"Phosphorus concentrations" refers to the amount of phosphorus present in a substance or environment, like water or soil. It indicates the level or quantity of phosphorus that is measured to understand its presence or impact. Full definition
It basically regulates the calcium and phosphorus concentration in the body. (planetsupplement.com)
Over the same period phosphorus concentrations had not increased. (bitsofscience.org)
Scientists have developed a model which gives the maximum potential capacity of water masses to produce cyanobacteria at different phosphorus concentrations reaching lakes and reservoirs from agricultural or industrial activities. (sciencedaily.com)