engleski

Modeling of transport and atrazine biodegradation in agricultural soil

Atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] is the most commonly used herbicide for suppressing broadleaf and grassy weeds in agriculture, especially in corn, sorghum and sugar cane crops. Although successful in controlling weed growth, atrazine is a pollutant of environmental concern due to its toxicity, slow biodegradation and transport through soil layers to groundwater. Atrazine biodegradation occurs in several reaction steps, i.e. hydroxyatrazine, cyanuric acid, followed by complete mineralization to CO2 and NH4+. In this work only the primary atrazine biodegradation is considered and the applied model is based on atrazine disappearance. The balance for atrazine biodegradation is evaluated by using Monod and first-order kinetics. Biodegradation is complemented with convective-dispersion transport of atrazine in soil and influx of water due to rainfall. The model is given by coupled second order partial differential convection-dispersion equation with time-variable boundary condition. For simulation purposes the finite difference approximation is applied which accounts for discrete atrazine concentration and microbial culture profiles in a soil column during time. The kinetic parameters are based on atrazine biodegradation kinetics under laboratory conditions (Bošnjak et al, 2010, Cheyns et al, 2010). Based on simulation data, prediction of soil contamination by atrazine is given and bioremediation procedure using mixed microbial culture as seed culture is proposed.

atrazine; biodegradation; modeling

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