contain four main components: the atmosphere, the oceans, ice and snow covered regions, and land surfaces with vegetation cover. It is these components and the interactions between them that produce our climate.
Example-global warming: past data trends, effects of oceans on climate, air movement, el nino.

4. II. All Environmental Systems Consist of Matter
Atom, Elements, Ions, Compounds, Mixtures, Molecules
Atomic Number, Mass Number,
Isotopes
Organic-Carbon containing compounds, (all organic compounds contain carbon but not all carbon compounds are organic) linked with H, O, S, N, Cl, F/can be natural or synthetic
Examples: sugar, vitamins, hormones, DDT
Include hydrocarbons-only H and C: methane, octane
Chlorinated ydrocarbons: DDT, PCB’s
Chloroflourocarbons: refrigerants (freon)
Genes-sequence of nuceotides
Chromosomes-combinations of genes

5. Ionic vs. Molecular Substances
Ionic bonds, Covalent Bonds, Hydrogen bonds

6. 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

7. 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

8. 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

9. IV. Energy is a Fundamental Component of Environmental Systems
Energy: The ability to do work or transfer heat
LOCOE: Energy not created or destroyed-changes form-degraded to a lower quality.
Heat Transfer: Convection: lighter molecules rise, heavy ones sink to bottom and there is a turn over. Conduction: Vibrating molecules collide with others and heat is transferred=a pan on the stove gets hot. Radiation: Heat is transferred through air
High quality energy: Coal, oil, U-235
Low Quality: dispersed-heat in ocean
Ionizing-ability to release electrons-break bonds.

10. 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 quality
Example: When converting from electrical to light energy some energy is converted to low quality heat

11. 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.

12. Heat Transfer:
Convection: lighter molecules rise, heavy ones sink to bottom. Heat is transferred through gas and liquid
Conduction: 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

13. V. Systems Analysis: Flow of Matter and Energy in the Environment
Inputs/Outputs: Salt content of Mono Lake
Feedback loops occur when output of matter or energy is fed back into system
Examples: recycling aluminum; homeostasis
Positive: Positive and negative don't imply consequences of the feedback have positive or negative final effect. The negative feedback loop tends to slow down a process, while the positive feedback loop tends to accelerate it. a change in one direction causes a further change in that direction. From an economic standpoint, population growth is good. More births = more people to work, can support more births.
Example: For example, warming will tend to reduce snow cover and so reduce the amount of solar energy reflected back into space. This is an example of a positive feedback because the extra energy absorbed increases the warming. Climate models include these feedbacks.
Negative: change leads to a lessoning of the effect: homeostasis-body temp goes up, body systems respond by cooling it.
Time Delay: EX: epidemeology studies-cancer
Synergy: The whole is greater than sum of individual parts; The effect of two chemicals/toxins greater than the sum of the two individuals.Ex: Ibuprofin and acetomyacin/ two different pesticides

14. Open System/Closed System

15. 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!

17. Positive and Negative Feedback Loop
This diagram represents a positive feedback loop. Decreasing vegetation in a valley causes increasing erosion and nutrient losses that in turn cause more vegetation to die, resulting in more erosion and nutrient losses. Question: Can you think of another positive feedback loop in nature?
This diagram illustrates a negative feedback loop. When a house being heated by a furnace gets to a certain temperature, its thermostat is set to turn off the furnace, and the house begins to cool instead of continuing to get warmer. When the house temperature drops below the set point, this information is fed back to turn the furnace on until the desired temperature is reached again.