subject name: environment and you this is a research project. Lake Ecology: A Ca
ID: 278019 • Letter: S
Question
subject name: environment and you
this is a research project.
Lake Ecology: A Case Study
Assignment 2
Overview
The objective of this assignment is to familiarize you with environmental research and analysis. Your goal is to discover why immature fish in a test fish hatchery are dying. You will accomplish this task by going through a case study in which water samples were obtained from a local lake where a test hatchery was located and various water sampling tests were conducted in series of experiments.
You will be given background information on the procedures performed as well as the data that was obtained from the experiments that were conducted in order to accomplish your goal.
Essentially, water samples were taken and specific tests of those water samples were conducted. You will compare the test results given to the literature provided in this handout to determine which of these tests are out of the theoretical norm.
Lake Case Study, Part 1
This part of the case study is devoted to analyzing the data given to form a hypothesis about what is causing the breathing problems in the fish. Because of the suspicion that something in the water is leading to the breathing difficulties that the fish are experiencing, the fish hatchery supervisor ordered samples of the lake water be taken and analyzed. She mentions a number of potential causes for the problem.
Dissolved Oxygen: If the levels of dissolved oxygen in the lake were too low, the fish would have trouble breathing and may die.
Metals: The presence of dissolved metals in the lake may cause problems if the metal concentrations are high enough.
Pesticides: High levels of pesticides have been shown to be harmful to fish.
Your assignment is to discover which one of these possibilities (if any) is the cause of the fish dying.
The background information provided will help you solve the mystery.
Analytical Laboratory
Ten different water samples from various areas around the lake were taken and sent to an analytical laboratory. Three types of analysis were performed.
STOP! Think about it: Why were 10 different water samples taken? Why were they taken from various areas of the lake?
For statistical purposes, the more samples you take; the better. The greater the sample size, the more data there is. However, in a research setting, it is not economically feasible to collect and run tests on a very large number of samples. A good rule of thumb to follow is to test in triplicate. If you can test more than that, your data is just that much more reliable.
Another consideration that needs to be taken in to account is where the samples were taken. Do you want all of your test samples to be taken in the same vicinity or do you want to spread them out? For thorough testing, you would want a wide range of sample areas (take some near the shore, near the dock, in the middle of the lake, etc…).
* Dissolved Oxygen: You can titrate for dissolved oxygen. The results are reported in ppm (parts per million) oxygen. 1 ppm = 0.001 g/liter
* Metals: You can analyze for four different metals: calcium, lead, mercury, and iron. The method used for metal analysis is atomic absorption (AA) spectroscopy, a modern analytical method using an instrument. In an atomic absorption spectrophotometer a liquid sample is introduced into a flame. When the sample enters the flame, the water immediately evaporates and the metals in the sample vaporize. This produces a high concentration of metallic atoms in the flame. A beam of light is directed through the flame and the metallic atoms absorb some of this light. The amount of light that is absorbed tells you the concentration of metals originally dissolved in the liquid sample. A summary of the method follows:
Unknown sample is introduced into flame.
Flame vaporizes metals in sample producing metallic atoms.
Metal atoms absorb part of a light beam shining through flame.
Light absorbed is measured to determine how much metal was in sample.
The AA results are reported in parts per million, ppm (1 ppm = 0.001 g/liter), except for mercury, which is reported in parts per billion, ppb (1 ppb = 0.000001 g/liter).
* Pesticides: An extremely important analytical method called Gas Liquid Chromatography (GLC) is used to determine the pesticide levels in the water. Three common environmental contaminants DDT, Dieldrin, and PCB's are determined. In GLC, a liquid sample containing a mixture of pesticides is injected into the instrument with a syringe. Inside the instrument the pesticides move through a column at different rates, which separates them from each other so that they exit the column at different times. When the pesticides come out of the column, they pass through a detector, which sends a signal to a recorder. The signal is registered as a peak on a piece of moving chart paper. The position of the peaks tells you what the substances are and the size of the peaks tells you how much of each is in the mixture. Pesticide levels are reported in parts per trillion, ppt. 1 ppt = 0.000000001 g/liter.
Results
This week's analyses of the lake water show results in the following ranges:
Temperature 17–20 °C
Calcium 20–26 ppm
Lead 0.6–0.72 ppm
Mercury 2-4 ppb
Iron 1.2–1.8 ppm
Pesticides low (fractional ppt range)
D.O. more than adequate for aquatic life
Assignment
1. Analyze the data from the water samples provided and do some research to figure out exactly what the problem is. Use the Library Literature below (Note: you don’t have to go to library, but refer to the information below in this handout) to research information on various metals, pesticides, and dissolved oxygen.
2. Using the experimental information (presented in Results above) about the lake water and literature information provided (below), develop a hypothesis about what is causing breathing difficulties for the fish in the lake.
STOP! PLEASE DO NOT PROCEED TO PART II OF THIS ASSIGNMENT BEFORE FORMULATING YOUR HYPOTHESIS. You will need to write this hypothesis while preparing the report for this assignment.
Library Literature
Use the library literature below to look up references for the chemicals analyzed. Research the information on various metals, pesticides, and dissolved oxygen to develop a hypothesis about what is causing the breathing difficulties for the fish in the lake.
Dissolved Oxygen
Heavy Metals- Calcium, Lead, Iron, Mercury
Pesticides
Lake Case Study, Part II
After some initial experiments the cause of the breathing problems has been narrowed to the presence of either iron or lead in the water of the lake. The results of these experiments are not clear-cut however, so some additional controlled experiments in which the conditions are known must be done to try to establish the culprit.
In this part of the experiment, the laboratory was used again. This time fish tanks were available to observe the fish under controlled conditions to see how they behave (in particular, if they die). The number of fish who die in a tank under a given set of conditions can be compared to a tank that has all the same conditions except for the variable being tested. As an example, if a researcher wanted to test the effect of a 100 ppm concentration of Ca on fish at 20 °C, they could look at two tanks: a control tank containing plain water at 20°C and another tank containing water with 100ppm Ca at 20°C. If significantly more fish die in the 100 ppm Ca tank than in the control tank, then we would suspect that 100ppm Ca is toxic to fish.
Controlled tests on the fish under appropriate conditions were performed to decide whether iron or lead was causing the breathing problems. Below are the data that were obtained.
Table 1. Effects of iron on fish.
Chemical
Level (ppm)
Duration (Days)
Mortality (%)
Control Mortality (%)
Iron
1.2
1
7.5
0.0
Iron
1.2
2
12.5
0.0
Iron
1.2
3
20.0
0.0
Iron
1.2
4
25.0
0.0
Iron
1.2
5
35.0
0.0
Iron
1.2
6
50.0
0.0
Iron
1.2
7
60.0
0.0
Iron
1.8
1
7.5
0.0
Iron
1.8
2
15.0
0.0
Iron
1.8
3
20.0
0.0
Iron
1.8
4
32.5
0.0
Iron
1.8
5
35.0
0.0
Iron
1.8
6
50.0
0.0
Iron
1.8
7
55.0
0.0
Table 2. Effects of lead on fish.
Chemical
Level (ppm)
Duration (Days)
Mortality (%)
Control Mortality (%)
Lead
0.6
1
0.0
0.0
Lead
0.6
2
2.5
0.0
Lead
0.6
3
5.0
0.0
Lead
0.6
4
5.0
0.0
Lead
0.6
5
5.0
0.0
Lead
0.6
6
5.0
0.0
Lead
0.6
7
7.5
0.0
Lead
0.72
1
0.0
0.0
Lead
0.72
2
2.5
0.0
Lead
0.72
3
5.0
0.0
Lead
0.72
4
5.0
0.0
Lead
0.72
5
5.0
0.0
Lead
0.72
6
7.5
0.0
Lead
0.72
7
7.5
0.0
Assignment: Write a report
Write up a scientific report describing the data given and stating your conclusions based on these results. Your conclusions should be supported by the data provided. Please refer to the rubric posted on Canvas to prepare you report.
The report must be typed, double spaced, and prepared in a word document. The report will be due on Canvas on a date listed on the course schedule. Late work will not be accepted.
The report should follow the following outline as well as a rubric posted on Canvas to earn all 40 points. Please use subheadings appropriately for different sections of the report. A sample report is posted on Canvas (inside week 4 module) for you to refer to for formatting.
Student name
Course
Date
Report title
Introduction: Give the background to the topic. Why is it important? Briefly tell what you are going to do in the experiment. Testing a hypothesis? Predicting a phenomenon? Write down your hypothesis in this section.
Methods: Explain what organisms, materials, and procedures were used in the experiments. How did you do it?
Results: Present the findings. Point out key or unexpected results. Include tables, graphs, etc. in this section.
Discussion and conclusion: What was the significance of your results? Explain the importance of the experiment, and discuss whether or not your outcome was consistent with what was expected.
Grading criteria for the report are identical to those used by the English department:
Focuses and develops ideas effectively, showing creativity and insight.
Organizes ideas in a purposeful and logical manner, moving the reader (listener) smoothly through the text (subject).
Uses sentence structure and word choice effectively with a sense of control.
Commits few, if any, errors in grammar/usage and mechanics.
Chemical
Level (ppm)
Duration (Days)
Mortality (%)
Control Mortality (%)
Iron
1.2
1
7.5
0.0
Iron
1.2
2
12.5
0.0
Iron
1.2
3
20.0
0.0
Iron
1.2
4
25.0
0.0
Iron
1.2
5
35.0
0.0
Iron
1.2
6
50.0
0.0
Iron
1.2
7
60.0
0.0
Iron
1.8
1
7.5
0.0
Iron
1.8
2
15.0
0.0
Iron
1.8
3
20.0
0.0
Iron
1.8
4
32.5
0.0
Iron
1.8
5
35.0
0.0
Iron
1.8
6
50.0
0.0
Iron
1.8
7
55.0
0.0
Explanation / Answer
Ans.The case study is about fishes living in a lake which are dying due a suspicious reason. The unknown reason can include any of the 3 affects which are:
1)Low Dissolved Oxygen: If the levels of dissolved oxygen in the lake were too low, the fish would have trouble breathing and may die.
2)High concentration of Metals: The presence of dissolved metals in the lake may cause problems if the metal concentrations are high enough.
3)High concentration of Pesticides: High levels of pesticides have been shown to be harmful to fish.
Now we have selected the sample of the water from 10 different areas of the lake so that we can get the actual reason of this cause . By taking various sample our report can have a better accuracy and precision of results. Calculating the amount of metals and pesticides in water from differents regions of lake can be helpful in knowing thw cause of the problems that from where these hazardous elements are being added and we can eliminate them from being added to the water. So we took samples from different parts and tested the presence of various metals in water and upto how much concentration.
After getting the results from the lab we can conclude that the Dissolved Oxygen is not a problem as it is sufficient to support forms in water. Next we came to metals concentration , with the data given we can comment that the amount of metals like Iron and Lead is much higher than the normal concentration in water and thus this could be a possible threat to the aquatic life forms. The results of lab reports also showing vey less percentage of the pesticides and thus only 1 potential threat is there which is higher concentration of metals present in the lake water.
Looking at the various i can comment that we the concentartion of iron and lead is increasing for every day by a few percentage and also prelonged exposure of these metals for a longer peroid of time which are affecting not only the maturefishes but also the egg hatchings.Due to the exposure of these metals we are facing huge increase in the mortality rate of the fishes and other aquatic lifeforms . So its high time that we need to control all this before that lake turns into a pool of heavy chemical metals.
We need to look at all the potentials threats and treat them properly , we can introduce biological metals eating bacterias(Pseudomonas aeruginosa) which can level the concentation of metals in water . We need to take quick steps in order to secure the life of the rest of the aquatic lifeforms present there.
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