engleski

Transport processes affecting organic contaminants fate within soil vadose zone in arable landscapes

Crop production takes place in the soil vadose (critical) zone, one of the most complex terrestrial systems due to a wide range of processes occurring within its boundaries. As human population is increasing exponentially, there is a large pressure on soil and water resources, as well as on food production in the agroecosystems. Organic compounds used to support agricultural production (e.g., pesticides) or applied to the soil surface through wastewater irrigation (e.g., pharmaceuticals) can contaminate the critical zone environment. In arable landscapes, specific spatial heterogeneities related to tillage and trafficking can influence the movement of water and contaminants. The topsoil structure is characterized by spatial patterns with locally compacted zones. Contrasting hydraulic properties of more/less compacted soil zones or soil layers can trigger preferential flow, leading to nonequilibrium solute transport. Numerical modeling is used as a predictive tool for describing various crop management systems (e.g., water management, compost application, tillage), with the purpose of achieving more environmentally sustainable production. In this context, combining state of the art numerical simulations with laboratory analytical methods and field observations has proven to be the most efficient approach for quantification of local scale processes. Selected examples of long-term field experiments, supported by numerical modeling, and dealing with organic contaminants fate (pesticides: isoproturon, glyphosate ; pharmaceutical: carbamazepine) will be presented. The fate of these contaminants was linked to soil properties and correctly estimated in the absence of preferential flow. However, there is still difficulty in estimation and modeling of preferential and non-uniform transport in structured soils commonly found in arable landscapes. The variety of processes difficult to describe in the terms of quantifying the fate of organic contaminants within the soil vadose zone still needs to be resolved, including non-equilibrium sorption in macropores, particle-facilitated transport, microbial degradation, and mass transfer.

critical zone, non-equilibrium transport, agroecosystems, pesticides, pharmaceuticals, numerical modeling

nije evidentirano