Solid-Liquid Partitioning
Last updated
Last updated
Pesticides will partition into particulate and dissolved forms. The fraction of pesticide in each phase is a function of the pesticide’s partition coefficient and the water body’s suspended solid concentration:
8:4.1.1
8:4.1.2
where is the fraction of total pesticide in the dissolved phase, is the fraction of total pesticide in the particulate phase, is the pesticide partition coefficient (m/g), and is the concentration of suspended solids in the water (g/m).
The pesticide partition coefficient can be estimated from the octanol-water partition coefficient (Chapra, 1997):
8:4.1.3
where is the pesticide partition coefficient (m/g) and is the pesticide’s octanol-water partition coefficient (mg (mg ). Values for the octanol-water partition coefficient have been published for many chemicals. If a published value cannot be found, it can be estimated from solubility (Chapra, 1997):
8:4.1.4
where is the pesticide solubility (moles/L). The solubility in these units is calculated:
8:4.1.5
where is the pesticide solubility (moles/L), is the pesticide solubility (mg/L) and is the molecular weight (g/mole).