Which of the following best describes the transfer of nitrates and the impact on the environment and human health?

Nitrates increase the growth of algae in surface water bodies, killing fish.

Detergents containing nitrates are carried from land to water by rain, contaminating drinking water and causing digestive problems in

humans.

Nitrates from leaky septic tanks enter the groundwater and are converted in the human body into nitrites, which are poisonous and could be fatal for infants.

Nitrates increase the amount of organic substances in water and lowers the amount of dissolved oxygen, killing fish.

Nitrates increase the growth of algae in surface water bodies, killing fish.

Explanation:

Nitrates are used by algae as a food source and their excessive supply can result into uncontrolled growth of algal biomass. The phenonmenon of excessive growth of algae in a lake environment is known as eutrophication. When the growth of algae keeps increasing, it results into low sunlight penetration in the water body especially in deeper zones. Therefore, organsims inside water will consume all oxygen and the lack of oxygen will result into their death including fish population. Keep in mind that nitrates are not directly toxic to the fish or other animals. Instead, some studies have argued that nitrates are beneficial up to a certain limit.