Question 1Fish kills suddenly occur in a popular estuarine lake fed by a river during summer in East Gippsland. Explain what factors might lead you to suspect poisoning by algae or photosynthetic bacteria, which ones might be responsible, how you would sample to investigate this and what action should be taken by the local authorities, including health advice to the local population and holiday visitors.
Question 2A large dinner table of people celebrating a birthday in Far North Queensland are taken separately to hospital early the next morning complaining of nausea, headaches and convulsions. On investigation by the food authorities, the restaurant owner is told that what they ate at the restaurant was to blame. The restaurant owner vehemently insists that the coral trout and shellfish served to the diners was fresh, having just been caught that morning, the first time fishermen have been allowed by fisheries authorities to fish in estuaries and on the offshore reef for a fortnight after a violent storm and flooding.
A. Explain to the restaurant owner how and why the food he served caused the problem, including the organisms and toxins responsible but that he is not to blame.
B. If the diners sue, who should they sue? What could the body that they sue have done to prevent this?
C. Could they have tested the food, and if so, how? And why did they not do this routinely?
Question 3Environmental activists are concerned that the effluent from a factory maybe toxic. The local Council asks you to conduct a Microtox® test and report if the effluent is toxic. The effluent is released into a lake in such a way that the effluent will never exceed 1.5% of the normal volume of water held in the lake.
A. Explain the basis of this test and describe how you would conduct this test to determine the validity or otherwise of the activists' concerns?
B. What are the advantages and limitations of this method of testing the toxicity of chemicals and mixtures of chemicals?
C. If your results in the Microtox® test demonstrate toxicity, what management actions would you recommend to the Council?
Question 4Give 2 examples of “new generation pesticides” and explain why these are considered different to the older pesticides.
Question 5A. Define bioavailability and discuss why the bioavailability of soil contaminants is important in soil ecotoxicology.
B. A common soil ecotoxicity test uses the compost worm, Eisenia fetida, as the test species. Explain the advantages and disadvantages of using this species to test for soil contamination.
C. What is described by the log Kow of a chemical? How does this factor influence the environmental toxicology of the relevant chemical? What type of chemical is usually characterised by its log Kow? State two examples of such chemicals.
Question 6A. What are the key differences between human toxicology and ecotoxicology when inferring effects from sensitivity data?
B. Define and differentiate between the terms “precision” and “accuracy” in ecotoxicology. Compare the relative precision and accuracy of rapid and conventional ecotoxicity tests at the species and community levels. Give reasons for why they are similar or different.
C. Which factors may lead to the over and underestimation of effects of chemicals in the field when using standard toxicity test data for an organism assumed to be sensitive. List 3 factors that influence the effects and briefly justify your statement
Question 7A. What is meant by primary, secondary and tertiary treatment of wastewater.
Briefly describe which type and how treatment of wastewater is conducted at the Werribee Wastewater Treatment Plant.
B. What is the class of water produced after treatment at Werribee and for what purpose can it be used?
Question 8: Scenario 1A. You are an Environmental Officer for the EPA and have been alerted to the fact that an effluent with high concentrations of the chemical trenbolone which has androgenic properties and the trace metal copper has been discharging for over an year into a local wetland where endemic fish populations live.
With the aid of flow diagrams outline how you would conduct an ecological risk assessment to evaluate if this effluent had affected the fish in the creek.
B. Distinguish between hazard and risk in this case study. Discuss what type of ERA you are conducting and why it is important to do so.
Question 8: Scenario 2A. You are an Environmental Officer for the EPA and have been alerted to the fact that an effluent with high concentrations of the chemical trenbolone which has androgenic properties and the trace metal copper has been discharging for over an year into a local wetland where endemic fish populations live.
With the aid of flow diagrams outline how you would conduct an ecological risk assessment to evaluate if this effluent had affected the fish in the creek.
B. Distinguish between hazard and risk in this case study. Discuss what type of ERA you are conducting and why it is important to do so.
Question 9A toxicity test was conducted using the duckweed Lemna in the laboratory using copper sulfate as the reference toxicant to estimate the toxicity of the unknown effluent X. 5 healthy plants of duckweed with 4 fronds each were added to each test beaker. 10 test beakers were used containing either control M-Hoagland’s medium or the listed concentrations of copper sulfate or effluent in the medium. Beakers were covered and placed in a growth cabinet and incubated at 25°C in continuous illumination. After 7 days the number of fronds was counted in each test beaker and the results are listed below.
Conc. of Copper Sulfate (mg/L) Number of fronds after 7 days
0 (control) 50
0.25 43
0.50 38
1.00 33
1.25 31
2.50 26
Conc. of X (%) Number of fronds after 7 days
0 (control) 52
0.5 50
2.0 48
5.0 44
15 37
30 33
A. Define what it meant by the IC50 and LOEC of a toxicant? Using the results and the graph paper provided plot the results and calculate the IC50 and LOEC of copper sulphate and the effluent E for Lemna in the experiment above.
B. What preliminary conclusion/s can you draw about the toxicity of the effluent E based on the results of this experiment? How would you improve the experimental design?
C. List the advantages and disadvantages of the above toxicity test to evaluate the toxicity of effluent X when compared to the Daphnia acute toxicity test that you conducted in the laboratory.