Identifying sediment sources in the tees catchment

Abstract

The main objective of this research is to identify the sources of suspended sediments in the River Tees. Earlier work in the Tees has focused on the extent of heavy metal concentrations in the river sediments as a result of mining m the upper catchment, but this is the first time that an attempt has been made to fingerprint the sources of suspended sediment. The idea of identifying sediment sources by fingerprinting was similar to that used by other authors, i.e. attempting to determine a distinctive chemical fingerprint for the different landuse, geology or subcatchments in the Tees. Field sediment samples were collected from potential source areas throughout the catchment and suspended sediment samples were collected from strategic points on the River Tees and its main tributaries. The samples were prepared using a sequential extraction procedure before analysis by ICP-AES. The samples were then subjected to several statistical procedures to determine which metals could classify the samples between the different source groups. Principal Components Analysis was the most successful tool for allowing interpretation of different sediment sources, identifying three possible sources for sedmient. These were the upstream bed and bank sediments, samples collected from the Leven catchment and the third source, which appeared to be the middle catchment agricultural areas. The data was subjected to a two-stage statistical analysis, as used by previous authors, but the data failed to provide a reliable fingerprint for use in a mixing model. Water samples collected along with suspended sediment showed distinct differences between the upper catchment and the lower tributaries, with samples from the lower Tees showing a degree of mixing. An attempt to use a mixing model failed, possibly owing to the small number of samples.