Water Quality Lab
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School
Northern Virginia Community College *
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Course
121
Subject
Geography
Date
Dec 6, 2023
Type
docx
Pages
10
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Water Quality Lab Worksheet
Part I Questions to be answered using diagrams of the biogeochemical cycles
provided with this lecture prior to lab
Hydrologic Cycle
1.
In the hydrologic cycle what are the two primary routes water from precipitation
may take in returning to the ocean?
2.
How is this route being altered due to human activities?
Nitrogen Cycle
1.
What are the human alterations to the nitrogen cycle?
2.
What are the links between the hydrologic and nitrogen cycles?
3.
How would you expect the alteration in the hydrologic cycle to affect nitrogen
levels in lakes and streams?
The Sulfur Cycle
1.
What three human activities have increased atmospheric levers of sulfur dioxide?
2.
Follow the fate of sulfur dioxide in the atmosphere.
What would you expect the
pH to be of a lake located in a region of higher than normal concentrations of
atmospheric sulfur dioxide?
The Phosphate Cycle
1.
How does the phosphate cycle differ from the other cycles observed?
2.
What are the sources of human input?
3.
Is this cycle linked to the hydrologic cycle?
Explain
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Part II
A.
Predicting water quality
Although the sources and reservoirs vary among the nutrient cycles, water as a
major medium for transfer remains consistent.
Precipitation moves across the
land as surface run-off carrying dissolved nutrients.
In a pristine landscape the
rate at which
surface run-off moves is slowed by vegetation allowing greater
percolation through the soil which acts as a natural filtering system.
However,
in a disturbed environment the proportion of run-off directly reaching streams,
lakes and ultimately the ocean is much higher, with impervious surfaces such as
pavement and buildings experiencing
much greater runoff (100 %), compared to
lawn/grass( 30% ) and forest (25%).
As a consequence the alterations in local
hydrologic cycles attributed to landscape alterations are frequently reflected in
the water conditions of lakes. Likewise, alterations to localized nitrogen,
phosphorus and sulfur cycles may be magnified by disturbed hydrologic cycles
and readily detected in lakes.
Before we actually conduct water quality tests for the NOVA lake, we are going to
make a prediction based on the percentage of forested surface area in the
watershed .
Landscape analysis is now frequently conducted using GIS
software rather than physically assessing the land.
We will be using a free
computer application called icanopy to evaluate the Accotink Creek Watershed
where the Annandale campus is located.
1.
Go to the following site
http://www.itreetools.org/canopy/index.php
to determine
the percentage of landcover types in our watershed, Accotink Creek watershed.
You can outline your own watershed by following the instructions in Method A
below.
Or you can use the shape and project files already prepared for as outline
in Method B.
Method A
a.
Click on “define project area”
and zoom in on the map that includes all of the
watershed.
b.
Create a polygon of the water shed by clicking on the polygon shape (
).
Using the picture of the map provided to you
sketch the shape onto the map.
c.
Outline the watershed by clicking on points outlining the watershed.
When
you click on the first point a polygon will be created.
Click “Finish: Hint: it will
be easier to sketch the watershed in the map versus satellite view.
Continue with
the rest of the exercise surveying the watershed.
Method B
Select the
Load Shapefile Boundary option. Upload the files provided by your instructor
to create the Accotink watershed outline.
Continue with
the rest of the exercise
surveying the watershed.
BEGIN SURVEYING
Once you have outlined your watershed you will survey randomly chosen transects
within your watershed.
you should use the default selections for landcover
Tree/Shrub
Grass/Herbaceous
Impervious Buildings
Impervious Road
Impervious Other
Water
Soil/Bare Ground
Click on “configure and begin your survey”
Click “Begin Survey” and evaluate 200
points within the watershed. When you are finished click on
“Report”
Landcover type
Percentage of Watershed*
Lawn
Impervious surface
(buildings, road, etc)
Forested
Total
100%
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Source: In Stream Corridor Restoration: Principles, Processes, and Practices (10/98) By the Federal Interagency Stream
Restoration Working Group (FISRWG) (15 Federal agencies of the U.S.)
2.
Using the figure above, estimate
the percentage of runoff from our watershed.
_______
3.
Given this figure, do you expect to find signs of impairment in our lake?
Explain
4.
Assuming you are not going to tear down buildings or roads, how might you
improve the infiltration of our watershed.
5.
Keeping in mind what you now know about the nitrogen, phosphorus and sulfur
nutrient cycles, particularly the human sources, do you expect to find indicators
of altered regional cycles in our lake?
What might these sources be?
B.
Testing and Interpreting Water Quality
Prior to water testing each group should perform a physical survey of the area,
noting any odors, unusual coloring or films on the water, noticeable disturbances
of the area around the pond, etc
Record any observations from the collection site:
Following your instructor’s directions for collection method and the test
instructions in the water testing kit.
Enter the results below.
Test
Sample 1
Sample 2
Temperature
pH
Nitrate
Phosphate
Chloride
Unpolluted Stream or Pond
pH
Between
6.5 to 8.6
Nitrate
Less than 1 mg/l
Phosphate
Between .01 and .03 mg/
Chloride
Less than 5mg/l
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1
ppm = 1 mg per liter
C.
Using the standards provided above which tests indicate pollution in our lake?
D.
Were these results what you expected? __________ Why or why not?