LEACHING AND EUTROPHICATION

• Nitrate and phosphate applied to soil as fertiliser dissolve in soil water and move through the soil into nearby water bodies, a process called leaching
• The resulting increase in inorganic nutrient concentrations in water bodies is called eutrophication
• Eutrophication encourages the growth of algae on the water surface, leading to an algal bloom
• The algal bloom blocks sunlight, causing submerged plants to die as they cannot photosynthesise
• Saprobiotic bacteria aerobically respire as they decompose the dead plant remains, using up dissolved oxygen from the water
• The decrease in dissolved oxygen in the water leads to fish dying, as there is not enough oxygen for them to aerobically respire