Answer and Explanation:
The question is incomplete because the “above information” was not given; however, based on the hint provided, a general description could still be given, thus:
Dead zones are zones or areas in some of the world’s water bodies; they contain excessive quantities of nutrient pollution from both human and natural activities. Dead zones are either depleted of oxygen, or contain low quantities of oxygen (i.e., they are hypoxic) because of a process called eutrophication which occurs when concentrations of nutrients (such as Phosphorus and Nitrogen) become too high in water bodies, to such an extent that little or no forms of life exist in them.
Human activities ,which are the major causes of eutrophication, lead to creation dead zones:
Human waste from sewage treatment plants, leaked septic tanks, industrial plants, indiscriminate littering of human and animal droppings, all contain nutrients that are often washed into water bodies such as rivers, oceans, lakes, etc. Accumulation of nutrients increases concentration levels to an extent that harms many forms of life.
Farming activities associated with the use of agricultural fertilizers, are also one of the major causes of eutrophication and creation of dead zones. Although the intention of using fertilizers is to make soils more fertile, they also contain nutrients (Nitrogen, Phosphorus, etc.) that are often overused or misused in such a way that, whenever there is natural and manmade water runoff, it carries them (the nutrients) into water bodies and increases the concentration of nutrients beyond certain limits; this endangers the life of aquatic species, and kills many or all of them.