Vernier Software and Technology
Vernier Software & Technology

Physical Profile of a Lake

Figure from experiment 21 from Biology with Vernier


Lakes are different from streams and rivers because the water they contain is not quickly replaced by fresh water. In a lake, the flushing and changing of water can take anywhere from a year to 100 years, depending on the size of the lake and the watershed that flows into it. This makes lakes very susceptible to damage by pollution. Acid deposition is common in lakes and can result in acid shock if a lake has a low alkaline content or if the soils surrounding it have very little acid-neutralizing capacity. Acid shock can damage or kill aquatic life in the lake.

The density of water increases as the temperature decreases. When water reaches 4°C its density begins to decrease until it freezes. Because the density of water differs with temperature, lakes undergo a process known as thermal stratification. In summer, thermal stratification separates a lake into different regions at different depths. This prevents mixing of water and nutrients between the lake surface and the lake bottom. In winter, the water temperature decreases at the surface, and the cooler water sinks to the lake bottom. Because the water at the bottom of the lake is warmer than the sinking surface water, it begins to rise to the surface. This causes a mixing of the water, which brings nutrients from the bottom to the surface, and dissolved oxygen in the surface waters to the bottom.

In this experiment, you will investigate thermal stratification and how it affects the placement of nutrients and dissolved oxygen. You will be taking water samples at various depths throughout the lake. The water will then be analyzed for dissolved oxygen (DO), pH, and total dissolved solids (TDS). An extended Temperature Probe will then be used to measure water temperature at the same depths the water samples were taken from.


In this experiment, you will

  • Use a Water Depth Sampler to collect water samples at different depths in the lake.
  • Measure DO, pH, and TDS of the collected water samples.
  • Use a Temperature Probe to measure water temperature at various depths.

Sensors and Equipment

This experiment features the following Vernier sensors and equipment.

Option 1

Option 2

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

Standards Correlations

See all standards correlations for Biology with Vernier »

Biology with Vernier

See other experiments from the lab book.

1Energy in Food
2Limitations on Cell Size: Surface Area to Volume
3Acids and Bases
4Diffusion through Membranes
5Conducting Solutions
6AEnzyme Action: Testing Catalase Activity
6BEnzyme Action: Testing Catalase Activity
8The Effect of Alcohol on Biological Membranes
9Biological Membranes
11ACell Respiration (O2)
11BCell Respiration (CO2)
11CCell Respiration (Pressure)
11DCell Respiration (CO2 and O2)
12ARespiration of Sugars by Yeast
12BSugar Fermentation
13Population Dynamics
14Interdependence of Plants and Animals
15Biodiversity and Ecosystems
16AEffect of Temperature on Respiration
16BEffect of Temperature on Fermentation
17Aerobic Respiration
18Acid Rain
19Dissolved Oxygen in Water
20Watershed Testing
21Physical Profile of a Lake
23AEffect of Temperature on Cold-Blooded Organisms
23BEffect of Temperature on Cold-Blooded Organisms
24ALactase Action
24BLactase Action
25Primary Productivity
26Control of Human Respiration
27Heart Rate and Physical Fitness
28Monitoring EKG
29Ventilation and Heart Rate
30Oxygen Gas and Human Respiration
31APhotosynthesis and Respiration (O2)
31BPhotosynthesis and Respiration (CO2)
31CPhotosynthesis and Respiration (CO2 and O2)

Experiment 21 from Biology with Vernier Lab Book

<em>Biology with Vernier</em> book cover

Included in the Lab Book

Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.

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Dev Reference: VST0059

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