Mineral nanoparticles are abundant in soils however; their role in soil processes is still poorly understood. In this PhD thesis, natural nanoparticles in soil and water samples were characterised using novel analytical techniques. Furthermore, the adsorption of organic matter and phosphate on the surfaces of the nanoparticles was studied since these adsorption processes strongly affect the sequestration of organic carbon in soils as well as the availability of phosphate.
Characterisation of nanoparticles from different soils revealed that the smallest and most reactive particles consist of Fe-(hydr)oxide. Characterization of nanoparticles in water samples from a field site revealed that Fe-(hydr)oxide and clay minerals contribute substantially to the transport of phosphate from clay soils to adjacent surface waters. Furthermore, Fe-(hydr)oxides nanoparticles show strong interactions with organic matter. As a consequence, Fe-(hydr)oxide nanoparticles play an important role in the formation of soil aggregates and improve the water retention capacity of the soil. The results of the adsorption study showed that phosphate solubility increased with an increasing organic matter content of the soil. Modelling of these adsorption interactions is thus important to improve the predictions of phosphate availability and mobility in soils. Nanoparticles, in particular Fe-(hydr)oxide nanoparticles, thus play an important role in several soil processes and consequently affect the physical and chemical properties of the soil.
This research was financed by the EU 7th framework project SoilTrEC (Soil Transformations in European Catchments, www.soiltrec.eu).