Question

3. Give two explanations for why low nutrient lakes often appear to be deep blue. Give two examples of why lakes can appear to be green (state which case is likely to have high nutrients and which is likely to have low nutrients).

Answer 1

low nutrient lakes are pristine in nature and are a symbol of minimal human activity in and ariund the area.

one main reason the lake appears blue is the minimal presence of algae.algae levels increase when waste rich in nutrients like nitrogen and potassium are dumped into the lakes increasing the nurtient content available to the aquatic plants.less algae means less chlorophyll and hence blue colour.

the other reason is the characteristics of the soil.if the soils are heavily permeable,it gives less time for the algal action to take place and the water bodies seem blue with less water plants.

the green lakes are often seen when there is a huge dumping of waste and sewage into these water bodies and is a symbol of human interference in the natural processes. this sometimes causes heavy eutrophication and leads to the death of fish by blocking sunlight and diffusion of oxygen.

the below lake has a geenish tinge and is caused probably due to huge algal growth rates. the second one seems to be free from human interference.(image source:google search)