Historic mining has produced widespread Pb, Zn,Cd, and Cu contamination in the fluvial deposits of theTyne River Basin, northeast England. Detailedmineralogical analysis of contemporary overbank riversediment, mining-age
alluvium, and mine-waste tipsand of suspended solids in river waters has defineda general weathering reaction paragenesis of Pb-,Zn-, Cd-, and Cu-bearing minerals: sulfides
carbonate,silicate, phosphate, and sulfate weathering products
iron and manganese oxyhydroxides. Textural andchemical evidence suggests that the sulfides alterto carbonates in high pH/pCO
2,limestone-dominatedsource terrains. These minerals and other contaminant metal-rich minerals such as silicates andmanganese oxyhydroxides decline and disappeardownstream in lower pH shale/sandstone-dominatedenvironments. The concomitant decrease in totalPb, Zn, Cd, and Cu sediment contents in the Tyne andpossibly other metal contaminated rivers may berelated to these essentially chemical weathering anddispersion processes. These are augmented byphysical, hydrodynamic processes that to a largeextent effect dilution by premining Quaternary sedimentand by uncontaminated sediment from tributaries.