Vernier Software & Technology

# Primary Productivity

## Introduction

Oxygen is vital to life. In the atmosphere, oxygen comprises over 20% of the available gases. In aquatic ecosystems, however, oxygen is scarce. To be useful to aquatic organisms, oxygen must be in the form of molecular oxygen, O2. The concentration of oxygen in water can be affected by many physical and biological factors. Respiration by plants and animals reduces oxygen concentrations, while the photosynthetic activity of plants increases it. In photosynthesis, carbon is assimilated into the biosphere and oxygen is made available, as follows:

${\text{6 }}{{\text{H}}_{\text{2}}}{\text{O }} + {\text{ 6 C}}{{\text{O}}_{\text{2}}}\left( {\text{g}} \right) + {\text{ energy}} \to {{\text{C}}_{\text{6}}}{{\text{H}}_{{\text{12}}}}{{\text{O}}_{\text{6}}} + {\text{ 6 }}{{\text{O}}_{\text{2}}}\left( {\text{g}} \right)$

The rate of assimilation of carbon in water depends on the type and quantity of plants within the water. Primary productivity is the measure of this rate of carbon assimilation. As the above equation indicates, the production of oxygen can be used to monitor the primary productivity of an aquatic ecosystem. A measure of oxygen production over time provides a means of calculating the amount of carbon that has been bound in organic compounds during that period of time. Primary productivity can also be measured by determining the rate of carbon dioxide utilization or the rate of formation of organic compounds.

## Objectives

In the Preliminary Activity, you will gain experience using a Dissolved Oxygen Probe as you measure the DO level of a water sample provided by your teacher. You will also learn how to calculate respiration rate, gross productivity, and net productivity.

After completing the Preliminary Activity, you will first use reference sources to find out more about primary productivity before you choose and investigate a researchable question dealing with primary productivity.

## Sensors and Equipment

This investigation features the following Vernier sensors and equipment.

### Option 2

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

## Investigating Environmental Science through Inquiry

See other experiments from the lab book.

 1 Seasons and Angle of Insolation 2 A Local Weather Study 3 Investigating Dissolved Oxygen 4 Water Quality 5 Long Term Water Monitoring 6 Water Treatment 7 Investigating Salinity 8 Soil Temperature 9 Soil Salinity 10 Soil pH 11 Soil Moisture 12 Soil and Acid Rain 13 Managing Garden Soil Moisture 14 Cell Respiration (CO2) 15 Biodiversity in Ecosystems 16 Biochemical Oxygen Demand 17 Water Cycle Column Investigations 18 Decomposition Column Investigations 19 Ecocolumn Investigations 20 Global Warming 21 UV Investigations 22 Comparing Sunscreens 23 Primary Productivity 24 Modeling Population Growth 25 Insulation Study 26 Fossil Fuels 27 Energy Conversion 28 Wind Power 29 Photovoltaic Cells 30 Investigation of Passive Solar Heating 31 The Effect of Acid Deposition on Aquatic Ecosystems 32 Measuring Particulates 33 Investigating Indoor Carbon Dioxide Concentrations 34 A Pollution Study

### Investigation 23 from Investigating Environmental Science through Inquiry Lab Book

#### 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.