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The Deterioration of Water Quality

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The deterioration of water quality is a worldwide problem. Water pollution affects nearly every living organism, from humans, animals, to water fleas. In this laboratory experiment, we tested the LD50 of several household items. For our group in particular we tested the effects of CLR and Wisk Detergent by transferring Daphnia magna, also known as water fleas, from their freshwater culture container to test tubes filled with several different concentrations of each pollutant. We could then determine the LD50 of each pollutant by recording how many Daphnia survived after a specific period of time. We determined that CLR has higher toxicity levels then the detergent, which is what our group had predicted and the results supported. Our group did perform several errors throughout the procedure that may have affected the results, however, they still coincided with the other sections results as well. The significance of this lab is to promote the protection of our water quality and to realize the affect household pollutants can have on organisms and freshwater.


In 1948, the Federal Water Pollution Control Act was the first U.S law to be put in place to protect our environment and population from the danger of water pollution (USEPA, 2014). Following this law, the public gained more awareness to potential problems to our environment and more amendments were added in 1972 leading to the Clean Water Act. The CWA prohibited the discharge of pollutants in toxic levels into any body of water such as oceans, lakes, streams, and other waterways (Morgan, J.G., and M.E. Brown Carter, 2007). In order to gauge the toxicity of water, environmentalist have experimented with the use of organisms that are considered environmental indicators. In this specific lab experiment we utilized Daphnia magna to test the toxicity of particular pollutants. Daphnia, often referred to as water fleas, reproduce quickly and have a short life span which makes them an excellent organism to use for experimental procedures (De Coen, W.M, and Janssen, C. R. , 1997). The Daphnia are also extremely sensitive to environmental pollutants thus when placed in water that is affected with said pollutants, they will die off at a rate that correlates to the LD50 of the particular pollutant. LD50 is the concentration that is lethal to 50% of test subjects (Morgan, J.G., and M.E. Brown Carter, 2007). In our procedure, we placed the Daphnia in different levels of concentrations between two separate pollutants, CLR and Wisk Detergent. CLR is a formula that contains lactic acid, gluconic acid, propylene glycol, and n-Butyl ether and is used for removing calcium, lime, and rust deposits in the household (Jelmar, 2013). Wisk Detergent is composed of triethanolamine, methylisothiazolinone, fragrance, and alcohol ethoxylates, along with several other cleaning agent ingredients, and is used to clean laundry (EWG, 2014). Once familiar with our household pollutants and several of their ingredients listed, we hypothesized that the LD50 of CLR is lower than the LD50 of detergent. From this, we predicted that if more daphnia survive in the concentrations of detergent than in the CLR concentrations, then CLR is considered more toxic.

Materials and Methods

For this specific experiment, we divided into groups of four and were assigned two separate pollutants. The pollutants assigned to our group were CLR and Wisk Detergent. We tested both pollutants at five separate concentrations and with a control. For each concentration, we labeled a test tube with the pollutant name and concentration. Our concentrations for this experiment were 100%, 50%, 25%, 12.5%, and 6.25%. The 100% concentration contained 50 ml of pollutant; The 50% contained 25 ml pollutant and 25 ml distilled water; The 25% contained 12.5 ml pollutant and 37.5 ml distilled water; The 12.5% contained 6.25 ml pollutant and 43.75 ml distilled water; and 6.25% contained 3.125 ml pollutant and 46.875 ml distilled water. Each pollutant was also being tested in a controlled concentration which consisted of only 50 ml distilled water.

Once each test tube contained the correct concentration, we used plastic pipets to transfer the Daphnia magna from the lake water into the test tubes. Each test tube was to hold six daphnia of relatively the same size. After each transfer, we washed the test tube with distilled water to avoid back-transferring the test solutions into the Daphnia culture containers. Each group waited for approximately an hour after the daphnia were transferred to the test tubes and then we recorded how many died per concentration.




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