A soil profile is a vertical section of soil extending from the ground surface down to the parent rock or unconsolidated material. It reveals a sequence of distinct layers called horizons, each possessing unique physical, chemical, and biological characteristics. The formation of a soil profile is the result of long-term interactions among climate, organisms, topography, parent material, and time. In environmental chemistry, the study of soil profiles is essential because each horizon influences the movement, transformation, and storage of nutrients, pollutants, water, and organic matter. The uppermost layer is known as the O horizon, which consists primarily of organic matter such as decomposing leaves, twigs, roots, and microorganisms. This horizon is rich in humus, giving it a dark color and high fertility. It supports intense biological activity and plays a significant role in nutrient cycling, moisture retention, and carbon sequestration. Forest soils generally have a well-developed O horizon, while it may be thin or absent in cultivated lands. Below the O horizon lies the A horizon, commonly called the topsoil. It is a