Temporal changes in the metal and phosphorus content of suspended sediment transported by Yorkshire rivers, U.K. over the last 100 years, as recorded by overbank floodplain deposits

摘要

Cores of overbank deposits were collected from locations along the Rivers Swale and Aire in Yorkshire, U.K. The middle and lower reaches of the river Aire drain heavily industrialized and urbanized areas, whereas the River Swale drains a predominantly rural catchment, although Pb and Zn mining in the headwater areas in the 19th century introduced contaminated sediment. Downcore changes in the heavy and trace metal (Al, Cr, Cu, K, Pb, Sr and Zn) and phosphorus (P) content of the floodplain sediment were used to provide evidence of temporal changes in the contaminant content of the fine-grained sediment transported by the study rivers over the last ca. 100 years. The core collected from the downstream site on the River Aire shows upcore increases in P content, which reflects the expansion of the urban area during this period. Variations in the metal content of the deposited sediment over the period represented by the core reflect changes in the extent and type of industrial activity in the catchment. For the cores from the River Swale, there are no major upcore changes in the P content of the sediment, but there was a period characterized by increased levels of Pb and Zn which can be linked to metal mining activities.