Analyzing the Deteriorating Effects of Acid Precipitation on Natural Landscaping

Aleesa Muir

Tables and Graphs Created by Aleesa Muir All Pictures Taken by Candus Muir

PURPOSEThe purpose of this investigation is to explore the susceptibility of rocks to weathering from acid rain (3.8–4.3 pH) as compared to “normal” rain (5.1–5.6 pH). This information would be beneficial because over time rocks deteriorate due to acid rain. As more homeowners, businesses, cities, and landscapers are looking to xeriscape to reduce their carbon footprint, they need to be more knowledgeable about rock choices when it comes to landscaping needs based on different environments encountered.

HYPOTHESISIf comparing the susceptibility of weathering with different types of rocks to acid rain, then the weathering of the rock will increase for all of the rocks. Research indicates that acid rain, compared to “normal” rain, accelerates the chemical weathering process; however, minerals in the rock and the formation of the rock influence how susceptible the rock is to deteriorating. Metamorphic rocks will be the least susceptible to weathering because they are formed by heat and pressure, therefore making them more compact. Sedimentary and igneous rocks will vary in susceptibility to weathering based on the formation of the rock. The cementation between the layers in a sedimentary rock will determine the compaction of the rock and how the rock reacts with acid. The rate at which an igneous rock cools will determine if the rock will be more porous or compact affecting its rate of weathering.

VARIABLESIndependent: Type of rocks

Dependent: Weathering/deterioration of rocks

Control: Rock with “normal” rain (5.1–5.6 pH)

Colorado Moss

Siloam Stone

Mountain Granite

Table Mountain

Lava Moss

Pioneer Granite

CONSTANTS• Amount of raining time; • Volume of rock; • Method of measuring weathering of rock; • Amount of acid rain; • Temperature of environment; • Method of pouring acid rain; • Rain system equipment set-up; • Distance the rain is above the rock; • Speed of the acid rain; • Range of acidity level of rain: o Acidic 3.8–4.3 pHo Normal 5.1–5.6 pH

OPERATIONAL DEFINITION Method of Measuring the Deterioration of the Rock

• Measure the mass (g) of the rocks before the experiment;

• Place rocks in respective positions; • Begin acid rain (process) for 7 consecutive days; • Stop acid rain and remove rocks; • Rinse rocks with distilled water; • Allow rocks to dry for 3 consecutive days; • Measure the mass (g) of the rock after

7 days of drying; • Find the percent lost of mass (g).

ENGINEERING the RAIN SYSTEM

Six prototypes were considered prior to the final rain system design. The following eleven slides show the evolution in the development of the rain system.

Control Rain System (5.1-5.6 pH) Acid Rain System (3.8-4.3 pH)

RAIN SYSTEM PROTOTYPE 1

RAIN SYSTEM PROTOTYPE 2

I changed Prototype1 because I found watering cans and thought it would be a better design.

Prototype 2: Changed from a funnel to a watering can.

RAIN SYSTEM PROTOTYPE 3

Acid Rain Control

Igneous A

Igneous B

Metamorphic A

Metamorphic B

Sedimentary A

Sedimentary B

I changed Prototype 2 because I tested the pumps and they were not able to pump enough water.

Prototype 3: Changed the type of pump and how the system was set up.

RAIN SYSTEM PROTOTYPE 3 Cont’d

Side View

Top View

RAIN SYSTEM PROTOTYPE 4

Control “Normal Rain” – 5.1-5.6Acid Rain – 3.8-4.3

I changed Prototype 3 because the water might not be distributed evenly when comparing the rocks at the front and the rocks at the end.

Prototype 4: I changed the system to allow for even water distribution.

RAIN SYSTEM PROTOTYPE 5

Acid Rain – 3.8-4.3 Control “Normal Rain” – 5.1-5.6

I changed Prototype 4 because I wanted a thicker shelf to allow for stability in placement of the rocks.

Prototype 5: I changed the shelf that holds the rocks to Plexiglas to allow for greater stability.

RAIN SYSTEM PROTOTYPE 6

Control “Normal Rain” – 5.1-5.6Acid Rain – 3.8-4.3

I changed Prototype 5 because the Plexiglas was to hard to cut without cracking.

Prototype 6: I changed the platform on which the rocks sit to wood.

RAIN SYSTEM PROTOTYPE 6

Working on Prototype 6

RAIN SYSTEM PROTOTYPE 7

Acid Rain – 3.8-4.3 Control “Normal Rain” – 5.1-5.6

I changed Prototype 6 because I did not want the glue from the wood to affect/react with the acid.

Prototype 7: I changed the platform on which the rocks sit on to a plastic trellis.

FINAL DESIGN

Rain System Diagram Drip Line Tubing (15.2×0.6id cm)

Spray Heads

Port

8-Port Manifold

Manifold ValvesAdjustable

Adjustable Water Flow

Vertical Pipe (15.2×1.3id cm)

PVC Pipe Spacer (12.7×2.5cm)

T-Joint PVCPVC Elbow(1.9-1.3 cm)

PVC Plug

Vinyl Tubing (5.1×1.3id cm)

PVC Elbow(2.5-1.3 cm)

Vinyl Tubing (10.2×1.3id cm)

PVC Pipe (1.3-2.5 cm)

PVC Pipe (1.3-2.5 cm)

Vinyl Tubing (5.1×1.9id cm)

Zip Strip

Fountain PumpVinyl Tubing

(2.5×1.3id cm)

Tub (75.7 L)

BUILDING THE RAIN SYSTEM

Working on Final Prototype 7

1. Cut tubes.• 2 – Vinyl tubing (1.3id cm) [5.1cm long]• 1 – Vinyl tubing (1.3id cm) [10.2cm long]• 1 – Vinyl tubing (1.3id cm) [2.5cm long]• 1 – Vinyl tubing (1.9id cm) [5.1cm long]• 6 – Drip line tubing (0.6id cm) [15.2cm long]

2. Connect tubes and pipes to form tube system.3. Adjust tubes and pipes to desired positions.4. Connect pump to tube system.

• Zip strip tubes to pipes for tight and secure fit.5. Connect spray heads to 15.2cm×0.6cm drip line tubes.6. Connect 6 drip line tubes to 8-port manifold.

• Place caps over 2 unused drip line ports.7. Place tube system and pump into tub centering the vertical PVC

pipe (15.2×1.3id cm) in middle of tub. 8. Measure the top of the vertical PVC pipe to the inside wall of the

tub in order to get the lattice radius.

RAIN SYSTEM - PROCEDURE

9. Draw circumference on lattice using the radius measurements.• Use a pencil, marker, and a string to draw a circle. • Make sure there is a hole in the center for vertical pipe to fit

through.10. Cut lattice circle.11. Cut the 2.5cm PVC pipe 12.7cm long and slide the PVC pipe

over the 15.2×1.3id cm vertical PVC pipe (lattice will rest on this PVC pipe).

12. Place lattice flat over the tube system (in the tub). • Align the end of the vertical pipe with the center hole of the

lattice.• Place the pump cord threw a slot on the side of the lattice and

out of the tub.13. Attach 8-port manifold (on top side over lattice) onto vertical pipe

(threaded), securing the lattice in between PVC pipe (12.7×2.5cm) and 8-port manifold.

RAIN SYSTEM – PROCEDURE Cont’d

14. Cut the 10.2cm PVC pipe (15.2 cm long) for drip lines to go over the rocks.

• Drill and cut 6 slots 1.3cm down from one end of the PVC (spacing the holes equal distance apart around the PVC).

15. Place the 15.2×10.2cm PVC pipe over the manifold so it is resting on the lattice.

16. Attach the 15.2×10.2cm PVC pipe to lattice using zip strips. 17. Position the 6 drip line tubes in the 1.3cm slots on the PVC pipe

(1 drip line per slot).18. Pour water in the tub so the pump is fully submerged.19. Plug pump into outlet to make water flow and drip line

adjustments.20. Repeat steps 1 – 19 to assemble a second rain system.

RAIN SYSTEM – PROCEDURE Cont’d

EXPERIMENTAL PROCEDURE1. Ensure all rocks have an approximate volume of 100 cmᶟ using

Archimedes principle.2. Identify the current pH level of the distilled water.

• Fill each of the two tubs with approximately 22.7 L of distilled water.

3. Create a rainwater solution using sulfuric acid and distilled water.• Normal (control) rain: 5.1 – 5.6 pH• Acid rain: 3.8 – 4.3 pH • Record the pH levels of each type of rain solution in data table.

4. Set up two rain systems (see diagram 1).5. Measure the initial mass (g) of each rock type used in trial.

• Record the mass (g) of each rock in the data table.6. Verify the rain system is operating as designed.7. Place each rock type on a predetermined station number

identified within the rain system.

EXPERIMENTAL PROCEDURE Cont’d

8. Initiate the rain systems by plugging in each pump.• Make adjustments (rock or water) to ensure each rock is

receiving optimal water coverage.• Allow the rain system to run for seven (7) consecutive days.• Verify three (3) or more times per day to insure that the rain system is still operating correctly.

9. Record the pH of rain in data table one time each day for the 7 days.• Add sulfuric acid to each tub to achieve the correct range of pH levels.o Normal (control) rain: 5.1 – 5.6 pHo Acid rain: 3.8 – 4.3 pH

Preparing to make the acid rain.

EXPERIMENTAL PROCEDURE Cont’d

10. Rinse each rock with distilled water after the conclusion of the 7 days (168 hours.)

11. Allow the rocks to dry for 7 days.12. Identify the ending mass (g) of each rock.

• Record the mass (g) of each rock in data table.13. Repeat steps 2 - 12 three more times (for a total of 4 trials.)

• Based on the previous trial rock location, move each type of rock counter clock wise to a different station number after each trial.

Chiseling the rocks to create a volume of 100 cm3.

Problems/SolutionsProblem: Rocks were sometimes hard to break

• Solution: Use a chisel Problem: Rocks had weak points and would break into pieces less than 100cmᶟ

• Solution: Get more rocksProblem: The wood platform could possibly cause chemical changes

• Solution: Used all plasticProblem: Distilled water was too acidic for the control

• Solution: Bought different brand; 3rd attempt home delivery service Problem: 60 GPH pump was too weak

• Solution: Bought a stronger pumpProblem: Spray heads possibly varied in pressure

• Solution: Rotated the rocks clockwise each trialProblem: pH tester stopped working

• Solution: Borrowed a pH probe from the high school; recalibrated pH probe as needed; borrowed a second pH probe when the probe would not recalibrate

Analyzing the Average Percent Loss (%) of Various Rocks - Comparing Acid to Normal Rain

Type of Rock Rock NamePercent Loss (%)

Acid Control

Sedimentary

Colorado Moss (CM) Sandstone

0.25 0.16

Siloam Stone (SS) Limestone

0.08 0.04

Metamorphic

Mountain Granite (MG)

Gneiss0.11 0.10

Table Mountain (TM)

Quartzite0.00 0.00

Igneous

Lava Moss (LM)

Vesicular Basalt0.21 0.11

Pioneer Granite (PG)

Granite0.07 0.08

TABL

E

Co

lora

do

Mo

ss (C

M)

S

an

dS

ton

e

Silo

am

Sto

ne

(

SS

)

L

ime

sto

ne

Mo

un

tain

Gra

nite

(M

G)

G

ne

iss

Ta

ble

Mo

un

tain

(

TM

)

Q

ua

rtzite

La

va

Mo

ss (

LM

)

V

esic

ula

r B

asa

lt

Pio

ne

er

Gra

nite

(

PG

)

G

ran

ite

Sedimentary Metamorphic Igneous

0

0.05

0.1

0.15

0.2

0.25

0.3

0.25

0.0800000000000001

0.11

0

0.21

0.07

0.16

0.04

0.1

0

0.11

0.0800000000000001

Analyzing the Average Percent Loss (%) of Various Rocks - Comparing Acid to Normal Rain

Percent Loss (%) Acid

Percent Loss (%) Control

Type of Rock

Pe

rce

nt

Lo

ss

(%

)

Independent Variable

Type of

Rain

Average (Mean) Mass (g) of Rock

Average ∆ in Mass

(g)

Plus or

Minus

Random Error (RE)

UnitsLow

RangeLow %

High Range

High %

Colorado Moss (CM)

Sandstone

Acid 242.1 0.6

±

0.5

Grams (g)

0.1 0.04 1.1 0.45

Control 247.6 0.4 0.3 0.1 0.04 0.7 0.28

Siloam Stone (SS)

Limestone

Acid 238.8 0.2 0.0 0.2 0.08 0.2 0.08

Control 240.3 0.1 0.1 0.0 0.00 0.2 0.08

Mountain Granite (MG)

Gneiss

Acid 276.7 0.3 0.3 0.0 0.00 0.6 0.21

Control 288.4 0.3 0.1 0.2 0.07 0.4 0.14

Table Mountain (TM) Quartzite

Acid 286.2 0.0 0.0 0.0 0.00 0.0 0.00

Control 284.5 0.0 0.1 0.0 0.00 0.1 0.04

Lava Moss (LM)

Vesicular Basalt

Acid 188.3 0.4 0.4 0.0 0.00 0.8 0.42

Control 189.5 0.2 0.1 0.1 0.05 0.3 0.16

Pioneer Granite (PG)

Granite

Acid 274.7 0.2 0.2 0.0 0.00 0.4 0.15

Control 263.4 0.2 0.1 0.1 0.04 0.3 0.11

PRECISION of TRIALS

Colorado Moss

Siloam Stone

Mountain Granite

Table Mountain

Lava Moss Pioneer Granite

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

Comparing Average Percent Loss (%) Showing Precision of Various Rock Types Exposed to Acid Rain

Type of Rock

Pe

rce

nt

Lo

ss

(%

)

Colorado Moss

Siloam Stone

Mountain Granite

Table Mountain

Lava Moss

Pioneer Granite

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

Comparing Percent Loss (%) Showing Precision of Various Rock Types Exposed to Normal Rain

Type of Rock

Pe

rce

nt

Lo

ss

(%

)

Precision:• Low Random Error: Showed consistency

o Acid: 0.0 – ‘SS’ and ‘TM’o Control: 0.1 – ‘SS,’ ‘MG,’ ‘TM,’ ‘LM,’ and ‘PG.’

• High Random Error: o Acid: ‘LM’ – 0.4 (porous); ‘CM’ – 0.5 (cement) o Control: ‘CM’ – 0.3

Acid Rain: • No statistical difference: ‘CM,’ ‘SS,’ ‘MG,’ ‘LM,’ ‘PG’• Statistical difference: ‘TM’ compared to ‘SS’ and ‘CM’

Normal Rain (Control): • No statistical difference: ‘CM,’ ‘SS,’ MG,’ ‘LM,’ ‘PG’ • Statistical difference: ‘TM’ compared to ‘MG’ and ‘LM’

STATISTICAL ANALYSIS

LIMITATIONS

• Type of rocks• pH of rain• Type of acid• Volume of rocks (100cm3)• Pressure of sprinkler system• Number of days of rain

CONCLUSION• The general pattern of the data shows that the type of rock (independent variable) did affect the deterioration of the rocks (dependent variable). As the type of rock (IV) varied, the weathering/deterioration of the rocks (DV) varied. All rocks other than ‘TM’ decreased in mass. • The data collected partially supported the original hypothesis. When comparing the metamorphic rocks to the other types of rocks, only one metamorphic rock weathered the least as measured by average percent (%) loss. • Metamorphico Table Mountain – 0%o Mountain Granite – 0.11

• Sedimentary o Colorado Moss – 0.25%o Siloam Stone – 0.08%

• Igneous o Lava Moss - 0.21% o Pioneer Granite - 0.07%

CONCLUSION Cont’d• These findings lead me to conclude that the susceptibility to

weathering depends more on the minerals in the rock. • How fast the rock deteriorates does not appear to be due to the

type of rock. • Most of the rocks tested did weather more with acid rain when

compared to the control (normal rain), leading me to hypothesize that this pattern would be evident in all types of rocks (including ‘Pioneer Granite’ and ‘Table Mountain’) if given enough time.

• Further testing is necessary, including an extended period of time, in order to confirm results.

• Based on the data collected, my revised hypothesis is if comparing the susceptibility of weathering with different types of rocks to acid rain, then the rocks will weather depending on what minerals make up the rock, and possibly the density of the rock.

FURTHER RESEARCH

• Categorize rocks based on mineral composition

• Test increasing pH concentrations to see if a mathematical correlation exists between pH level and the amount of deterioration of the rock

• Analyze if the density of the rock affects the amount of deterioration associated with acid rain

APPLICATIONInvestigating how different types of rock weather because of acid rain would be beneficial to homeowners, businesses, cities, and landscapers. Rocks deteriorate over time due to acid rain. The principle behind this test was to find out which type of rock weathered the least in order to preserve the landscape as designed, while saving money in the long term. Based on the data, most rocks weathered more with acid rain compared to normal rain. The only rock that did not weather was ‘Table Mountain’. ‘Table Mountain’ appears to be a rock resistant to acid rain; therefore, this rock would be an ideal choice for longevity.

This concludes my presentation.