Evers, J. (2022, May 19). Dead zone. National Geographic Society. Retrieved July 8, 2022, from https://education.nationalgeographic.org/resource/dead-zone

Dead zones are often due to a process known as eutrophication. This process happens when cyanobacteria get too many nutrients and proceed to grow extremely fast. This growth is attributed to there being too much nitrogen and phosphorus in the area that these bacteria grow. Eutrophication is more common than ever because of our ever developing agricultural and industrial practices. This article says that we emit 2 times more nitrogen and 3 times more phosphorus than natural cycles. One of the first identified dead zones was observed in Chesapeake bay in 1970 because the western side of the city was used for poultry farming.

In developing countries many dead zones are caused by poorly treated wastewater management. Some sources of fossil fuels cause atmospheric nitrogen levels to rise. The atmospheric nitrogen follows a similar path as the carbon cycle, and gets absorbed into the ocean creating an unbalance in nitrogen level causing the oceans to be more prone to algae blooms and dead zones.