The Intergovernmental Panel on Climate Change (IPCC) predicts that the number of extreme precipitation events will increase considerably by the end of the century for mid-latitude land masses (IPCC, 2013). Consequently, flooding events in the UK are predicted to increase in frequency and magnitude. Flooding may provide links between source and receptors, potentially resulting in human and environmental health issues. Physical movement and deposition of sediment contaminated with potentially harmful elements (PHE) in floodplains can result in PHEs can entering storage and persisting for thousands of years (Foulds et al. 2012). Floodplains may then act as a secondary source of pollution. As a result, receptor exposure to PHEs can occur via direct ingestion, dermal contact and inhalation. Transfer to foodstuffs in urban and peri-urban agriculture system is increasingly a problem.

It is known that the mobility of PHEs is affected by flooding; however most studies have determined absolute PHE concentrations only, so there is scope for improving our understanding of biogeochemical processes occurring during and after flood events. Characterising changes in, for example, the solid phase distribution and the bioaccessibility of chemical and biological contaminants before, during and after drying and wetting cycles will provide essential new knowledge of contaminant mobility and redistribution in catchments.

This project will take a geochemical and geomorphological approach to understand the behaviour and fate of PHEs within a catchment system and address the following aims:

• Can we predict the sites in a catchment where significant re-suspension, physical redistribution, mobilisation and solubilisation of PHEs may occur under different flooding scenarios?
• How do wetting and drying cycles affect PHE mobility, availability and bioaccessibility?
• What are the impacts of PHE mobilisation to receptors (humans and livestock)?