Have you ever wondered what happens when you pee into the Ocean? Or if it is harmful to you or the organisms around? Whether you have or haven’t been much curious, I am going to explain the biochemical processes and consequences of this habit that most people have.

Our urine is made mostly out of water, for more than 90% to be exact, ions such as sodium (Na⁺), chloride (Cl^–), potassium (K⁺) and others (depending on what foods you consume and how much you drink during the day), and urea (CH₄N₂O). The sea water, however, is a mixture of chloride, sodium, sulfate (SO²₄^–), magnesium (Mg²⁺), calcium (Ca²⁺), potassium ions and water.

When we urinate into the Sea, the ions within our urine get assimilated in different metabolic pathways, whereas urea reacts with water molecules to form ammonia and CO₂. This is where the bacteria arrives into the story. The Oceans are full of microorganisms that are involved in an extremely important process – nitrification – that is part of the nitrogen cycle.

In the first phase of nitrification, ammonia reacts with oxygen to form nitrite and a hydrogen ion (see the simplified chemical reaction below). This process could not occur without the help of bacteria of the family Nitrosomonas. Nitrite has to be further oxidized. 

NH₃ + O₂^– → NO₂^– + H⁺

In the second phase of nitrification, nitrite and more oxygen react together and form nitrate (see the chemical reaction below). This reaction takes place thanks to bacteria of the Nitrobacter family. Nitrate is ultimately converted into gaseous nitrogen (N₂) through an anaerobic process called denitrification, and released into the atmosphere.

NO₂^– + O₂ → NO₃^–

Another metabolic pathway in which ammonia plays an important role is through nitrogen assimilation in algae. Gaseous nitrogen is extremely difficult to assimilate due to its triple bond between the two atoms of nitrogen and, therefore, must be acquired either under the form of ammonium (NH₄⁺; mostly occurs in the chloroplast) or via the reduction of nitrate to ammonium (occurs in the cytoplasm).

NH₃ + H⁺ → NH₄⁺

Ammonium has to be fixed into glutamate for the proper metabolic function, and glutamate is furtherly converted into other amino acids in a process called anaplerosis, in which glutamate is used to fill the gaps related to the Citric acid Cycle intermediate take out.

The Oceans are also so vast that the dilution is extreme and, therefore, no harm is done to the environment if you pee in it every now and then.