Environmental Science 1021F/G final- AY.pdf

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Western University
Environmental Science
Environmental Science 1021F/G
Geoff Stewart

Food and Land III Food and Soil Resources Pests and Pesticides • Pest – unwanted organism that interferes with human activities; subjective – "A weed is a plant whose virtues have not yet been discovered" - Waldo Emerson • Pesticide – kills or controls undesirable organisms • 100 species (1%) cause 90% of the damage • Disturbs predator-prey cycles in natural ecosystems and polyculture Pesticides: Types 1. Insecticides – block reproduction, airways, nervous system 2. Herbicides – disrupt plant growth and metabolism 3. Fungicides 4. Rodenticides Pesticide History • Before pesticides – Crop rotation, vary planting times, plant diversity, hedgerows • Based  on  plants  natural  “instincts” • First generation – Sulphur, lead, arsenic, mercury – Nicotine sulphate, pyrethrum, rotenone • Second generation – Synthetic organic compounds (eg DDT), broad- and narrow-spectrum, persistence reduction, some natural The Case For Pesticides • Saves human lives – Malaria, bubonic plague, typhus • Increase food supplies and profits; lower costs • Work faster and better than alternatives • Health risk *may* be insignificant compared to benefits – 3000-6000 death/yr (EPA) • New pesticides are safer and used at lower rates than older pesticides The Case Against Pesticides: What are the true costs? • Genetic resistance – insects and plants • Kill non-target organisms, incl. natural predators – Can increase other pests – Harm wildlife • Pesticide movement • Human health threat; 20,000–40,000 deaths • Environmental health threat • Still 6% decrease in yield loss to pests • Economic threshold of use • Use reduced without yield decrease Alternatives to Synthetic Chemical Pesticides • Some based on biomimicry, part of Integrated Pest Management (IPM) 1. Change cultivation practices (cultural) 2. Biological pest control – Insect birth control (hormones/pheromones) – Predators 3. Hot water 4. Genetically-resistant plants – Recall: associated problems What Are the Environmental Issues? Food Consumption After the Farmgate • Energy and waste: – Plant, irrigate, fertilize, apply pest control, harvest – Transport for processing – Store, clean, cook, mix, preserve, package – Transport to the grocery store – Keep food chilled/frozen, displayed – Transport and preparation at home/restaurants – Disposal transport How much energy is used? • 17% of US energy consumption used to get food to the table – 18% of that for on-farm food production – 82% of that for food processing, transportation, marketing and preparation!!! • Most energy is from non-renewable fossil fuels – Release GHG’s  and  other  pollutants How can you decrease the energy cost of your food? • Choose – locally/native/organically grown food – foods in season – less processed, whole foods – foods with less packaging – to eat less meat, especially red meat (lower trophic level = less energy waste) – see next slide – to compost – to garden Food and Land IV Forests, Invasive Species and Biodiversity Managing and Sustaining Forests • Forests classified by age and structure 1. Old-growth forests (22%) 2. Second-growth forests (63%) 3. Tree farms/plantations (5%) Ecological Services of Forests • Carbon sink • Energy flow and nutrient cycling • Erosion protection • Air and water purification • Water control • Local and regional climate regulation • Wildlife habitat Economic Services of Forests • Fuel wood • Lumber • Paper • Livestock grazing • Recreation • Jobs • Other resources (minerals, medicine, food) Forest Types of the World • Classified by climate – Tropical – Temperate – Boreal (taiga) Canada’s  Forest  Regions • Boreal - largest • Taiga • Aspen Parkland • Subalpine • Montane • Coastal • Columbia • Carolinian • Great-Lakes St. Lawrence • Acadian Carolinian Zone – Our backyard • Most threatened landscape − 33%  of  Canada’s  spp-at-risk − 25% of Canadians live in region, 90% of Ontarians • Biodiversity hotspot − ~2,300 spp. of vascular plants Types of Forest Management 1. Even-aged management − Trees maintained about same age and size − Harvested at once and replanted: biodiversity low, monocultures − Shade intolerant or fast growing tree species 2. Uneven-aged management • Maintain trees at many ages and sizes • Biodiversity high, shade tolerant and shade intermediate • Natural regeneration • Long-term sustainable production; selective cutting Harvesting Methods Uneven-aged A. Selective cutting – High grading Even-aged A. Shelterwood cutting B. Seed tree cutting C. Clear cutting – Strip cutting Tropical Deforestation: Causes • Rapid and increasing – Disagreements of how rapid • Primary (basic) causes • Secondary causes -process – Roads – High-grading – Ranchers – Settlers – Land abandoned Tropical Deforestation: Environmental Impacts • Roads Lead to Forest Degradation • Increased human activity – Increased erosion and runoff – Increased flooding – Exposure to invasive species/diseases – Habitat fragmentation – Biodiversity loss • Loss of resources – Biodiversity, medicine, fuel, food Solutions: Reducing Tropical Deforestation • Teach and subsidize sustainable agriculture and forestry • Phase out subsidies for unsustainable methods • Debt-for-nature swap – Encourages protection • Certification • Reduce illegal cutting • Reduce poverty and control population growth Global Solutions: Sustainable Forestry • Sustainable management practices – Longer rotations, more selective or strip cutting; less clear-cutting, seed-tree or shelterwood cutting – Minimize fragmentation • Reduce road building; limit equipment type • Leave dead trees behind • Natural pest control • Include ecological services in economic value Deforestation and climate change • Reduction of carbon sinks and release of CO 2 • Change in hyrdrologic cycle and albedo • Invasive insect/plant/pathogen distribution • Complex interactions Invasive species: Insects, pathogens, plants Biodiversity is the best defence against invasive species: WHY??? Competition for food • Gypsy Moth – Many hardwoods • European Buckthorn Giant Hogweed • Emerald Ash Borer – Ash trees • Kudzu Natural Disaster Insurance November 19, 2004, Slovakia • Massive windstorm swept through Tatra National Park • 50% planted with Spruce (Picea abies) monoculture (1930s): flattened • Other 50%: high biodiversity, not damaged • Replanting plans: increased biodiversity; no more monocultures Mangroves– A natural buffer Deforestation affects us in ways we would never have previously imagined • Mangroves: woody, specialized tropical trees; found where rainforests meet oceans • Mangrove forest provided natural buffer to villages in Indonesia and Samoa from Tsunamis Air Part I Air Pollution The Atmosphere • Several layers – Different temps., pressure, density and composition – Thermosphere – Mesosphere – Stratosphere (17-50km) – Troposphere (0-17km) Stratosphere • Composition similar to troposphere • Has less water vapour, less matter, more ozone than troposphere • Good ozone (ozone layer) – Keeps UV from reaching  Earth’s   surface – O2+ UV sun = good O 3 Troposphere • Contains the air we breathe – N (78%), O (21%), water vapour (0-4%), CO (0.038%), Ar (<1%) 2 • Involved in biogeochemical cycles (nutrient cycling) • Responsible for weather and climate • Bad ozone (ground level ozone) • VOCs + NO(x) + sun = bad O 3 Outdoor Air Pollution • Air pollution definition – Chemicals in the atmosphere @ concentration high enough to affect climate/harm organisms and materials • 3 sources – 1. Mobile – 2. Stationary – 3. Natural • Dust, volatile organic compounds (VOCs) from plants, plant decay, forest fires, volcanoes, sea spray • Increased concentration due to fossil fuel burning; esp. vehicle emissions Primary and secondary pollutants 1. Photochemical Smog • NO + VOCs + heat + UV = 100s pollutants (including X bad ozone) • NO 2s the cause of the brownish haze Photochemical Smog • Hotter temps lead to higher levels – NO +XVOCs + heat + UV = 100s pollutants • Humans: irritate eyes, respiratory tract • Damage to crops and trees How can trees cause photochemical smog???? • Some species emit VOCs – Problematic if forested areas close to urban areas – Esp. urban areas with high NO and sunlight x – Selectivity in species planting encouraged in urban areas – Considerations for tree farms . Industrial Smog • Consists of sulphur dioxide (SO ), droplets of sulphuric acid, suspended solid particles 2 • Burning coal and oil contribute • Smelting metal sulphide ores • Less problematic in developed countries Air pollution • Factors that reduce formation – Rain, snow and salty sea spray – Wind • Factors that increase formation – Urban buildings – Hills and mountains – High temperatures – Grasshopper effect Emission Reduction • Prevention – Burn low sulphur coal – Remove sulphur – Convert coal to liquid or gas fuel – Shift to less polluting fuels • Dispersion/cleanup – Smokestacks – Scrubbers – Tax pollution Reducing Motor Vehicle Air Pollution • Prevention – Alternative/mass transit – Less polluting engines/fuels – Improve fuel efficiency – Remove old cars – Tax write off for low-polluting/energy efficient cars – Driving restrictions in polluted areas • Cleanup – Emission control devices – Exhaust inspections – Stricter emission standards Air Pollution From Acid Deposition • NO and SO f2rm acids and salt particles 1. Wet deposition – acidic rain, snow, fog, clouds 2. Dry deposition – acidic particles Acid Deposition Effects • Respiratory diseases • Toxic metal leaching • Damage to structures and buildings • Fish death in aquatic systems • Soil pH changes (roots) – Reduced productivity of forests and crops • Nutrient leaching, Ca deficiency, synergistic effects with other pollutants, metal toxicity, increase susceptibility – Reduce soil buffering capacity • Direct plant damage • Promote acid-loving mosses Solutions to Acid Deposition • Prevention techniques same for reducing emissions Clean-up of Acid Deposition:  Add lime to neutralize acidified lakes  Add phosphate fertilizer for lakes  Powered limestone for acid soils  Plant acid-resistant plants Air Part II Ozone Depletion, Greenhouse Gases and Climate Ozone Depleting Chemicals  Chlorofluorocarbons (CFCs)  Hydrochloro-fluorocarbons (HCFCs)  Hydrofluorocarbons (HFCs)  Halons  Carbon tetrachloride Ozone Depletion by CFC Compounds --------------------------------------- Misconception: Ozone Loss and the Greenhouse Effect • The greenhouse effect is NOT a result of ozone layer depletion!!!!! Two distinct phenomena; two different locations • FACTS – Ozone loss • Loss of good ozone (ozone layer) in stratosphere – Greenhouse effect • Trapping of heat by greenhouse gases in troposphere Ozone Loss and the Greenhouse Effect • Some connections • CFC’s  and  water  vapor  deplete  ozone  layer  AND  are  GHG’s • Greenhouse effect causes stratosphere to cool, where good ozone layer is • This creates clouds – increases ozone depletion Atmospheric Effects on Climate • The  Earth’s  natural  and  enhanced  greenhouse  effect Main Greenhouse Gases  CO2 Potential: 1  Methane Pot: 21  Nitrous Oxide Pot: 310  CFC-12 Pot: 6200-7100  HCFC-22 Pot: 6500  Perfluoromethane Pot: 6500  Sulfur hexa-fluide Pot: 23900 Human Activities the Increase Greenhouse Gases 1. Increased fossil fuel use 2. Deforestation/grassland clearing 3. Increased in cattle raising 4. Growing rice 5. Inorganic fertilizer use - Recall  natural  GHG’s - N (78%), O (21%), water vapour (0-4%), CO (2.038%) The Greatest GHG offenders • United States (25%) – Landfills – livestock – natural gas/oil - coal • European Union (12%) • China (11%) • Russia (7%) • Japan (5%) • India (5%) • Canada (2%) What is climate? • Long-term conditions • Average precipitation and temperature • Main factors determining climate – Global air circulation and water circulation, amount of solar energy (latitude) Global air circulation: Determined by four factors 1. Uneven  heating  of  Earth’s  surface • Direct sun @ equator vs
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