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Environmental Science
Luc Bernier

Lecture 2 – What is Environmental Science? 1. Introduction 2. What is the Environment? 3. How do we study environmental problems? 4. Evaluating Environmental Science 5. Other discourses on the environment 6. Environmental Problems ANNOUNCEMENTS Labs Get your custom courseware Labs start the week of January 11th Quote • Science is an adventure of the human spirit. It is essentially an artistic enterprise, stimulated largely by curiosity, served largely by disciplined imagination, and based largely on faith in the reasonableness, order, and beauty of the universe. Warren Weaver 1. Introduction The control of nature is a phrase conceived in arrogance … born when I was supposed that nature exists for the convenience of man Rachel Carson Rachel Carson: • Naturalist, author, government scientist • 1907-1964 • Author of Silent Spring • Influential in changing views towards the environment What is the “environment”? The old view: - “Natural” world apart from human society The more recent perspective: - Humans exist within the environment and our interactions with other parts of it matter Environmental Science: - Study of how the natural world works, how humans affect their environment, and how the environment affects humans in return How does Science study environmental problems? - Ask a Question - Do experiments to collect data  Interpret data  well tested and accepted - Formulate hypothesis to explain data - Do more experiments to test hypothesis - Revise hypothesis if necessary - Well tests and accepted hypothesis becomes scientific theories Assumes: - fixed natural laws - causality - can be sensed and reasoned - Interactive combinations of theory and observations Hypothesis: - An informal new idea, which has not been widely tested Theory: - A hypothesis capable of explaining a wide array of observations. (evolution) Unifying theories: - Close approximation to truth. These are theories which survive repeated testing Styles of study: - Field Study: monitor to determine spatial and temporal variability Vegetation history of Crawford Lake: Experimental Research: field or lab Variables and testing hypothesis - Variable: a quantity or condition that may vary - Independent - Dependant - Manipulated - Responding Modelling: simulation, prediction Numbers in Science: - go beyond qualitative understanding of a problem - allow us to visualize relationships and make predictions - allow us to analyse the strength of a relationship and to discover new ones Uncertainties: - Natural - Measurement Accuracy: extent to which a measurement agrees with the true or accepted value Precision: degree of exactness with which a quantity is measured. A very precise measurement may not be accurate. Evaluating Environmental Science: - What is the data underlying the theory? - Is there a logical link between the data and the theory? - Does the explanation account for all of the data? - Are there biases behind the explanations? - Does the scientific community support the theory? - Theories are subject to external factors The Frontiers of Science: beyond the fringes Other discourses on the environment Environmental Studies: Incorporate Social Sciences to the study of environmental problems Environmentalism: Social movement dedicated to protecting the natural world Environmental Problems: - Global Warming - Water Pollution - Industrialization **How many times does an experiment need to be repeated to prove a hypothesis? **Are environmental science and environmentalism exclusive one from another? Lecture 3: 1. What are Ecosystems? - Ecosystem: A community of different species interacting with one another and their environment in such a way as to perpetuate their grouping - Perpetuate: i.e. sustain What is a Biome? - A large relatively distinct terrestrial region with similar: climate, soil, plants and animals regardless of where it occurs in the world Community: - A complex interacting network of plants animals and microbes Population: - Individuals of the same species interacting In a specific area at the same time Species: - Group of organisms the resemble one another in appearance, behaviour, chemistry, and genetics Organism: - any form of life 2. How are they organized? Types of components: - all living organisms in a given area – biotic - all the non-living components of the ecosystem – abiotic What are the major ABIOTIC components of an Aquatic ecosystem? - Salinity - Temperature - Chemical nutrients - Oxygen Content - pH - sunlight - pressure - temperature - nutrients - sediments - depth Law of imitating Factors: - Limiting factor: factor that limits growth - Abiotic - Defines optimum and limits tolerance for each factor - Species can not exist outside of limits of tolerance for any one factor 3. How are organisms organized within ecosystems? Categories of Organisms: Producers: - autotrophic - self-feeding organisms - e.g. green plants - convert sunlight to energy via photosynthesis - 6C02 + 6H20  C6H1206 + 602 - Energy may also be found in-inorganic compounds Consumers: - Heterotrophic - i) primary consumers: herbivores – feed directly on producers - ii) secondary consumers: carnivores- feed on primary - iii) tertiary consumers: omnivores- feed on both 4. What is a biomass? What is a biomass pyramid? - Considers all total mass of members: producers and consumers - As you move higher up the pyramid the efficiency of energy conversion decreases Question- algae blooms- currents bring up nutrients from the deep ocean Lecture 4: 1. What makes up an ecosystem? - A) Interactions between spheres (bio, atmos, litho, hydro,) - B) Elements: the building blocks of matter o Key elements in all living organisms: nitrogen, oxygen, carbon, hydrogen, phosphorus, sulphur: found in air, water, rock and soil - C)Energy: the ability to move matter o No matter can be moved or transformed without being released or transformed 2. How does energy get transferred in an ecosystem? - 1 Law of thermodynamics: energy is neither created nor destroyed, but can be converted from on form to another nd - 2 Law of thermodynamics: in any energy conversion you will end up with less useable energy then you started with, where the disorganization or entropy occurs. As energy flows through a food web it is degraded and less and less usable - Trophic level efficiency: ratio of production of one trophic level to the production of the next lower trophic level. It is never high - Production: growth of organic material from inorganic material (e.g. soil, rock and water) involves a Gain in potential energy, with the construction of complex molecules from simple ones - Decay: involves the loss of energy as it is released during the decay process, where complex molecules are broken down to form simple ones 3. What is sustainability? - the ability of a system to function and survive over a period of time - current generation is able to meet its own needs without compromising the ability of future generations to meet their own needs 4. What are the principles of ecosystem sustainability? I. Recycle Nutrients: to maintain sustainability ecosystems dispose of wastes and replenish nutrients by recycling of elements II. Use sunlight as a basic energy source: ecosystems use sunlight as their source of energy III. Overgrazing does not occur: size of the consumer population is maintained to prevent overgrazing/overuse from occurring- maintain carrying capacity Nutrient Cycling: - the end-product and by-products of one system are the food and/or the essential nutrients for another system - Advantage: prevents waste accumulation - Assumption: ecosystem will not run out of nutrients 5. What are the Human impacts on the principles of sustainability? - Society is failing to care for the environment and sustain it - Population increases beyond carrying capacity - Massive decline in environmental quality - Massive decline in environmental quality: i.e. Easter island How to prevent a global version of the decline of easter island? - Understand how the natural world works - Understand how human and natural systems interact - Accurately assess the status and trends of crucial natural ecosystems - Establish long-term sustainable relationships with the natural world Questions: 1. What would happen to an ecosystem if? a) all its decomposers and detritus feeders were eliminated? b) all its producers were eliminated? 1. What is Biodiversity? - the sum of all total organisms in an area - takes account to: diversity, genes, populations, communities - different indication ex. Species richness - insects outnumber all other species - up 2 to million species have been identified - estimates that total biodiversity ranges between 3 to 100 million species - insects distribute of up to 72% of known animals - beetles distribute of up to 40% of insects - some organisms are difficulty identified - small species often overlooked - some biomes are difficult to access Distribution: - unevenly distributed - living organism are distributed unevenly across earth - species richness increases towards the equator- latitudinal gradient 2. Why is it important to ecosystem function? - species are structural components of ecosystems - dominant species tend to regulate major ecosystem processes including energy flow and nutrient cycling - keystone species: have a strong or wide-reaching impact far out of proportion to its abundance. i.e. beaver dams hydrology, and sea urchins vs. otters Maintenance: - purify air and water - detoxifies and decomposes wastes - stabilizes and moderates Earths climates - cycles nutrients - renew soil - pollinates plants (including crops) - maintain genetic resources: 3. What are the benefits of Biodiversity to humans? - moderates floods and droughts - controls pests and diseases - provides fuel, food and shelter - crop varieties, livestock breeds, medicines - pharmaceutical products on origins of plants generate up to 150 billion in sales - certain plants and compounds and treat cancers and diseases 4. What are Human impacts on Biodiversity? - Pollution - Habitat alteration - Invasive species - Over harvesting - Climate change - Modification of species genetic Protecting Habitats: - best way to preserve biodiversity - 3000+ protected areas worldwide - Problem is they are too small or isolated - Money is a major issue - Some areas have lost biodiversity Areas of Much concern: - tropical rainforests, deserts, and islands - Brazil, Australia Biodiversity Hotspots: - relatively small areas of land - contain many endemic species - at high risk from human activities The Amazon: - major hotspot for biodiversity - home to unique organisms Questions: 1. Explain why you are for or against requiring labels including those of genetically engineered components in any food items 2. You are a lawyer arguing in court for sparing an undeveloped old-growth tropical rainforest and a coral reef from destruction by development. If the judge decides you can only save on of these ecosystems, which one? Lecture 6 – Nutrient Cycling 1. What are Nutrients? - Nutrients: any chemical required for the proper function of organisms - Two types: inorganic chemicals and organic chemicals - Macronutrients: required by living organisms in large quantities - Micronutrients: required by living organisms in small quantities - Vary from 0.0001-0.01% within organisms 2. How does nutrient cycling work? - Transfers , chemical transformations, and recycling of nutrients in ecosystems - The earth does not: - gain matter from outer space nor lose matter to outer space - Remember!: law of conservation of matter dictates that atoms cannot be created, lost or changed - Because of the finite pool of matter, nutrients have to be recycled, within and between ecosystems - Remember!: fundamental to sustainability of ecosystem 3. What is a nutrient budget? - quantitative estimate of the rates of nutrient input and output, to and from an ecosystem, or within the system itself - each compartment stores quantities of material - nutrients remain in each compartment for varying amounts of time (residence time, sources vs. sinks) - fluxes: transfers of material between compartments Carbon Cycle Facts: Vast quantities are transferred from one compartment to another - numbers refer to petagrams of carbon - 1 petagram = 1 billion metric tons Two important Abiotic processes: - sedimentation/ burial on land: mineralization in oceans - weather of carbon minerals, combustion of fossil fuels - *1/6 of atmospheric C02 is used by photosynthesis* - equivalent amount released by respiration Phosphate cycle facts: - found in rocks and minerals as phosphate: PO4 3- - releases in slow processes - typically bound in insoluble chemical precipitates - limits availability to living organisms - P does not have a gas phase - Only recycled if the wastes containing it are deposited in the ecosystem from which it came Nitrogen Cycle Facts: - same as carbon having a gas phase - same as phosphate it often has a limiting factor to living organisms - most important processes are mediated by bacteria within nitrogen fixation, and denitifrication 4. What are some of the major human impacts on nutrient cycling? - C cycle - 40% of terrestrial primary production is diverted by human activity - atmospheric co2 levels have increased by 35% over pre-industrial levels - higher than for over 400 000 years - has consequences on climate change = global warming Human impact on the P cycle - mostly through the use of fertilizers - human use has increased 4 times the amount of P entering soils and surface waters Human impact on the N cycle: - used in fertilizers - fossil-fuel combustion: NOx - rate of transfer from air to land: 2 times faster Overall: - atmospheric pollution - eutrophication - acidification Question: 1. Nitrogen and Phosphorous fertilizers are critically important to the practice of modern intensive agriculture yet those materials are manufactured from non- renewable resources, and may not be so readily available in the future. What would be the consequence for agricultural production if N and P fertilizers were to become more expensive and less available? Lecture 7- Soils 1. What is soil? - a natural body consisting of layers or horizons and or organic material of variable thickness, which differ form the parent material in their morphological, physical,, chemical, mineralogical properties and their biologic characteristics - 90% of the worlds food comes from agricultural systems SOIL= FOOD - expansion of Roman empire may be linked to a need for soils of better quality - weathering produces soils, through physical (wind, rain), chemical (water, gases) and biological (tree, roots) methods - solids are important for they support growth, habitation, and biodiversity - Soil Profile: *vertical arrangement of all the soil horizons down the parent material* (a.k.a. stratigraphy) - Soil horizon: a layer of mineral or organic soil or soil material parallel to the land surface - Mineral Horizons: o A: formed at/or near the surface; zone of mineral leaching, o Ah: accumulation of organic material o Ae: loss of organic material o B: enrichment of mineral and or organic material - Organic soils: O horizons o Contain more then 17% organic carbon organic horizon o OL: organic matter from leaves, twigs, woody material - Boreal Forests: 353yrs decay rate - Temperate: 4 to 17 yrs - Tropical 0.4yrs - Why the difference?: temperature, moisture, pressure, bacteria 2. What is the significance of soil texture? - Soil texture: the size of soil particles - Weathering of rocks produces smaller and smaller fragments called: Grains - Grain size: measured by the diameter of the fragments - Sand 0.0625-2.00mm - Silt 0.002-0.0625mm - Clay< 0.002mm - Two basic considerations: soils with larger particles, have larger pores thus greater aeration and infiltration whereas smaller particles have more surface area relative to their volume this molecules such as water tend to cling to their surfaces How to determine grain size: - In the field: rub on teeth, spit, roll - Sieving: good for larger grain sizes, for sand > - Settling Velocity: stokes law (for smaller grain sizes) Stokes Law: - Settling velocity is proportional to the square of the particles diameter - V= Velocity (distance/time) - Ps= particle density (cm-3 - Pw = fluid density - G = acceleration due to gravity - D= particle diameter - N= viscosity of fluid - t= time - h= - v= volume - D^2= v * 18 * n/g * (ps- pw) - V* 18 * n= d^2 * g * (ps-pw) - V=[(ps-pw)gd^2]/18n - Soil Structure: - Combination or arrangement of primary soil particles in to secondary particles o Aggregates, peds - Defines the nature of the system of pores and channels in soils - Described by shape, size, degree of development o Granular, plate-like, block like, prism like - Many soil particles held in a single mass or cluster - Larger aggregates are composed of smaller Formation of Soil Aggregates: - physical and chemical processes (Abiotic): o flocculation of clays o volume changes in clay materials o difference in properties under varying moisture 3. How do plants and soil interact? - Experimental work demonstrates an 85-90% decline in plant productivity with top soil loss - Plants protect soil from o Erosion o Evaporative water loss - Soil Fertility o Soils ability to promote plant growth o Dependant on water, air (oxygen), pH and salinity - Mineral Nutrients - Land Plant composition (# of atoms): o Nitrogen 35 o Carbon 1200 o Hyrdrogen 1900 o Oxygen 900 o Phosphorus variable o Sulphur 1 - Sources of nutrients 1. Weathering (slow process) 2. Decay of organics (much faster) - Leaching o The process of removing materials from the soil by water - Problem: o Nutrients can be removed from the soil as water moves through it o Reduces soil fertility and may contribute to water pollution 4. Soil communities - Critical in the formation of humus: partly decomposed organic matter 5. Human impacts - Overcultivation - Overuse of fertilizers - Overgrazing - Deforestation Question: You have a 1m tall settling tube filled with water. You add your sample to the tube. After 8 minutes one size fraction has settled to the bottom, After 32 hours the second fraction has settled. What are the two different grain sizes? Should developed nations fund reforestation projects in developing nations to combat erosion and deforestation? Should governments provide farmers with financial incentives to use technologies such as no-till farming and crop rotation? Lecture 8: 1. What is soil Water? - Types of soil water o Hygroscopic: water that is bonded to the individual soil grains o Capillary: water that is held in the soil by matrix forces  Returns to the atmosphere by evaporation and transpiration o Gravitational: eventually becomes groundwater - The route that water follows is important because it: o Affects chemical composition of the water o Is critical to plant survival based upon aspects of soil water Important Soil Attributes: - Infiltration rate: the speed at which water can percolate in to the ground - Water Holding Capacity: the ability to hold water after it infiltrates - Evaporative Water loss: the depth of water lost from the soil by evaporation - Aeration: the porosity of soil 2. What is Groundwater - Water contained within the saturated zone (i.e. phreatic zone) - Volume is a balance between recharge and discharge - Recharge zones: precipitation, irrigation - Discharge zones: springs, wells What is an aquitard/aquifer? - Aquitard: layer of non-porous rock or sediment the can hinder the movement of water - Aquifer: the layer of porous rock or sediment that can hold and transmit water - Confined vs. Unconfined: What are the consequences of overdrawing groundwater? - Falling Water Tables o Ogallala Aquifer U.S o 1/5 of irrigated land o withdrawal 2x faster then recharge rate o water table may have dropped 30-60 meters o non-renewable vs. renewable o Diminishes surface water - Land subsidence o Water provides a buoyant support o Removal of support and land sinks o Parts of California - Salt water intrusions: saltwater drawn in to freshwater 3. How does irrigation affect soil quality? What is irrigation? - Supplying water to croplands by artificial means - Turns inadequate cropland in to adequate cropland - Problems include: Water logging due to over irrigation (water suffocates roots) - Types include: gravity, drip, sprinkler What is Salinization? - Accumulation of salts in and on the soil to the point that plant growth is suppressed How can it occur? - fresh water contains salts - salt remains when water is evaporated - salt accumulates - inhibits production and causes plant death Postive Feedback Mechanism: - Low ppt  low productivity increased water levels through irrigation initial increase in productivity  increase salination  decrease on productivity increase in erosion  decrease in productivity  increase in desertification 4. What is the significance of soil erosion? Types: - Splash: soil compacted when rainfall hits bare soil - Sheet: a more or less even layer of soil is lost from the land surface due to the rain and runoff from a rainstorm - Rill: caused by runoff water, creating small, linear soil depressions in the soil surface - Gully: produced by running water, resulting in the formation of gullies Consequences: - After deforestation of a hillside: less stable soils lead to erosion - Flooding of lands - Destruction of land What is Desertification? - Deterioration of land in arid, semi-arid and dry sub humid areas due to changes I climate and human activitie - 1/6 of the world population affected by desertification - 25% of words total land area - 70% of all drylands Should cities in dry areas such as Las Vegas be allowed to increase their populations? So that they will require more water? Ground Water Contamination: 1. How Serious is it? - Largely hidden from view - Difficult to monitor o Out of sight, out of mind for decades o Often only detected once contamination is widespread - Extent of the problem poorly quantified o Function of awareness - Once contaminated, an aquifer may be usable for a long period of time *EXAM*Potential Sources: - Point Source: a specific spot where large quantities of pollutants are discharger o On-site septic systems o Leaky tanks or pipelines containing petroleum products o Leaks or spills of industrial chemicals at factories o Municipal landfills - Non-point source: a diffuse source of pollutants often consisting of small point sources o fertilizers dispersed on agricultural land o pesticides sprayed on agricultural land and forests o contaminants in wet and dry atmospheric fallout Contaminants move in soils as plumes: - bodies of contaminated groundwater flowing from a specific source - influenced by: o local groundwater flow patterns o character of the aquifer o the density of contaminants Leaking Gas Tank Example: - major contribution to point source pollution - in the 1950s and 60s used to be made of steel o many corroded after a while o up to half of them leaked after 15 years - Big Problem: 1L of gas contaminates up to 1,000,000L of ground water - In Canada a particular problem in the Atlantic - In the U.S, EPA embarked on a decade-long clean up program - In 2005: 449,000 leaks confirmed - Initial cleanup for 416,000 2. Love Canal: - Built by William Love in the 1890’s - For planned industrial community in the Niagara Falls area - Meant to transport waters from the Niagara River - 1942, Hooker Chemical and Plastics Corp purchased the site of the love canal - until 1953: disposed about 22,000 tons of mixed chemical wastes into the canal - in 1955: local schoolboard bought it for 1.00 - school constructed on land - suburban neighbourhood developed after - Heavy Rain and Snowfalls in 1975 and 76 - Hooker land subsided: 55-gallon drums surfaced - Surface water contaminated - Oily residue and noxious chemical odours in basements - In and around the area: 421 chemicals were found - In air, water, and soil samples - 1978: federal states of emergency declared in the area - health concerns; abandoned by residents - led U.S congress in 1980 to enact the Superfund Law o Cleanup program for toxic waste sites around the U.S. o required waste dumpers to pay cleanup costs - 129 million in lawsuits and clean up costs - Area inhabited again since 1988 3. Arsenic in Bangladesh - Extensive program, led by UNICEF in the 1970s to dig artesian wells - Mid- 1990s wells found to be contaminated with arsenic o Can cause skin disorders o Cancer o Patients were coming to hospitals with arsenic poisoning 4. Not an easily solved problem: - preventing pollution of groundwater is the best strategy - cost of clean ups are very high: US 400 million/year - pumping treating and injecting it back takes a long time: about 1 trillion$ *MIDTERM: part a: defentions 12 of them- choose 10 Part b: short answer 5 questions (may have 2 parts) 1: Diagrams of Cycles 2: Stokes Law 1. What are the available water resources? - a renewable resource - ecosystems depend on freshwater - represents only a small fraction of water resources - developing countries have no access to water and are limited to clean drinking water - freshwater resources are unevenly distributed where Canada has 20 times more water per citizen then china 2. What are Wetlands? - Areas that are inundated by water, with saturated soils to a depth of a few cms for a few days per year - Three components are used to determine a wetland: o Hydrology o Type of vegetation o Type of soil - Saturation must be sufficient for the development of wetland soils, where poor drainage, lack of oxygen and growth of adapted vegetation can occur Natural service functions of wetlands - A natural sponge for water - Store water during high river flow - Releases stored water during low river flows - Buffer for inland areas from storms and high waves in coastal areas - Usually areas of groundwater recharge and discharge - nursery grounds for fish, shelfish and aquatic birds with up to 45% of endangered animals and 26% plants - highly productive with the cycling of many nutrients and chemicals, aiding in the purification of water, trapping sediment and toxins, and storing organic carbon 3. How is Water used? How do we use the worlds freshwater? - 54% of global surface runoff is used - the withdrawal rate is growing exponentially but varies worldwide with 70% used for irrigation and 80% evaporating - consumptive use: water is removed from an aquifer or surface water body and is not returned - non-consumptive use: does not remove or only temporarily removes, water from aquifer or surface water Increasing water supplies: - build damns and reservoirs to store runoff - bring surface water from another area - withdraw groundwater - desalinate salt water: make fresh water - improve efficiency of water use - developed countries transport water - developing countries: settlements where the water is Watershed Transfers: - watershed: an area of land that forms the drainage of a stream or river - some have excess water where others have shortages - solution: balance this through transfers - transfer by tunnels, aqueducts and pipes - reality: interconnectivity, action reaction, always an effect “You can’t do just one thing” 5. What is the Exxon Valdez oil Spill? - March 24 , 1989 - 44 million gallons of oil was spilled Effects: - 13% of harbour seals - 28% sea otters - 100 000 – 645 000 seabirds Of oil spilled - evaporated 20% - deposited ] on the shoreline: 50% - collected by skimming and waste recovery: only 14% - Demonstrated that the technology for cleaning oil spills was inadequate - More then 3 billion U.S was spent - 20 years after oil still exists The Great Lakes: A chemical hotspot - more then 360 chemicals have been found - many are persistent toxic chemicals - e.g. DDT, Mercury, - human health hazards - destructive to aquatic systems - various species of fish suffer from tumours and lesions - 7 of 10 species of fish are almost extinct - populations of birds and mammals on decline because of compounds What can be done to reduce pollution? - Identify the materials causing the pollution - Identify th
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