U. B. Section 2 Monitoring Chemicals in the Environment

What do you know about water quiz: True or False 1 What do you know about water quiz: True or False 1. Rain, hail, and snow provide Earth with new sources of water. 2. Humans eat more water than they drink. 3. Water can dissolve more substances than any other liquid. 4. Water is the only naturally occurring substance that is found on Earth as a solid, a liquid, and a gas. 5. Falling raindrops are shaped like tears. 6. The purest possible water is what aquatic life depends upon for health. 7. The greatest home use of water in Canada is for drinking. 8. Like most other liquids, water contracts (gets smaller) when it freezes. 9. Approximately 3% of the water on Earth is fresh water. 10. The largest fresh water lake entirely in Canada is Lake Superior, located in Ontario.

The Quality of Chemicals in the Environment can be Monitored Monitoring – keeping track of chemicals or populations in the environment to ensure they stay at safe and healthy levels.

Various chemicals in the environment must be monitored so that water and air quality can be protected. The ozone layer - the function of the ozone layer is to shield the Earth from damaging ultraviolet radiation from the sun. Q: How would increased UV rays affect humans? Q: What do the satellite photos indicate on p.212? ( use a ruler )

Ozone Changes 1979-2008

2.1 Monitoring water Quality Water Quality Clarity, or how clear the water is, is not a good indicator of water quality since acidic lakes are often clear and lifeless. Water quality is determined by what the water is to be used for.

Guidelines exist for 5 categories of water: Human drinking water Recreation Livestock drinking water Irrigation Protection of aquatic life Scientists monitor water quality with both biotic and chemical indicators.

A. Biological indicators – organisms that live in water help determine its quality. 1. Microbiological – samples are taken from water sources people use to determine the number and type of microscopic organisms, such as bacteria, that are there in order to avoid illness. 2. Aquatic - invertebrates (animals without backbones) such as insects, crustaceans, worms and mollusks can be used as indicators of water quality since different invertebrates prefer different living conditions, such as dissolved oxygen, pH and temperature.

In Aquatic Environments, the diversity of all organisms decreases as acidity increases and dissolved oxygen decreases.

B. Chemical Factors that Affect Organisms 1. Measuring Chemicals – the concentration of chemicals is measured in parts per million (ppm) or milligrams per litre (mg/L). 1 ppm means there is 1 unit of that chemical in 1 million units of solution. Eg. How many ppm is 0.02 mL juice in 100 mL solution? 0.02mL = x (ppm) = 200 ppm 100mL 1 000 000

2. Dissolved Oxygen – the amount of oxygen dissolved in a body of water depends upon: water temperature - more oxygen in cold water Turbulence - more oxygen in turbulent water amount of photosynthesis number of organisms living in it - they consume oxygen. 5 ppm of oxygen will support most organisms. See Figure 2.4, p.217.

3. Phosphorus and Nitrogen Content – these nutrients are added to water by sewage and runoff from fertilized fields. Higher concentrations leads to increased growth of algae and green plants and eventually a buildup of dead matter. This encourages a decomposer bloom, then bacteria increases to decompose the algae, then, dissolved oxygen decreases. As a result, many fish and insects die. See Figure 2.7, p. 219.

4. Acidity – as the pH of a water system drops the diversity of plants and animals that can live in the water decreases. Below 4.5, most fish disappear. Acid deposition is a problem in areas where soil and water lack bases to neutralize it. (eg, Canadian Shield) Spring acid shock occurs when acid builds up in the snow and then is released into the waterways as the snow melts, causing a dramatic drop in pH that seriously affects water organisms.

5. Pesticides – some have long term toxic effects because they don’t degrade and become trapped in the tissues of animals. Many today are engineered to decompose after 1 season so they are no longer toxic. One problem: resistance. As pests become resistant to pesticides, more must be developed and more chemicals are added to the soil. As this happens, one or more pesticides may combine to form even more toxic substances.

6. Measuring Toxicity – different chemicals affect organisms in different ways, so it can be difficult to compare the toxicity of a substance to other substances. A measurement called LD50 indicates the amount of the substance that will cause 50% of the population to die (LD = lethal dose). The greater the toxicity of a substance the lower the LD50 is. LD50 testing is done on rats and mice and is given either orally or applied to the skin. See table, p. 221.

LD50 DOSE WHICH KILLS 50% OF TEST ANIMALS

ORAL LD50 VALUES nicotine 0.3 mg/Kg (mice) 2,3,7,8-TCDD 0.002 mg/Kg (guinea pig) 0.3 mg/Kg (mouse) 5 mg/Kg (hamster) 1,3,6,8-TCDD >1500 mg/Kg (guinea pig) >3000 mg/Kg (mouse) octa-CCD >4000 mg/Kg (mouse) 2,3,7,8-TCDF 0.1 mg/Kg (guinea pig) >6 mg/Kg (mouse)

PCBs 1295 mg/Kg (rat) Aspirin 1100 mg/Kg (mouse) sodium cyanide 6.4 mg/Kg (rat) caffeine 127 mg/Kg (mouse) methylisocyanate 305 mg/Kg (rat) ethanol 1200 mg/Kg (rat) sodium chloride 3750 mg/Kg (rat)

7. Heavy Metals – metals such as copper, lead, zinc, mercury, cadmium and nickel have densities greater than 5 g/cm3 and are therefore called heavy. They occur naturally in the environment but not usually in large amounts. Human activities can increase the amount of these metals – acid water can dissolve lead pipes, cadmium can be found in fertilizer as an impurity and garbage can contain many of these metals. These metals are toxic to many organisms, but are very harmful for children. Their use in products is now limited and waste disposal is closely monitored to keep these metals from entering the environment.

Section 2.2 Air Quality Air is made up of 78% nitrogen, 21% oxygen, less than 1% argon and other trace gases (0.03%). It’s quality is determined by 1) measuring the pollutants (more accurate) 2) estimating the amount of emissions from pollution sources.

1. Sulfur Dioxide (SO2(g)) – this pollutant comes from industrial processes, like the oil and gas industry in Alberta, and from the burning of fossil fuels (coal, oil and gas). It contributes to smog and acid rain and can affect your respiratory system. Scrubbers are used to remove up to 99% of sulfur from industrial emission by using limestone (calcium carbonate) to convert it to a useful product called gypsum, and carbon dioxide.

2. Nitrogen Oxides (NOX(g)) – the X indicates either NO or NO2 2. Nitrogen Oxides (NOX(g)) – the X indicates either NO or NO2. These pollutants are formed mainly by fossil fuel emissions and by combustion at generating plants and industrial processes. NO is formed first and then it combines with oxygen in the air to form NO2, which is a brown gas that gives smog its color. These pollutants also affect the respiratory system and eyes and contribute to acid rain.

3. Carbon Monoxide (CO(g)) – ‘the silent killer’, colorless and odorless, it is a deadly gas that is produced by the burning of fossil fuels and can be produced when anything containing carbon is burned (wood like when heating homes or in forest fires, natural gas, cigarettes and industrial processes). Catalytic converters make CO2 out of CO since it is very toxic when inhaled – it leads to headaches, sleepiness, brain damage and death. Catalytic converters use Platinum and Palladium to remove pollutants from vehicle exhaust.

4. Ground-Level Ozone (O3(g)) – a colorless, odorless gas in the upper atmosphere that protects the earth from harmful UV radiation. At the earth’s surface, ozone is formed by reactions between oxygen, nitrogen and volatile organic chemicals (VOCs – emitted from solvents and gasoline). Ozone at the earth’s surface is a pollutant because it affects the respiratory systems of people with asthma, lung disease and colds. It also negatively affects crops such as wheat, soybeans and onions and causes plastics to deteriorate.

Monitoring the Atmosphere Section 2.3 Monitoring the Atmosphere

1. Carbon Dioxide - A Greenhouse Gas We live in a natural greenhouse, where gases in the atmosphere trap heat from the sun’s radiation. These greenhouse gases include water, methane, nitrogen oxides and carbon dioxide. CO2 is released naturally into the air by people breathing, driving vehicles and combusting materials. With the large amount of people doing all of these things, what effect will the increased amount of carbon dioxide have on the planet?

Many scientists support the theory that human activities enhance the greenhouse effect which increases the global temperature (global warming). This trend can lead to climate change, increase the amount of violent storms and flooding, and increase the spread of disease. Behind water, carbon dioxide contributes most to the greenhouse effect. See Figure 2.17, p. 231 for the upward trend of CO2 concentration in our atmosphere from 1960 until today.

Global warming is increasing due to natural processes such as volcanic eruptions and forest fires, but also because of human activities. Some countries have begun to reduce CO2 emissions by turning to alternate energy sources such as wind and are also investing in forest projects to increase the amount of CO2 absorbed.

2. The Ozone Layer The ozone layer is 15 to 50 km above the earth and protects us from UV rays. Scientists have found that this layer has become thinner over the years, some places so thin that they are called holes. As a result, more UV rays are getting to the earth’s surface and many effects are being seen, from skin cancer, to cataracts, to death of plankton. CFCs, or cholorfluorocarbons, are thought to cause thinning of the ozone layer. They were used in refrigerators, aerosol cans, and fire extinguishers.

UV causes CFCs to break down into substances (like chlorine) that breakdown ozone into O2(g). One chlorine molecule can break down 100 000 ozone molecules. In colder regions (south pole), ice particles in the atmosphere speed up this reaction. Many countries have signed international agreements to reduce the use of CFCs.

global warming link