# Degradation

Pesticides in both the particulate and dissolved forms are subject to degradation. The amount of pesticide that is removed from the sediment via degradation is:

&#x20;           $$pst_{deg,sed} = k_{p,sed} *pst_{rchsed}$$                                                              7:4.2.8

​where $$pst_{deg,sed}$$ is the amount of pesticide removed from the sediment via degradation (mg pst), $$k_{p,sed}$$ is the rate constant for degradation or removal of pesticide in the sediment (1/day), and $$pst_{rchsed}$$ is the amount of pesticide in the sediment (mg pst). The rate constant is related to the sediment half-life:&#x20;

&#x20;           $$k_{p,sed} =\frac{0.693}{t_{1/2,sed}}$$                                                                                 7:4.2.9

where $$k_{p,sed}$$ is the rate constant for degradation or removal of pesticide in the sediment (1/day), and $$t_{1/2,sed}$$ is the sediment half-life for the pesticide (days).
