Keywords

modelling, hydromorphology, organic matter, biogeochemical model, metals

Start Date

1-7-2012 12:00 AM

Description

European rivers are facing multiple sources of pollution, including metals, pesticides and nutrients. To understand the factors controlling their transport, modelling can be used to predict their fate. Usually, however, only one class of components is considered, often neglecting inner interactions. This paper proposes a methodological approach towards understanding the main processes describing the fate of trace pollutants interacting with hydrological processes and suspended solids. The model is evaluated in the middle course of the Garonne River in France and developed in three stages, each integrating a new type of process. The first describes the hydromorphology of the sector studied and transport processes. The second adds the sorption-desorption of metals onto suspended solids in the water. The third and final stage makes the organic matter reactive, and therefore produced and consumed along the river. The influence of each process is quantifiable at each stage. Preliminary results for one data set suggest that the concentrations of two metals in the river cannot be explained by hydrodynamic processes alone. Furthermore, during low water conditions, many metals correlate significantly with dissolved organic carbon or particulate organic carbon, whereas these correlations do not exist during flood events. A contaminant model must therefore include hydrodynamics, sorption and organic carbon production and consumption.

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Jul 1st, 12:00 AM

Modelling multi-pollutant fate in a large river: Role of hydro-morphological and physicochemical parameters

European rivers are facing multiple sources of pollution, including metals, pesticides and nutrients. To understand the factors controlling their transport, modelling can be used to predict their fate. Usually, however, only one class of components is considered, often neglecting inner interactions. This paper proposes a methodological approach towards understanding the main processes describing the fate of trace pollutants interacting with hydrological processes and suspended solids. The model is evaluated in the middle course of the Garonne River in France and developed in three stages, each integrating a new type of process. The first describes the hydromorphology of the sector studied and transport processes. The second adds the sorption-desorption of metals onto suspended solids in the water. The third and final stage makes the organic matter reactive, and therefore produced and consumed along the river. The influence of each process is quantifiable at each stage. Preliminary results for one data set suggest that the concentrations of two metals in the river cannot be explained by hydrodynamic processes alone. Furthermore, during low water conditions, many metals correlate significantly with dissolved organic carbon or particulate organic carbon, whereas these correlations do not exist during flood events. A contaminant model must therefore include hydrodynamics, sorption and organic carbon production and consumption.