Fine sediment-associated contaminants in gravel bed rivers: Evaluating storage times and turnover using fallout radionuclides (FRNs)

Summary

Excess fine sediment supply and its associated contaminants can have detrimental effects on water quality and river ecology with sediment deposition on, and subsequent infiltration in, streambeds impacting riverine habitats. Fallout radionuclides (FRNs) are used as tracers in aquatic systems, and the ⁷Be/²¹⁰Pb_ex ratio is a useful indicator for sediment residence/storage time. Suspended and submerged mid-channel bar sediments were collected during five surveys within a 5 km reach of a typical temperate lowland agricultural river system. Solids were analysed by gamma (⁷Be and ²¹⁰Pb_ex) and inductively coupled plasma (ICP, trace metals and phosphorus) spectrometry, and analysed for total nitrogen and organic carbon, to assess se