Calibration of diffusion-advection process models for organochlorine pesticides in a tropical river

This paper deals with the calibration of diffusion-advection process models for organochlorine pesticides (OCPs) in a river of tropical country called Tucutunemo River, Venezuela. The novelties consist of the following aspects: 1) modeling of pesticides of type organochlorine including DDT and DRIN and their isomers such as: p.p'-DDT, o.p'-DDT, p.p'-DDD, p.p'-DDE, o.p'-DDE, Aldrin, Dieldrin, and Endrin. 2) Determination of parameters and statistical adjustment of diffusion and biochemical transformation coefficients in mathematical expressions derived from Fick's law, and modified equations from the biofilter reactors to simulate the attached biofilm on support medium to the attached biofilm on sediments in the river bed. Four scenarios are proposed for modeling: 1) molecular diffusion without biochemical transformation, 2) molecular diffusion with biochemical transformation, 3) advective diffusion without biochemical transformation, 4) advective diffusion with biochemical transformation. The combination of advective diffusion with biochemical transformation results in the best fit to explain the removal of the OCPs along the river.