Effects of Pollutants on Algal Growth

Lab Report: Effects of Pollutants on Algal Growth
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Abstract
The primary goal of this study was to examine the relationship between phosphorus, nitrogen, and acid rain and algal growth. The objective was to determine the impact of different levels of phosphorous and nitrogen elements on algal growth. Additionally, the study sought to understand the influence of acid water on the growth of algal. Three hypotheses guided this study. First, it was hypothesized that algal growth would increase, given that the concentration of nitrogen pollution increased. Second, algal growth was expected to expand with the increase in the concentration of phosphorus pollution. Lastly, it was hypothesized that algal growth would decrease as the concentration of acid rain pollution increased. The results of this study were consistent with the expectations and supported the above hypotheses. This study confirms that excessive concentration of nitrogen and phosphorus pollutants in waterways promoted eutrophication, which is hazardous to aquatic life.
Lab Report: Effects of Pollutants on Algal Growth
Introduction
The term algae is used to describe a diverse group of polyphyletic eukaryotic organisms that mostly thrive in water bodies and depend on photosynthesis to convert solar energy into chemical energy for storage and their future use. Besides water, algae also require other nutrients to grow. Nitrogen and phosphorus are essential nutrients for the growth of phytoplankton and aquatic plants, including algae. Elevated levels of nitrogen and phosphorous, as well as other substances, find their way in the waterways through non-point sources such as agricultural runoff, fertilizer spills, construction sites, and urban areas. Additionally, other sources of nutrients include point sources such as sewage and industrial discharges (Shen, Niu, Wang, Wang, and Zhao, 2013; Ansari and Gill, 2014). Therefore, it is critical to understand the effect of excess nutrients in the waterways to algae and other aquatic organisms.
Excessive concentration of nitrogen and phosphorus in water bodies can be miserable to the aquatic life, including algae. Shen et al. (2013) assert that high levels of these elements in the water bodies remove the limitations of phosphorous and nitrogen experienced by phytoplankton leading to an algal bloom, also known as eutrophication. There is a high likelihood that eutrophication can promote the growth of bacteria and reduce the concentration of dissolved oxygen within the water, significantly altering aquatic life (Shen et al., 2013, p.2). Ansari and Gill (2014) note that episodes of oxygen are experienced following the eutrophication of water bodies as a result of the decomposition of the algal organic matter. Aleksandrov, Krek, Bubnova, and Danchenkov (2018) argue that eutrophication is one of the most critical environmental issues in water basins and can disrupt the aquatic life by causing death to countless organisms. Consequently, it is essential to understand the appropriate concentration of nitrogen and phosphorus in water bodies to avoid the adverse effects of eutrophication.
Despite their significance, elevated levels of nitrogen and phosphorous are considered pollutants in the waterways. This study investigated the relationship between the two nutrients and algal growth. Controlled amounts of nitrogen and phosphorus were used to quantify this relationship. Three hypotheses guided this study. First, it was hypothesized that algal growth would increase, given that the concentration of nitrogen pollution increased. Second, algal growth was expected to grow with an increase in the concentration of phosphorus pollution. Lastly, it was hypothesized that algal growth would decrease as the concentration of acid rain pollution increased. Understanding the effect of pollution in the water systems was critical in this study.
Methods
The study needed seven 25 ml test tubes. The following treatment types were prepared using the seven test tubes: control, low nitrogen, high nitrogen, low phosphorus, high phosphorous, low acid rain, high acid rain. A labeling tape was used to label each of the test tubes with the respective section number, group number (group 2), and treatment type using a permanent marker. The labeling was done as follows: Control = C, Low nitrogen = LN, High nitrogen = HN, Low phosphorous = LP, High phosphorous = HP, Low acid rain = LAR, and High acid rain = HAR.
Next, controlled amounts of water, algae, and the pollutants were added into the test tubes. Separate pipettes were used when adding each type of the element as well as for the algae. The amounts added to each test tube were recorded in table 1 below:
Table 1: Algae, pollutant, and water quantities added to each test tube depending on the treatment type
TubeAlgaePollutantWaterControl2.5 mL0 mL12.5 mLLow
(N, P, AR)2.5 mL1.5 mL11.0 mLHigh
(N, P, AR)2.5 mL3.0 mL9.5 mL
For the control treatment type, test tube C was filled with 2.5 mL algae, 12.5 mL distilled water, and zero amounts of pollutants. For the low nitrogen treatment type, test tube LN was filled with 2.5 mL algae, 1.5 mL nitrogen pollutants, and 11.0 mL distilled water. For the high nitrogen treatment, test tube HN was filled with 2.5 mL algae, 3.0 mL nitrogen pollutants, and 9.5 mL distilled water. For the low phosphorous treatment, test tube LP was filled with 2.5 mL algae, 1.5 mL phosphorous pollutant and 11.0 mL distilled water. For high phosphorous treatment type, test tube HP was filled with 2.5 algae, 3.0 mL phosphorous pollutants, and 9.5 mL distilled water. For the low acid rain treatment type, test tube LAR was filled with 2.5 mL algae, 1.5 mL acid rain treatment type, and 11.0 mL distilled water. Lastly, 2.5 mL algae, 3.0 mL acid rain (simulated vinegar), and 9.5 mL distilled water were added to test tube HAR for the high acid rain treatment type.
A plug made by wrapping a piece of a cotton ball in a small square piece of gauze was inserted into the mouth of each of the seven test tubes. The test tubes were then placed in the location designated by the instructor. The instructor then placed the test tubes under the plant-growth light for the next two weeks until the end of the activity. A thorough cleanup was then carried out using paper towels to wipe any spillage from the table, after which all materials were returned to their original locations.
The growth of algae within the two weeks was to be indicated by the absorbance. A spectrometer was used to determine the absorbance in each of the seven test tubes. A spectrometer was used to measure the absorbance of the inoculum for the control, test tube C, in order to record the initial cell density at the beginning of the study. After the two weeks, the spectrometer was used to determine the absorbance of each of the seven test tubes. To determine the absorbance of the distilled water (the control), the following was done. First, the spectrometer was calibrated to zero using distilled water. A cuvette was then filled with distilled water up to 75 percent full. A tissue wipe was used to dry the exterior of the cuvette dry. T...