Sci 207 week 2 lab water quality and contamination

Environmental Science Table of Contents

21

Lab 2 Water Quality and Contamination

Water Quality and Contamination

Concepts to Explore

• Usable water

• Ground water

• Surface water

• Ground water contaminates

• Water treatment

• Drinking water quality

Figure 1: At any given moment, 97% of the planet’s water is in the oceans. Only a small fraction of the remaining freshwater is usable by humans, underscoring the importance of treating our water supplies with care.

Introduction

It is no secret that water is one of the most valuable resources on planet Earth. Every plant and animal re- quires water to survive, not only for drinking, but also for food production, shelter creation and many other ne- cessities. Water has also played a major role in transforming the earth’s surface into the varied topography we see today.

While more than 70% of our planet is covered in water, only a small percent of this water is usable freshwater. The other 99% of the water is composed primarily of salt water, with a small percentage being composed of

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Water Quality and Contamination

glaciers. Due to the high costs involved in transforming salt water into freshwater, the Earth’s population sur- vives off the less than 1% of freshwater available. Humans obtain freshwater from either surface water or groundwater.

Surface water is the water that collects on the ground as a result of precipitation. The water that does not evaporate back into the atmosphere or infiltrate into the ground is typically collected in rivers, lakes, reser- voirs, and other bodies of water and is easily accessible.

Precipitation

Precipitation Precipitation

Cloud formation

Transpiration

Evaporation

Evaporation

Groundwater

Figure 2: Water is a renewable source, purified and delivered across the planet by the hydrological cycle.

Groundwater, on the other hand, is precisely as the name suggests; water located underneath the ground. This water is stored in pores, fractures and other spaces within the soil and rock underneath the ground’s sur- face. Precipitation, along with snowmelt, infiltrates through the ground and accumulates in available under- ground spaces.

Aquifers are areas in which water collects in sand, gravel, or permeable rock from which it can be extracted for usable freshwater. The depth of aquifers vary from less than 50 feet to well over 1,500 feet below the sur- face of the ground. The water within an aquifer typically does not flow through as it would through a river or stream, but instead soaks into the underground material, similar to a sponge. As aquifers are depleted by hu- man use, they are also recharged from precipitation seeping into the ground and restoring the water level. However, many times the recharge of the aquifers does not equal the amount of water that has been extract- ed. If that cycle continues, the aquifer will eventually dry up and will no longer be a viable source of groundwa- ter.

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Water Quality and Contamination

Water is the only substance that is found naturally in three forms: solid, liquid,

and gas

If the entire world’s supply of water could fit into a one- gallon jug, the fresh water

available to use would equal less than one tablespoon

Approximately 66% of the human body consists of wa-

ter - it exists within every organ and is essential for its

function

While the water that precipitates down in the form of rain is relatively pure, it does not take long for water to pick up contaminants. There are natural, animal, and human-made sources of water pollutants. They can travel freely from one location to another via streams, rivers, and even groundwater. Pollutants can also trav- el from land or air into the water. Groundwater contamination most often occurs when human-made products such as motor oil, gasoline, acidic chemicals and other substances leak into aquifers and other groundwater storage areas. The most common source of contaminants come from leaking storage tanks, poorly main- tained landfills, and septic tanks, hazardous waste sites and the common use of chemicals such as pesti- cides and road salts.

The dangers of consuming contaminated water are high. Many deadly diseases, poisons and toxins can reside in the contaminated water supplies and severely affect the health of those who drink the water. It is also believed that an increased risk of cancer may result from ingesting contaminated groundwater.

With the many contaminants that can infiltrate our wa- ter supply, it is crucial that there be a thorough water treatment plan in place to purify the water and make it drinkable. While each municipality has its own water treatment facility, the process is much the same at each location.

Figure 3: Sedimentation tanks, such as those shown above, are used to settle the sludge and remove oils and fats in sewage. This step can remove a good por- tion of the biological oxygen demand from the sew- age, a key step before progressing with the treat- ments and eventually releasing into the ground or body of water.

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Water Quality and Contamination

The process begins with aeration in which air is added to the water to let trapped gases escape while increasing the amount of oxygen within the water. The next step is called coagulation or flocculation, in which chemicals, such as filter alum, are added to the incoming water and then stirred vigor- ously in a powerful mixer. The alum causes compounds such as carbonates and hydroxides to form tiny, sticky clumps called floc that attract dirt and other small particles. When the sticky clumps combine with the dirt they become heavy and sink to the bottom. In the next step, known as sedimentation, the heavy particles that sank to the bottom during coagula- tion are separated out and the remaining water is sent on to filtration. During filtration, the water passes through filters made of layers of sand, charcoal, gravel and pebbles that help filter out the smaller particles that have passed through until this point. The last step is called disinfection in which chlorine and/or other disinfectants are added to kill any bac-

Figure 4: Fresh water is essen- tial to humans and other land- based life. Contaminated water must be treated before it can be released into the water supply.

teria that may still be in the water. At this point the water is stored until it is distributed through various pipes to city residents and businesses.

After the water goes through the treatment process, it must also pass the guidelines stated in the Safe Drinking Water Act in which various components are tested to ensure that the quality of the water is sufficient for drinking. There are currently over 65 contaminants that must be monitored and maintained on a regular basis to keep local drinking water safe for the public. Some of these chemical regulations include lead, chromium, selenium and arsenic. Other com- ponents such as smell, color, pH and metals are also monitored to ensure residents are provid- ed clean and safe drinking water.

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Water Quality and Contamination

Experiment 1: Effects of Groundwater Contamination

In this lab you will test the effects of common pollutants on groundwater. When mixed with water, everyday items such as laundry detergent, oil, and vinegar can alter the color, smell, and taste of water. You have likely observed these changes through everyday activities such as adding laundry detergent to water in the washing machine, or noticing oil within a puddle on the street. Many of these chemicals end up dispersing throughout our environment, and while soil bacteria can reduce many of these contaminants, they may not be able to stop them from reaching our groundwater sources located beneath the soil. In Experiment 1 you will test the ability of soil to remove oil, vinegar, and laundry detergent from the environment before it reaches groundwa- ter. Follow the procedure below to complete Experiment 1 on the effects of groundwater contamination.

Materials

(8) 250 mL Beakers

Permanent marker

3 Wooden stir sticks

100 mL Graduated cylinder

10 mL Vegetable oil

10 mL Vinegar

10 mL Liquid laundry detergent

100 mL Beaker

240 mL Soil

Funnel

Cheesecloth

*Scissors

*Water

*You must provide

Procedure

1. Download the Week 2 Lab Reporting Form from the course instructions. As you conduct all 3 experi-

ments, record hypotheses, observations, and data on that form.

2. Read through the Experiment 1 procedure and then record your hypotheses on the ability of oil, vinegar,

and laundry detergent to contaminate groundwater on the Week 2 Lab Reporting Form. You should pro-

vide one hypothesis for each situation.

3. Use the permanent marker to label the beakers 1 - 8.

4. Set Beakers 5 - 8 aside. Fill Beakers 1 - 4 with 100 mL of water using your 100 mL graduated cylinder.

5. Record your observations of the water in Beaker 1 in Table 1 on the Week 2 Lab Reporting Form. Re-

member to use a safe wafting technique to smell the solutions.

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Water Quality and Contamination

6. Add 10 mL of vegetable oil to Beaker 2. Mix thoroughly with a wooden stir stick. Record your observations

of the water in Beaker 2 in Table 1 on your Week 2 Lab Reporting Form. (Don’t forget to wash the gradu-

ated cylinder between use!)

7. Add 10 mL vinegar to beaker 3. Mix thoroughly with a wooden stir stick. Record your observations of the

water in Beaker 3 in Table 1 on your Week 2 Lab Reporting Form.

8. Add 10 mL of liquid laundry detergent to beaker 4. Mix thoroughly with a wooden stir stick. Record your

observations of the water in Beaker 4 in Table 1 on your Week 2 Lab Reporting Form.

9. Cut your piece of cheesecloth into five different pieces (reserve one piece for the next experiment). Fold

one piece of the cheesecloth so that you have a piece 4 layers thick and big enough to line the funnel.

Place it inside the funnel.

10. Measure out 60 mL of soil using the 100 mL beaker and place it into the cheesecloth-lined funnel.

11. Place the funnel inside Beaker 5.

12. Pour the contents of Beaker 1 (water) through the funnel so that it filters into Beaker 5 for one minute.

Record your observations of the filtered water in the beaker in Table 1 on your Week 2 Lab Reporting

Form.

13. Discard the cheesecloth and soil from the funnel.

14. Repeat Steps 9 - 13 for Beakers 2, 3, and 4 and complete the Post-Lab questions on the Week 2 Lab Re-

porting Form. (Filter the contents of Beaker 2 into Beaker 6, the contents of Beaker 3 into Beaker 7, and

the contents of Beaker 4 into Beaker 8).

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Water Quality and Contamination

Experiment 2: Water Treatment With the many pollutants that are added to our water supply from daily human activity, it is important that we have a way to filter our water to make it safe for drinking. Wastewater treatment plants use sophisticated techniques to make water potable. In Experiment 2, you will use a similar technique to test the effectiveness of one filtering method on the ability to purify contaminated water. Follow the procedure below to complete Experiment 2 on the effects of one method of water treatment.

Materials

100 mL Potting soil

(2) 250 mL Beakers

(2) 100 mL Beakers

100 mL Graduated cylinder

40 mL Sand

20 mL Activated charcoal

60 mL Gravel

1 Wooden stir stick

Alum

Funnel

Cheesecloth

Bleach

Stopwatch

*Water

*You must provide

Procedure

1. Read through the Experiment 2 procedure and then record your hypothesis on the ability of your filtration

technique to remove contaminants on your Week 2 Lab Reporting Form.

2. Add 100 mL of soil to the 250 mL beaker. Fill to the 200 mL mark with water.

3. Pour the soil solution back and forth between the two 250 mL beakers for a total of 15 times.

4. After the solution is created, pour 10 mL of the now “contaminated” water into a clean 100 mL beaker.

This sample will be used to compare to the “treated” water at the end of the filtration process.

5. Add 10 grams of alum (all of the contents in the bag you have been given) to the 250 mL beaker contain-

ing the “contaminated” water. Slowly stir the mixture with a wooden stir stick for 1-2 minutes. Let the so-

lution sit for 15 minutes.

6. In the meantime, rinse out the empty 250 mL beaker. Place the funnel into the clean 250 mL beaker. Fold

a piece of cheesecloth so that you have a piece 4 layers thick that is big enough to line the funnel. Place

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Water Quality and Contamination

it inside the funnel.

7. Begin layering the funnel, starting by pouring 40 mL of sand into the cheesecloth-lined funnel, then 20 mL

activated charcoal, then 40 mL gravel. Use a 100 mL beaker to measure these amounts.

8. To solidify the filter, slowly pour clean tap water through the filter until the funnel is full. Discard the rinse

water from the beaker and repeat four more times. Return the funnel to the top of the beaker and let sit for

5 minutes before emptying the beaker and continuing the experiment.

9. Now, without mixing up the current sediment in the “contaminated” water jar, pour about 3/4 of the “contaminated” water into the funnel. Let it filter through the funnel into the beaker for 5 minutes.

10. Note the smell of the filtered water, comparing it to the 10 mL sample taken from the mixture in Step 3.

11. Remove the filter and add a few drops of bleach solution to the filtered water within the beaker. Stir the

water and bleach combination slowly for about 1 minute.

12. The “contaminated” water has now been filtered. Compare the newly created “treated” water with the 10

mL sample of the initial “contaminated” water and answer the Post-Lab questions on the Week 2 Lab Re-

porting Form.

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Water Quality and Contamination

Experiment 3: Drinking Water Quality

Bottled water is a billion dollar industry within the United States alone. Still, various reports have shown that many bottled water products contain the same chemical contaminants as our tap water. In Experiment 3, you will test the quality of two separate bottled waters and your tap water by measuring a variety of chemical com- ponents within the water. Follow the procedure below to complete Experiment 3 on drinking water quality.

Materials

Dasani® bottled water

Fiji® bottled water

Ammonia test strips

Chloride test strips

4 in 1 test strips

Phosphate test strips

Iron test strips

(3) 250 mL Beakers

Permanent marker

Stopwatch

Parafilm®

Pipettes

(3) Foil packets of reducing powder

*Tap water

*You must provide

Procedure

1. Read through the Experiment 3 procedure and then record your hypothesis on which water source you

believe will have the most and least contaminants on the Week 2 Lab Reporting Form.

2. Label three 250 mL beakers Tap Water, Dasani® and Fiji®. Pour 100 mL of the each type of water into

the corresponding beakers.

Ammonia Test Strip

3. Locate the ammonia test strips. Begin by placing the test strip into the tap water sample and vigorously

moving the strip up and down in the water for 30 seconds, making sure that the pads on the test strip are

always submerged.

4. Remove the test strip from the water and shake off the excess water.

5. Hold the test strip level, with the pad side up, for 30 seconds.

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Water Quality and Contamination

6. Read the results by turning the test strip so the pads are facing away from you. Compare the color of the

small pad to the color chart at the end of the lab. Record your results in Table 2 on the Week 2 Lab Re-

porting Form.

7. Repeat the procedure for both Dasani® and Fiji|® bottled water. Record your results for both in Table 2

on the Week 2 Lab Reporting Form.

Chloride Test Strip

8. Locate the chloride test strips. Begin by immersing all the reaction zones (the pads) of the test strip in to

the tap water sample for 1 second.

9. Shake off the excess liquid from the test strip and after 1 minute, determine which color row the test strip

most noticeably coincides with on the color chart at the end of the lab. Record your results in Table 3 on

the Week 2 Lab Reporting Form.

10. Repeat the procedure for both Dasani® and Fiji® Bottled Water. Record your results for both in Table 3.

4 in 1 Test Strip

11. Locate the 4 in 1 test strips. Begin by dipping the test strip in the tap water for 5 seconds with a gentle

back and forth motion.

12. Remove the test strip from the water and shake once, briskly, to remove the excess water.

13. Wait 20 seconds and then using the color chart at the end of this lab, match the test strip to the pH, Total

Alkalinity, Total Chlorine, and Total Hardness on the color chart. Be sure to do all of the readings within

seconds of each other. Record your results in Table 4 on the Week 2 Lab Reporting Form.

14. Repeat the procedure for both Dasani® and Fiji® Bottled Water. Record your results for both in Table

4.

Phosphate Test Strip

15. Locate the phosphate test strips. Being by dipping the test strip into the tap water for 5 seconds.

16. Remove the test strip from the water and hold horizontal, with the pad side up, for 45 seconds. Do not

shake the excess water from the test strip.

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Water Quality and Contamination

17. Compare the results on the pad of the test strip with the color chart at the end of this lab. Record your

results in Table 5 on the Week 2 Lab Reporting Form.

18. Repeat the procedure for both Dasani® and Fiji® bottled water. Record your results for both in Table 5.

Iron Test Strip

19. Locate the iron test strips. Begin by removing 70 mL of water from each beaker and discarding it, leaving

a total of 30 mL within each of the three beakers.

20. Beginning with the tap water, open one foil packet and add the powder contents to the beaker. Cover the

beaker with a piece of Parafilm® and shake the beaker vigorously for 15 seconds.

21. Remove the Parafilm® and dip the test pad of the iron test strip into the tap water sample, rapidly moving

it back and forth under the water for 5 seconds.

22. Remove the strip and shake the excess water off. After 10 seconds, compare the test pad to the color

chart at the end of this lab. If the color falls between two colors in the color chart, estimate your result.

Record your results in Table 6 on the Week 2 Lab Reporting Form.

23. Repeat the procedure for both Dasani® and Fiji® Bottled Water. Record your results for both in Table 6

on the Week 2 Lab Reporting Form and then answer all of the post lab questions on the Week 2 Lab Re-

porting Form.

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Water Quality and Contamination

Test Strip Key:

Ammonia (mg/L):

Chloride (mg/L):

4 in 1 Test Strip:

0 10 30 60 100 200 400

0

500

1000

1500

2000

≥3000

*Note there are four pads on this test strip. From top to bottom (with the bottom of the strip being the handle), the pads test for pH, Chlorine, Alkalinity, and Hardness.

Example:

pH:

pH Chlor. Alk. Hard

(test strip handle)

Total Chlorine (mg/L):

Total Alkalinity (mg/L):

Total Hardness (mg/L):

0 0.2 1.0 4.0 10.0

0 40 80 120 180 240 500

0 50 120 250 425 1000

Soft Hard Very Hard

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Water Quality and Contamination

Test Strip Key (cont.):

Phosphate (ppm): 0 10 25 50 100

Total Iron (ppm): 0 0.15 0.3 0.6 1 2 5

1. Form based on your observations.

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Weather and Climate Change

Appendix Good Lab Techniques

36

Good Lab Techniques

Good Laboratory Techniques

Science labs, whether at universities or in your home, are places of adventure and discovery. One of the first things scientists learn is how exciting experiments can be. However, they must also realize science can be dangerous without some instruction on good laboratory practices.

• Read the protocol thoroughly before starting any new experiment. You should be familiar with the action required every step of the way.

• Keep all work spaces free from clutter and dirty dishes.

• Read the labels on all chemicals, and note the chemical safety rating on each container. Read all Material Safety Data Sheets (provided on www.eScienceLabs.com).

• Thoroughly rinse lab ware (test tubes, beakers, etc.) between experi- ments. To do so, wash with a soap and hot water solution using a bottle brush to scrub. Rinse completely at least four times. Let air dry

• Use a new pipet for each chemical dispensed.

• Wipe up any chemical spills immediately. Check MSDSs for special handling instructions (provided on www.eScienceLabs.com).

• Use test tube caps or stoppers to cover test tubes when shaking or mixing – not your finger!

A B C

Figure 1: A underpad will prevent any spilled liquids from contaminating the sur- face you work on.

Figure 2: Special measuring tools in make experimentation easier and more accu- rate in the lab. A shows a beaker, B graduated cylinders, and C test tubes in a test tube rack.

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Good Lab Techniques

• When preparing a solution, refer to a protocol for any specific instructions on preparation. Weigh out the desired amount of chemicals, and transfer to a beaker or graduated cylinder. Add LESS than the required amount of water. Swirl or stir to dissolve the chemical (you can also pour the solution back and forth between two test tubes), and once dissolved, trans- fer to a graduated cylinder and add the required amount of liquid to achieve the final volume.

• A molar solution is one in which one liter (1L) of solution con- tains the number of grams equal to its molecular weight.

For example:

1M = 110 g CaCl x 110 g CaCl/mol CaCl

(The formula weight of CaCl is 110 g/mol)

Figure 3: Disposable pipettes aid in ac- curate measuring of small volumes of liquids. It is important to use a new pi- pette for each chemical to avoid con- tamination.

• A percent solution can be prepared by percentage of weight of chemical to 100ml of solvent (w/v) , or volume of chemical in 100ml of solvent (v/v).

For example:

20 g NaCl + 80 mL H2O = 20% w/v NaCl solution

• Concentrated solutions, such as 10X, or ten times the normal strength, are diluted such that the final concentration of the solution is 1X.

For example:

To make a 100 mL solution of 1X TBE from a 10X solution:

10 mL 10X TBE + 90 mL water = 100ml 1X TBE

• Always read the MSDS before disposing of a chemical to insure it does not require extra measures. (provided on www.eScienceLabs.com)

• Avoid prolonged exposure of chemicals to direct sunlight and extreme temperatures. Immediately se- cure the lid of a chemical after use.

• Prepare a dilution using the following equation:

c1v1 = c2v2

Where c1 is the concentration of the original solution, v1 is the volume of the original solution, and c2 and v2 are the corresponding concentration and volume of the final solution. Since you know c1,

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Good Lab Techniques

c2, and v2, you solve for v1 to figure out how much of the original solution is needed to make a cer- tain volume of a diluted concentration.

• If you are ever required to smell a chemical, always waft a gas toward you, as shown in the figure below.. This means to wave your hand over the chemical towards you. Never directly smell a chemical. Never smell a gas that is toxic or otherwise dangerous.

• Use only the chemicals needed for the activity.

• Keep lids closed when a chemical is not being used.

• When diluting an acid, always slowly pour the acid into the water. Never pour water into an acid, as this could cause both splashing and/or an explosion.

• Never return excess chemical back to the original bottle. This can contaminate the chemical sup- ply.

• Be careful not to interchange lids between different chemical bottles.

• When pouring a chemical, always hold the lid of the chemical bottle between your fingers. Never lay the lid down on a surface. This can contaminate the chemical supply.

• When using knives or blades, always cut away from yourself.

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Lab 2
Concepts to Explore
Introduction
Experiment 1: Effects of Groundwater Contamination
Procedure
Experiment 2: Water Treatment
Materials
Procedure
Experiment 3: Drinking Water Quality
Materials
Procedure
Ammonia Test Strip
Chloride Test Strip
4 in 1 Test Strip
Phosphate Test Strip
Iron Test Strip
Ammonia (mg/L):
pH:
Total Chlorine (mg/L):
Test Strip Key (cont.):
Phosphate (ppm):
Appendix