APES
Name
Date
Period
Measuring Toxicity in Aquatic Ecosystems
Introduction
Environmental Scientists are concerned with the toxicity of commonly used substances. Toxicity refers to the ability of a
chemical to cause injury or death, especially by chemical means. Aquatic ecosystems are particularly vulnerable to toxic
chemicals. As economic consumers, we can have an impact in helping the environment by choosing products that are less toxic.
In this lab we will measure the toxicity of four household cleaning substances: 409 All Purpose Cleaner, vinegar, bleach and
Simple Green. Each group will test one cleaner at varying concentrations, and we will use class data for comparative purposes.
We will be using a small aquatic organism, brine shrimp to test the toxicity of each of the various cleaning substances. You will
design a controlled experiment to test one of the substances and then use class data for comparative purposes. The results of this
experiment will be presented in a formal lab report.
Write an Introduction to this lab using the information above as well as your text (Chapter 14) and any necessary internet
research. Include definitions and explanations of the following terms: bioassay, median lethal dose, poison, dose- response curve,
and threshold. Your Introduction should be 2-3 paragraphs typed.
Complete the Experimental Design worksheet below.
Title/ Purpose: (What are you hoping to learn?)
Hypothesis: (What do you expect to happen?)
Independent Variable (what you will be testing):
Treatments of I.V.
(indicate the
control treatment):
Number of trials
you will conduct
for each treatment:
Dependent Variable (your method of measurement/ what you data will be):
Constants (or controls for all treatments):
Materials and Procedure List the materials you will use and write a step-by-step procedure of your experiment. Note:
Measurements should be taken after 30 minutes and 24 hours. For the sake of consistency, all groups will use the same
concentrations: 0%, 1%, 2%, 5% and 10%. Use additional paper and include in your lab report.
Data / Results
Create a graph to illustrate your data and the data collected by other groups. Use your graph to calculate the
median lethal dose LD50 for each of the chemicals. (See page 357). Attach graphs to the Data section of
your lab.
Discussion
This is a written summary and analysis of results that should be thorough and detailed. Usually two to four
good paragraphs will be appropriate. Answer the questions:
• What does the data tell you? Interpret results by including comparisons (for example, to other
scientific research) and speculations.
• Why do you think you obtained these results? Include explanation of possible error or deviation
from expected results.
• Attach on a separate sheet of paper.
Conclusion
What is the principle finding or conclusion of the lab activity? This should be a clear evaluation of your
hypothesis statement and a summary of your lab findings.
Attach on a separate sheet of paper.
Vocabulary Review
Be certain you know the definitions of the following terms.
Bioassay
median lethal dose (LD50)
poison
dose- response curve
threshold level
linear dose response
non-linear dose response
Data Table: % Mortality of Brine Shrimp in Various Cleaning Solutions- 1 hour Observations
0ml Cleaner
50 ml Water
(Control)
[0% Cleaner]
Concentration/
Solution
Exp 1
409 Cleaner
% mortality
Exp 2
% mortality
Average
% mortality
Exp 1
Simple Green
% mortality
Exp 2
% mortality
Average
% mortality
Exp 1
Vinegar
% mortality
Exp 2
% mortality
Average
% mortality
Exp 1
Bleach -
% mortality
Exp 2
% mortality
Average
% mortality
0.5 ml Cleaner
49.5 ml Water
1 ml Cleaner
49 ml Water
2.5 ml Cleaner
47.5 ml Water
5 ml Cleaner
45 ml Water
[1% Cleaner]
[2% Cleaner]
[5% Cleaner]
[10% Cleaner]
Observations
Data Table: % Mortality of Brine Shrimp in Various Cleaning Solutions- 24 Hour Observations
0ml Cleaner
50 ml Water
(Control)
[0% Cleaner]
Concentration/
Solution
0.5 ml Cleaner
49.5 ml Water
1 ml Cleaner
49 ml Water
2.5 ml Cleaner
47.5 ml Water
5 ml Cleaner
45 ml Water
[1% Cleaner]
[2% Cleaner]
[5% Cleaner]
[10% Cleaner]
Observations
Exp 1
% mortality
Exp 2
Chlorox
Cleaner w/
Bleach
% mortality
Average
% mortality
Exp 1
Simple Green
% mortality
Exp 2
% mortality
Average
% mortality
Exp 1
Vinegar
% mortality
Exp 2
% mortality
Average
% mortality
Exp 1
Bleach -
% mortality
Exp 2
% mortality
Average
% mortality
Data Table: % Mortality of Brine Shrimp in Various Cleaning Solutions- 1 Hour Data
Concentration/
Solution
0ml Cleaner
50 ml Water
(Control)
[0% Cleaner]
0.5 ml Cleaner
49.5 ml Water
1 ml Cleaner
49 ml Water
2.5 ml Cleaner
47.5 ml Water
5 ml Cleaner
45 ml Water
[1% Cleaner]
[2% Cleaner]
[5% Cleaner]
[10% Cleaner]
0
25
35
40
50
0
20
45
60
75
0
35
45
58
65
0
90
100
100
100
Exp 1
409- All
Purpose
Cleaner
% mortality
Exp 2
% mortality
Average
% mortality
Exp 1
Simple Green
% mortality
Exp 2
% mortality
Average
% mortality
Exp 1
Vinegar
% mortality
Exp 2
% mortality
Average
% mortality
Exp 1
Bleach -
% mortality
Exp 2
% mortality
Average
% mortality
Observations