The eutrophication that has taken place in Chesapeake Bay, the Gulf of Mexico, and other locations appears to be due to .

global warming from human use of fossil fuels

pesticide use along the waterways

heavy metals dumped in the sewage

weather alone, because it is only obvious in the summer

excess nutrients from fertilizers

EXCESS NUTRIENTS FROM FERTILIZERS

Explanation: Fertilizer is an organic or synthetic chemical materials which contains certain nutrients or chemical compounds required by plants for proper growth and development.

Euthrophication is the process of increase in the plant population in water bodies such as Algae and other higher plant species due to the release of nutrients into water bodies. This nutrients can be washed through the flooding of farm lands,erosion etc. Example of fertilizers include livestock manures,Ammonium nitrogen fertilizer,Nitrate nitrogen fertilizer,Amide nitrogen fertilizer,Agricultural waste etc.