Effect of Detergent on Elodea Growth

Elisbey Castillo 0071

AS Environmental Management

Miami Springs Senior High

Center US686

Research and Planning

The purpose of this experiment is to measure the effects of elodea growth when placed in different concentrations of detergent with phosphate. Around the 1960’s, plant growth in rivers and lakes began skyrocketing (Knud-Hansen, 1994). In large part this was due to an increasing amount of phosphate from detergents in sewage water. Detergents are common in both domestic and industrial use; although detergents are a common household product, they are also used in pesticide formulations and for the dispersion of  oil spills at sea (Knud-Hansen, 1994). Phosphate in detergent is an effective builder, it minimizes the use of other active ingredients, and is non-toxic to aquatic organisms; however phosphate also behaves as a nutrient (“Phosphate Recovery,” n.d.). Although it isn’t uncommon to find phosphorus in lakes and river from erosion of runoff from soil, an excessive amount of it acts as a fertilizer. The input of excessive nutrients by human activities due to urbanization and agriculture is called cultural eutrophication (Spoolman & Miller, 2012).

        Detergents cause the accelerate growth of algae in rivers and lakes; this uncontrolled growth impairs fishing, boating, swimming, the use of natural waters, as well as cause an imbalance on the ecology of the environment it affects (“Phosphate,” n.d.). When these plants eventually die and are decomposed by aerobic bacteria the biological oxygen demand (BOD) increases, thus depleting dissolved oxygen (DO) in the water, which can kill fish amongst other organisms. In the breakdown of the organic material by anaerobes, toxic byproducts are often produced (“Phosphate,” n.d.). However, as the public became increasingly aware of the environmental effects of phosphates, more and more people began choosing detergents without phosphate versus does with phosphate.

If the reaction of algae to nitrate and phosphate in their environment is to grow in abundance, what would be the effects on other freshwater plants like elodea? In order to test out the effects of detergents with phosphate versus phosphate-free detergents on freshwater plants, the experiment was  set up to answer the following question: What are the effects of phosphate versus phosphate free detergents on elodea? This experiment sets out to replicate the introduction of different percentages of detergents with phosphate versus those without, to fresh bodies of water, and their effect on aquatic plants (other than elodea). Thus allowing the plants to result in a similar outcome as they would have in the same scenario in real life. If elodea is placed in varying concentrations of detergent with phosphate, then they will grow more than those in phosphate-free detergent.

        The experiment will consist of nine cups; four of the nine cups will be filled with 3%,6%,12.5%, and 25% concentrations of detergent with phosphate, while the other four will have the same percentages but with phosphate-free detergent;as for the remaining cup, it will be placed as the control and simply filled with tap water. After that has been completed the percentages for each cup will be written on then with marker to avoid confusion.  In order to achieve the desired percentages a 100 milliliter graduated cylinder will be needed, as well as something to mix the solutions. This procedure will be repeated two more times for a total of three trials. The plants will be placed outside under a shed and measured every four days; the growth of the elodea in detergent with phosphate and without will be compared to each other and to the control, and the results assessed.

Data Collection and Presentation

Before beginning trial 1, the elodea assigned to each cup was measured before being placed in the varying concentrations in order to accurately compare their growth throughout the experiment. All of the elodea were vibrantly green and healthy, and none seemed to be showing signs of withering. The elodea for the control for both detergents measured 7 cm before being placed in the cup. For the phosphate-less detergent, the elodea in 3% and 25% both measured 6.5 cm, for 6% it measured 6.7 cm, and finally for 12.5% the elodea measured 7.5 cm. For the detergent with phosphate, the elodea for 3% measured 7.5 cm, for 6% it measured 6.6 cm, the one for 12.5% measured 7 cm. and the elodea for 25% measured 6.8 cm.  

On the fourth day, the elodea for both detergents began turning a darker shade of green.

The control for both measured 6. 8 cm which was 2 mm less than it did at the beginning. Other than the control, the growth of the elodea in the concentrations of phosphate-less detergent stayed constant. In comparison the elodea in the concentrations of detergent with phosphate showed an average increase of 2 mm per plant, except for the 25% which remain at a constant 6.8 cm.

         By the eight day, all the elodea began losing their color and turning white, and the growth either remained constant or began to spiral down. While being removed from the water for recording, the elodea in water was too weak and fell apart, therefore it could not be recorded for the duration of the experiment. The elodea in the phosphate-less detergent concentrations all decreased by at least 3 mm or more, except for the elodea in the 6% concentration which remained 6.7 cm. As for the elodea in the detergent with phosphate, they all decreased by at least 1 mm or more.

After twelve days the elodea were looking their worst as the leaves and stem of all the elodea became extremely thin and transparent. In the process of removing the elodea in the 3% concentration for both the detergent with and without phosphate, they fell apart just like the one in water had done four days before, and therefore the measurements could not be recorded for that concentration that day. The rest of the elodea in the detergents with and without phosphate remained the same length, except for the elodea in the 12.5% phosphate-less detergent concentration which had an increase of 1 mm.

Trial 1: No Phosphate

Trial 1: Phosphate

For trial 2, the elodea for each concentration was measured before beginning the experiment, just as it had been done in trial 1. Both detergents had the same control, and the elodea for it measured 6.5 cm. For the phosphate-less detergent the elodea for 3% it was 8.3 cm, 6% was 7.3 cm, for 12.5% it was 7.4 cm, and finally for 25% the elodea measured 6.4 cm. As for the elodea meant for the detergent with phosphate, 3% was 6.8 cm, 6% was 6.5 cm, 12.5% was 5.9 , and the elodea for 25% measure 7.1 cm.

On the first four days of trial 2, the elodea had also turned a darker green; the elodea in the control decreased by 5mm. The elodea with phosphate-less detergent decreased an average of at least 1mm or more in length, except for 3% which remained constant. For the detergent with phosphate, the elodea also decreased but by an average of 2mm with the exception of the 3% and the 12.5% concentrations whose elodea length remained unchanged.

By the eighth day, the trend from trial 1 continued, the elodea began losing their color and turning white as well. Just as in the first trial, the elodea that was in the control broke apart and could not be measured for the rest of the experiment. The elodea in the phosphate-less detergent concentrations decreased by an average of 3mm, except for the 6% and 12.5% concentrations in which the elodea remain the same length. The elodea in the detergent with phosphate also decreased in length; with an average of 2mm. However, the elodea in the 25% concentration remained the same length of 6.7 cm.

On the final four days,  the leaves and stem of all the elodea became thin and transparent as they too had done in the first trial. The elodea in the phosphate-less detergent concentration of 3% decreased by 1.9 cm, while the elodea in the 6% and 25% concentrations increased by an average of 2mm; the elodea in the 12.5% remained constant. As for the elodea in the detergent with phosphate, the elodea in the 3% concentration broke apart; however the rest stayed the same length except for the elodea in the 6% concentration which increased by 2mm.  

Trial 2: No Phosphate

Trial 2: Phosphate

The final trial, trial 3, started out the same as every other; the elodeas’ initial length was measured. Again there was one control for both detergents, and the elodea measured 7.8 cm. For the phosphate-less detergent the elodea measured 6.3 cm for the 3% concentration, the 6% measured 6.7 cm, 12.5% was 6.2 cm, and the elodea for 25% was 6.3 cm. The elodea in 3% concentration for the detergent with phosphate measured 6.8 cm, 6% was 6.4cm, 12.5% was 7.8cm, and finally the elodea for 25% concentration measured   5.6 cm.

On the first four days the elodea turned a darker green, which has also happened in trial 1 and trial 2. The control for both detergents remained a constant 7.8 cm. The elodea in the 3% and 12.5% concentrations with phosphate-less detergent remained the same length as the first time they were measured; however the 6% concentration decreased by 2mm and the 25% concentration decreased by 5mm. Elodea in the phosphate detergent concentrations experience a minimum increase of 1mm, with the exception of the 12.5% and 25% concentrations which remained the same.

By the eighth day the elodea once again began losing their color and turning white. Upon removing the elodea from the water, it was too weak and broke into piece as the controls in prior trials had. The elodea in phosphate-less detergent concentrations all showed a decreased by a minimum of 2mm or more. While the elodea in the phosphate detergent concentrations was  quite erratic. The elodea in the 6% concentration of detergent with phosphate had a decrease of 8mm, while elodea in the 25% increased by 1mm; however elodea in the 3% and 12.5% concentrations remained the same.

On day twelve the leaves and stem of all the elodea became thin and transparent. Elodea in the 3% concentration of phosphate-less detergent, broke apart upon removal from solution; otherwise the elodea in the phosphate-less concentrations increased by a minimum of 2mm, except the 25% concentration which remained at a constant 5.2cm. As for the elodea in the solutions with phosphate detergent, they all decreased by a minimum of 1mm, except for the 12.5% which increased by 1mm.

Trial 3: No Phosphate

Trial 3: Phosphate

Conclusion and Evaluation

The goal of this experiment was to replicate the response of aquatic plants when introduced to phosphate in nature. When aquatic plants in lakes, rivers etc. are introduced to phosphate from detergents found in sewage, they experience excessive growth which can cause detrimental problems to humans and the other organisms that inhabit the same body of water; as proven by the experiment in the first four days of phosphate exposure, the elodea plants experienced significant growth compared to the ones in phosphate free detergent. As the experiment continued the elodea in the detergent with phosphate began to decrease in length, which means that the hypothesis made about the experiment was incorrect. Although the elodea in the detergent with phosphate did show initial growth, it dwindled as the experiment continued. An unexpected incident was the breaking apart of the elodea as they were taken out of the solutions, there could have been a number of variables that could have affected them in such a way. However, because the experiment was conducted outside  the data was limited by variations in temperature, which elodea are sensitive to. If the temperature had been a controlled variable the results would have probably more similar to those studied and research by scientists.

Work Cited

Phosphate Recovery. (n.d.). Retrieved March, 2016, from

   http://www.nhm.ac.uk/research-curation/research/projects/phosphate-recovery/pfile14.htm

Knud-Hansen, C. (1994, February). Historical Perspective of the Phosphate Detergent Conflict. Retrieved March, 2016, from

   http://www.colorado.edu/conflict/full_text_search/AllCRCDocs/94-54.htm

Phosphate. (n.d.). Retrieved March, 2016, from https://www.msu.edu/course/lbs/171l/

   Phosphate.html

Spoolman, S. E., & Miller, G. T. (2012). Living in the Environment. Belmont, CA: Brooks/Cole.