Analysis

Through the evidence, there was a relative increase of algae mass as concentrations of fertilizers was employed.

Overall Gain (instant release from trial #1):

|Final amount – Initial amount| x 100%
|Initial amount|
= (0.0548g – 0.0089g) / 0.0089g x 100%
= 515.73%
Overall increase of 515.73%

The overall increase represents the increase in algal mass when comparing the mass obtained from the extra high concentration and the mass in the medium concentration trial.

From the results obtained, one can see that there is an overall gain of 515.73%, which supports the idea of eutrophication of bodies of water from agricultural runoff and concentrations of nutrients in the runoff. Although there was a decrease in the step between the medium concentrations to the high concentration of instant release fertilizer, the overall effect of the fertilizer, from the very lowest concentration to the highest, can be seen to be following the pattern of algae growth in nutrient rich environments.

*The changes between medium concentration to high concentration, along with the values of change from high concentration to extra high concentration are not shown to avoid complication, and to avoid a lengthy results page. The full calculations of all changes can be seen through a link at the bottom of this page.

 

Overall Gain (slow release from trial #1)

|Final amount – Initial amount| x 100%
|Initial amount|
= (-0.1620g – 0.0131g) / 0.1620g x 100%
= 108.09%
Decrease of 108.09% overall

The overall increase represents the increase in algal mass when comparing the mass obtained from the extra high concentration and the mass in the medium concentration trial.

 

Overall Gain (instant release from trial #2)

|Final amount – Initial amount| x 100%
|Initial amount|
= (0.0432g – 3.0859g) / 3.0859g x 100%
= -98.60%
Overall decrease of 98.60%

The overall increase represents the increase in algal mass when comparing the mass obtained from the extra high concentration and the mass in the medium concentration trial.

 

Overall Gain (slow release from trial #2)

|Final amount – Initial amount| x 100%
|Initial amount|
= (0.0121g – 4.0665g) / 4.0665g x 100%
= -99.70
Overall decrease of 99.70%

From the results of trial #1, one can see that there was a decrease of algae mass as the concentration of the slow release fertilizer increased. This does not support the idea of the growth rate of algae in a nutrient rich environment, as the algae mass should have increased. However, there is a portion within the slow release fertilizer that does follow the idea of increased growth rates with increased fertilizer, which can be found from the increase from medium concentration to high concentration, as there was an increase of 341.98% of the initial mass. However, one can see that the overall change in algae mass in both the timed-release fertilizer and instant release fertilizers showed a decrease. This again does not strengthen the idea of an algae boom in a nutrient rich environment, as previously stated. Thus, one can see that the second trial yielded inconclusive results in comparison to the evidence obtained in the first trial. Overall, although one portion of the entire investigation utilizing slow release fertilizers was increasing, the overall effect of the slow release fertilizer is an exception to the pattern portrayed with the instant release of fertilizer.

Also, through the evidence, one can see that there was a decrease in the overall mass of the control, as the filter paper before the filtering of the water within the control was heavier than was at the end. Although the value is a negative number, one can see that it is very near zero (less than 0.1g), and thus is not very significant in the present investigation.

Based on the evidence obtained through trial #1, the increase of instant release fertilizers had a positive effect on the algae population, as it encouraged growth, and resulted in an algae boom. However, within the slow release fertilizers, there was a negative effect, as the overall gain in mass through the various concentrations of medium, high, and extra-high yielded a negative percentage.

Through the second trial, one can see that there is a dramatic increase in algae mass in both types of fertilizer with 800 µg/L as a concentration. Without taking that concentration into account, as seen in graph 3, one can see that the instant release fertilizers would always yield a higher mass of algae. With the control group being presented as the starting point for comparison between different concentrations, and thus the 0 growth point, one can see that there is a very small variation, as the control group had less than a 0.01g variation. However, the visual observations conducted in this investigation contradict the empirical data collected. Through the visual observations, one can see that as concentration increased, the amount of algae present, as denoted by the colouration and clarity of the water increased, with the green colouration, and the cloudiness of the water. The instant release fertilizers followed this pattern very distinctly. However, the slow release fertilizers did not follow this pattern as much, as there was little to no algal growth in the slow release fertilizer, even in the extra high concentration container. With the visual observations conflicting with the empirical evidence, it shows that there may have been source of error that created abnormal values for empirical evidence.

Through the visual observations based on the overall process and timeframe of the investigation, one can see that there was another organism present in containers with high nutrients present in the water. Although the mould-like organism lacked green pigmentation, it thrived in conditions similar to the blue-green algae, as they grew much faster in the container with extra high concentration of instant release fertilizer compared to the high concentration of instant release fertilizer. Water depletion was present in all of the containers, and periodical refilling of water until 16 litres was achieved was conducted. However, in comparison between each of the containers, the container with the extra high concentration of instant release fertilizer had water loss the quickest, along with the high concentration of instant release fertilizer. This pattern was continued, and was similar in the containers with slow release fertilizers. Water loss was through evaporation, bubbling out of the container due to the aeration, and other means. Through the investigation, the process of the growth of algae followed the traditional algae boom cycle, as there was a significant lag phase of approximately two weeks at the beginning of the investigation. An algae boom occurred after that lag phase, as large numbers of algae particles grew and multiplied in a very short timeframe. Also, from the first filling of the containers, a slight smell of chlorine was present, although most of it was filtered through. Throughout the investigation, the smell of chlorine slowly faded away, and was soon replaced by the smell of algae.

The full calculations of all changes in the experiment can be found here

Graphs of each of the trials are located here

Discussion:

Within the investigation conducted, there were many aspects that affected the results, and the investigation itself. This can be traced from the beginning of the procedure, with the water collection from the faucet. Although the chlorine was filtered out of the water, many other chemicals were still present, in order to keep the water safe for consumption. Prime water for the investigation was lake or river water, as it would correctly simulate bodies of water which agricultural runoff leeches into. However, that was inaccessible, as 112 litres of water was necessary to conduct the investigation. Distilled water was also considered as a source of water to simulate the lakes and rivers, but such procedure was unpractical, as the expenses required to fill seven containers with 16 litres of distilled water each would be too high. Since the use of distilled and actual river water was unpractical, each of the containers was therefore seeded with 15mL of river water from the North Saskatchewan River. With some algae particles in the 15mL, it would emulate agricultural runoff (represented by the fertilizers) entering natural bodies of water (seeded filtered water).
Furthermore, the use of lights was an important aspect. A balance between effectiveness of the light and the cost were an issue. Thus, in the end, the lighting was done by two Sylvania Grow-lux wide spectrum lights. These lights were operated for 16 hours so that it could emulate an average day in spring / summer, when the algae would thrive. The water temperature being that of room temperature emulated these conditions.

With the beginning of the investigation, the three concentrations: medium, high, and extra high, were used instead of low, normal and high, because of the growth of the algae. To ensure that the algae had a chance of growing and producing an algae boom, the lowest concentration was decided to be the medium concentration. Although the concentrations were different, the ratios, and growth rates would yield relatively the same results. Also, medium concentration of fertilizer was chosen to become the starting point for the investigation as the three concentrations could then simulate the average use of fertilizer, higher, and excessive use of fertilizer, which is common within the agricultural community, where soil conditions are unfavourable.
During the growth phase of the investigation, there were visual observations of dust and debris collecting within the container. The debris can be traced from the aerator, which was constantly pumping air into the container. Through the constant use of the aerator, pieces detached from the air stone, and thus creating pieces of debris on the bottom of the container. This problem could be easily solved by utilizing an aerator that does not have pieces falling off due to constant use. A different aerator would then be able to provide the necessary oxygen within the water, without interfering with the evidence by adding extra mass into the filter paper. Dust particles from the air, along with many other things, even small flies, fell into the container of water. These particles then affected the results, as they also added mass to the evidence collected, similar to the problem with the aerator. Applying a protective layer on top of the container can solve this, so that dust, and other particles would not be able to exit. This protective layer could also help reduce water loss due to evaporation and bubbling from the container, as the film would keep the water inside the container.
Through the collection of data, the contents in each of the containers were vacuum filtered, using the Whatman no.1 filter paper. The filtering process required one filter paper in the beginning, but utilizing only one filter paper at a time proved to be a problem, as it was easily torn apart by the suction of the vacuum created. The process was quickly changed so that two filter papers were used each time, in order to avoid breaking the filter paper. A solution to this problem is to utilize stronger filter paper, so that it will not break, when using only one filter paper at a time. Also, as the collection occurred, particles along the side of the container were seen as algae particles and was thus scraped into the water and filtered. As the mould-like organism may not have been algae particles, this presented a source of error, as extra mass would have been added into the evidence, with the non-algae particles included in the mass. The other organisms may have been caused by the seeding process, as there would have been many organisms present in each of the 15mL of North Saskatchewan River water that acted as a seed for each container. This problem would not be able to be solved, and would thus create a weakness in this investigation, as there would always be particles of other organisms in any sample of water, which would yield several organisms present in the investigation, not only algae.

While determining the mass of the algae present in each of the containers, the results yielded abnormal values. As seen in the evidence collected, some values of the slow release fertilizer, which would promote algae growth much less than the instant release fertilizers, had “more” algae present, according to the electronic balance. This can be seen as a source of error, as all values that are being recorded and calculated are very small masses, and small amounts of anything, such as dust or hair, could alter the values greatly. Thus, through this source of error, the evidence was altered dramatically, by outside particles, to give inaccurate results. From this knowledge, one can see that the values collected are seen to be inconclusive, as those results did not provide a solid pattern and relation between the two types of fertilizer, in the first trial. However, the visual observations provide evidence of a pattern present in each of the containers, which was being followed by both types of fertilizers. Through the visual observations, the growth pattern of the algae could be seen, and the direct relationship between the growth rate of the algae and the concentration of fertilizer can be clearly seen. This shows that the quantitative data collected in this investigation is invalid, and to be rejected, whereas the visual, or qualitative data seems to follow the growth pattern, and in turn, support that pattern.

Conclusion:

Shown through the visual observations, one can see that there is a potential of limiting eutrophication of natural bodies of water by reducing the amount of agricultural runoff. A solution to limiting the amount of agricultural runoff can be seen through the use of timed-release fertilizers, as it limits the amount of fertilizer released at a given time. Through this method, when utilized on a large-scale agricultural project, it would have a large impact on the agricultural runoff produced, thus limiting the eutrophication of nearby bodies of water. Although it may not be practical to replace all agricultural fertilizer with timed release fertilizers, as the amount of nutrients released at any given time is very small, there is a large potential in converting a portion of fertilizers used into timed release fertilizers, so that there may be a mix of the instant release fertilizers, and the timed release fertilizers. In this way, there can be large crop yields, yet limited eutrophication levels in nearby bodies of water.