EVERYDAY SCIENCE

Detailed explanation-1: -An overabundance of nutrients-primarily nitrogen and phosphorus-in water starts a process called eutrophication. Algae feed on the nutrients, growing, spreading, and turning the water green. Algae blooms can smell bad, block sunlight, and even release toxins in some cases.

Detailed explanation-2: -The most common nutrients causing eutrophication are nitrogen N and phosphorus P. The main source of nitrogen pollutants is run-off from agricultural land, whereas most phosphorus pollution comes from households and industry, including phosphorus-based detergents.

Detailed explanation-3: -Eutrophication is caused by human actions due to their dependence on using nitrate and phosphate fertilizers. Agricultural practices (in crop fields) and the use of fertilizers on lawns, golf courses and other fields contribute to phosphate and nitrate nutrient accumulation.

Detailed explanation-4: -Eutrophication leads to an increased algal growth (because the level of nutrients increases). It can lead to a shift in species composition to fast growing algae species (including toxic species) and a shift from long lived macroalgae to more nuisance species.

Detailed explanation-5: -Eutrophication is caused by minerals such as Phosphorus and Nitrogen which reach natural water bodies via seeped fertilizers, insecticides, detergents, sewage and other effluents. These provide a substrate for algal growth and subsequent Eutrophication. Thus, the correct option is D .