Color variations in water are due to what materials?

• A. Suspended Particles and Dissolved Materials
• B. Algae
• C. Nutrients
• D. Temperature Gradients

Answer: (A)

Color variations in water come from how light interacts with substances dissolved or suspended in it. Suspended particles, like silt, clay, or plankton, scatter light in different directions, making water appear hazy or tinted. Dissolved materials—colored organic matter, minerals, and other solutes—absorb specific wavelengths of light, giving water colors ranging from brown and yellow to green or blue. The combination of light scattering by particles and light absorption by dissolved substances determines the water’s color.

Other possibilities don’t fit as neatly. Algae can color water when present in large amounts, but color variation isn’t limited to algal presence. Nutrients influence algae growth rather than directly coloring water. Temperature gradients affect water density and mixing, not its color.