Last year’s floods have led to high levels of lead contamination

One of the most surprising findings of the study by the River Basin Dynamics and Hydrology Research Group at UWA’s Institute of Geography and Earth Sciences is high lead levels in sediment deposited overbank during 2000’s floods on agricultural land adjacent to the River Swale in North Yorkshire. Earlier investigations by the Research Group have shown that the principal source of these contaminants is river bank erosion of floodplain soils in Swaledale that were polluted by mining activity in the 18th and 19th centuries.

More than 75% of the flood sediment samples analysed along a 69 mile (110 kilometre) length of the River Swale were found to exceed ICRCL (Inter-Departmental Committee on the Redevelopment of Contaminated Land) guidelines for maximum lead concentrations permitted in soils for grazing livestock, some by up to 1000%. Many other river systems in the UK, most notably the River Clyde, River Tyne and River Aire, are similarly polluted by historic metal mining and past industrial activity.

One very innovative aspect of the UWA team’s research, which is still in its first phase, has been the development and testing of a new computer model called TRACER, which can be used to forecast the long time dispersal of sediment-borne contaminants in river systems. Simulations of lead movement in the River Swale up to AD 2060 show that flooding in Swaledale and in the Vale of York will continue to deliver contaminants to agricultural land. The TRACER model represents a powerful new generic tool for predicting the transport, deposition and remobilisation of contaminants in river systems and potentially has worldwide applications, the Research group says.

“We can’t comment in detail until the full thesis is available,” Rob Walsh, spokesperson for the Environment Agency’s Northeastern Area told edie. “However the contamination of water from mining sources is a well documented national problem and needs to be tackled with a multi-agency approach including DEFRA, local authorities and their environmental health departments and, perhaps, the Food Standards Agency.”