Sediment budgets and metal fluxes in two contrasting urban lake catchments in Coventry, UK

Sediment and heavy-metals budgets for 1850-1954 and 1954-91 are presented for two urban lakes in Coventry, UK. The sediment accumulation rate increased at the city centre site, which has no catchment, but decreased at the urban peripheral site which does have a catchment. The increase reflects higher atmospheric fallout due to burgeoning transport and industry, with the decrease reflecting relatively little construction in the past 20 years in the suburban catchment. Heavy-metal accumulation rates increased at both sites, showing that the sediment being deposited is highly contaminated, particularly where sediment accumulation decreased. Comparison of the results with other sites found that they were ecosystem-specific and hence not transferable to other urban sites. However, the majority of contaminants produced in the urban environment remain there, only a small proportion being exported elsewhere. Zinc and lead were used as indicators of consumption and transport-related activities, the results indicating that lead-free fuels and increasing consumption of heavy metals in the catchment are reflected in the sediments deposited.