Eutrophication is observed in ...... .

What is $FOAM$?

Describe the integrated wastewater treatment project in the town of Arcata,California.

Aerosols reduce primary productivity by

Biological magnification refers to

In a pond near a village,a large number of fish suddenly die. Which of the following could be the reason for this?
$(a)$ Large amounts of urea and phosphate are used as fertilizers in nearby fields.
$(b)$ $DDT$ was sprayed in the entire area.
$(c)$ The pond water has become green and dirty.
$(d)$ The population of phytoplankton in the pond has decreased,reducing the photosynthetic capacity.
Which two of the above reasons are responsible?