Name: ________________
Can Lake Life Remain Despite Acid Rain?
Question: Why does acid rain harm some lakes more than others?
Background: Acid rain is caused by chemical pollutants in the air. These chemical
pollutants are mainly sulfur oxides and nitrogen oxides formed when coal and other
fossil fuels are burned in factories and cars. When sulfur oxide and nitrogen oxide
dissolve in water, they form sulfuric acid and nitric acid. Rainwater in unpolluted
areas has a pH of 5.5. Rainwater with a pH of lower than 5.5 is considered acid
rain.
When acid rain falls and collects in lake environments, it can change the pH of the
lake water. This impacts the plants and animals that live in the lake.
Activity: The Adirondack lakes located in the Adirondack Mountains of New York.
People that use the lakes have noticed than some of the lakes have less plants and
animals compared to other lakes. Compare the following lakes: Brant Lake, Big
Moose Lake, and Blue Mountain Lake in Data Table 1 and answer the following
questions.
Characteristic
Brant Lake
Big Moose Lake
Blue Mountain Lake
Size
5.7 km2
5.2 km2
5.5 km2
Elevation
243 m
556 m
545 m
Water Color
Clear
Brown
Clear
pH
7.6
5.5
7.2
Algae growth
Moderate
Low
Low
Phosphorus
Low
Low
Low
levels
Nitrogen levels Low
Moderate to high
moderate
Questions:
1. What are four characteristics Big Moose Lake and Blue Mountain Lake have in
common?
2. What are four characteristics Brant Lake and Blue Mountain Lake have in
common?
3. Algae typically grows in high nitrogen levels. Although Big Moose Lake has
moderate to high nitrogen levels, it has low algae growth. Make a hypothesis to
explain low algae growth in Big Moose Lake.
4. When water pH is low, the decomposition rates (breakdown of plant and animal
debris) slow down. Explain how the low pH of Big Moose Lake could affect its
appearance.
Organism
Trout
Bass
Perch
pH 6.5
pH 6.0
pH 5.5
pH 5.0
pH 4.5
pH 4.0
Frogs
Salamanders
Clams
Crayfish
Snails
Mayflies
Source: EPA, Acid Rain Program
5. Which animal is the most sensitive to acid rain?
6. Which animal is the least sensitive to acid rain?
7. Based on this information, which animals would you find in Brant Lake, but not in
Big Moose Lake?