Lead emissions from lost fishing sinkers

Lead sinkers used in salmon fishing in river mouth areas are lost in amounts of up to 200 tonnes year–1 in Sweden. An experimental field investigation has shown that the dissolution rate is about 20 mg cm–2 yr–1. No secondary corrosion coating has been observed except when the sinkers were fully or partially buried in fine sediments. The loss is larger in fast running waters, but there is no obvious relation between the loss and the water quality within the range present in the field sites. Approximately 1% of the deposited lead is dissolved yearly, provided it is not buried. An alternative to lead sinkers could be concrete sinkers with magnetite as a filler.