Environmental Systems Chapter 2 – Module 4

Mono Lake Terminal Lake (water flows in, but it doesn’t flow out) Alkaline – water picks up salts and minerals and deposits them in lake Mono brine shrimp and Mono Lake alkali fly support migrating birds (sandpipers, gulls and flycatchers)

Mono Lake 1913 – City of Los Angeles plans to redirect water away from Mono and Owen’s Lake Owen’s Lake redirected first, dried up, by 1930 it was an empty salt flat One of the nation’s largest sources of windblown dust – dust contains arsenic 1941 – start to redirect water away from Mono Lake By 1981 – depths decreased by half, salinity increased to more than twice that of the ocean Salinity killed algae, shrimp died due to lack of food, birds stayed away or were preyed upon by coyotes

Mono Lake 1994 – Audubon Society and environmentalists convinced the LA Dept of Water and Power to reduce the amount of water it diverted 2009 – water levels just short of 2/3 of its historic depth 2013 – brine shrimp are thriving and birds are returning. City of LA had to reduce water consumption Converted grass lawns to drought-tolerant native shrubs Low flow showerheads and toilets This is an example of the interconnectedness of humans and biotic and abiotic factors in the environment A change in one factor often has unexpected effects.

What is a system? Set of interacting components that influence one another by exchanging energy or materials. A change in one part of the system affects one or more other parts of the system Natural systems – set of interactions between living organisms, nonliving matter and energy

Matter Matter is anything that has mass and takes up space Mass – the amount of matter an object contains Weight – the force that results from gravity acting on mass. You would weigh less on the moon because gravity is weaker there, but you would have the same mass. Atom – is the basic unit of matter

Element A substance consisting of atoms with the same number of protons. 94 naturally occurring elements, 24 man-made Molecule – particles that contain more than one atom Compound – molecules that contain more than one element

Atomic Structure Atomic number = # of protons Mass number = total# of protons and neutrons Isotope = atoms of the same element with different # of neutrons Electron = negatively charged particle orbiting nucleus Proton = positively charged particle in nucleus Neutron = neutral particle in nucleus

Radioactivity Unstable isotopes spontaneously undergo radioactive decay – release material from the nucleus and may emit harmful radiation Half-life – the time it takes for one half of the radioactive atoms to decay Used to determine the length of time that a radioactive element is dangerous Carbon dating can be used to determine how long ago an organism died.

Chemical Bonds To form molecules or compounds, atoms must be held together by bonds Covalent Bonds – electrons are shared Ionic Bonds – electrons are transferred creating positively and negatively charged ions. The ions attract to form the bond. Hydrogen Bonds – unequal sharing of electrons creates partial charges. The attraction between partially charged molecules creates hydrogen bonds.

Covalent Bond

Ionic Bond

Water Polar molecule – unequal sharing of electrons creates partial charges Hydrogen bonds form between water molecules Gives water many unique properties Density Cohesion & Adhesion Capillary Action High Specific Heat – put a lot of energy in to change its temperature Universal Solvent

pH – the relative strength of acids and bases Basic or alkaline pH>7 Acid – substance that dissociates into hydrogen ions (H+) and a negative ion in solution Base – substance that forms hydroxide ions (OH-) and a positive ion in solution Water is Neutral H+=OH- Acidic pH<7

Chemical Reactions The separation of atoms from molecules or the recombination of atoms with other molecules Bonds between atoms change

Conservation of Matter The law of conservation of matter: Matter can neither be created or destroyed; it can only change form. Let’s prove this to be true. In a group you will design an experiment that will demonstrate the law of conservation of matter. You must write a lab write up for your experiment.

Biological Molecules Organic chemistry – based on carbon to carbon and carbon to hydrogen bonds Inorganic chemistry – do not contain carbon or carbon is bound to elements other than hydrogen (Carbon dioxide)

Biological Molecules Basis of Life Carbohydrates – sugars Main energy source of living things Proteins Structural, energy storage, transport, part of immune system Nucleic Acids – DNA and RNA Genetic information Lipids – fats, waxes, and steroids. Cell membranes and some hormones

Cells The smallest structural and functional component of organisms. All living things are made of cells.

Energy, Flows and Feedbacks Chapter 2 – Module 5

Energy Energy The ability to do work or transfer heat. The basic unit of energy is the Joule The amount of energy used when a 1-watt electrical device is turned on for 1 second. Power The rate at which work is done. energy = power × time unit kWh – energy use power = energy ÷ time unit kW – turbine’s power Joule - kg⋅m2⋅s−2

Energy Conversions

Different Types of Energy There are different forms of energy and they can be converted from one form to another. Potential – stored energy, ex water in a dam Chemical – potential energy stored in bonds Nuclear Thermal Kinetic – energy of motion Electrical Mechanical Electromagnetic – visible light, uv, infrared, microwaves, x-rays Sound

Electromagnetic Spectrum The longer the wavelength, the lower the energy

All matter contains some energy Temperature is the measure of the average kinetic energy of a substance. Changes in temperature can convert matter from one state to another.

The Laws of Thermodynamics First Law of Thermodynamics: Energy is neither created nor destroyed, but it can change from one form to another.

The Laws of Thermodynamics Second Law of Thermodynamics: When energy is transformed, the quantity of energy remains the same, but its ability to do work diminishes.

The Laws of Thermodynamics Second Law of Thermodynamics: When energy is transformed, the quantity of energy remains the same, but its ability to do work diminishes. All systems move towards increased entropy. Energy Efficiency - the ratio of the amount of energy in the desired form to the total amount of initial energy To calculate, multiply all individual efficiencies Energy Quality – based on how easily an energy source can be used for work Gasoline is a higher quality energy source compared to wood Entropy – disorder or randomness in a system. As energy loses its ability to do work, entropy increases.

Open and Closed Systems Open – exchanges matter and energy with other systems Closed – no exchange of matter and energy with other systems

Steady State A system in steady state. Inputs = Outputs System doesn’t change over time.

Negative and Positive Feedback Feedbacks are found throughout the environment. Triggered by a change in the environment Negative feedback loop A feedback loop in which a system responds to a change by returning to its original state, or by decreasing the rate at which the change is occurring. Reverses the change. Positive feedback loop A feedback loop in which change in a system is amplified, taken further from original state. Enhances the change.

Examples of Feedback Loops

Examples of Feedback Loops Change: Warmer temperatures on Earth Result: Increased evaporation of water Negative Feedback – low altitude clouds reflect sunlight back into space = less heating of surface, less evaporation, less warming Positive Feedback – high altitude clouds absorb additional energy = more heating of surface, more evaporation, more warming