1. Question: which aquatic phase to monitor for which compounds?
Water
SPM
Biota
Sediment
Approach: Estimate the dominant phase in
which organic compounds occur
in aquatic systems
Fraction of chemical in dissolved phase or
SPM is a function of
Kd (Kp): Distribution Coefficient
between D and P phases
SPM or TSM: Total Suspended Matter
foc: Fraction of TSM as OC (dry wt)

2. Role of Organic Matter
Partitioning of neutral organic molecules between
aqueous phase and Natural OM (surrogate is OC):
Analogous to partitioning into or dissolving
into an organic solvent
Koc is a property of solute’s hydrophobicity
foc is a property of Natural Organic Matter
Assume Koc  Kow