Environmental Chemistry

Section 2: The Quantity of Chemicals in the Environment can be Monitored

Objectives for Section 2.1 Describe and use examples of how biological monitoring can determine environmental quality Describe and use examples of how biological monitoring can determine environmental quality Identify chemical that will impact/affect the health and distribution of living organisms Identify chemical that will impact/affect the health and distribution of living organisms Apply and use measures of chemical concentrations in ppm, ppb and ppt Apply and use measures of chemical concentrations in ppm, ppb and ppt

Monitoring: keeping track of something for a specific purpose. Monitoring: keeping track of something for a specific purpose. Water quality is determined by what water is used for. It is regulated by technicians Water quality is determined by what water is used for. It is regulated by technicians Their are five categories of water use: Their are five categories of water use: 1. Human drinking water 2. Recreation such as swimming 3. Livestock drinking water 4. Irrigation 5. Protection of aquatic life 2.1:Monitoring Water Quality

Biological Indicators Scientist use organisms that live in the water to help determine water quality. Scientist use organisms that live in the water to help determine water quality. Microbiological Indicators Microscopic organisms such as bacteria can cause serious health problems if they are present in high enough numbers.( E coli bacteria) Microscopic organisms such as bacteria can cause serious health problems if they are present in high enough numbers.( E coli bacteria) Aquatic Invertebrates Invertebrates are animals without backbones. They are used for monitoring because different invertebrates prefer different living conditions. 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 Low Freshwater shrimp, many midge larvae, many worms including leeches. Some species have difficulty living in critical levels. Dissolved O 2 2 Very Low Many midge larvae, some worms including leeches Dissolved O 2 0 Critical No species of game fish exist, some midge larvae, some worms

Biological Indicators Which organisms indicate a high level of dissolved O 2 ? good water conditions Which organisms indicate a high level of dissolved O 2 ? good water conditions Which organisms indicate a low level of dissolved O 2 ? poor water conditions

Chemical Factors that Affect Organisms Water found in our environment may contain many different organic and inorganic compounds. The concentration of these compounds affects water quality. Water found in our environment may contain many different organic and inorganic compounds. The concentration of these compounds affects water quality. The following are monitored as indicators of water quality: The following are monitored as indicators of water quality: Dissolved oxygen Dissolved oxygen Acidity Acidity Heavy metals Heavy metals Plant nutrients (such as nitrogen and phosphorus) Plant nutrients (such as nitrogen and phosphorus) Pesticides Pesticides Salts (such as sodium chloride and magnesium sulfate) Salts (such as sodium chloride and magnesium sulfate)

Dissolved Oxygen The level of dissolved oxygen depends on: Temperature (due to change in seasons) Temperature (due to change in seasons) Turbulence (due to wind or the speed of moving water) Turbulence (due to wind or the speed of moving water) Photosynthesis of aquatic plants or algae Photosynthesis of aquatic plants or algae # of organisms using up the oxygen # of organisms using up the oxygen Dissolved oxygen is essential for the health of aquatic life.

Acidity Precipitation with a pH lower than 5.6 is considered acid rain/snow. Precipitation with a pH lower than 5.6 is considered acid rain/snow. Acid precipitation causes major problems in the spring when the snow melts and flows into aquatic systems. Spring acid shock causes serious harm to the eggs and young offspring of fish. Acid precipitation causes major problems in the spring when the snow melts and flows into aquatic systems. Spring acid shock causes serious harm to the eggs and young offspring of fish. As the acidity increases the diversity of organisms decreases! As the acidity increases the diversity of organisms decreases! Most fish disappear if the water’s pH falls to 4.5. Most fish disappear if the water’s pH falls to 4.5.

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

Plant Nutrients (Phosphorus and Nitrogen Content) Phosphorus and nitrogen are important for all living things, but too much can cause problems. Excess P and N 2 comes from: Phosphorus and nitrogen are important for all living things, but too much can cause problems. Excess P and N 2 comes from: Sewage outfalls Sewage outfalls Runoff from fertilized fields Runoff from fertilized fields

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

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) 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 Most are now used for ONE growing season They do however create organisms that can become RESISTANT to the pesticide 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 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 TOXICITY – describes how poisonous a substance is

Measuring Toxicity Toxins or poisons are substances that produce serious health problems or death when introduced into an organism. Toxins or poisons are substances that produce serious health problems or death when introduced into an organism. In order to compare toxins, a measurement called LD50 is used. In order to compare toxins, a measurement called LD50 is used. LD stands for lethal dose; 50 represents 50%. LD stands for lethal dose; 50 represents 50%. LD50 is the amount of a substance that causes 50% of animals to die if they are given a specified dose of the substance all at once. LD50 is the amount of a substance that causes 50% of animals to die if they are given a specified dose of the substance all at once. Table salt – 3000mg/kg, Caffeine – 192 mg/kg, DDT 87mg/kg (all given to rats by mouth) Table salt – 3000mg/kg, Caffeine – 192 mg/kg, DDT 87mg/kg (all given to rats by mouth)

Measuring Chemicals in the Environment The concentration of chemicals in the environment is usually measured in parts per million (ppm) 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 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) Some times the concentrations are expressed in parts per billion (ppb) or parts per trillion (ppt)

1 ppm is about the same as 1 drop of food colouring in a half filled bath tub 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 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 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 mL millilitres ppm = mg = mg = g or mL _ L 1 000mL mL L 1 000mL mL

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

Example 2 If there is 5mL of oxygen dissolved in 995 mL of water, how many ppm of dissolved oxygen is there? 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 = mL/mL ppm = 5 mL = mL/mL 1000mL 1000mL ppm = = 5000 ppm

Example 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? 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 6ppm means that there is 6mL of dissolved oxygen in mL of water

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