A lysimeter is a scientific tool used in environmental research to measure the amount of water and chemicals that move through the soil. It consists of a large container filled with soil and vegetation, with instruments to measure water infiltration, evaporation, and percolation. Lysimeters are used to study the effects of pollutants, fertilizers, and other substances on soil and water quality, as well as to understand the hydrological processes in different ecosystems. They are commonly used in agriculture, forestry, and environmental science research.