PPM is a shortcut for --->'Parts Per Million'.
In the maritime context, parts per million (ppm) is a unit of measurement that is used to express the concentration of a substance in a solution or mixture. It is a common unit of measurement that is used in many different fields, including marine biology, oceanography, and chemical engineering.
To express a concentration in ppm, you divide the mass of the substance in question by the mass of the solution or mixture, and then multiply the result by one million. For example, if you have a solution that contains 10 grams of salt dissolved in 1,000 grams of water, the concentration of salt in the solution would be 10 ppm (10 grams of salt / 1,000 grams of water x 1,000,000 = 10,000).
In the maritime context, ppm is often used to express the concentration of various substances in seawater, such as dissolved oxygen, nutrients, and pollutants. It is also used to express the concentration of substances in other marine environments, such as in the water column, in sediment, or in the atmosphere.