See Figure 2. Looking at the heat circulation in the ocean, what might happen to it, if large amounts of cold water are added in the Polar Regions as glaciers melt?

Cold water from polar regions will sink and the warm water from equator will flow over it. Density of water plays an important role in its sinking. Water coming from Polar Regions is cold and therefore it has high density due to which it sinks down and move with a slow pace towards the equator. Thus, addition of cold water from Polar Regions causes the warm water coming from equator to flow easily towards the pole thereby sinking the cold water.  

affects the water bodies: excessive use of fertilizers causes eutrophication. the fertilizers which are used on plants affect the quality of land on which it is used, further causing erosion of soil. the fertilizers used on plants contain harmful chemical fumes which affect the environment.