Question

How can these factors reduce bioavailability of an organic compound in the soil; low water solubility and sorption of substate by soil ?

Answer 1

Low water solubility reduce the bioavailability of an organic compound.

Reason: For solid-phase organic compounds utilization of solubilized substrate is more important. Thus low water solubility has greater impact on degradation of solid-phase organic compounds than liquid-phase organic compounds.

Sorption factor reduce the bioavailability of an organic compound.

Depending upon the sorption mechanism, organic compounds can be weakly or strongly bound to the soil.

Sorption of weakly bound or labile residues is reversible, and when a sorbed residue is released back into solution, it becomes available for microbial utilization.