High molecular weight and strongly hydrophobic organic compounds tend to partition to soils containing what?

High molecular weight and strongly hydrophobic organic compounds have a tendency to partition to soils that contain organic matter. This is primarily due to the nature of these compounds, which are not easily soluble in water and can interact more favorably with the organic components of the soil.

Organic matter in soils is composed of decomposed plant and animal material, which has complex structures and a high surface area. The hydrophobic characteristics of high molecular weight organic compounds make them more likely to bind to these organic residues rather than remaining in soil water. The presence of organic matter enhances the retention of such compounds within the soil matrix, contributing to their accumulation and altering their environmental behavior.

On the other hand, materials like sand and gravel have larger particle sizes and lower surface areas, which do not provide the same affinity for hydrophobic compounds as organic matter does. Clay particles, while having a large surface area, are typically associated with a high ionic charge that makes them more suited for binding polar compounds rather than highly hydrophobic ones. Thus, organic matter serves as a crucial medium for the retention and movement of high molecular weight hydrophobic organic compounds in the environment.