Contaminated sediment flux from eroding abandoned historical metal mines: Spatial and temporal variability in geomorphological drivers

摘要: Abstract Abandoned historical metal mines represent significant long-term sediment source locations contributing highly contaminated anthropogenic legacy sediments to river systems. Despite this, our understanding of spatial and temporal variability in the rates geomorphological drivers specific across abandoned remains poorly constrained. In this study, flux from two lead North Pennines, UK, was monitored over an 18 month period using repeat terrestrial laser scanning, enabling significance several common processes be quantified for first time. A novel budget approach is used integrate topographical change data with a pXRF survey surface concentrations. Approximately 434 t (289 t a−1) eroded entered stream area 0.023 km2. The majority erosion driven by dominant processes, gullying accounting 60% bank 30%. Redeposition material within minimal (3%), indicating very high levels coupling between network export vast (97%) mined area. Rates all erosive were episodic primarily magnitude, low frequency storm events. Metal concentrations exhibited considerable variability, notable hotspots around former ore processing areas on tailings heaps. However, 84% sampled excess available soil guideline values Pb 65% equivalent Zn, that mine sites still have potential sources contaminant metals pose risk wider environment. total, estimated 4.59 t 2.14 t Zn sediment-associated form during monitoring period. Although these overall inputs are high, they restricted particular spatially variable terms magnitude locations, delivered fairly discrete This provides invaluable information future management other targeted mitigation their effects.