TAILIEUCHUNG - Lecture Environmental science - Chapter 3: Ecosystems: How they work

Earth's ecosystems continue to exist because they are sustainable. Two fundamental characteristics are crucial to sustainability. First, ecosystems' energy source, the Sun, is non-depletable and non-polluting. Second, there is efficient recycling of nutrients and other chemicals through organisms and through geological and chemical processes that result in no waste accumulation in ecosystems. This chapter provide knowledge of ecosystems: How they work. | Ecosystems How they work Chapter 3 Biosphere II Purpose: recreate conditions of Earth (Biosphere I) * to understand our world better * space travel 5 acres in Arizona, 4000 species, 10 humans * problem: 02 + CO2 were absorbed by concrete * ants and cockroaches took over Recycle or Die This means that we have a limited supply of raw materials (formation of the earth) All matter is recycled through the lithosphere, hydrosphere, and atmosphere. Nothing is created nothing is destroyed All stable ecosystems recycle matter and get energy from the sun Physics Energy is measured in calories Calorie – amount of heat needed to raise 1 gram of water 1 degree Celsius. Kilocalorie = 1,000 calories 1st law of thermodynamics Energy cannot be created nor destroyed, only change forms (light to chemical) 2nd law of thermodynamics Energy transformation increases disorder (entropy) of the universe. Heat is the lowest grade of energy. Chemistry Atoms – basic units of matter Electron Proton Neutron Chemical bonds - how atoms are held together Ionic Covalent Molecule/compound – two or more atoms bonded together pH scale Base/alkaline Acid Know these elements Top 6 most abundant elements in living things (not in order) * NCHOPS Top 8 elements in the earths crust (in order) * O, Si, Al, Fe (iron), Ca, Na (sodium), P, Mg Only silly apes in college study past midnight. Organic Compounds C-C bonds and/or C-H bonds They can be natural or synthetic Natural: compounds that make up living systems Synthetic: man-made compounds 78% N2 21% O2 <1% Argon CO2 Major gases in the troposphere: Photosynthesis Very inefficient (Only 1% of the energy from the sun is used) Chlorophyll – absorbs light to drive photosynthesis Photosynthesis Continued Plants use glucose to: Construct other molecules Build their cell wall Store energy Source of energy Building blocks of living things Phospholipids Steroids Proteins Chains of amino acids Muscles Enzymes Nucleic acids Chain of nucleotides Deoxyribonucleic acid Ribonucleic acid Nitrogen cycle Main reserve in the atmosphere Living things must get N from ammonium (NH4) or nitrate (NO3) N from the atmo must be fixed Change N2 into ammonium or nitrate Rhizobium (bacteria living in roots of legumes) fig 3-10 Industrial Lightning Burning fossil fuels Phosphorus cycle No gas phase, only solid and liquid Man-made fertilizers contain organic phosphates Because P is a limiting factor in aquatic systems, it leads to eutrophication The rain forest is very good at recycling P, except when we cut it down Carbon cycle We will play the carbon cycle game Big hint = photosynthesis! element Main nonliving reservoir Main living reservoir Other nonliving reservoir Human-induced problem Carbon C Atmo CO2 Carbohydrates (CH2O)n And all organic molecules Hydro Carbonate (CO3-2) Bicarbonate (HCO3-) Litho minerals Global warming Carbon from fossil fuels underground are burned and released into the air as CO2 Nitrogen N Atmo N2 Proteins and other N- containing organic molecules Hydro Ammonium NH4+ Nitrate NO3- Nitrite NO2- Eutrophication Fertilizers contain human-made nitrates that end up in the water Phos-phorous P Litho rocks as PO4-3 *no gas phase DNA ATP phospholipids Hydro Phosphate PO4-3 Eutrophication Fertilizers contain human-made phosphates that end up in the water Cutting down rainforest stops recycling of P

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