Hydrogeology
Hydrogeology

Reactive transport modeling

Transport and biodegradation of organic contaminants in the hyporheic zone

The boundary between river systems and the adjacent aquifer (Hyporheic zone) is of outstanding ecologic and chemical relevance for the quality of drinking water in regions with intensive urban and agricultural use.

By using controlled field experiments and reactive transport modeling, the hyporheic zone was investigated with a) optimal natural tracers (Temperature and stablie water isotopes) and b) anthropogenic tracers (Acesulfame).

It was possible to simulate the transient dynamic of river-groundwater-exchanges and the redox-zoning of different high- and low-water cycles and to identify the decay of the radiocontrast agent Iomeprol as a co-metabolic process.

funded by BMU

Particular transport of organic contaminants (Co-transport of DOM and sulfonamides) and nanoparticles (Ag-Nanoparticle) in variable saturated soils

Colloids and nanoparticles are transported differently in soils under variable hydrogeochemical conditions due to their unique physicochemical properties. Using advective-transport equations will fail to describe their component-specific behavior in soils and groundwater.

Some artificial nanoparticles act as contaminants, such as silver-nanoparticles, while other artificial nanoparticles can be also used for soil remediation, such as carbon nanoparticles or iron nanoparticles. Transport of colloids and particles can be described by the colloid filtration theory.

However, further processes, such as aggregation or facilitated transport (DOM+sulfonamides) must be considered as well. Based on experimental and numerical investigations, key processes that drive colloid (DOM) and nanoparticle (Ag NP) transport under variable hydrogeochemical and hydrological conditions combining the classic colloid filtration theory (CFT) with the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory were identified.

The most important parameter beyond the ionic strength is the air-water interface that is responsible in a variable saturated system if the transport of the nanoparticles is retarded or facilitated.