Environmental Chemistry Section 2.1 Monitoring Water Quality

Monitoring Chemicals

Monitoring Water Quality

Water Quality Water quality is determined according to what the water is used for. There are five categories of water quality use: – 1) Human drinking water – 2) Recreation – 3) Livestock drinking water – 4) Irrigation – 5) protection of aquatic life

How Do We Test Water Quality? Scientists and technicians make sure that these guidelines are being met by monitoring water quality. They use biological and chemical indicators

Biological Indicators Scientists use organisms that live in water to help determine water quality. These indicators include fish, plants, worms, insects, plankton, protozoa, and bacteria

Microbiological Indicators Microscopic organisms such as bacteria can cause serious health problems Water samples are taken to determine the numbers and types of microscopic organisms Examples: E. coli

Aquatic Invertebrate Invertebrates are animals without backbones. They are used for monitoring because different invertebrates prefer different living conditions.

Examples of Indicators

Dissolved Oxygen level Consequences Dissolved O 2 8 Excellent Large variety of invertebrates (insect larvae, beetles, worms) Many species of fish and other desirable organisms Dissolved O 2 6 Good Few mayfly larvae, some stonefly larvae, some beetles, many midge larvae, many worms including leeches Dissolved O 2 4 Critical Freshwater shrimp, many midge larvae, many worms including leeches. Some species have difficulty living in critical levels. Dissolved O 2 2 Low Many midge larvae, some worms including leeches Dissolved O 2 2 Very Low No species of game fish exist, some midge larvae, some worms

Aquatic Environments If the pH of the water in an aquatic ecosystem is below 5 (acidic) you will not find many fish or insects there The diversity of all organisms decreases as acidity increases and dissolved oxygen decreases.

Chemical Factors That Affect Organisms Water in the environment is never completely pure It contains many different organic and inorganic compounds. The concentration (amount) of these compounds affects water quality

The following are monitored as indicators of water quality: Toxicity and LD 5= measurements (pg. 221) Dissolved oxygen (pg. 217) Acidity (pg. 220) Heavy metals (pg. 222) Plant nutrients (such as N and P) (pg. 219) Pesticides (pg. 221) Salts (such as NaCl and magnesium sulfate)

Measuring Chemicals in the Environment The concentration of chemicals in the environment is usually measured in parts per million (ppm) One part per million means that one unit of an element can be found in one million units of solution Some times the concentrations are expressed in parts per billion (ppb) or parts per trillion (ppt)

Measuring Chemicals in the Environment 1 ppm is about the same as 1 drop of food colouring in a half filled bath tub 1 ppb is about the same as 1 drop of food colouring in a swimming pool 1 ppt is about the same as 1 drop of food colouring in 1000 swimming pools

Determining ppm ppm= Part (g or mL) ie. 1 Part per million milliletres mL ppm = mg = mg = g or mL _ L 1 000mL mL

Example 1 If there are 20 mg of oxygen dissolved in 5 L of water, how many ppm of dissolved oxygen is there? 20 mg/5 L = 4 mg/L = 4 ppm

Example 2 If there is 5mL of oxygen dissolved in 995 mL of water, how many ppm of dissolved oxygen is there? ppm = g or mL mL ppm = 5 mL = x = 5025 ppm 995mL mL

Example 3 If there are 6ppm of dissolved oxygen in the water, this means that there is 6mL of dissolved oxygen in how many mL of water? 6ppm means that there is 6mL of dissolved oxygen in mL of water

Example 4 You add 1 mL of food coloring into 99 mL of water. What is the concentration of food coloring in ppm? 1mL = ____x____ 100mL x = 1mL x mL x = 0.01 x x = ppm

Dissolved Oxygen Dissolved oxygen is essential for the health of aquatic life An acceptable level of dissolved oxygen for aquatic life is between 5 and 8 ppm The level of dissolved oxygen in water depends on: – Temperature (due to change in seasons) – Turbulence (due to wind or speed of moving water) – Photosynthesis by plants and algae in the water – The number of organisms using up the oxygen

Plant Nutrients (Phosphorus and Nitrogen Content) Phosphorus and nitrogen are important for all living things, but too much can cause problems. Excess P and N2 comes from: Sewage outfalls Runoff from fertilized fields

Fertilizers - P & N content (pg. 219)

1. High amounts of P and N2 cause: 2. Increased growth in algae and green plants 3. Plants dies and becomes food for bacteria that decompose it 4. Bacteria increase in number 5. Increased bacteria use up dissolved oxygen 6. Fish and aquatic insects cannot survive

Acidity Read pg. 220 Precipitation with a pH lower than 5.6 is considered acid rain or snow When acid precipitation falls on aquatic ecosystems the acidity in the water increases and the diversity of living things decreases Spring acid shock causes serious harm to the eggs and young offspring of fish. – As the acidity increases the diversity of organisms decreases! – Most fish disappear if the water’s pH falls to 4.5.

Pesticides Some pesticides have long lasting effects as they do not break down quickly and last in the environment for a long period of time ( DDT) Most are now used for ONE growing season They do however create organisms that can become RESISTANT to the pesticide Larger numbers of pesticides are creating problems in the environment as if they are mixed together they create a TOXIC substance TOXICITY – describes how poisonous a substance is

one-drops-beneficial-bugs-onto-corn-fields/#.VTVqOxfmqlp

Salt Content Salinity increases can be harmful to fresh water habitats.

Measuring Toxicity Toxins are substances that produce serious health problems or death when introduced into an organism When we compare toxins we use a measurement called LD50 LD  Lethal Dose 50  50% LD50 is the amount of a substance that causes 50% of a group of test animals to die if they are given a specified dose of the substance all at once

Measuring Toxicity The lower the LD50 the more toxic a substance is

Read page 221 and fill in the table below SubstanceLD 50 (mg/kg or ppm) Subject/ Delivered The smaller the LD 50 measurement, the more toxic the substance is.

Heavy Metals

Heavy metals have a density of 5 g/cm 3 or higher Include copper, zinc, lead, mercury, cadmium and nickel They naturally occur in rocks and soil They are mined to make: batteries, tires, paints, pipes, thermometers and fertilizers Heavy metals must be monitored because they can be toxic to a variety of organisms

Heavy Metals Read pg. 222 and list examples of heavy metals and their possible health effects: Hg, Cu, Pb, and Zn – nervous system damage/death, Developmental Problems, Carcinogenic

Check and Reflect p.g. 224 # You add 1 mL of food dye to 99 mL of water in a beaker. What is the concentration of the solution in ppm? 2. You then take 1 mL of your solution from the second question and add it to 999 mL of water in another beaker. What is the concentration of the new solution in ppm?

Section 2.2: Monitoring Air Quality Air quality can be determined in two ways: By measuring levels of pollutants in the air (ground level ozone) By estimating the amount of emissions from pollution sources (Fort McMurray oil sands)

Composition of Air Air is comprised of: 78% Nitrogen 21% Oxygen > 1% Argon 0.03% Carbon Dioxide Traces of Hydrogen, and Neon

Sulfur Dioxide SO2(g) is a major air pollutant Forms both smog and acid rain Causes respiratory problems and eye problems Formed when sulfur is combined with oxygen

Sulfur Dioxide Can also be formed when fossil fuels are burnt (coal, oil, natural gas) Industrial and electrical plants use “scrubbers” to reduce the SO 2 emissions by 99% Limestone is reacted with the sulfur to produce gypsum

Sulfur Dioxide 2 SO 2(g) + 4 H 2 O (l) + 2 CaCO 3(s) + O2 (g)  CaSO 4 ·2 H 2 O (s) + 2 CO 2(g)

Nitrogen Oxides NOx(g) are also major air pollutants that form acid rain and smog The “x” in the formula indicate that it is a mixture of NO 2 and NO These are formed mainly from the combustion of fossil fuels, or industrial or electrical plants

Nitrogen Oxides Refer to page 226 – Skill Practice The nitrogen from the burning of the fossil fuel combines with the oxygen to form NO It then combines with the O2 in the atmosphere to form NO2 – (this gives a brown color)

Carbon Monoxide - CO(g) Is called the silent killer – colorless and odorless It is formed when substances burn that contain carbon CO(g) forms if there is not enough oxygen in the air to produce CO 2 (g) Main source is combustion of fossil fuels (burning wood, airplane exhaust, cigarette smoke)

Carbon Monoxide Carbon monoxide reduces the amount of oxygen that the blood carries in the body causing headaches, sleepiness, brain damage and possibly death FOR YOUR INFORMATION: – This is a reason why in the winter we are reminded to open the garage doors and move the car out to warm it up – allowing the CO to be released!

Ground Level Ozone – O3 Odorless and colorless gas It is made up of 3 oxygen atoms At ground level it is formed from reactions with nitrogen and VOC’s (volatile organic compounds) Most VOC’s come from man-made products like gasoline!

Ground Level Ozone – O3 Many large cities have warnings (TWN) especially in the summer as these pollutants are kept close to the earth’s surface due to the heat People with asthma, children, or respiratory problems or even a healthy adult that is outside in these conditions can do further damage to their lungs

Assignment Check & Reflect p.228 #1-3, 5 and 8

2.3 Monitoring the AtmosphereMonitoring the Atmosphere

Carbon Dioxide as a Greenhouse Gas Greenhouse gases help regulate the temperature on Earth by holding heat from the Sun in our atmosphere. Water vapour, carbon dioxide, methane, and nitrogen oxides are all greenhouse gases.

Carbon Dioxide as a Greenhouse Gas The “normal” concentration of CO 2 in air is about 0.03%. Burning of fossil fuels is adding excess CO2 into the atmosphere. Oceans and plants can only absorb some of the CO2.

The Green House Effect

Global Warming Enhanced Greenhouse Effect greenhouse effect made greater by human activities, such as burning fossil fuels and clearing land, that add greenhouse gases to the atmosphere Global Warming increased average temperatures worldwide caused by the enhanced greenhouse effect

What is going to happen in the future if the rate of global warming continues? Perhaps: Ecological boundaries will shift farther northward Permafrost in Canada’s north will continue to melt Water levels in the oceans will rise Polar ice caps will continue to melt Weather patterns will change The frequency and severity of storms will increase

Ozone Layer The thinning of the ozone layer in our upper atmosphere has been attributed to chemicals such as chlorofluorocarbons (CFCs). CFC molecules react with UV light to produce chloride ions (Cl - ) which break down O 3 into O 2.

The Ozone Layer Without the protection of the ozone layer, biological organisms at the surface experience damage to cells. Though many countries have banned the used of CFCs, they will persist in the atmosphere for many years

The ozone layer is actually quite thin; ozone is interspersed with other air gases like nitrogen, oxygen and carbon dioxide.

Good up high, but bad nearby! High-level ozone is beneficial. Ground-level ozone causes lung and other health problems. The ozone-depleting reaction is faster at lower temperatures, so scientists focus their monitoring of the ozone layer by taking photos of the polar regions.

Main Sources of Ozone-depleting Chemicals (CFC’s) Air conditioners for homes and automobiles Industrial refrigeration: (Truck that transports fruits from Florida!) Aerosol sprays: (hairspray, AXE) Examples in your life:

Assignment Section 2 Review p.234 #1-3 and 5-11