The question is as follows..
You have just been hired by a major chemical comp. Located on the west coast. In your first week your company is being accused of leaking toxic effluent into an inlet 5 km upstream of a major commercial salmon hatchery. In the past week thousands of young salmon have died. Everyone is upset at your company- the public, the environmentalists, the government and the politicians. Legal action is being threatened.
Your CEO insists that nothing in the effluent is toxic. In fact, he pointed out that it is treated before it is discharged. He is determined to vindicate the company, so he assembles a team to conduct some experiments to provide evidence that the effluent is not killing the salmon. You, should you choose to accept the assignment is to help in the design of these experiments and collection of data.
Knowing what you know about water quality and source protection, lists some tests and outline procedures that you think might help vindicate your company. Also, comment on whether the public etc... is justified in their accusations.
Here are some of my points that I think are valid...
-chemical tests on fish... mass spectrometer... reference comparing to poisons
- It can't be a chemical that bio accumulate because so many died so quickly...ie- lead aluminium, arsenic, mercury
- -test for pesticides, hydrogen sulphide... and other chemicals that remove oxygen in the river- suffocation
- tests vegetation around riverbank and other org. around
- LD50 of daphnia magna- indicator of toxins
- Micro-tox test.
- Chlorine dioxide--- pulp mill
- Look at logs kept by company.
- Verify calibration of company's instruments.
- Look into what the company makes, and their processes
- Interviews with employees who are involved with aspects of production
- Time of season... runoff???
- biological oxygen demand (BOC)
- chemical oxygen demand (COD)
- BOC/COD ratio
- total organic carbon (TOC)
- dissolved oxygen (CO)
- total dissolved solids (TDS)
- chemical components of the effluent
- measurement/calculation of the natural biota (determining if unusually high numbers are being found or unusual biota for the location are being found)
- -toxicity tests may also be considered
- Samples should be taken from upstream of the site, downstream, at the point of discharge from the chemical plant and at the hatchery
- collect samples of the dead fish and measure their tissues to determine if any chemicals or substances can be found in the tissue that can tie them with the chemical plant.
- the adjacent land uses to the hatchery, the plant and even upstream.. The land uses could include agricultural practices that may increase runoff of fertilizers, pesticides or manure into the river to cause contamination. Possibly the effluent can become harmful if it combines with fertilizer or some other substances and may only become enhanced due to that factor.
This is an interesting question, and I think worthy of lots of thought. My thinking divided the problem into three parts (a) test the effluent (b) test the fish (c) test the soil/riverbed sediment. There are many things that can kill fish, especially fish in the early stages of development, fish farms are well known for catching diseases.
In the tests you have listed, I think you should divide them up into the catagories on what you will be testing. When testing the ...
A description of tests needed to check for poision are given.
Chi square test statistics for Poisson distribution
At a local supermarket receiving dock, the number of truck arrivals per day is recorded for 100 days.
(a) Estimate the mean from the sample. (b) Calculate the expected frequencies assuming a Poisson
distribution. Show your calculations in a spreadsheet format. (c) Carry out the chi-square test, combining
end categories as needed to ensure that all expected frequencies are at least five. Show your
degrees of freedom calculation. (d) At α = .05, can you reject the hypothesis that arrivals per day
follow a Poisson process? Trucks
Arrivals per Day at a Loading Dock
Number of Arrivals
0 1 2 3 4 5 6 7 Total
Frequency 4 23 28 22 8 9 4 2 100