Metals and Organotins
The data collated indicates that the concentrations of metals within the study area all fall below the Cefas action level 2. There is only one exception in the Tilbury area which recorded tri-butyl tin (TBT) concentrations above the Cefas action level 2.
For the Shellhaven and Tilbury areas, a number of samples exceed the Cefas action level 1. These are mainly concentrations of TBT, chromium, copper, mercury, nickel, lead and zinc. Concerning the sediment quality guidelines, the majority of samples either fall below the lower interim sediment quality guideline or record values in between the threshold effect levels (TEL) and probable effect level (PEL) values. There are only three samples which exceed the higher PEL value and these are for lead and mercury in the Denton and Shellhaven areas.