Pollution's Impact On Algae: A Grade 6 Science Project

Algae are an essential part of the ecosystem, providing food for small animals and fish. However, certain pollutants can affect the growth of algae, causing an algal bloom that depletes the oxygen in the water and kills off other species. This science fair project will investigate the impact of pollution on algae growth and explore ways to prevent this ecological issue. Students will learn about eutrophication, algal blooms, and the far-reaching effects of water pollution. They will also understand the role of fertilizers, phosphates, and nitrates in oxygen depletion and explore solutions such as using natural fertilizers and proper sewage treatment. By conducting experiments with pond water, spring water, fertilizers, and detergents, students will observe the effects of different pollutants on algae growth and gain insights into the delicate balance of our natural environment.

How does acid rain affect algae?

Acid rain is a serious environmental issue that has had worldwide consequences, including the damage of biodiversity in intertidal zones. It is caused by the combustion of fossil fuels, which releases a large amount of sulfur dioxide and nitrogen oxide into the atmosphere. These gases react with water molecules in the air to form acid rain. When acid rain falls onto the earth, it can have detrimental effects on both the environment and human-made structures.

The ecological effects of acid rain are particularly evident in aquatic environments, where it can harm fish and other wildlife. As it flows through the soil, acidic rainwater can leach out aluminum, which is then released into streams and lakes. This process is exacerbated as more acid is introduced into the ecosystem. Some plants and animals can tolerate acidic waters and moderate amounts of aluminum, but others are acid-sensitive and will not survive as the pH declines. For example, most fish eggs cannot hatch at a pH of 5, and some adult fish will die at lower pH levels. Frogs have a critical pH of around 4, but the mayflies they eat are more sensitive and may not survive below a pH of 5.5.

Acid rain also affects plants and trees, as it leaches aluminum from the soil, which can be harmful. Additionally, it removes essential minerals and nutrients from the soil that trees require to grow. In areas with high elevations, acidic fog and clouds can strip nutrients from tree foliage, causing leaves and needles to turn brown or die. This makes the trees less able to absorb sunlight, making them weaker and less resistant to freezing temperatures.

The effects of acid rain on algae specifically have been studied in a laboratory setting. In one experiment, algae were exposed to different concentrations of fertilizer and observed for ten days. The results showed that increased concentrations of fertilizer led to greater algae growth. This is because fertilizers contain nitrogen and phosphorus compounds that act as pollutants, causing algae to reproduce rapidly. When these algae die, the decomposition process depletes the oxygen in the water, killing other aquatic life.

In another experiment, algae were exposed to simulated acid rain. The results showed that acid rain killed off the algae and other living things when the pH level of the water was outside the normal range. This is because algae, like other organisms, have specific pH requirements to survive. When the pH level becomes too low or too high, it can disrupt the biological processes of the algae, leading to their death.

How does fertiliser pollution affect algae?

Fertilisers are a common cause of pollution in bodies of water. They contain nitrogen and phosphorus, which are essential for the growth of algae and aquatic plants. However, when there is too much nitrogen and phosphorus in the water, it causes algae to grow faster than ecosystems can handle, leading to harmful algal blooms. This phenomenon is called eutrophication.

Eutrophication occurs when extra nutrients, such as those found in fertilisers, are added to a body of water. The algae or plant life in the body of water grows at a very fast rate or "blooms". As the plants grow, they deplete the oxygen dissolved in the water, causing other living things in the water that require this oxygen to begin to die off. Eventually, the body of water cannot sustain life and it becomes "dead".

Fertiliser runoff from intensive farming practices is a major cause of eutrophication. Chemical fertilisers are full of soluble phosphates and nitrates that run off the land during heavy rains and irrigation. These chemicals make their way into bodies of water, causing algal and plant blooms. When sewage runs into waterways, the decomposers in the waste also use up the oxygen in the water, leading to eutrophication.

The impact of algae on water quality is significant. As algae grow out of control, they reduce the clarity and visibility of the water. This, in turn, reduces photosynthesis by oxygen-producing aquatic plants, further decreasing the oxygen levels in the water. Some forms of blue-green algae can even be toxic, causing rashes, nausea, and respiratory problems in humans, and have been documented to kill livestock that drink from affected water sources.

To prevent eutrophication and the negative impacts of fertiliser pollution on algae growth, it is important to use fertilisers judiciously and to treat sewage properly before it re-enters the water cycle. Natural fertilisers like manure decompose more slowly, so the nutrients are not washed away quickly in runoff water like chemical fertilisers. Additionally, using water-insoluble fertilisers can help ensure that the fertiliser remains in the soil and does not leach into waterways.

How does detergent pollution affect algae?

Detergent pollution can have a significant impact on algae, leading to what is known as eutrophication. Eutrophication occurs when extra nutrients are added to a body of water, causing the algae or plant life to grow at a rapid rate, resulting in an algal bloom.

Detergents are organic compounds with both polar and non-polar characteristics. They are commonly used in households for laundry and washing machines, as well as for industrial purposes like washing vehicles. The major entry point of detergents into water ecosystems is through sewage works, finding their way into surface water.

Detergents that contain phosphates are highly caustic and can stimulate the growth of algae. This is because the nitrogen in these detergents reacts with phosphorus in the water, creating nutrients that promote the growth of algae in freshwater. As the algae grow, they consume the oxygen in the water, leading to oxygen depletion. This process of eutrophication slowly depletes the oxygen in the water, ruining the aquatic ecosystem.

Additionally, detergents can also contain surfactants, which are surface-active agents that help remove dirt from clothing. However, surfactants are highly toxic to aquatic life. They break down the protective mucus layer on fish, making them more vulnerable to parasites and bacteria. Surfactants also reduce the surface tension of water, making it easier for pollutants and pesticides to be absorbed by fish and other organisms.

The effects of detergent pollution on algae can be observed through experiments. By collecting pond water and adding different concentrations of detergents, the impact on algae growth and health can be monitored over time. These experiments can help raise awareness about the ecological consequences of detergent pollution and the importance of treating sewage properly to protect aquatic life.

How does sewage pollution affect algae?

Sewage pollution can have a significant impact on algae, and this relationship is essential to understanding the health of aquatic ecosystems. Here is some information on how sewage pollution affects algae:

Impact on Algal Growth and Water Quality

Sewage contains high levels of organic pollutants, including domestic waste, agricultural runoff, and industrial effluents. When sewage pollutes a body of water, it introduces excessive nutrients, particularly phosphorus and nitrogen compounds, which stimulate the growth of algae. This phenomenon, known as eutrophication, leads to an overabundance of algae, reducing water quality and affecting its use for various purposes. The increased algal growth can deplete the oxygen levels in the water, creating an oxygen-depleted environment that harms other aquatic organisms and disrupts the natural balance of the ecosystem.

Toxicity and Human Health Risks

Sewage pollution can also introduce toxic substances into the water, endangering both aquatic life and human health. Certain types of algae, such as blue-green algae, have the potential to be harmful and can form toxic blooms. These blooms can produce toxins that are dangerous to fish, mammals, birds, and even humans. Contact with or ingestion of these blooms can lead to various symptoms, including vomiting and diarrhoea, and can be fatal to dogs and livestock. Therefore, it is crucial to avoid contact with or ingestion of algal blooms and to report them to the relevant authorities.

Impact on Marine Life

Sewage pollution can have far-reaching consequences for marine life. It introduces pathogens, contaminants, and suspended solid materials into the ocean, affecting coral reefs and marine invertebrates. The increase in pathogens can lead to coral diseases such as white pox and black band disease. Additionally, the nutrients in sewage stimulate algal blooms, which block sunlight from reaching symbiotic algae that coral relies on for food and oxygen. This disruption can lead to coral bleaching and decrease coral reproductive capacity and skeletal integrity.

Use of Algae in Wastewater Treatment

Interestingly, algae also play a role in wastewater treatment and can be used to purify polluted waters. Algal-bacterial ponds utilize the symbiotic relationship between algae and bacteria to stabilize dissolved compounds and remove organic matter, nutrients, heavy metals, and even radioactive materials from wastewater. This method has gained popularity as a low-cost and effective alternative to conventional treatment systems.

How does phosphate pollution affect algae?

Phosphorus is a critical nutrient required for all life. The most common form of phosphorus used by biological organisms is phosphate, which plays a major role in the formation of DNA, cellular energy, and cell membranes. Phosphorus is a common ingredient in commercial fertilizers.

Algae, a normal part of the ecosystem of a pond, can be affected by certain pollutants, including phosphate. Phosphorus is one of the most important nutrients for plant growth, but too much phosphorus in a pond, river, or lake can cause algae and other aquatic plants to grow excessively. This is known as eutrophication, which results in bodies of water that are depleted of oxygen and are, in a sense, "dead".

During eutrophication, the algae or plant life in the body of water grows at a very fast rate or "blooms". As the plants grow, they begin to deplete the oxygen dissolved in the water, leading to low dissolved oxygen levels. This can have several negative consequences for the aquatic environment. Firstly, it can result in harmful algal toxins. Secondly, it can block the sunlight needed by other organisms and plants in the water. Finally, it can degrade habitat conditions for benthic macroinvertebrates and other aquatic life.

Sources of excess phosphorus that can contribute to eutrophication include fertilizers, runoff from urban areas, leaking septic systems, or discharges from wastewater treatment plants. Chemical fertilizers are full of soluble phosphates and nitrates that run off the land during heavy rains and irrigation, making their way into bodies of water.

While phosphorus is essential for normal growth in appropriate quantities, excess phosphorus can lead to water quality problems such as eutrophication and harmful algal growth. Even small increases in phosphorus levels can negatively affect water quality and biological conditions, as phosphorus generally occurs in small quantities in the natural environment.

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