Toxic metal enrichment and boating intensity: sediment records of antifoulant copper in shallow lakes of eastern England

Tributyltin (TBT), an aqueous biocide derived from antifouling paint pollution, is known to have impacted coastal marine ecosystems, and has been reported in the sediment of the Norfolk and Suffolk Broads, a network of rivers and shallow lakes in eastern England. In the marine environment, the 1987 TBT ban resulted in expanded use of alternative biocides, raising the question of whether these products too have impacted the Broads ecosystem and freshwaters in general. We examined the lake sediment record in the Norfolk and Suffolk Broads for contamination by copper (Cu), an active biocide agent, and zinc (Zn), a component of booster biocides, to assess their occurrence and potential for causing environmental harm in freshwater ecosystems. After the introduction of leisure boating, there was a statistically significant difference in Cu enrichment between heavily and lightly boated sites, whereas no such difference existed prior to that time. At the heavily boated sites, the onset of Cu enrichment coincided with a period of rapid increase in leisure boating. Such enrichment has been maintained to the present day, with some evidence of continued increase. We conclude that Cu-based antifouling has measurably contaminated lakes exposed to boating, at concentrations high enough to cause ecological harm. Similar findings can be expected at other boated freshwater ecosystems elsewhere in the world.