Answer: Attenuation
Explanation: Natural attenuation: in this method, the natural physical, chemical, and biological processes in soil and water gradually break down contamination or pollutants into harmless components. It helps reduce contamination concentration and soil and water to acceptable levels. Examples of natural attenuation processes include
- dilution or dispersal of pollutants in moving water
- volatilization or reduction of pollutants into vapor
- absorption or attachment of balloons to soil or vegetation
These processes are accomplish naturally. Little or no human intervention is necessary.