Pollution Science 9 PDF

Pollution Science 9  What is Pollution? “any alteration to the environment producing a condition that is harmful to living things” Let’s brainstorm some sources of pollution that you have heard about either in school or in the media: Sources There are two main categories...

Pollution Science 9  What is Pollution? “any alteration to the environment producing a condition that is harmful to living things” Let’s brainstorm some sources of pollution that you have heard about either in school or in the media: Sources There are two main categories of pollution sources Point source: small, defined area causing pollution Non-point source: wide area, not easily defined where pollution is coming from or what its effects may be Dilution and Concentration Dilution means pollution is becoming less concentrated. What could help dilute pollution in a stream? In the air? What factors could concentrate pollution?  Water Quality Water quality in Canadian rivers, national and by land use category, 2016 to 2018 period  Aquatic Environments ** As pH increases the diversity of all organisms will decrease Chemical Factors Affecting Organisms ∙Pure Water (H2O) is made up of SOLELY water molecules ∙Water in the environment is never completely pure Examples: dissolved oxygen, pH, heavy metals, plant nutrients (nitrogen/phosphorus), pesticides, salts (sodium chloride/ magnesium sulfate) 30  Water quality is set by the provincial and federal government in five categories : ∙ Human Drinking Water ∙ Recreation (ex. Swimming) ∙ Livestock Drinking Water ∙ Irrigation 7 ∙ Protection of Aquatic Life  How We Can Tell If Water Is Good- Biological Indicators Scientists∙ use organisms living within the water to determine water quality ∙ Examples: fish, plants, worms, insects, plankton, protozoa, and viruses ∙ 8 Microbiological Indicators ∙ microscopic organisms (bacteria) which can cause health problems, which is why samples of water are taken to maintain the levels of harmful bacteria build up These are organisms that tell us about the quality of the environment by their presence or absence in water Macroinvertebrates 9 Good quality water will have a large variety of organisms but a higher occurrence of organisms that need lots of oxygen: Stonefly, mayfly, caddisfly, beetle  Dissolved Oxygen ∙ This is essential for the health of aquatic life , insects and microorganisms Levels of DISSOLVED OXYGEN depend on several factors: ∙ Temperature ∙ Amount of photosynthesis ∙ Turbulence due to produced by plants/algae in the wind or speed of the water water ∙ Number of organisms that are using the oxygen 10  Quantifying Pollution Most times concentration of pollutants is reported as a “parts per” value – usually parts per million (ppm) or parts per billion (ppb) But what does this mean? \ Measuring Chemicals in the Environment Parts per Million (ppm) – chemical concentration in the environment Meaning: ONE UNIT OF THE ELEMENT CAN BE FOUND IN ONE MILLION UNITS OF THE SOLUTION 12 When one substance dissolves into another, a solution is formed. The solute is the substance that is being dissolved, while the solvent is the dissolving medium.  What is the concentration of a solution, in parts per million, if 0.02 gram of salt is dissolved in 1000. grams of solution? An aqueous solution has 0.0070 gram of oxygen dissolved in 1000. grams of water. PPM Practice A 50 L drum filled with concentrated sulfuric acid fell of a truck during an accident. It rolled into the lake and burst open. The entire contents of the drum spilled into the lake. The lake has 30 000 L of water in it. What is the concentration of sulfuric acid in the lake? PPM Practice A student added 70 mL of pee into a pool to make 1000 L of solution. Calculate the concentration of pee in parts per million PPM Practice The water in a swimming pool was analyzed for its chlorine content. It was found that 20 mL of a water sample contains 0.5 mL of free chlorine. What is the concentration of chlorine in ppm? Toxicity: how poisonous a substance is ** The mixing of different pesticides within our water systems can develop into a very deadly combination of chemicals Some pesticides have long term effects, due to remaining in the environment without being broken down. Most modern pesticides are broken down after one growing season due to bacteria. 18  Measuring Toxicity Toxins: (poisons) substances which can cause serious health problems or death LD50 – lethal dose at 50% (meaning: the amount of a substance that causes 50% of test animals to die if they are given a specific dose of that substance at once) 19 Formulas for pollution PPM - Solute divided by solution x 1,000,000 LD50 - Mass x LD50 The LD50 for rat poison is 0.27mg/kg. If a rat named Dwane with a mass of 0.85 kg ingested 0.50 mg of rat poison will it likely die? Mass = 0.85 kg Dosage = 0.50 mg LD50 = 0.27 mg/kg Max Dosage = Mass x LD50 = 0.85 kg x 0.27 mg/kg = 0.2295 mg = 0.23mg 0.50 mg > 0.23 mg - The dosage given (0.5 mg) is larger than the max dosage (0.23mg), therefore the rat will possibly die. (Note that the LD50 really only tells us how much poison is needed to kill half of the population) Find the amount of arsenic needed to reach the LD50 amount for a 1.75 kg duck. Arsenic LD50 = 13 mg/kg Mass = 1.75 kg Dosage LD50 = 13 mg/kg Max dosage = ? Max Dosage = Mass x LD50 = 1.75 kg x 13 mg/kg = 22.75 mg The maximum dosage that can be given to a 1.75 kg duck to reach its LD50 for arsenic is 22.75 mg Risk Management Many substances will have different effects in animals vs humans Tests on animals can be misleading Sometimes known risks are acceptable depending on the situation Every chemical has the potential to cause harm depending on type, duration and quantity of exposure. Pollution is not stationary – it does not only affect the area the pollutant is released in http://www.nature.nps.gov/air/aqbasics/images/AQBasicSources.gif  Types of Air Pollution: ∙Chemical ∙Physical ∙Biological 25 Air Quality can be measured in 2 ways: Levels of pollutants in the air ∙ ∙Estimating amount of emissions from Circumpolar Winds These winds carry pollution across the northern hemisphere, causing contamination of air hundreds of kilometers from the source  Sulfur Dioxide ∙Sulfur Dioxide ( SO2(g) ) is a major air pollutant (forming smog and acid rain). ∙It is produced through industrial processes and the burning of fuels that contain sulfur. ∙Scrubbers (filtering out impurities from gas) are used to reduce sulfur dioxide emissions by up to 99%. ∙ 28  Carbon Monoxide Carbon monoxide is called the silent killer because it is a colorless, odorless gas. Motor vehicles are the main producers of carbon monoxide, but other sources include the burning of wood (forest fires produce large quantities) in fireplaces and stoves, natural gas, industrial processes, airplanes and cigarettes. 40  Catalytic Converters ∙ If inhaled, carbon monoxide reduces the amount of oxygen in the blood and can cause headaches, sleepiness, chest pains, brain damage and death. Catalytic converters are used to convert carbon monoxide into carbon dioxide. 30  Ground Level Ozone ∙ Ozone ( O3(g) ) is an odorless, colorless gas that has 3 oxygen atoms ∙It is produced by through the breakdown of other pollutants in our environment by sunlight and by electrical discharges Ground level ozone forms from reactions between oxygen, nitrogen oxides and compounds that are volatile organic compounds (VOC?s), in the presence of sunlight and heat.  Carbon Dioxide As A Greenhouse Gas Carbon dioxide occurs naturally in the environment, but increasing amounts that are being produced by various human activities is creating a concern globally. The Greenhouse Effect The Greenhouse Effect is a naturally occurring event , the result of 32 greenhouse gases (water vapor, carbon dioxide, and other gases) trapping some of the outgoing energy - retaining heat in a way somewhat similar to the glass panels of a greenhouse. It is not just human activities that are contributing to global warming, but volcanoes and forest fires are also part of the cause. Global Warming 33 Our Great Solution The concentration of chemicals in the environment can be changed using different techniques. Dispersion is the scattering of a substance away from its source Dilution reduces the concentration of a pollutant by mixing it with large quantities of air or water 34  Transport In Air And Water The direction and distance that airborne and water chemicals travel are determined by various factors, including: The properties of the chemical pollutant The wind speed or Water Speed The direction of the prevailing winds 50  Pollution on the Move Potentially harmful substances are spread and concentrated in the environment in various ways. TRANSPORT IN AIR 1. Release of the chemical at the source 2. Dispersion of the chemical in the atmosphere (the chemicals scatter in various directions) 3. Deposition of the chemical in soil or water  Transport In Groundwater ∙ Water that soaks into the soil is collected in a zone called the groundwater zone. ∙ The top ∙ of the groundwater zone in the soil is called the water table. ∙ Certain contaminants can remain collected in the groundwater for long periods of time (because they are heavy metals) Factors that affect the movement of contaminants in groundwater include the number and connection of pores  Transport In Groundwater ∙ Water that soaks into the soil is collected in a zone called the groundwater zone. ∙ The top∙ of the groundwater zone in the soil is called the water table. ∙ Certain contaminants can remain collected in the groundwater for long periods of time (because they are heavy metals) Factors that affect the movement of contaminants in groundwater include the number and connection of pores Hydrocarbons hydrocarbon, any of a class of organic chemical compounds composed only of the elements carbon (C) and hydrogen (H). Hydrocarbons are the principal constituents of petroleum and natural gas. They serve as fuels and lubricants, plastics, fibres, rubbers, solvents, explosives, and industrial chemicals. Some of these hydrocarbon emissions are carried by the air, or water where they can clog up soil pores keeping them close to the source of the contamination and increasing the concentration. Many Hydrocarbons are toxic to plants and animals  Heavy Metals Definition: have a density of 5 g/cm3 or more (meaning they are five or more times heavier than an equal volume of water) Usually these metals occur naturally in rocks, soil and occasionally water Some of them are dangerous to health or to the environment (e.g. mercury, cadmium, lead, chromium), some may cause corrosion (e.g. zinc, lead), some are harmful in other ways. Biodegradation occurs in the environment because living things (earthworms, bacteria and fungi) are actively breaking down organic substances, including many pollutants. Some of these organisms are aerobic (Need air) some are anaerobic (Don’t need air) Microorganisms are especially important in the biodegradation of pollutants.  Factors Affecting Biodegradation During the winter, biodegradation is slow, because of numerous factors ∙ temperature ∙ soil moisture ∙ pH ∙ oxygen supply and ∙ nutrient availability.  Phytoremediation Phytoremediation is a technique that can be used to reduce the concentration of harmful chemicals in the soil or groundwater. Plants have been used to clean up metals, hydrocarbons, solvents, pesticides, radioactive materials, explosives, and landfill leachates. The plants are able to absorb and accumulate large amounts of these chemicals. When the plants have matured, they are harvested, burned or composted. Photolysis is the breakdown of compounds by sunlight. ∙ The formation of ozone is an example of this process ∙ Photodegradable plastic is made of chemicals that react when exposed to sunlight. In three months, the plastic becomes a fine powder