What is Eutrophication?

When it rains, nitrates added to the soil by fertilisers can run off into water courses, such as lakes. This is called leaching. The high level of nitrates in the water accelerates the growth of plants at the surface of the water. As these grow in size, they block the sunlight from reaching the plants below. As light provides the activation energy required for photosynthesis to take place (6CO2 + 6H20 + (energy/light) → C6H12O6 + 6O2O), as light becomes the limiting factor, the rate of reaction of photosynthesis slows and eventually stops. Without the ability to photosynthesise the plants die due to lack of oxygen for respiration. Saprobionts decompose the dead and decaying plants, releasing CO2 as they respire. As they use the oxygen in the lake and release CO2, the fish and other aerobic organisms can no longer respire (6CO2 + 6H20 + (energy) → C6H12O6 + 6O2). These organisms then also die. The saprobionts then increase exponentially as they continue to decompose by means of anaerobic respiration.