Eutrophication - Cabarrus County Schools
Eutrophication Adapted from: http://www.lakescientist.com/lakefacts/waterquality/ http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/problems_in_environment/pollutionrev4.shtml
Overview: A major problem with the use of fertilisers occurs when they're washed off the land by rainwater into rivers and lakes. The resulting increase of nitrate or phosphate in the water encourages algae growth, which forms a bloom over the water surface. This prevents sunlight reaching other water plants, which then die. Bacteria break down the dead plants and use up the oxygen in the water so the lake may be left completely lifeless. Explanation: How does eutrophication cause fish kills? One of the negative impacts of eutrophication and increased algal growth is a loss of available oxygen. These oxygenpoor conditions can kill fish and other aquatic organisms such as amphibians. However, how does eutrophication actually lower oxygen levels when it is common knowledge algae produce oxygen? It is true algae produce oxygen (photosynthesis), but only when there is enough light. Eutrophication reduces the clarity of water and underwater light. In eutrophic lakes, algae are starved for light. When algae don’t have enough light they stop producing oxygen and in turn begin consuming oxygen (cellular respiration). Moreover, when the large blooms of algae begin to die, bacterial decomposers further deplete the levels of oxygen (cellular respiration). As a result, eutrophication can quickly remove much of the oxygen from a lake, leading to an anoxic — and lethal — underwater environment.
Overview: A major problem with the use of fertilisers occurs when they're washed off the land by rainwater into rivers and lakes. The resulting increase of nitrate or phosphate in the water encourages algae growth, which forms a bloom over the water surface. This prevents sunlight reaching other water plants, which then die. Bacteria break down the dead plants and use up the oxygen in the water so the lake may be left completely lifeless. Explanation: How does eutrophication cause fish kills? One of the negative impacts of eutrophication and increased algal growth is a loss of available oxygen. These oxygenpoor conditions can kill fish and other aquatic organisms such as amphibians. However, how does eutrophication actually lower oxygen levels when it is common knowledge algae produce oxygen? It is true algae produce oxygen (photosynthesis), but only when there is enough light. Eutrophication reduces the clarity of water and underwater light. In eutrophic lakes, algae are starved for light. When algae don’t have enough light they stop producing oxygen and in turn begin consuming oxygen (cellular respiration). Moreover, when the large blooms of algae begin to die, bacterial decomposers further deplete the levels of oxygen (cellular respiration). As a result, eutrophication can quickly remove much of the oxygen from a lake, leading to an anoxic — and lethal — underwater environment.
