What does pH measure in a solution?

pH measures the concentration of hydrogen ions in a solution, which is crucial for determining the acidity or alkalinity of that solution. Specifically, the pH scale ranges from 0 to 14, where lower values indicate higher concentrations of hydrogen ions, reflecting increased acidity, and higher values indicate lower concentrations, reflecting increased alkalinity. A pH of 7 is considered neutral, meaning the concentration of hydrogen ions is equal to the concentration of hydroxide ions.

Understanding pH is vital in various environmental contexts, as it affects the solubility and biological availability of nutrients, metals, and other substances in water, influencing ecosystem health and stability. While factors such as oxygen concentration, nutrient levels, and salt concentrations play important roles in environmental assessments, they are measured through different parameters and are not directly related to the pH level. Hence, the focus on hydrogen ions in the definition of pH is integral to understanding its significance in environmental science.