Understanding Matter and Energy in Environmental Science
School
Western University**We aren't endorsed by this school
Course
GEOGRAPH 1022B
Subject
Biology
Date
Dec 12, 2024
Pages
6
Uploaded by MagistrateDugong6372
ESCI 1100 Lecture 4Introduction to Environmental Science September 19, 2023 Our Physical Environment Understanding how the environment works requires knowing:1.How matter (any material that has a mass and occupies space) and energy enter and cycle through the natural world2.How human activities affect these natural processesMatter and Energy Knowledge required to understand environmental processes/functions ●Physical, geological, chemical and biological Required basic concepts ●Atoms, isotopes (stable and radioactive), ions, molecules, compounds, solutions, bonding, pH, organic, inorganic ●Conservation of matter and energy Thermodynamic1st Law: conservation of Matter●‘Energy can’t be created of destroyed, only transformed from one form to another’➔Ex. photosynthesis = solar changed to chemical energy 2nd Law: thermodynamics ●‘Amount of energy available to do work in the universe is decreasing with time’➔Conversion of energy to not work is not 100% efficient ➔Energy loss = heat = not ‘usable’ energyComposition (matter) of Environmental ‘Spheres’Elements are substances with specific properties that cannot be broken down into substances with other propertiesThe most abundant elements in the Earth are oxygen, hydrogen,silicon, nitrogen, and carbon●3 to 8 major elements●Proportions differAtoms and Elements are Chemical Building Blocks ●Atoms are the smallest units that still have all of the element’s chemical properties●Atoms of each of the elements are made up of three particles:●Protons, which are positively-charged and determine the element’s atomic number
●Neutrons, which have no charge●Electrons, which are negatively-charged●Protons and neutrons are found within the dense center of the atom called its Nucleus➔The element’s mass number is determined by its number of protons and neutrons➔Electrons orbit the nucleus●Atoms of the same element always have the same number of protons●The number of electrons can change, creating ions●Within an element, the number of neutrons may also vary, creating atoms with different masses called isotopes➔Isotopes have special notations indicating their atomic mass.●Some isotopes are radioactive, meaning they “decay” and change their identity by emitting subatomic particles and high-energy radiation➔Isotopes with this property are called radioisotopes●Radioisotopes do the most damage when they enter the bodies of living organisms through eating or breathing➔After Fukushima, scientists began regularly testing food and water for radioisotopesAtoms Bond to Form Molecules and Compounds●Molecules are combinations of two or more atoms chemically bonded together, such as O2➔If the molecule is made of two or more different elements, it is classified as a compound, such as water (H2O) and carbon dioxide (CO2.●Atoms form bonds due to the attraction they have for each other’s electronsAtoms and Elements are Chemical Building Blocks ●Covalent bonds form when electrons are shared between atoms●In some covalent compounds, such as water, one part of the molecule attracts electrons more strongly, creating oppositely-charged poles➔The charged ends of water molecules attract each other, forming a weak interaction called hydrogen bonds●If the strength of attraction within a molecule is sufficiently unequal, an electron will be transferred from one atom to another➔This creates oppositely charged ions, which attract each other, forming an ionic bond●Atoms and molecules can also come together in mixtures, where they don’t react with each other➔Evenly distributed mixtures are called solutions.Matter Is Composed of Organic and Inorganic Compounds●Organic compounds are made of carbon atoms joined together with covalent bonds●One important class of organic compounds is the hydrocarbons, which only contain hydrogen and carbon➔Fossil fuels and petroleum products like plastic are mostly made of hydrocarbons
Macromolecules Are the Building Blocks of Life●Organic compounds also include polymers, long chains of repeated molecules➔Polymers and lipids are referred to as macromolecules, because they are so large.●Proteins are polymers made of amino acids.➔They are found in skin, hair, muscles; as part of the immune system; and as enzymes that catalyze chemical reactions●Nucleic acids, including deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), carry the hereditary information for organisms➔Contain the blueprints for producing all of the proteins in living organisms ●Nucleic acids are polymers made of molecules called nucleotides➔Regions of D N A that encode for specific proteins are called genes●Carbohydrates include simple and complex sugars, such as:➔Glucose, or blood sugar➔Cellulose, a complex carbohydrate found in leaves, bark, stems, and roots➔Chitin, which is found in insect exoskeletons●Lipids include a diverse group of molecules that do not dissolve in water:➔Fats and oils, which store energy➔Waxes, which are structural➔Steroids, which are part of hormonesHydrogen Ions Determine Acidity●In any aqueous solution, a small number of water molecules split apart into hydrogen ions (H+) and hydroxide ions (OH−)●Pure water contains equal concentrations of these two ions and is considered neutral➔Acidic solutions have higher concentrations of hydrogen ions➔Basic or alkaline solutions have higher concentrations of hydroxide ions●The pH scale quantifies the acidity or alkalinity of a solution➔Pure water has a H+concentration of 10-7 and a pH of 7➔Acids have a pH of below 7➔Bases have a pH above 7●The pH scale is logarithmic, meaning each step in the scale represents a 10- fold change in H+concentrationEnergy: An Introduction●Energy is the capacity to change the position, composition, or temperature of matter➔When energy causes an object to move, it is a force that can accomplish work●Potential energy is the energy of position or composition➔For example, river water held behind a dam contains potential energy●Kinetic energy is the energy of motion➔River water rushing through a dam and downstream contains kinetic energy●Energy is able to be converted back and forth between these two forms.Energy Comes in Different Forms ●Converting molecules with high-energy bonds (such as glucose) to molecules with low-energy bonds (such as carbon dioxide) releases kinetic energy.
●Energy Is Always Conserved, but It Changes in QualityLight Energy from the Sun Powers our Planet●Organisms called autotrophs use the sun’s radiation directly to produce their own food➔They use a process called photosynthesis to transform molecules with low-energy bonds (water and carbon dioxide) into sugar molecules with high-energy bonds.Photosynthesis Converts Solar Energy to Chemical Energy●Photosynthesis occurs within cell organelles called chloroplasts●A pigment called chlorophyll uses solar energy to initiate a series of reactions called lightreactions●Light reactions split water molecules into hydrogen ions (H+), oxygen molecules (O2), and small high-energy molecules of ATP and NADPH●The Calvin cycle reactions link together carbon atoms to form sugarsExample: Photosynthesis ●Stores chemical energy➔Solar energy converts H2O and CO2into carbohydrates and O2➔Causes increased weight (biomass gain)●Example: green plants & algae●Water + carbon dioxide + sunlight glucose (sugar) + oxygen●6H2O + 6CO2+ solar energy → C6H12O6+ 6O2Example: Respiration ●Releases chemical energy➔O2used to burn carbohydrates to produce energy & do work➔Results in decreased weight (biomass loss)●Example: humans●Glucose (sugar) + oxygen → water + carbon dioxide + energy●C6H12O6+ 6O2→ 6H2O + 6CO2+ energyGeology: The Physical Basis for Environmental Science●Geology is the study of Earth’s physical features, processes, and history➔These processes shape the landscape, lay the foundation of environmental systems, and provide resources like metals and fossil fuels●At the Earth’s center is a dense core made of solid iron at the center surrounded by molten iron●The core is surrounded by a thick layer of less dense, elastic rock called the mantleEarth Consists of Layers ●The asthenosphere is an area of the upper mantle with especially soft rock●The lithosphere contains the uppermost mantle and the crust➔The crust is a thin, brittle, low-density layer of rock that covers the entire surface
Plate Tectonics Shapes Earth’s Geography●Heat from the Earth drives loops of convection currents that cycle material upward and downward➔This creates about 2–15cm of movement of large plates of lithosphere every year, called plate tectonicsThere Are Three Types of Plate Boundaries1.At divergent plate boundaries, plates move apart as magma rises to the surface and cools2.At transform plate boundaries, plates slip and grind alongside each other. This causes earthquakes3.When two plates come together, it is known as a convergent boundaryThe Rock Cycle Produces a Diversity of Rock Types ●A rock is any solid aggregation of minerals●A mineral is any naturally occurring solid element or inorganic compound with a crystal structure, distinct chemical composition, and physical properties●Over time, rocks and their minerals are heated, melted, cooled, broken down, and reassembled in a process called the rock cycle●Magma is made of liquid rock that has melted at high temperatures. When magma erupts and reaches the surface, it is called Lava ●Rock that forms when lava or magma cool is called igneous rockThe Rock Cycle Produces a Diversity of Rock Types●As rock weathers from wind and water, particles called sediment come to rest downwind or downstream●Sediment layers accumulate over time and are compacted as they are buried➔Minerals may seep through them and cement particles together. This forms sedimentary rock, like sandstoneEarthquakes Result from Movement at Plate Boundaries and Faults●An earthquake is a sudden release of energy at a tectonic plate boundary➔Earthquakes may also occur in the interior of tectonic plates due to stretching and pulling from forces within the Earth.Volcanoes Arise from Rifts, Subduction Zones, or Hotspots●A volcano is formed where molten rock, ash, or hot gas erupts through the Earth’s surface➔Often found in subduction zones of convergent plate boundaries➔Japan is the most volcanically active nation, with 100 active volcanoes or about 10% of the world’s total●Lava may also be emitted at hotspots, localized areas where plugs of molten rock from the mantle erupt through the crust.●The type of eruption released by volcanoes can be very different
➔At Mount Kilauea, lava has been slowly flowing downhill since 1983➔Mount Saint Helens unleashed a huge amount of cinder and ash in a 1980 eruption➔The Roman city of Pompeii was buried in a pyroclastic flow of gas, ash, and rock that erupted from Mount Vesuvius in A.D.79.●There was a 0.4–0.7° Celsius decrease in global temperatures following the eruption of Mount Tambora in 1815Landslides Are a Form of Mass Wasting●Landslides occur when large amounts of rock or soil collapse and flow downhill●The downward gravitational movement that causes this is called mass wasting➔Most commonly affects unstable hillsidesTsunamis Can Follow Earthquakes, Volcanoes, or Landslides●Earthquakes, volcanic eruptions, and large coastal landslides can all displace huge volumes of ocean water instantly, triggering a tsunami➔The 2011 tsunami that hit northeastern Japan was triggered by an earthquakeWe Can Worsen or Lessen the Impacts of Natural Hazards●Earthquakes, tsunamis, and volcanoes are referred to as “natural hazards,” but our decisions can worsen their impacts➔Living in areas prone to hazards, such as floodplains➔Damming or diking rivers➔Clearcutting forests on slopes, inducing mass wasting➔Human-induced climate change●Altering these decisions, as well as implementing better engineering technology, can help to minimize our risk