Week 7 Assignment

Week 7 Assignment – Water Quality and Availability

Background

Suppose you were hiking along a stream or lake and became thirsty. Would it be safe to drink the water? In many cases, it would not. Contaminants affect freshwater on or beneath the Earth’s surface. Though the sources of these contaminants vary, all can make water unfit to drink if they are allowed to increase beyond safe limits.

In this lab, you will:

· Analyze the results of the tests of water samples from a variety of fresh water sources.

· Determine how to threat the water samples to make them safe to drink.

To begin work on your lab access see the Water Quality and Availability Instructions [DOCX] and the Water Quality and Availability template [DOCX] below.

Water Quality and Availability Instructions

1. Examine the table below that specifies safety levels and treatments for different contaminants. You will use information in this table throughout this lab.

Contaminants	Safety Levels	Treatments
Acidity (pH)	6.5 – 8.5 pH level	Add sodium hydroxide to the acidic water to raise the pH level to neutral.
Metals (ml/L)	< 1.3	1. Add chlorine at the beginning of the treatment process to solidify the metals, allowing them to be filtered out. 2. Add zinc orthophosphate to prevent further corrosion of pipes.
Coliform Bacteria (ml)	0.00	Add chlorine at the beginning and end of the treatment process.
Pesticides/Herbicides (mg/L)	< 0.04	1. Add activated carbon during the treatment process. 2. Add chlorine at the end of the treatment process.
Nitrates (mg)	< 10.0	1. Add activated carbon during the treatment process. 2. Add chlorine at the end of the treatment process.

2. On your Water Quality and Availability Template, determine which contaminations are outside the safe range for the various water samples. The water samples were taken at a:

· Subsurface city site.

· Surface lake site.

· Surface mountain stream site.

· Surface rural site.

· Subsurface suburban well.

3. Enter the unsafe contaminations, if any, for each site in Column 7 of your Water Quality and Availability Template.

4. Specify in Column 8 of the Water Quality and Availability Template how to treat each water sample to make it safe. If the water is safe to drink, state this.

5. Answer the related questions.

Water Quality and Availability Template

Instructions

For each water sample:

· Specify the type of contamination(s) if any (Column 7).

· Indicate the treatment necessary to make the water safe (Column 8).

Sample	Acidity (pH)	Metals (mg/L)	Coliform Bacteria (ml)	Pesticides/ Herbicides (mg/L)	Nitrates (mg)	Type of Contamination	Treatment Performed
City	4	0.006 copper	0.13	0.00001 carbofuran	0.8
Lake	7	0.6 iron	0.33	0.0008 carbofuran	0.6
Mountain	6.8	0.006 iron	0.00	0.0001 carbofuran	12.4
Rural	7	0.0027 copper	0.00	0.08 carbofuran	6.7
Well	8.2	1.44 iron	0.00	0.004 carbofuran	0.6

Questions

1. How do the contaminants in the surface water samples compare/contrast with those in the subsurface or groundwater samples?

2. Why might groundwater and surface water have different contaminants?

3. Generally, farmers do not farm on the sides of mountains or in remote areas. Likewise, industries do not build factories in these areas. Moreover, these areas are usually not highly populated by people. What types of contaminants, if any, were found in the mountain water? How do you explain the presence of any contaminants?

4. What are pH levels? In your explanation be sure to address its characteristics, its contribution to pollution, and the chemicals used to treat low pH levels?

5. Water tested in an old building recently showed high copper and iron content and low pH levels. A water reading taken 20 years before, showed low pH levels and only minimal traces of copper and iron. None of the new buildings on the same street showed signs of metallic contaminants; all reported lower than normal pH readings. How do you explain these readings?