PEARLNEQ is a parameter fitting tool to estimate values for non-equilibrium sorption (NEQ) parameters. Non-equilibrium sorption (also known as aged sorption or kinetic sorption) is one of the higher tiers options in pesticide regulatory leaching assessments in the EU. The non-equilibrium sorption parameters obtained with PEARLNEQ can then be used with pesticide leaching models such as PEARL.
PEARL and PEARLNEQ assume a Freundlich two-site sorption submodel to describe non-equilibrium sorption: one site for equilibrium sorption and a second site for long-term sorption kinetics (non-equilibrium sorption). Here, equilibrium sorption sites are defined as the adsorption sites that have reached equilibrium in a well-stirred suspension of the soil in water after 24 hours of shaking a. The non-equilibrium sorption sites are then defined as the adsorption sites which do not reach equilibrium within these 24 hours. PEARL assumes first order degradation kinetics for the compounds present in the liquid phase and sorbed to the equilibrium sites. However, compounds sorbed to the non-equilibrium sites are assumed not to degrade.
