Environmental Chemistry Presentation PDF

ENVIRONMENTAL CHEMISTRY Unit Overview:Where Biology and Chemistry Meet In Matter and Chemical Change, we looked at properties and changes of matter and how chemistry can be used to explain them. This unit we, will look at chemistry as it relates to biology and the environment. Let us begin… Wha...

ENVIRONMENTAL CHEMISTRY Unit Overview:Where Biology and Chemistry Meet In Matter and Chemical Change, we looked at properties and changes of matter and how chemistry can be used to explain them. This unit we, will look at chemistry as it relates to biology and the environment. Let us begin… What does chemistry have to do with biology? We are all made of chemicals Food also made of chemicals Broken down by digestive system into molecules that are absorbed into blood These chemicals or nutrients are used for: Energy Growth Body- building Cell repair Nutrients- essential for life Nutrients can be organic or inorganic Organic Compounds Organic Molecule Role in Nutrition Dietary Source Carbohydrates Energy source for metabolism Rice Grains Potatoes Fruits Protein Structural molecule for body, helps chemical reactions Meat Eggs Dairy Legumes Nuts Lipids Storage of unused chemical energy Vegetable oil Nut oil Legumes Some dairy Elements for Healthy Bodies:Minerals Minerals you need a lot of is called a macromineral Minerals you only need a little of are called trace elements, which are found in enzymes and vitamins All living things need 16 naturally occurring elements Plants need 18 elements We need 22 elements Elements for Healthy Bodies: Needed for strong bones and teeth Nerve conduction Muscle contraction Blood clotting Bone formation Forms compounds that store and release energy (ATP) Calcium Phosphorus Elements for Healthy Bodies: Component of Bones and teeth Essential for enzyme function Helps regulate nerve function Helps regulate nerve signals and muscle activity (heart rate) Protein formation Regulates acid/base balance in body Magnesium Potassium Elements for Healthy Bodies:What is one crucial role for…. Sulphur? Used in some amino acids Iron? Red blood cells, regulates oxygen transport Iodine? Major part of thyroid hormones that regulate metabolism Getting these Minerals As humans, we cannot extract the mineral directly from the ground But plants can… and do Root hairs specially designed to uptake and concentrate these minerals They are then transported to other parts of the plant where they are used to create organic compounds such as proteins, lipids and vitamins. Without plants, we would not be able to obtain the nutrients we need. Substrates Other organisms get their minerals through absorbing them from a substrate  A substrate is a material on which an organism moves or lives. Some organisms attach themselves to the substrate, others obtain their nutrients from their substrate.  For example – the lichens in this photo are using the rocks as a substrate. 13 Fertilizers: Nutrients for Plants Often, we help plants grow by giving them fertilizer Fertilizers imitate nitrogen cycle, adding nitrates, ammonia and urea Phosphorus provided as phosphate compounds Potash acts as source of potassium Numbers on bag indicate percent of each substance 14 Impact of Using Fertilizers Use of artificial fertilizers has increased amount of nitrogen in environment as much as 140 million tonnes/year What are the pros and cons of this use? Increased plant growth Land not normally suitable for farming, can yield large crops when High yield crops plants Fertilizer used Properly watered Fertilizer and water can be an expensive price for productivity Single crop = increased chance of impact by disease Pesticides can be used to reduce loss of crops, but are not without cost or environmental impact Eg: Harmful Algal Blooms Pros Cons 17 Harmful Algal Bloom Rapid growth of algae that can deplete the oxygen dissolved in the water and block sunlight required by other organisms in the aquatic ecosystem Summary Living things need nutrients to survive These nutrients can be organic or inorganic We obtain our nutrients from our food which includes plants Plants are capable of absorbing minerals from the soil, and using them to make proteins, lipids and vitamins Fertilizers are one way that can be used to enhance plant growth, but their use in not without impact Looked at nutrients needed for living things Organic vs Inorganic Nutrients Exit slips from last class Nitrogen Cycle Investigate the use and movement of pesticides and their impact on the environment Bioaccumulation Biomagnification DDT Last Class This Class Pesticides Three types of pesticides Herbicides: these chemicals are designed to kill plants. Some are selective (eg. Killex), while others are not (eg. Round-up) Insecticides: these chemicals are designed to kill insects eg. Raid, DDT, dieldrin Fungicides: these are designed to kill fungus Ingestion vs Absorption Ingestion – taking in a material. For us, this is equivalent to eating Absorption – this can occur in several ways: Digestive tract Respiratory tract (after inhalation) Skin DDT DDT (dichlorodiphenyltrichloroethane) is an insecticide that kills mosquitos and other insects. Originally seen as great, was going to solve the problem of malaria Hand unforeseen consequences higher up the food chain due to BIOACCUMULATION and BIOMAGNIFICATION Birds feeding on insects were laying eggs with shells too thin to allow chicks to survive. Bioaccumulation vs Biomagnification Bioaccumulation is an increase in concentration of a material from the environment over time in an organism in a food chain Biomagnification is an increase in concentration of a pollutant from one link in a food chain to another In order for this to occur, the pollutant must be long-lived, mobile, soluble in fats, and biologically active DDT Restriction Four reasons restriction of DDT has been a struggle: DDT helped reduce malaria incidence; incidence increased again after DDT banned Replacements not as safe or effective Substitutes are more expensive Pesticide resistance is on the rise Nitrogen Cycle Science 9 I can Describe the steps in the nitrogen cycle and the human activities that imitate the nitrogen cycle Discuss the pros and cons of using fertilizers Water cycle With a partner, outline the water cycle. Start with the water in a lake. What path does it take to go back to the lake? Make sure you include living organisms in your cycle. Nutrient Cycles The Water Cycle Sun’s rays evaporate huge amounts water Water vapour rises in the atmosphere - cools and condenses Clouds form from condensed water droplets Water falls back to the lithosphere as precipitation Water returns and erodes rocks and picks up other materials Absorbed by plants and other organisms - enters biosphere Nitrogen (N) is an essential component of DNA, RNA, and proteins, the building blocks of life. All organisms require nitrogen to live and grow. The majority (78%) of the Earth’s atmosphere is N2. Nitrogen The process for changing free nitrogen into nitrogen atoms which can combine with other elements to form compounds which can be used is called nitrogen fixation 33 This can happen in three ways. Biological Environmental Human Nitrogen Fixation Nitrogen Cycle 34 BIOLOGICAL: Bacteria (called Nitrogen-fixing bacteria) These bacteria form symbiotic relationships with host plants. The bacteria live in nodules found in the roots of the legume family of plants (e.g. beans, peas, and clover) The Nitrogen Cycle Most organisms cannot use nitrogen in the form in which it exists in the air Soil bacteria convert nitrogen into ammonium Soil bacteria convert ammonium into nitrate Plants absorb both forms of nitrogen - nitrate and ammonium Different bacteria convert nitrate back into nitrogen gas atmosphere Excess nitrate and ammonium eventually enter the lithosphere Nitrogen Cycle Video Nitrogen Uptake The ammonia (NH3) produced by nitrogen-fixing bacteria is usually quickly incorporated into protein and other organic nitrogen compounds (organisms!).  It’s either absorbed by a plant, by the bacteria itself, or by another soil organism.  Organisms at the top of the food chain (like us!) eat and grow, uptaking nitrogen (that has already been fixed). DenitrificationNO3- --> N2 Denitrification bacteria removes nitrogen from ecosystems, and converts it back to atmospheric N2. This completes the cycle Lightning is also a way to convert nitrogen in the air into nitrogen compounds used by plants 40 HUMAN IMPACT Burning fossil fuels, using synthetic nitrogen fertilizers, and cultivation of legumes all fix nitrogen. Human Actıvıtıes Many chemicals are released into the air, water and soil every day. 41 Activities such as agriculture, sanitation, water and waste treatment, industrial processes, manufacturing, and transportation can change the concentration of different chemicals and cause an imbalance Agricultural Activities Farmers must have an understanding of chemistry to produce crops that will give a good yield. Fertilizers 42 Often, we help plants grow by giving them fertilizer Fertilizers imitate nitrogen cycle, adding nitrates, ammonia and urea Phosphorus provided as phosphate compounds Potash acts as source of potassium Numbers on bag indicate percent of each substance Increased plant growth Land not normally suitable for farming, can yield large crops when High yield crops plants Fertilizer used Properly watered Fertilizer and water can be an expensive price for productivity Single crop = increased chance of impact by disease Pesticides can be used to reduce loss of crops, but are not without cost or environmental impact Eg: Harmful Algal Blooms Fertilizer Pros Cons Acids and Bases Science 9 After this lesson I will be able to… Compare acids and bases Identify acids and bases based on pH List pH indicators and describe ways to use them Discuss the effects of acid rain and ways to neutralize acids What are acids and bases? Chemicals that produce acidic substances -pH less than 7 Chemical s that produce basic substances- pH more than 7 Acids: Bases: What are the properties of acids and bases? Taste: Sour Feels: Stings Acidic: adjective used to describe acids Taste: Bitter Feels: Slippery Basic: adjective used to describe bases Acids Bases Tasting and feeling unknown chemical are UNACCEPTABLE methods of identification. Indicators Are substances that have a colour change when they react with acids and bases What is an example will we seen this year? Bromothymol Blue Universal Indicator (has a range of colours based on pH) Litmus- A chemical indicator Mixture of plant compounds extracted from certain lichens Looks light pink before reactions In the presence of acid it turns red. In the presence of base it turns blue This is not an exact value… it just give an approximation of how acidic or basic a substance is Neutralization Acids and bases react together when they are mixed. This type of reaction is called Neutralization. Both the acid and the base are used up in this type of reaction. A salt and water are produced. pH Scale More specific way of comparing acids and basis Scale is from 0-14 pH: 7.0 is neutral Lower than 7 is acidic, higher than 7 is basic Each pH unit represents a 10 fold increase in acidity or alkalinity pH Scale Universal indicator or pH paper will change a colour characteristic of a certain pH Colours are matched against a chart that shows the range of colours for known pH values. Rainwater is naturally slightly acidic. When this water combines with chemicals in the atmosphere such as sulfur dioxide or nitrogen dioxide, the effect results in Acid Rain(with a pH as low as 3 ­ in some parts of Canada) This can have devastating effects on living organisms. 56 Normal Rain/Snow = pH of 5.6 Anything lower than the normal is to be considered ACID RAIN/SNOW When acid rain/snow enters the water system it affects the acidity of the water, resulting in a decrease of diversity among surrounding plants and animals ** When acidic deposits build up over the winter and melt in the spring this can dramatically lower the pH of the water ** Process is referred to as SPRING ACID SHOCK What is Acid Rain? Rain and Snow containing acidic compounds H2SO3(aq) Sulfurous Acid H2SO4(aq) Sulfuric Acid HNO2(aq) + HNO3(aq) Nitrous and Nitric Acid H2CO3(aq) Carbonic acid Neutralizing Acid Using Chemistry to Control Acid Effects Scrubbers Use limestone mixed with water. Toxic gases are passed through this mixture that absorbs sulfur particles, preventing them from entering the atmosphere. Using Chemistry to Control Acid Effects Catalytic converters They contain a ceramic or wire honeycomb coated in a metal such as platinum that act as a catalyst for complete combustion The converter aids in the formation of carbon dioxide and water so that less carbon monoxide and nitrogen oxides are produced 20 Check and Reflect (pg.195, see next slide) Questions: 1-5 63 Waste Treatment Science 9 Where does the waste from our bathrooms go? How old is the water you drink? You could be drinking the same water molecules as someone who lived 1000 years ago Wastewater Treatment Can we reuse our waste? How? Wastewater Treatment Goal is to take water that has been “used” and return it to the environment with minimal pollutants Primary Treatment – physical separation of large solids and sediments Secondary Treatment – bacteria decompose organic matter and, once removed (BIOSOLIDS), the remaining water is treated with chlorine, ozone or UV light Tertiary Treatment – percolation of water through plant bed to remove phosphates or nitrates Sewage includes: dissolved and un-dissolved materials from your kitchen, bathroom and laundry. Septic tank (rural areas) - A septic tank is a large underground container that traps grease and large solids. The remaining liquid waste is distributed through pipes with holes; the pipes lead into a drainage area containing gravel. Bacteria and other micro­organisms as well as soil break down the organic waste and use it as a source of food energy. This system mimics the way in which decomposers normally recycle biodegradable wastes. 75 Sanitary Landfills Used for normal household and industrial waste Garbage is compacted and covered daily with earth and sometimes clay. Clay liner at bottom prevents leachate from reaching groundwater supplies. Methane gas – a product of anaerobic biodegradation of waste – is piped off before it becomes a hazard Secure Landfills where hazardous waste is placed in or on land and that is designed, constructed and operated to prevent any pollution from being caused by the facility outside the area of the facility Fuel Combustion The burning of hydrocarbons (fossil fuels –including coal, oil and natural gas - from dead plants and animals) produces large amounts of carbon dioxide and water vapor.Sulfur dioxides and Nitrogen oxides, traces of mercury and lead are also produced. ∙ hydrocarbon + oxygen carbon dioxide + water + energy 78 Industrial Process The generation of electrical energy , mineral processing and fertilizer production can release harmful chemicals ( sulfur dioxides and nitrogen oxides ) into the air. Natural gas contains compounds such as methane, ethane, propane, and butane. If natural gas contains hydrogen sulfide (H2S) it is called 'sour gas'. If it doesn't it is called 'sweet'. When hydrogen sulfide is removed, sulfur dioxide is produced There are over 6,000 sour gas wells and 18,000 kilometres of operating sour gas pipelines in Alberta. Sour gas is processed at approximately 250 plants in Alberta, 80 Biological Molecules Science 9 Biological Molecules Essential to Life Our bodies need about 25 elements for normal growth. Carbon (C), oxygen (O), and hydrogen (H) are the most common chemical elements in living things. Sugar, starch, fat, oil, wax, and proteins Are called organic molecules because they are mainly made of carbon and hydrogen. Nutrients- essential for life Nutrients can be organic or inorganic Organic Compounds Organic Molecule Role in Nutrition Dietary Source Carbohydrates Energy source for metabolism Rice Grains Potatoes Fruits Protein Structural molecule for body, helps chemical reactions (enzymes) Meat Eggs Dairy Legumes Nuts Lipids Storage of unused chemical energy Veg oil Nut oil Legumes Some dairy Nucleic Acids Building blocks of DNA Don’t Need to Know Till High School These are called “Macronutrients” because they are needed in large amounts Many biological molecules are polymers: they are long chains of building blocks, called monomers Extra information * Elements for Healthy Bodies:Minerals Minerals you need a lot of is called a macromineral Minerals you only need a little of are called trace elements, which are found in enzymes and vitamins All living things need 16 naturally occurring elements Plants need 18 elements We need 22 elements Elements for Healthy Bodies: Needed for strong bones and teeth Nerve conduction Muscle contraction Blood clotting Bone formation Forms compounds that store and release energy (ATP) Calcium Phosphorus Elements for Healthy Bodies: Component of Bones and teeth Essential for enzyme function Helps regulate nerve function Helps regulate nerve signals and muscle activity (heart rate) Protein formation Regulates acid/base balance in body Magnesium Potassium Elements for Healthy Bodies:What is one crucial role for…. Sulphur Used in some amino acids Iron Red blood cells, regulates oxygen transport Iodine Major part of thyroid hormones that regulate metabolism Getting these Minerals As humans, we cannot extract the mineral directly from the ground, But plants can… and do Root hairs specially designed to uptake and concentrate these minerals They are then transported to other parts of the plant where they are used to create organic compounds such as proteins, lipids and vitamins. Without plants, we would not be able to obtain the nutrients we need. Vitamin: a organic compound which are essential for normal growth and nutrition and are required in small quantities in the diet because they cannot be synthesized by the body. Check and Reflect Pg 203 # 1,2,3,4,5,7,8 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 Protection of Aquatic Life 107 How We Can Tell If Water Is Good- Biological Indicators 108 ∙ Scientists use organisms living within the water to determine water quality Examples: fish, plants, worms, insects, plankton, protozoa, and viruses 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 109 Macroinvertebrates These are organisms that tell us about the quality of the environment by their presence or absence in water 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 Turbulence due to wind or speed of the water Amount of photosynthesis produced by plants/algae in the water Number of organisms that are using the oxygen 110 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 \ 112 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 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? 50 L 50 L + 30 000 L X 1 000 000 = 1663 ppm 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 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 0.070 L 1000 L X 1 000 000 = 70 ppm 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? 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? 0.5 mL 20 mL X 1 000 000 = 25 000 ppm 122 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. 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) 123 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 possibly 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) 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? Find the amount of arsenic needed to reach the LD50 amount for a 1.75 kg duck. Arsenic LD50 = 13 mg/kg 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 The LD50 of caffeine is 150–200 milligrams per kilogram of body mass. Let’s say 175 mg/kg Caffeine LD50 Let’s take a 55 kg person. One Can of Monster Energy Drink has 160-300 mg of Caffeine So 175 mg/kg x 55 kg = a lethal dose = 9625 mg So 9625 mg / 300 mg per can = 32 cans. At this dosage, half of the 55kg people will die. Going above 400 mg daily, the recommended dose for adults, can cause unpleasant side effects that are probably familiar to you: jitteriness, insomnia, irritability. (The American Academy of Pediatrics recommends kids 12 to 18 years old stay below 100 mg of caffeine a day, or one cup of coffee.) That’s because caffeine can speed up the heart beat and disturb the body’s blood flow — which, in extreme cases, can be fatal. 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. Check and Reflect pg. 224 Questions: 1, 6, 7, 8, 9 & 10 132 134 http://www.nature.nps.gov/air/aqbasics/images/AQBasicSources.gif Pollution is not stationary – it does not only affect the area the pollutant is released in Air Quality can be measured in 2 ways: Levels of pollutants in the air Estimating amount of emissions from pollution sources 136 Types of Air Pollution: Chemical Physical Biological 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%. 139 Carbon Monoxide 40 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. ∙ 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. Catalytic Converters 141 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 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. 143 Global Warming 144 It is not just human activities that are contributing to global warming, but volcanoes and forest fires are also part of the cause. 145 Check and Reflect pg. 224 Questions: 1, 3, 4, 6, 7, 8, 9 & 10 assess your learnıng Page. 234­-235 Questions 1, 2, 5, 6, 7, 8, 146 Pollution on the Move 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 Our Great Solution 148 50 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 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 (tiny spaces between soil grains) in the soil. ∙ 151 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 (tiny spaces between soil grains) in the soil. ∙ 153 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. 154 Hydrocarbons 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. 155 Heavy Metals Changing the Concentration of Harmful Chemicals in the Environment 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) 158 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. 159 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. 160 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 161 60 Check and Reflect Page 266 2, 3, 4, 5, 9, 10, 12, 14, 15, 18, 23 At the moment, the four elements – which occupy the 113th, 115th, 117th and 118th positions – have the monikers Uut, Uup, Uus, and Uuo respectively. That will change now, though, thanks to scientists from Russia, the U.S., and Japan.